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| Quiescence and Activation of Stem and Precursor Cell Populations in the Subependymal Zone of the Mammalian Brain Are Associated with Distinct Cellular and Extracellular Matrix Signals.
July 28, 2010 at 5:27 PM
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| | Quiescence and Activation of Stem and Precursor Cell Populations in the Subependymal Zone of the Mammalian Brain Are Associated with Distinct Cellular and Extracellular Matrix Signals. J Neurosci. 2010 Jul 21;30(29):9771-9781 Authors: Kazanis I, Lathia JD, Vadakkan TJ, Raborn E, Wan R, Mughal MR, Eckley DM, Sasaki T, Patton B, Mattson MP, Hirschi KK, Dickinson ME, Ffrench-Constant C The subependymal zone (SEZ) of the lateral ventricles is one of the areas of the adult brain where new neurons are continuously generated from neural stem cells (NSCs), via rapidly dividing precursors. This neurogenic niche is a complex cellular and extracellular microenvironment, highly vascularized compared to non-neurogenic periventricular areas, within which NSCs and precursors exhibit distinct behavior. Here, we investigate the possible mechanisms by which extracellular matrix molecules and their receptors might regulate this differential behavior. We show that NSCs and precursors proceed through mitosis in the same domains within the SEZ of adult male mice-albeit with NSCs nearer ependymal cells-and that distance from the ventricle is a stronger limiting factor for neurogenic activity than distance from blood vessels. Furthermore, we show that NSCs and precursors are embedded in a laminin-rich extracellular matrix, to which they can both contribute. Importantly, they express differential levels of extracellular matrix receptors, with NSCs expressing low levels of alpha6beta1 integrin, syndecan-1, and lutheran, and in vivo blocking of beta1 integrin selectively induced the proliferation and ectopic migration of precursors. Finally, when NSCs are activated to reconstitute the niche after depletion of precursors, expression of laminin receptors is upregulated. These results indicate that the distinct behavior of adult NSCs and precursors is not necessarily regulated via exposure to differential extracellular signals, but rather via intrinsic regulation of their interaction with their microenvironment. PMID: 20660259 [PubMed - as supplied by publisher] | | |
| Expression of Huntington's disease protein results in apoptotic neurons in the brains of cloned transgenic pigs.
July 28, 2010 at 5:27 PM
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| | Expression of Huntington's disease protein results in apoptotic neurons in the brains of cloned transgenic pigs. Hum Mol Genet. 2010 Jul 21; Authors: Yang D, Wang CE, Zhao B, Li W, Ouyang Z, Liu Z, Yang H, Fan P, O'Neill A, Gu W, Yi H, Li S, Lai L, Li XJ Neurodegeneration is a hallmark of many neurological diseases, including Alzheimer's, Parkinson's, and the polyglutamine diseases, which are all caused by misfolded proteins that accumulate in neuronal cells of the brain. Although apoptosis is believed to contribute to neurodegeneration in these cases, genetic mouse models of these diseases often fail to replicate apoptosis and overt neurodegeneration in the brain. Using nuclear transfer, we generated transgenic Huntington's disease (HD) pigs that express N-terminal (208 amino acids) mutant huntingtin with an expanded polyglutamine tract (105Q). Postnatal death, dyskinesia, and chorea-like movement were observed in some transgenic pigs expressing mutant huntingtin. Importantly, the transgenic HD pigs, unlike mice expressing the same transgene, displayed typical apoptotic neurons with DNA fragmentation in their brains. Also, expression of mutant huntingtin resulted in more neurons with activated caspase-3 in transgenic pig brains than in transgenic mouse brains. Our findings suggest that species differences determine neuropathology and underscore the importance of large mammalian animals for modeling neurological disorders. PMID: 20660116 [PubMed - as supplied by publisher] | | |
| Role of Lef1 in sustaining self-renewal in mouse embryonic stem cells.
July 28, 2010 at 5:27 PM
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| | Role of Lef1 in sustaining self-renewal in mouse embryonic stem cells. J Genet Genomics. 2010 Jul;37(7):441-449 Authors: Huang C, Qin D Embryonic stem cells (ESCs) can self-renew indefinitely while maintaining the ability to generate all three germ-layer derivatives. Despite the importance of ESCs in developmental biology and their potential impact on regenerative medicine, the molecular mechanisms controlling ESC behavior are incompletely understood. Previously, activation of the canonical Wnt signaling pathway has been shown to contribute to mouse ESC self-renewal. Here we report that ectopic expression of Lef1, a component of the Wnt signaling pathway, has a positive effect on the self-renewal of mouse ESCs. Lef1 up-regulates Oct4 promoter activity and physically interacts with Nanog, two key components of the ESC pluripotency machinery. Moreover, siRNA for Lef1 induced mouse ESC differentiation. Our results thus suggest that in response to Wnt signaling Lef1 binds to stabilized beta-catenin and helps maintain the undifferentiated status of ESCs through modulation of Oct4 and Nanog. PMID: 20659708 [PubMed - as supplied by publisher] | | |
| Accessing Protein Methyltransferase and Demethylase Enzymology Using Microfluidic Capillary Electrophoresis.
July 28, 2010 at 5:27 PM
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| | Accessing Protein Methyltransferase and Demethylase Enzymology Using Microfluidic Capillary Electrophoresis. Chem Biol. 2010 Jul 30;17(7):695-704 Authors: Wigle TJ, Provencher LM, Norris JL, Jin J, Brown PJ, Frye SV, Janzen WP The discovery of small molecules targeting the >80 enzymes that add (methyltransferases) or remove (demethylases) methyl marks from lysine and arginine residues, most notably present in histone tails, may yield unprecedented chemotherapeutic agents and facilitate regenerative medicine. To better enable chemical exploration of these proteins, we have developed a highly quantitative microfluidic capillary electrophoresis assay to enable full mechanistic studies of these enzymes and the kinetics of their inhibition. This technology separates small biomolecules, i.e., peptides, based on their charge-to-mass ratio. Methylation, however, does not alter the charge of peptide substrates. To overcome this limitation, we have employed a methylation-sensitive endoproteinase strategy to separate methylated from unmethylated peptides. The assay was validated on a lysine methyltransferase (G9a) and a lysine demethylase (LSD1) and was employed to investigate the inhibition of G9a by small molecules. PMID: 20659682 [PubMed - as supplied by publisher] | | |
| Liquid-liquid two phase systems for the production of porous hydrogels and hydrogel microspheres for biomedical applications: A tutorial review.
July 28, 2010 at 5:27 PM
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| | Liquid-liquid two phase systems for the production of porous hydrogels and hydrogel microspheres for biomedical applications: A tutorial review. Acta Biomater. 2010 Jul 23; Authors: Elbert DL Macroporous hydrogels may have direct applications in regenerative medicine as scaffolds to support tissue formation. Hydrogel microspheres may be used as drug delivery vehicles or as building blocks to assemble modular scaffolds. A variety of techniques exist to produce macroporous hydrogels and hydrogel microspheres. A subset of these relies on liquid-liquid two phase systems. Within this subset, vastly different types of polymerization processes are found. In this review, the history, terminology and classification of liquid-liquid two phase polymerization and crosslinking are described. Instructive examples of hydrogel microsphere and macroporous scaffold formation by precipitation/dispersion, emulsion and suspension polymerizations are used to illustrate the nature of these processes. The role of the kinetics of phase separation in determining the morphology of scaffolds and microspheres is also delineated. Brief descriptions of miniemulsion, microemulsion polymerization and ionotropic gelation are also included. PMID: 20659596 [PubMed - as supplied by publisher] | | |
| High-content screening of small compounds on human embryonic stem cells.
July 28, 2010 at 5:27 PM
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| | High-content screening of small compounds on human embryonic stem cells. Biochem Soc Trans. 2010 Aug 1;38(4):1046-50 Authors: Barbaric I, Gokhale PJ, Andrews PW Human ES (embryonic stem) cells and iPS (induced pluripotent stem) cells have been heralded as a source of differentiated cells that could be used in the treatment of degenerative diseases, such as Parkinson's disease or diabetes. Despite the great potential for their use in regenerative therapy, the challenge remains to understand the basic biology of these remarkable cells, in order to differentiate them into any functional cell type. Given the scale of the task, high-throughput screening of agents and culture conditions offers one way to accelerate these studies. The screening of small-compound libraries is particularly amenable to such high-throughput methods. Coupled with high-content screening technology that enables simultaneous assessment of multiple cellular features in an automated and quantitative way, this approach is proving powerful in identifying both small molecules as tools for manipulating stem cell fates and novel mechanisms of differentiation not previously associated with stem cell biology. Such screens performed on human ES cells also demonstrate the usefulness of human ES/iPS cells as cellular models for pharmacological testing of drug efficacy and toxicity, possibly a more imminent use of these cells than in regenerative medicine. PMID: 20659001 [PubMed - in process] | | |
| Role of stem-cell-derived hepatic endoderm in human drug discovery.
July 28, 2010 at 5:27 PM
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| | Role of stem-cell-derived hepatic endoderm in human drug discovery. Biochem Soc Trans. 2010 Aug 1;38(4):1033-6 Authors: Medine CN, Greenhough S, Hay DC Accurate prediction of human drug toxicity is a vital part of the drug discovery process. However, the safety evaluation process is hindered by the availability and quality of primary human liver models with which to study drug toxicity. In an attempt to overcome this limitation, research has focused on deriving human hepatocytes from a number of sources, including progenitors from fetal and adult liver, human cell lines derived from liver tumours, immortalized human hepatocytes and pluripotent stem cells. The major hurdles in developing scalable and high-fidelity human hepatocytes from hepatic cell lines and fetal and adult progenitors have been limited organ availability, homogeneous cell purification, short-term cell culture, and the rapid loss of hepatocyte phenotype and function in culture. Therefore it has been necessary to find alternative sources of human hepatocytes which circumvent these issues. The research in our group has focused on generating human hepatic endoderm from the scalable pluripotent stem cell populations, human embryonic stem cells and induced pluripotent stem cells. We have developed efficient and scalable models of human hepatocyte differentiation from these cell populations. Moreover, stem-cell-derived hepatic endoderm displays many of the functional attributes of primary human hepatocytes. Our research is now focused on developing defined culture systems and improving cell culture microenvironments in order to improve our understanding of the mechanisms regulating human liver development. This will in turn facilitate the generation of broad-range functioning hepatic endoderm in vitro. By taking these approaches, we believe that it will be possible to improve the predictive nature of our in vitro models, revolutionizing the manner in which industry measures human drug toxicity and having an impact on drug attrition. PMID: 20658999 [PubMed - in process] | | |
| Periostin advances atherosclerotic and rheumatic cardiac valve degeneration by inducing angiogenesis and MMP production in humans and rodents.
July 28, 2010 at 5:27 PM
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| | Periostin advances atherosclerotic and rheumatic cardiac valve degeneration by inducing angiogenesis and MMP production in humans and rodents. J Clin Invest. 2010 Jul 1;120(7):2292-306 Authors: Hakuno D, Kimura N, Yoshioka M, Mukai M, Kimura T, Okada Y, Yozu R, Shukunami C, Hiraki Y, Kudo A, Ogawa S, Fukuda K Valvular heart disease (VHD) is the term given to any disease process involving one or more of the heart valves. The condition can be congenital or acquired, for example as a result of atherosclerosis or rheumatic fever. Despite its clinical importance, the molecular mechanisms underlying VHD remain unknown. We investigated the pathophysiologic role and molecular mechanism of periostin, a protein that plays critical roles in cardiac valve development, in degenerative VHD. Unexpectedly, we found that periostin levels were drastically increased in infiltrated inflammatory cells and myofibroblasts in areas of angiogenesis in human atherosclerotic and rheumatic VHD, whereas periostin was localized to the subendothelial layer in normal valves. The expression patterns of periostin and chondromodulin I, an angioinhibitory factor that maintains cardiac valvular function, were mutually exclusive. In WT mice, a high-fat diet markedly increased aortic valve thickening, annular fibrosis, and MMP-2 and MMP-13 expression levels, concomitant with increased periostin expression; these changes were attenuated in periostin-knockout mice. In vitro and ex vivo studies revealed that periostin promoted tube formation and mobilization of ECs. Furthermore, periostin prominently increased MMP secretion from cultured valvular interstitial cells, ECs, and macrophages in a cell type-specific manner. These findings indicate that, in contrast to chondromodulin I, periostin plays an essential role in the progression of cardiac valve complex degeneration by inducing angiogenesis and MMP production. PMID: 20551517 [PubMed - indexed for MEDLINE] | | |
| Reduced versican cleavage due to Adamts9 haploinsufficiency is associated with cardiac and aortic anomalies.
July 28, 2010 at 5:27 PM
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| | Reduced versican cleavage due to Adamts9 haploinsufficiency is associated with cardiac and aortic anomalies. Matrix Biol. 2010 May;29(4):304-16 Authors: Kern CB, Wessels A, McGarity J, Dixon LJ, Alston E, Argraves WS, Geeting D, Nelson CM, Menick DR, Apte SS Here, we demonstrate that ADAMTS9, a highly conserved versican-degrading protease, is required for correct cardiovascular development and adult homeostasis. Analysis of Adamts9(+/LacZ) adult mice revealed anomalies in the aortic wall, valvulosinus and valve leaflets. Abnormal myocardial projections and 'spongy' myocardium consistent with non-compaction of the left ventricle were also found in Adamts9(+/LacZ) mice. During development, Adamts9 was expressed in derivatives of the Secondary Heart Field, vascular smooth muscle cells in the arterial wall, mesenchymal cells of the valves, and non-myocardial cells of the ventricles, but expression also continued in the adult heart and ascending aorta. Thus, the adult cardiovascular anomalies found in Adamts9(+/LacZ) hearts could result from subtle developmental alterations in extracellular matrix remodeling or defects in adult homeostasis. The valvular and aortic anomalies of Adamts9(+/LacZ) hearts were associated with accumulation of versican and a decrease in cleaved versican relative to WT littermates. These data suggest a potentially important role for ADAMTS9 cleavage of versican, or other, as yet undefined substrates in development and allostasis of cardiovascular extracellular matrix. In addition, these studies identify ADAMTS9 as a potential candidate gene for congenital cardiac anomalies. Mouse models of ADAMTS9 deficiency may be useful to study myxomatous valve degeneration. PMID: 20096780 [PubMed - indexed for MEDLINE] | | |
| Analysis of Wnt pathway genes during ex vivo expansion and neutrophil differentiation of umbilical-cord-blood-derived CD34 cells.
July 28, 2010 at 5:27 PM
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| | Analysis of Wnt pathway genes during ex vivo expansion and neutrophil differentiation of umbilical-cord-blood-derived CD34 cells. Vox Sang. 2010 Apr;98(3 Pt 1):e290-4 Authors: Gallagher RC, Tura-Ceide O, Turner M, Barclay R Previous work has shown that optimal ex vivo expansion and differentiation of CD34(+) progenitor cells into neutrophils is by addition of Flt3-L, SCF and G-CSF. Here we report that a variety of genes involved in the WNT pathway are transcriptionally active in both undifferentiated and differentiated umbilical cord blood CD34(+) cells, however statistically significant changes in gene expression are not always consistent across UCB samples. PMID: 20059757 [PubMed - indexed for MEDLINE] | | |
| Immune-related zinc finger gene ZFAT is an essential transcriptional regulator for hematopoietic differentiation in blood islands.
July 28, 2010 at 2:35 PM
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| | Immune-related zinc finger gene ZFAT is an essential transcriptional regulator for hematopoietic differentiation in blood islands. Proc Natl Acad Sci U S A. 2010 Jul 26; Authors: Tsunoda T, Takashima Y, Tanaka Y, Fujimoto T, Doi K, Hirose Y, Koyanagi M, Yoshida Y, Okamura T, Kuroki M, Sasazuki T, Shirasawa S TAL1 plays pivotal roles in vascular and hematopoietic developments through the complex with LMO2 and GATA1. Hemangioblasts, which have a differentiation potential for both endothelial and hematopoietic lineages, arise in the primitive streak and migrate into the yolk sac to form blood islands, where primitive hematopoiesis occurs. ZFAT (a zinc-finger gene in autoimmune thyroid disease susceptibility region / an immune-related transcriptional regulator containing 18 C(2)H(2)-type zinc-finger domains and one AT-hook) was originally identified as an immune-related transcriptional regulator containing 18 C(2)H(2)-type zinc-finger domains and one AT-hook, and is highly conserved among species. ZFAT is thought to be a critical transcription factor involved in immune-regulation and apoptosis; however, developmental roles for ZFAT remain unknown. Here we show that Zfat-deficient (Zfat (-/-)) mice are embryonic-lethal, with impaired differentiation of hematopoietic progenitor cells in blood islands, where ZFAT is exactly expressed. Expression levels of Tal1, Lmo2, and Gata1 in Zfat (-/-) yolk sacs are much reduced compared with those of wild-type mice, and ChIP-PCR analysis revealed that ZFAT binds promoter regions for these genes in vivo. Furthermore, profound reduction in TAL1, LMO2, and GATA1 protein expressions are observed in Zfat (-/-) blood islands. Taken together, these results suggest that ZFAT is indispensable for mouse embryonic development and functions as a critical transcription factor for primitive hematopoiesis through direct-regulation of Tal1, Lmo2, and Gata1. Elucidation of ZFAT functions in hematopoiesis might lead to a better understanding of transcriptional networks in differentiation and cellular programs of hematopoietic lineage and provide useful information for applied medicine in stem cell therapy. PMID: 20660741 [PubMed - as supplied by publisher] | | |
| Case Control Series of Intrathecal Autologous Bone Marrow Mesenchymal Stem Cell Therapy for Chronic Spinal Cord Injury.
July 28, 2010 at 2:35 PM
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| | Case Control Series of Intrathecal Autologous Bone Marrow Mesenchymal Stem Cell Therapy for Chronic Spinal Cord Injury. Neurorehabil Neural Repair. 2010 Jul 26; Authors: Kishk NA, Gabr H, Hamdy S, Afifi L, Abokresha N, Mahmoud H, Wafaie A, Bilal D BACKGROUND: Autologous bone marrow mesenchymal cells that include stem cells (MSCs) are a clinically attractive cellular therapy option to try to treat severe spinal cord injury (SCI). OBJECTIVE: To study the possible value of MSCs injected intrathecally to enhance rehabilitation. METHODS: This case control, convenience sample included 64 patients, at a mean of 3.6 years after SCI. Forty-four subjects received monthly intrathecal autologous MSCs for 6 months and 20 subjects, who would not agree to the procedures, served as controls. All subjects received rehabilitation therapies 3 times weekly. Subjects were evaluated at entry and at 12 months after completing the 6-months intervention. By the ASIA Impairment Scale, ASIA grading of completeness of injury, Ashworth Spasticity Scale, Functional Ambulation Classification, and bladder and bowel control questionnaire. RESULTS: No differences were found in baseline measures and descriptors between the MSC group and control group. Although a higher percentage of the MSC group increased motor scores by 1-2 points and changed from ASIA A to B, no significant between-group improvements were found in clinical measures. Adverse effects of cells included spasticity and, in 24 out of the 43 patients developed neuropathic pain. One subject with a history of post-infectious myelitis developed encephalomyelitis after her third injection. CONCLUSION: Autologus MSCs may have side effects and may be contraindicated in patients with a history of myelitis. Their utility in treating chronic traumatic SCI needs further study in pre-clinical models and in randomized controlled trials before they should be offered to patients. PMID: 20660620 [PubMed - as supplied by publisher] | | |
| A comparative study of seeding techniques and three-dimensional matrices for mesenchymal cell attachment.
July 28, 2010 at 11:43 AM
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| | A comparative study of seeding techniques and three-dimensional matrices for mesenchymal cell attachment. J Tissue Eng Regen Med. 2010 Jul 26; Authors: Griffon DJ, Abulencia JP, Ragetly GR, Fredericks LP, Chaieb S Mesenchymal stem cells (MSCs) offer significant potential as a cell source in tissue-engineering applications because of their multipotent ability. The objective of this study was to evaluate the behaviour of MSCs during the seeding phase, using four different seeding techniques (spinner flask, custom vacuum system combined with a perfused bioreactor or with an orbital shaker, and orbital shaker) with four different scaffold materials [polyglycolic acid, poly(lactic acid), calcium phosphate and chitosan-hyaluronic acid]. Scaffolds were selected for their structural and/or chemical similarity with bone or cartilage, and characterized via scanning electron microscopy (SEM) and measurement of fluid retention. Cell attachment was compared between seeding techniques and scaffolds via cell-binding kinetics, cell viability and DNA quantification. SEM was used to evaluate cell distribution throughout the constructs. We discovered from cell suspension kinetics and DNA data that the type of loading (i.e. direct or indirect) mainly influences the delivery of cells to their respective scaffolds, and that dynamic seeding in a spinner flask tended to improve the cellularity of polymer constructs, especially mesh. Regardless of the seeding method, bone marrow-derived MSCs displayed a superior affinity for calcium phosphate scaffolds, which may be related to their hydrophobicity. MSCs tended to aggregate into flat sheets, occluding the external pores of matrices and affecting cell distribution, regardless of seeding technique or scaffold. Taken together, these results provide insight into the design of future experiments using MSCs to engineer functional tissue. Copyright (c) 2010 John Wiley & Sons, Ltd. PMID: 20661904 [PubMed - as supplied by publisher] | | |
| Site-specific tissue inhibitor of metalloproteinase-1 governs the matrix metalloproteinases-dependent degradation of crosslinked collagen scaffolds and is correlated with interleukin-10.
July 28, 2010 at 11:43 AM
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| | Site-specific tissue inhibitor of metalloproteinase-1 governs the matrix metalloproteinases-dependent degradation of crosslinked collagen scaffolds and is correlated with interleukin-10. J Tissue Eng Regen Med. 2010 Jul 26; Authors: Ye Q, van Amerongen MJ, Sandham JA, Bank RA, van Luyn MJ, Harmsen MC We have previously shown that the foreign body reaction (FBR) against crosslinked collagen type I (Col-I) differs between subcutaneous and epicardial implantation sites; Col-I was quickly degraded epicardially, whereas degradation was attenuated subcutaneously. The current study set out to dissect the nature and regulation of the MMP-based degradation of implanted Col-I in mice during the FBR. Immunohistochemistry showed that MMP-2, MMP-8 and MMP-13 were present in subcutaneous and epicardial implants, whereas only MMP-9 was also present epicardially. Western blotting showed that MMP-8 and MMP-9 were mainly present in their inactive proform. In contrast, collagenase MMP-13 and gelatinase MMP-2 were the predominant active MMPs at both sites. Interestingly, the major MMP inhibitor TIMP-1 was solely observed in subcutaneous implants, which is why MMP-13 and MMP-2 are not able to degrade the collagen scaffold at the subcutaneous implantation site. Interleukin 10 (IL-10), a potent inducer of TIMP-1 expression, was also mainly detected subcutaneously; giant cells were the main source. Therefore, we surmise that IL-10, through regulation of the balance between MMPs and TIMP-1, suppresses the FBR against implanted biomaterials. Together, our findings would provide cues and clues to improve future therapies in regenerative medicine that are based on the tuned regulation of the degradation of biomaterial scaffolds. Copyright (c) 2010 John Wiley & Sons, Ltd. PMID: 20661871 [PubMed - as supplied by publisher] | | |
| Embryoid bodies formation and differentiation from mouse embryonic stem cells in collagen/Matrigel scaffolds.
July 28, 2010 at 11:43 AM
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| | Embryoid bodies formation and differentiation from mouse embryonic stem cells in collagen/Matrigel scaffolds. J Genet Genomics. 2010 Jul;37(7):451-460 Authors: Zhou J, Zhang Y, Lin Q, Liu Z, Wang H, Duan C, Wang Y, Hao T, Wu K, Wang C Embryonic stem (ES) cells have the potential to develop into any type of tissue and are considered as a promising source of seeding cells for tissue engineering and transplantation therapy. The main catalyst for ES cells differentiation is the growth into embryoid bodies (EBs), which are utilized widely as the trigger of in vitro differentiation. In this study, a novel method for generating EBs from mouse ES cells through culture in collagen/Matrigel scaffolds was successfully established. When single ES cells were seeded in three dimensional collagen/Matrigel scaffolds, they grew into aggregates gradually and formed simple EBs with circular structures. After 7 days' culture, they formed into cystic EBs that would eventually differentiate into the three embryonic germ layers. Evaluation of the EBs in terms of morphology and potential to differentiate indicated that they were typical in structure and could generate various cell types; they were also able to form into tissue-like structures. Moreover, with introduction of ascorbic acid, ES cells differentiated into cardiomyocytes efficiently and started contracting synchronously at day 19. The results demonstrated that collagen/Matrigel scaffolds supported EBs formation and their subsequent differentiation in a single three dimensional environment. PMID: 20659709 [PubMed - as supplied by publisher] | | |
| Evaluating the utility of cardiomyocytes from human pluripotent stem cells for drug screening.
July 28, 2010 at 11:43 AM
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| | Evaluating the utility of cardiomyocytes from human pluripotent stem cells for drug screening. Biochem Soc Trans. 2010 Aug 1;38(4):1037-45 Authors: Dick E, Rajamohan D, Ronksley J, Denning C Functional cardiomyocytes can now be derived routinely from hPSCs (human pluripotent stem cells), which collectively include embryonic and induced pluripotent stem cells. This technology presents new opportunities to develop pharmacologically relevant in vitro screens to detect cardiotoxicity, with a view to improving patient safety while reducing the economic burden to industry arising from high drug attrition rates. In the present article, we consider the need for human cardiomyocytes in drug-screening campaigns and review the strategies used to differentiate hPSCs towards the cardiac lineage. During early stages of differentiation, hPSC-cardiomyocytes display gene expression profiles, ultra-structures, ion channel functionality and pharmacological responses reminiscent of an embryonic phenotype, but maturation during extended time in culture has been demonstrated convincingly. Notably, hPSC-cardiomyocytes have been shown to respond in a highly predictable manner to over 40 compounds that have a known pharmacological effect on the human heart. This suggests that further development and validation of the hPSC-cardiomyocyte model as a tool for assessing cardiotoxicity is warranted. PMID: 20659000 [PubMed - in process] | | |
| Efficient isolation of cardiac stem cells from brown adipose.
July 28, 2010 at 11:43 AM
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| | Efficient isolation of cardiac stem cells from brown adipose. J Biomed Biotechnol. 2010;2010:104296 Authors: Liu Z, Wang H, Zhang Y, Zhou J, Lin Q, Wang Y, Duan C, Wu K, Wang C Cardiac stem cells represent a logical cell type to exploit in cardiac regeneration. The efficient harvest of cardiac stem cells from a suitable source would turn promising in cardiac stem cell therapy. Brown adipose was recently found to be a new source of cardiac stem cells, instrumental to myocardial regeneration. Unfortunately, an efficient method for the cell isolation is unavailable so far. In our study we have developed a new method for the efficient isolation of cardiac stem cells from brown adipose by combining different enzymes. Results showed that the total cell yield dramatically increased (more than 10 times, P < .01) compared with that by previous method. The content of CD133-positive cells (reported to differentiate into cardiomyocytes with a high frequency) was much higher than that in the previous report (22.43% versus 3.5%). Moreover, the isolated cells could be the efficiently differentiated into functional cardiomyocytes in optimized conditions. Thus, the new method we established would be of great use in further exploring cardiac stem cell therapy. PMID: 20414349 [PubMed - indexed for MEDLINE] | | |
| IV.1. Scaffolds & surfaces.
July 28, 2010 at 11:43 AM
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| | IV.1. Scaffolds & surfaces. Stud Health Technol Inform. 2010;152:187-201 Authors: Partap S, Lyons F, O'Brien FJ PMID: 20407195 [PubMed - indexed for MEDLINE] | | |
| Defined high protein content surfaces for stem cell culture.
July 28, 2010 at 11:43 AM
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| | Defined high protein content surfaces for stem cell culture. Biomaterials. 2010 Jul;31(19):5137-42 Authors: Doran MR, Frith JE, Prowse AB, Fitzpatrick J, Wolvetang EJ, Munro TP, Gray PP, Cooper-White JJ Unlocking the clinical potential of stem cell based therapies requires firstly elucidation of the biological mechanisms which direct stem cell fate decisions and thereafter, technical advances which allow these processes to be driven in a fully defined culture environment. Strategies for the generation of defined surfaces for human embryonic stem cell (hESC) and mesenchymal stem cell (MSC) culture remain in their infancy. In this paper we outline a simple, effective and efficient method for presenting proteins or peptides on an otherwise non-fouling Layer-by-Layer (LbL) self-assembled surface of hyaluronic acid (HA) and chitosan (CHI). We are able to generate a surface that has both good temporal stability and the ability to direct biological outcomes based on its defined surface composition. Surface functionalization is achieved through suspending the selected extracellular matrix (ECM) protein domain or extracted full-length protein in buffer containing a cross-linking agent (N-hydroxysulfosuccinimide/N-(3-Dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride) over the LbL HA-CHI surface and then allowing the solvent to evaporate overnight. This simple, but important step results in remarkable protein deposition efficiencies often exceeding 50%, whereas traditional cross-linking methods result in such poor deposition of non-collagenous proteins that a.) quantification of bound amounts of protein is outside the resolution of commonly utilized protein assays, and b.) these surfaces are both unable to support cell attachment and growth. The utility of the protein-modified HA-CHI surfaces is demonstrated through the identification of specific hESC attachment efficiencies and through directing MSC osteogenic outcomes on these fully defined surfaces. This simple and scalable method is shown to enable the development of defined stem cell culture conditions, as well as the elucidation of the fundamental biological processes necessary for the realization of stem cell based therapies. PMID: 20378164 [PubMed - indexed for MEDLINE] | | |
| Oxygen mass transfer in a human tissue-engineered trachea.
July 28, 2010 at 11:43 AM
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| | Oxygen mass transfer in a human tissue-engineered trachea. Biomaterials. 2010 Jul;31(19):5131-6 Authors: Curcio E, Macchiarini P, De Bartolo L On June 2008, the first human tissue-engineered trachea replacement was performed using decellularized (de-antigenised) cadaveric donor trachea, seeded with recipient epithelial cells on the internal surface of the graft and mesenchymal stem-cell-derived chondrocytes on the external. During the follow-up, cytological analysis at 4 postoperative days showed a migration of the stem-cells derived chondrocytes from the outer to the inner surface of the first 2 cm of the graft length. With the aim to rationalize these clinical findings, and under the hypothesis that cellular migration is driven by the oxygen gradients developing from the external part of the construct (exposed to O(2) deficiency) towards the better oxygenated epithelial region, an accurate computational model of oxygen transport in the trachea engineered construct was developed and solved using finite element method (FEM). Results confirm that critical limitation to oxygen transport prevalently occurs from proximal to middle section, within the first 2.8 cm of longitudinal length, in good agreement with experimental observation. In the proximal section, recognized as the most critical part of the engineered construct, the severe O(2) mass transfer limitation causes a drastic reduction of the diffusive flux within a distance of 650 microm. At cell density of 1 x 10(7)cells/cm(3), the 30% c.a of the total section area is under oxygen deficiency (O(2) partial pressure below the critical threshold of 38 mmHg). Along the whole tracheal construct, the Thiele modulus ranges within 2.3 and 3.7 in the external chondrocyte compartment, confirming thus the importance of the mass transfer limitation to oxygen diffusion rate. In general, the efficiency of the O(2) transport reduces considerably in the region close to proximal section. PMID: 20378162 [PubMed - indexed for MEDLINE] | | |
| The effects of co-culture with fibroblasts and angiogenic growth factors on microvascular maturation and multi-cellular lumen formation in HUVEC-oriented polymer fibre constructs.
July 28, 2010 at 11:43 AM
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| | The effects of co-culture with fibroblasts and angiogenic growth factors on microvascular maturation and multi-cellular lumen formation in HUVEC-oriented polymer fibre constructs. Biomaterials. 2010 Jul;31(19):5091-9 Authors: Sukmana I, Vermette P In the present study, polymer monofilaments were embedded in fibrin seeded with human umbilical vein endothelial cells (HUVEC) to guide HUVEC attachment and migration in order to form oriented vessel-like structures between adjacent monofilaments. Histology and fluorescent fibrin experiments confirmed that microvessel-like structures, which were developing between polymer monofilaments embedded in fibrin, contained a lumen. The effect of human fibroblasts and growth factors (VEGF and bFGF) over the microvessel formation process was tested. The effects of VEGF and bFGF were dose-dependent. The effect of VEGF was optimum at the lower concentration tested (2 ng/mL), while that of bFGF was optimum at the higher tested concentration (20 ng/mL). Furthermore, the use of fibroblasts significantly improved the maturation of the microvessels compared to control and to samples cultured with VEGF and bFGF. PMID: 20347133 [PubMed - indexed for MEDLINE] | | |
| Aortic valve repair for congenital and balloon-induced aortic regurgitation.
July 28, 2010 at 11:43 AM
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| | Aortic valve repair for congenital and balloon-induced aortic regurgitation. Semin Thorac Cardiovasc Surg Pediatr Card Surg Annu. 2010;13(1):60-5 Authors: Jonas RA Current techniques for aortic valve replacement in the child carry multiple disadvantages. Longer-term follow-up of the Ross procedure has documented disappointing late results for an increasing proportion of patients. Many challenges continue to face the development of a tissue-engineered valve with growth potential. In this setting, aortic valve repair is a useful temporizing procedure that allows a child to have an excellent quality of life, free from the need for anticoagulation and the risk of thromboembolism. Repair techniques are primarily based on the use of autologous pericardium to extend leaflets and support prolapsing leaflets. These methods appear to be particularly applicable in the setting of balloon-induced aortic valve regurgitation. An increasing number of centers are reporting satisfactory midterm results with aortic valve repair. PMID: 20307863 [PubMed - indexed for MEDLINE] | | |
| Potential of an injectable chitosan/starch/beta-glycerol phosphate hydrogel for sustaining normal chondrocyte function.
July 28, 2010 at 11:43 AM
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| | Potential of an injectable chitosan/starch/beta-glycerol phosphate hydrogel for sustaining normal chondrocyte function. Int J Pharm. 2010 May 31;391(1-2):115-24 Authors: Ngoenkam J, Faikrua A, Yasothornsrikul S, Viyoch J An injectable hydrogel for chondrocyte delivery was developed by blending chitosan and starch derived from various sources with beta-glycerol phosphate (beta-GP) in the expectation that it would retain a liquid state at room temperature and gel at raised temperatures. Rheological investigation indicated that the system consisting of chitosan derived from crab shell and corn starch at 4:1 by weight ratio (1.53%, w/v of total polymers), and 6.0% (w/v) beta-GP (C/S/GP system) exhibited the sharpest sol-gel transition at 37+/-2 degrees C. The C/S/GP hydrogel was gradually degraded by 67% within 56 days in PBS containing 0.02 mg/ml lysozyme. The presence of starch in the system increased the water absorption of the hydrogel when compared to the system without starch. SEM observation revealed to the interior structure of the C/S/GP hydrogel having interconnected pore structure (average pore size 26.4 microm) whereas the pore size of the hydrogel without starch was 19.8 microm. The hydrogel also showed an ability to maintain chondrocyte phenotype as shown by cell morphology and expression of type II collagen mRNA and protein. In vivo study revealed that the gel was formed rapidly and localized at the injection site. PMID: 20206248 [PubMed - indexed for MEDLINE] | | |
| A micro-channel-well system for culture and differentiation of embryonic stem cells on different types of substrate.
July 28, 2010 at 11:43 AM
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| | A micro-channel-well system for culture and differentiation of embryonic stem cells on different types of substrate. Biomed Microdevices. 2010 Jun;12(3):505-11 Authors: Liu L, Luo C, Ni X, Wang L, Yamauchi K, Nomura SM, Nakatsuji N, Chen Y We have developed a combined micro-channel and micro-well system for easy cell loading, culture and post-culture operation on a chip. To demonstrate the reliability of the system, on chip cell culture and differentiation were performed with different types of substrates made of culture dish, glass cover slide and polydimethylsiloaxe (PDMS). As expected, mouse embryo fibroblasts (MEF) showed different adhesion and growth rate on different substrates. When embryonic stem (ES) cells were co-cultured with MEFs, the formation of ES colonies is efficient on both glass and Petri dish, although PDMS could also be used. Finally, ES cell differentiation with neuron growth factors was performed on different substrates, showing clear advantages of using culture Petri dish over both glass and PDMS. PMID: 20177790 [PubMed - indexed for MEDLINE] | | |
| Enhanced differentiation of retinal progenitor cells using microfabricated topographical cues.
July 28, 2010 at 11:43 AM
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| | Enhanced differentiation of retinal progenitor cells using microfabricated topographical cues. Biomed Microdevices. 2010 Jun;12(3):363-9 Authors: Steedman MR, Tao SL, Klassen H, Desai TA Due to the retina's inability to replace photoreceptors lost during retinal degeneration, significant interest has been placed in methods to implant replacement cells. Polymer scaffolds are increasingly being studied as vehicles for cellular delivery to degenerated retinas. Previously, we fabricated poly(methyl methacrylate) thin film scaffolds that increased survival and integration of implanted retinal progenitor cells (RPCs). Additionally, these scaffolds minimized the trauma and cellular response associated with implantation of foreign bodies into mouse eyes. Here, we demonstrate that biodegradable polycaprolactone (PCL) thin film scaffolds can be fabricated with integrated microtopography. Microfabricated topography in a PCL thin film enhanced the attachment and organization of RPCs compared to unstructured surfaces. Using real-time quantitative polymerase chain reaction we also observed that attachment to microtopography induced cellular differentiation. RPCs grown on PCL thin films exhibited an increase in gene expression for the photoreceptor markers recoverin and rhodopsin, an increase in the glial and Müller cell marker GFAP, and a decrease in SOX2 gene expression (a marker for undifferentiated progenitor cells) compared to cells grown on unmodified tissue culture polystyrene (TCPS). PMID: 20077017 [PubMed - indexed for MEDLINE] | | |
| Hypoxia enhances proliferation of mouse embryonic stem cell-derived neural stem cells.
July 28, 2010 at 11:43 AM
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| | Hypoxia enhances proliferation of mouse embryonic stem cell-derived neural stem cells. Biotechnol Bioeng. 2010 Jun 1;106(2):260-70 Authors: Rodrigues CA, Diogo MM, da Silva CL, Cabral JM Neural stem (NS) cells can provide a source of material with potential applications for neural drug testing, developmental studies, or novel treatments for neurodegenerative diseases. Herein, the ex vivo expansion of a model system of mouse embryonic stem (mES) cell-derived NS cells was characterized and optimized, cells being cultivated under adherent conditions. Culture was first optimized in terms of initial cell plating density and oxygen concentration, known to strongly influence brain-derived NS cells. To this end, the growth of cells cultured under hypoxic (2%, 5%, and 10% O(2)) and normoxic (20% O(2)) conditions was compared. The results showed that 2-5% oxygen, without affecting multipotency, led to fold increase values in total cell number about twice higher than observed under 20% oxygen (20-fold vs. 10-fold, respectively) this effect being more pronounced when cells were plated at low density. With an optimal cell density of 10(4) cells/cm(2), the maximum growth rates were 1.9 day(-1) under hypoxia versus 1.7 day(-1) under normoxia. Cell division kinetics analysis by flow cytometry based on PKH67 tracking showed that when cultured in hypoxia, cells are at least one divisional generation ahead compared to normoxia. In terms of cell cycle, a larger population in a quiescent G(0) phase was observed in normoxic conditions. The optimization of NS cell culture performed here represents an important step toward the generation of a large number of neural cells from a reduced initial population, envisaging the potential application of these cells in multiple settings. PMID: 20014442 [PubMed - indexed for MEDLINE] | | |
| Identification of human placenta-derived mesenchymal stem cells involved in re-endothelialization.
July 28, 2010 at 3:01 AM
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| | Identification of human placenta-derived mesenchymal stem cells involved in re-endothelialization. J Cell Physiol. 2010 Jul 23; Authors: Tu TC, Kimura K, Nagano M, Yamashita T, Ohneda K, Sugimori H, Sato F, Sakakibara Y, Hamada H, Yoshikawa H, Son HN, Ohneda O Human placenta is an attractive source of mesenchymal stem cells (MSC) for regenerative medicine. The cell surface markers expressed on MSC have been proposed as useful tools for the isolation of MSC from other cell populations. However, the correlation between the expression of MSC markers and the ability to support tissue regeneration in vivo has not been well examined. Here, we established several MSC lines from human placenta and examined the expression of their cell surface markers and their ability to differentiate toward mesenchymal cell lineages. We found that the expression of CD349/frizzled-9, a receptor for Wnt ligands, was positive in placenta-derived MSC. So, we isolated CD349-negative and -positive fractions from an MSC line and examined how successfully cell engraftment repaired fractured bone and recovered blood flow in ischemic regions using mouse models. CD349-negative and -positive cells displayed a similar expression pattern of cell surface markers and facilitated the repair of fractured bone in transplantation experiments in mice. Interestingly, CD349-negative, but not CD349-positive cells, showed significant effects on recovering blood flow following vascular occlusion. We found that induction of PDGFbeta and bFGF mRNAs by hypoxia was greater in CD349-negative cells than in CD349-positive cells while the expression of VEGF was not significantly different in CD349-negative and CD349-positive cells. These findings suggest the possibility that CD349 could be utilized as a specialized marker for MSC isolation for re-endothelialization. J. Cell. Physiol. (c) 2010 Wiley-Liss, Inc. PMID: 20658518 [PubMed - as supplied by publisher] | | |
| c- and N-myc Regulate Neural Precursor Cell Fate, Cell Cycle, and Metabolism to Direct Cerebellar Development.
July 28, 2010 at 3:01 AM
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| | c- and N-myc Regulate Neural Precursor Cell Fate, Cell Cycle, and Metabolism to Direct Cerebellar Development. Cerebellum. 2010 Jul 25; Authors: Wey A, Cerdeno VM, Pleasure D, Knoepfler PS Separate murine knockout (KO) of either c- or N-myc genes in neural stem and precursor cells (NSC) driven by nestin-cre causes microcephaly. The cerebellum is particularly affected in the N-myc KO, leading to a strong reduction in cerebellar granule neural progenitors (CGNP) and mature granule neurons. In humans, mutation of N-myc also causes microcephaly in Feingold Syndrome. We created a double KO (DKO) of c- and N-myc using nestin-cre, which strongly impairs brain growth, particularly that of the cerebellum. Granule neurons were almost absent from the Myc DKO cerebellum, and other cell types were relatively overrepresented, including astroglia, oligodendrocytes, and Purkinje neurons. These findings are indicative of a profound disruption of cell fate of cerebellar stem and precursors. DKO Purkinje neurons were strikingly lacking in normal arborization. Inhibitory neurons were ectopic and exhibited very abnormal GAD67 staining patterns. Also consistent with altered cell fate, the adult DKO cerebellum still retained a residual external germinal layer (EGL). CGNP in the DKO EGL were almost uniformly NeuN and p27KIP1 positive as well as negative for Math1 and BrdU at the peak of normal cerebellar proliferation at P6. The presence of some mitotic CGNP in the absence of S phase cells suggests a possible arrest in M phase. CGNP and NSC metabolism also was affected by loss of Myc as DKO cells exhibited weak nucleolin staining. Together these findings indicate that c- and N-Myc direct cerebellar development by maintaining CGNP and NSC populations through inhibiting differentiation as well as directing rapid cell cycling and active cellular metabolism. PMID: 20658325 [PubMed - as supplied by publisher] | | |
| Human Umbilical Vein-Derived Dopaminergic-Like Cell Transplantation with Nerve Growth Factor Ameliorates Motor Dysfunction in a Rat Model of Parkinson's Disease.
July 28, 2010 at 3:01 AM
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| | Human Umbilical Vein-Derived Dopaminergic-Like Cell Transplantation with Nerve Growth Factor Ameliorates Motor Dysfunction in a Rat Model of Parkinson's Disease. Neurochem Res. 2010 Jul 24; Authors: Li M, Zhang SZ, Guo YW, Cai YQ, Yan ZJ, Zou Z, Jiang XD, Ke YQ, He XY, Jin ZL, Lu GH, Su DQ Mesenchymal stem cells are capable of differentiating into dopaminergic-like cells, but currently no report has been available to describe the induction of human umbilical vein mesenchymal stem cells (HUVMSCs) into dopaminergic-like cells. In this study, we induced HUVMSCs in vitro into neurospheres constituted by neural stem-like cells, and further into cells bearing strong morphological, phenotypic and functional resemblances with dopaminergic-like cells. These HUVMSC-derived dopaminergic-like cells, after grafting into the brain of a rat model of Parkinson's disease (PD), showed a partial therapeutic effect in terms of the behavioral improvement. Nerve growth factor was reported to improve the local microenvironment of the grafted cells, and we therefore further tested the effect of dopaminergic-like cell grafting combined with nerve growth factor (NGF) administration at the site of cell transplantation. The results showed that NGF administration significantly promoted the survival of the grafted cells in the host brain and enhanced the content of dopaminergic in the local brain tissue. Behavioral test demonstrated a significant improvement of the motor function of the PD rats after dopaminergic-like cell grafting with NGF administration as compared with that of rats receiving the cell grafting only. These results suggest that transplantation of the dopaminergic-like cells combined with NGF administration may represent a new strategy of stem cell therapy for PD. PMID: 20658188 [PubMed - as supplied by publisher] | | |
| Three-dimensional culture of mandibular human osteoblasts on a novel albumin scaffold: growth, proliferation, and differentiation potential in vitro.
July 28, 2010 at 3:01 AM
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| | Three-dimensional culture of mandibular human osteoblasts on a novel albumin scaffold: growth, proliferation, and differentiation potential in vitro. Int J Oral Maxillofac Implants. 2010 Jul-Aug;25(4):699-705 Authors: Gallego L, Junquera L, Meana A, Garcia E, Garcia V Purpose: Bone tissue engineering is a promising approach for bone reconstruction in oral and maxillofacial surgery. The aim of this study was to investigate the microstructure and biocompatibility of a novel albumin scaffold developed from human serum on human alveolar osteoblasts. Materials and Methods: Samples of mandibular bone were obtained during routine oral surgery. Osteoblast cells were cultured and plated in a spongy, noncalcified protein scaffold prepared with plasmatic albumin crossed with a glutaraldehyde-type agent (study group) and in a large-particle mineralized cancellous allograft (control group). Measurement of the differentiation marker alkaline phosphatase and histologic examination were performed after 30 days of incubation. The cultures were examined for cell growth patterns and morphology by scanning electron microscopy and histomorphometry. Results: Cultured osteoblasts showed comparable phenotypic profiles and expressed alkaline phosphatase in albumin scaffold. Hematoxylin-eosin staining revealed a bonelike extracellular matrix in study scaffold and mineralization of osteoblasts cultured in the albumin scaffold was confirmed by von Kossa staining. Conclusion: Osteoblasts were able to proliferate in vitro and synthesize a bonelike extracellular matrix and mineralized tissue. The results indicate that this novel albumin scaffold is a favorable substrate for the growth and differentiation of osteoblasts and a promising material for bone tissue engineering and repair of bone defects. Int J Oral Maxillofac Implants 2010;25:699-705. PMID: 20657864 [PubMed - in process] | | |
| Cancer stem cells in bladder cancer: a revisited and evolving concept.
July 28, 2010 at 3:01 AM
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| | Cancer stem cells in bladder cancer: a revisited and evolving concept. Curr Opin Urol. 2010 Jul 22; Authors: Chan KS, Volkmer JP, Weissman I PURPOSE OF REVIEW: Recently, the prospective isolation and characterization of cancer stem cells (CSCs) from various human malignancies revealed that they are resistant to radiation and chemotherapies. Therefore, CSCs may be the 'roots' and ideal target for therapeutic intervention. Here, we will focus on reviewing the historical perspective, recent literatures on bladder cancer stem cells and their clinical implications. RECENT FINDINGS: CSCs have been prospectively isolated from bladder cancer tissues from patient specimens, established cancer cell lines and xenografts, based on the expression of a combination of cell surface receptors, cytokeratin markers, drug transporters and the efficient efflux of the Hoechst 33 342 dye (side population). Further, global gene expression profiling of CSCs revealed an activated gene signature of CSCs similar to that of aggressive bladder cancer, supporting the concept that a tumor cell subpopulation is contributing to bladder cancer progression. Finally, our studies on the preclinical targeting of bladder CSCs in vitro and in xenografts using a blocking antibody for CD47 reveal promising efficacy. SUMMARY: Functionally distinct CSCs exist in human bladder cancer and can be prospectively isolated. Continuing research will be important to identify their cell of origin, programs balancing self-renewal and differentiation and to identify additional therapeutic options to target bladder CSCs. PMID: 20657288 [PubMed - as supplied by publisher] | | |
| Will Tissue-Engineered Urinary Bladders Change Indications for a Laparoscopic Cystectomy?
July 28, 2010 at 3:01 AM
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| | Will Tissue-Engineered Urinary Bladders Change Indications for a Laparoscopic Cystectomy? Surg Innov. 2010 Jul 23; Authors: Drewa T, Chlosta P, Czajkowski R Radical open cystectomy is a treatment of choice for muscle invasive urinary bladder cancer. Laparoscopic radical cystectomy (LapRC) is surgically advanced and is an extremely difficult technique but presents many advantages. Urinary diversion (conduit, pouch or neobladder) when performed during laparoscopy necessitates a conversion to open procedure. Urinary diversion using an autologous bowel is associated with longer operative times and complications. The authors have analyzed the LapRC procedure and its 2 main parts-that is, bladder resection and urinary diversion. The emphasis was on the operative time and complications related to the urinary diversion procedure. A urinary diversion created in vitro could make the LapRC totally intracorporeal, and it could be completed within an acceptable time. Tissue engineering techniques used for urinary diversion after cystectomy shorten the operative time and help avoid serious complications related to bowel surgery. LapRC with tissue-engineered urinary diversion could become a management of choice for muscle invasive bladder cancer. PMID: 20656759 [PubMed - as supplied by publisher] | | |
| Microelastic properties of lung cell-derived extracellular matrix.
July 28, 2010 at 3:01 AM
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| | Microelastic properties of lung cell-derived extracellular matrix. Acta Biomater. 2010 Jul 22; Authors: Soucy PA, Werbin J, Heinz W, Hoh JH, Romer LH Mechanical properties of the extracellular microenvironment regulate cell behaviors including migration, proliferation, and morphogenesis. Although elastic moduli of synthetic materials have been studied, little is known about the properties of naturally produced extracellular matrix. Here, we utilized atomic force microscopy to characterize the microelastic properties of decellularized cell-derived matrix from human pulmonary fibroblasts. This heterogeneous three-dimensional matrix had an average thickness of 5+/-0.4 mum and a Young's modulus of 105+/-14 Pa. Ascorbate treatment of the lung fibroblasts prior to extraction produced a two-fold increase in collagen I content, but did not affect the stiffness of the matrices compared to matrices produced in standard medium. However, fibroblast-derived matrices that were crosslinked with glutaraldehyde demonstrated a 67% increase in stiffness. This work provides a microscale characterization of fibroblast-derived matrix mechanical properties. An accurate understanding of native three-dimensional extracellular microenvironments will be essential for controlling cell responses in tissue engineering applications. PMID: 20656080 [PubMed - as supplied by publisher] | | |
| Ingrowth of Human Mesenchymal Stem Cells into Porous Silk Particle Reinforced Silk Composite Scaffolds: An In Vitro Study.
July 28, 2010 at 3:01 AM
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| | Ingrowth of Human Mesenchymal Stem Cells into Porous Silk Particle Reinforced Silk Composite Scaffolds: An In Vitro Study. Acta Biomater. 2010 Jul 22; Authors: Rockwood DN, Gil ES, Park SH, Kluge JA, Grayson W, Bhumiratana S, Rajkhowa R, Wang X, Kim SJ, Vunjak-Novakovic G, Kaplan DL Silk fibroin protein is biodegradable and biocompatible, exhibiting excellent mechanical properties for various biomedical applications. However, porous 3D silk fibroin scaffolds, or silk sponges, usually fall short in matching the initial mechanical requirements for bone tissue engineering. In the present study, silk sponge matrices were reinforced with silk microparticles to generate protein-protein composite scaffolds with desirable mechanical properties for in vitro osteogenic tissue formation. It was found that increasing the silk microparticle loading led to a substantial increase in the scaffold compressive modulus from 0.3 MPa (nonreinforced) to 1.9 MPa for 1:2 (matrix:particle) reinforcement loading by dry mass. Biochemical, gene expression, and histological assays were employed to study the possible effects of increasing composite scaffold stiffness, due to microparticle reinforcement, on in vitro osteogenic differentiation of human mesenchymal stem cells (hMSCs). Increasing silk microparticle loading increased the osteogenic capability of hMSCs in the presence of bone morphogenic protein-2 (BMP-2) and other osteogenic factors in static culture for up to six weeks. The calcium adsorption increased dramatically with increasing loading, as observed from biochemical assays, histological staining, and microCT (muCT) analysis. Specifically, calcium content in the scaffolds increased by 0.57, 0.71, and 1.27 mg (per mug of DNA) from 3 to 6 weeks for matrix to particle dry mass loading ratios of 1:0, 1:1 and 1:2, respectively. In addition, muCT imaging revealed that at 6 weeks, bone volume fraction increased from 0.78% for nonreinforced to 7.1% and 6.7% for 1:1 and 1:2 loading, respectively. Our results support the hypothesis that scaffold stiffness may strongly influence the 3D in vitro differentiation capabilities of hMSCs, providing a means to improve osteogenic outcomes. PMID: 20656075 [PubMed - as supplied by publisher] | | |
| Engineering systems for the generation of patterned co-cultures for controlling cell-cell interactions.
July 28, 2010 at 3:01 AM
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| | Engineering systems for the generation of patterned co-cultures for controlling cell-cell interactions. Biochim Biophys Acta. 2010 Jul 22; Authors: Kaji H, Camci-Unal G, Langer R, Khademhosseini A BACKGROUND: Inside the body, cells lie in direct contact or in close proximity to other cell types in a tightly controlled architecture that often regulates the resulting tissue function. Therefore, tissue engineering constructs that aim to reproduce the architecture and the geometry of tissues will benefit from methods of controlling cell-cell interactions with microscale resolution. SCOPE OF THE REVIEW: We discuss the use of microfabrication technologies for generating patterned co-cultures. In addition, we categorize patterned co-culture systems by cell type and discuss the implications of regulating cell-cell interactions in the resulting biological function of the tissues. MAJOR CONCLUSIONS: Patterned co-cultures are a useful tool for fabricating tissue engineered constructs and for studying cell-cell interactions in vitro, because they can be used to control the degree of homotypic and heterotypic cell-cell contact. In addition, this approach can be manipulated to elucidate important factors involved in cell-matrix interactions. GENERAL SIGNIFICANCE: Patterned co-culture strategies hold significant potential to develop biomimetic structures for tissue engineering. It is expected that they would create opportunities to develop artificial tissues in the future. PMID: 20655984 [PubMed - as supplied by publisher] | | |
| Epicardium-derived cells enhance proliferation, cellular maturation and alignment of cardiomyocytes.
July 28, 2010 at 3:01 AM
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| | Epicardium-derived cells enhance proliferation, cellular maturation and alignment of cardiomyocytes. J Mol Cell Cardiol. 2010 Jul 22; Authors: Weeke-Klimp A, Bax NA, Bellu AR, Winter EM, Vrolijk J, Plantinga J, Maas S, Brinker M, Mahtab EA, Gittenberger-de Groot AC, van Luyn MJ, Harmsen MC, Lie-Venema H During heart development, cells from the proepicardial organ spread over the naked heart tube to form the epicardium. From here, epicardium-derived cells (EPDCs) migrate into the myocardium. EPDCs proved to be indispensible for the formation of the ventricular compact zone and myocardial maturation, by largely unknown mechanisms. In this study we investigated in vitro how EPDCs affect cardiomyocyte proliferation, cellular alignment and contraction, as well as the expression and cellular distribution of proteins involved in myocardial maturation. Embryonic quail EPDCs induced proliferation of neonatal mouse cardiomyocytes. This required cell-cell interactions, as proliferation was not observed in transwell cocultures. Western blot analysis showed elevated levels of electrical and mechanical junctions (connexin43, N-cadherin), sarcomeric proteins (Troponin-I, alpha-actinin), extracellular matrix (collagen I and periostin) in cocultures of EPDCs and cardiomyocytes. Immunohistochemistry indicated more membrane-bound expression of Cx43, N-cadherin, the mechanotransduction molecule focal adhesion kinase, and higher expression of the sarcoplasmic reticulum Ca(2+) ATPase (SERCA2a). Newly developed software for analysis of directionality in immunofluorescent stainings showed a quantitatively determined enhanced cellular alignment of cardiomyocytes. This was functionally related to increased contraction. The in vitro effects of EPDCs on cardiomyocytes were confirmed in three reciprocal in vivo models for EPDC-depletion (chicken and mice) in which downregulation of myocardial N-cadherin, Cx43, and FAK were observed. In conclusion, direct interaction of EPDCs with cardiomyocytes induced proliferation, correct mechanical and electrical coupling of cardiomyocytes, ECM-deposition and concurrent establishment of cellular array. These findings implicate that EPDCs are ideal candidates as adjuvant cells for cardiomyocyte integration during cardiac (stem) cell therapy. PMID: 20655924 [PubMed - as supplied by publisher] | | |
| Pericellular Conditions Regulate Extent of Cell-Mediated Compaction of Collagen Gels.
July 28, 2010 at 3:01 AM
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| | Pericellular Conditions Regulate Extent of Cell-Mediated Compaction of Collagen Gels. Biophys J. 2010 Jul 7;99(1):19-28 Authors: Stevenson MD, Sieminski AL, McLeod CM, Byfield FJ, Barocas VH, Gooch KJ Cell-mediated compaction of the extracellular matrix (ECM) plays a critical role in tissue engineering, wound healing, embryonic development, and many disease states. The ECM is compacted as a result of cellular traction forces. We hypothesize that a cell mechanically remodels the nearby ECM until some target conditions are obtained, and then the cell stops compacting. A key feature of this hypothesis is that ECM compaction primarily occurs in the pericellular region and the properties of the ECM in the pericellular region govern cellular force generation. We developed a mathematical model to describe the amount of macroscopic compaction of cell-populated collagen gels in terms of the initial cell and collagen densities, as well as the final conditions of the pericellular environment (defined as the pericellular volume where the collagen is compacted (V( *)) and the mass of collagen within this volume (m( *))). This model qualitatively predicts the effects of varying initial cell and collagen concentrations on the extent of gel compaction, and by fitting V( *) and m( *), provides reasonable quantitative agreement with the extent of gel compaction observed in experiments with endothelial cells and fibroblasts. Microscopic analysis of compacted gels supports the assumption that collagen compaction occurs primarily in the pericellular environment. PMID: 20655829 [PubMed - as supplied by publisher] | | |
| A Review of the mechanical behavior of CaP and CaP/polymer composites for applications in bone replacement and repair.
July 28, 2010 at 3:01 AM
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| | A Review of the mechanical behavior of CaP and CaP/polymer composites for applications in bone replacement and repair. Acta Biomater. 2010 Jul 21; Authors: Johnson AJ, Herschler BA Repair of load-bearing defects resulting from disease or trauma remains a critical barrier for bone tissue engineering. Calcium phosphate (CaP) scaffolds are among the most extensively studied for this application. However, CaPs are reportedly too weak for use in such defects and therefore have been limited to non load-bearing applications. This paper reviews the compression, flexural, and tensile properties of CaPs and CaP/polymer composites for applications in bone replacement and repair. This review reveals interesting trends that have not previously been reported, to our knowledge. Data are classified as bulk, scaffolds and composites, then organized in order of decreasing strength, allowing for general comparisons of magnitudes of strength both within and across classifications. Bulk and scaffold strength and porosity overlap significantly and scaffold data are comparable to bone both in strength and porosity. Further, for compression, all composite data fall below that of the bulk and most of the scaffold. Another interesting trend revealed is that strength decreases with increasing beta-tricalcium phosphate (beta-TCP) content for CaP scaffolds and with increasing CaP content for CaP/polymer composites. The real limitation for CaPs appears to be not strength, but the toughness and reliability, which are rarely characterized. We propose that research should focus on novel ways of toughening CaPs and discuss several potential strategies. PMID: 20655397 [PubMed - as supplied by publisher] | | |
| Microencapsulation of islets within alginate/poly(ethylene glycol) gels cross-linked via Staudinger ligation.
July 28, 2010 at 3:01 AM
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| | Microencapsulation of islets within alginate/poly(ethylene glycol) gels cross-linked via Staudinger ligation. Acta Biomater. 2010 Jul 20; Authors: Hall KK, Gattás-Asfura KM, Stabler CL Functionalized alginate and PEG polymers were used to generate covalently linked alginate-PEG (XAlgPEG) microbeads of high stability. The cell-compatible Staudinger ligation scheme was used to chemoselectively cross-link phosphine-terminated poly(ethylene glycol) (PEG) to azide-functionalized alginate, resulting in XAlgPEG hydrogels. XAlgPEG microbeads were formed by co-incubation of the two polymers, followed by ionic cross-linking of the alginate using barium ions. The enhanced stability and gel properties of the resulting XAlgPEG microbeads, as well as the compatibility of these polymers for the encapsulation of islets and beta cells lines, were investigated. Our data show that XAlgPEG microbeads exhibit superior resistance to osmotic swelling compared to traditional barium cross-linked alginate (Ba-Alg) beads, with a 5-fold reduction in observed swelling, as well as resistance to dissolution via chelation solution. Diffusion and porosity studies found XAlgPEG beads to exhibit properties comparable to standard Ba-Alg. Our data found XAlgPEG microbeads to be highly cell compatible with insulinoma cell lines, as well as rat and human pancreatic islets, where the viability and functional assessment of cells within XAlgPEG were comparable to Ba-Alg controls. The remarkable improved stability, as well as demonstrated cellular compatibility, of XAlgPEG hydrogels makes them an appealing option for a wide variety of tissue engineering applications. PMID: 20654745 [PubMed - as supplied by publisher] | | |
| Melatonin reduces hippocampal beta-amyloid generation in rats exposed to chronic intermittent hypoxia.
July 28, 2010 at 3:01 AM
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| | Melatonin reduces hippocampal beta-amyloid generation in rats exposed to chronic intermittent hypoxia. Brain Res. 2010 Jul 20; Authors: Ng KM, Lau CF, Fung ML The deposition of neurotoxic beta-amyloid plaques plays a central role in the pathogenesis of Alzheimer's disease. At the molecular level, the generation of beta-amyloid peptides involves the site-specific cleavage of the precursor protein by beta-site APP cleavage enzyme (BACE) and presenilin. Although acute or chronic sustained hypoxia appears to increase the generation of beta-amyloid peptides via the HIF-1alpha dependent upregulation of BACE, the effect of chronic intermittent hypoxia (CIH) on the generation of beta-amyloid peptides remains uncertain. In this study, we have evaluated such contention in the rat hippocampus, and we found that short-term CIH exposure (3 days) caused significant increases in the generation of beta-amyloid peptides, and the expressions of BACE, presenilin and HIF-1alpha protein levels, in the hippocampus of CIH rats. Moreover, the CIH-induced hippocampal beta-amyloid peptide generation could be abolished by a daily pharmacological administration of melatonin (10mg/kg), which reduced the BACE but not presenilin expression, Also, there was no significant differences in the hippocampal HIF-1alpha protein levels between the melatonin- and vehicle-treated CIH groups. Our study not only provided the first evidence that short-term CIH exposure could induce the beta-amyloid peptide generation in the hippocampus, but also pointed out the therapeutic value of melatonin in reducing beta-amyloid peptide generation in patients suffered from chronic obstructive sleep apnea syndrome. PMID: 20654588 [PubMed - as supplied by publisher] | | |
| Superior Osteogenic Capacity of Human Embryonic Stem Cells Adapted to Matrix-Free Growth Compared to Human Mesenchymal Stem Cells.
July 28, 2010 at 3:01 AM
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| | Superior Osteogenic Capacity of Human Embryonic Stem Cells Adapted to Matrix-Free Growth Compared to Human Mesenchymal Stem Cells. Tissue Eng Part A. 2010 Jul 23; Authors: Bigdeli N, de Peppo GM, Lennerås M, Sjövall P, Lindahl A, Hyllner J, Karlsson C Human mesenchymal stem cells (hMSCs) represent a promising source of cells for bone tissue engineering. However, their low frequencies and limited proliferation restrict their clinical utility. An alternative is the use of human embryonic stem cells (hESCs), but labor-intensive expansion with the need for coating support limits their clinical use. We have previously derived a cell line from hESCs denoted matrix-free growth (MFG)-hESC that are independent of coating support for expansion, and we here compare its osteogenic capacity to that of hMSCs. Microarray analysis of hMSCs and MFG-hESCs revealed differential expression of genes involved in ossification. MFG-hESCs have significantly higher expression of secreted phosphoprotein 1 (SPP1) during osteogenic differentiation, whereas the opposite was true for alkaline phosphatase (ALPL), transforming growth factor, beta 1 (TGFB2), runt-related transcription factor 2 (RUNX2), and forkhead box C1 (FOXC1), as well as the activity of the ALPL enzyme, demonstrating that these two cell types differentiate into the osteogenic lineage using different signaling pathways. von Kossa staining, time-of-flight secondary ion mass spectrometry, and measurement of calcium and phosphate in the extracellular matrix demonstrated a superior ability of the MFG-hESCs to produce a mineralized matrix compared to hMSCs. The superior ability of the MFG-hESCs to form mineralized matrix compared to hMSCs demonstrates that MFG-hESCs are a promising alternative to the use of adult stem cells in future bone regenerative applications. PMID: 20653416 [PubMed - as supplied by publisher] | | |
| Clinical experience with expanded use of the Ross procedure: a paradigm shift?
July 28, 2010 at 3:01 AM
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| | Clinical experience with expanded use of the Ross procedure: a paradigm shift? J Heart Valve Dis. 2010 May;19(3):279-85 Authors: Weymann A, Dohmen PM, Grubitzsch H, Dushe S, Holinski S, Konertz W BACKGROUND AND AIM OF THE STUDY: The study aim was to evaluate the short-term survival and functional outcome after the Ross procedure, with expanded inclusion criteria. METHODS: A total of 91 patients (21 females, 70 males; mean age 57.3 +/- 13.1 years; range: 0.1-74 years) underwent aortic valve replacement (AVR) with a Ross procedure at the authors' institution during the year 2007. The underlying valve diseases were stenosis in 60 patients, regurgitation in 17, and a mixed lesion in 14. Seven patients suffered from acute infective endocarditis, and in five patients the Ross operation was a reoperative procedure. Forty-four patients (48%) underwent surgery in association with concomitant procedures, which included predominantly coronary artery bypass surgery, mitral valve repair or replacement, or procedures of the ascending aorta. RESULTS: The mean cardiopulmonary bypass and aortic cross-clamp times were 147 +/- 31 min (range: 87-246 min) and 124 +/- 26 min (range: 73-195 min), respectively. Hospital mortality was 2.2%. No patient died during the follow up period. The aortic gradient was decreased from 5.1 +/- 2 mmHg at discharge, to 3.2 +/- 1 mmHg during follow up (p < 0.05); at the same times, the mean gradient of the decellularized tissue-engineered pulmonary valve was 2.8 +/- 1 mmHg and 2.7 +/- 1 mmHg, respectively. An echocardiographic examination of neo-aortic valve competence at 12 months revealed no or trivial aortic valve regurgitation in 80 patients, and mild (grade 1+) regurgitation in nine patients. No patient required reoperation of the autograft during follow up. Two patients underwent reconstruction of the right ventricular outflow tract. At 12 months' follow up, all patients enjoyed normal social interactions, were in NYHA functional class I or II, and free from complications. CONCLUSION: The Ross procedure can be offered as an alternative to standard prosthetic AVR with an excellent short-term outcome. The former inclusion/exclusion criteria for this procedure should be re-evaluated. PMID: 20583389 [PubMed - indexed for MEDLINE] | | |
| Adult stem cells therapy for urine incontinence in women.
July 28, 2010 at 3:01 AM
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| | Adult stem cells therapy for urine incontinence in women. Ginekol Pol. 2010 May;81(5):378-81 Authors: Stangel-Wójcikiewicz K, Majka M, Basta A, Stec M, Pabian W, Piwowar M, Chancellor MB The past few years brought high development in obtaining and culturing autologous adult stem cells. In this paper we review publications of experimental investigations and clinical trials of the muscle-derived cells and the application in the treatment of stress urinary incontinence among women. Mesenchymal stem cells (MSCs) can be obtained from bone marrow but it is associated with a painful biopsy procedure. Collection of muscle-derived stem cells (MDSCs) is less harmful because the skeletal muscle biopsy is performed with a small caliber needle in local anesthesia. The stem-based therapy could be the next step in the treatment of urinary incontinence. There are still many elements of therapy such as effectiveness or long-term side effects which need to be researched. PMID: 20568520 [PubMed - indexed for MEDLINE] | | |
| [De-novo generation of vascularized tissue using different configurations of vascular pedicles in perforated and closed chambers]
July 28, 2010 at 3:01 AM
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| | [De-novo generation of vascularized tissue using different configurations of vascular pedicles in perforated and closed chambers] Wien Med Wochenschr. 2010 Mar;160(5-6):139-46 Authors: Dolderer JH, Kehrer A, Schiller SM, Schröder UH, Kohler K, Schaller HE, Siegel-Axel D Growing three-dimensional tissue within a chamber requires vigorous angiogenesis initiated by, for example, an arteriovenous fistula or a ligated vascular pedicle. Growth may also be enhanced by contact with the external environment. In this study tissue growth in a rat model, vascularized via an arteriovenous loop (AV Loop) or ligated pedicle, was compared in chambers that were either closed or perforated. Chambers were harvested at 4 weeks and tissue volume and histology compared. In perforated chambers, more tissue were generated using the ligated pedicle (0.75 ml+/-0.04) than the AV Loop (0.59 ml+/-0.01). Perforated chambers generated larger volumes of tissue than closed chambers because they encouraged tissue ingrowth through the perforations. Both vessel configurations supported tissue growth but, interestingly, the ligated pedicle resulted in significantly more tissue in the perforated chambers. PMID: 20364417 [PubMed - indexed for MEDLINE] | | |
| Potential application of adipose-derived stem cells and their secretory factors to skin: discussion from both clinical and industrial viewpoints.
July 28, 2010 at 3:01 AM
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| | Potential application of adipose-derived stem cells and their secretory factors to skin: discussion from both clinical and industrial viewpoints. Expert Opin Biol Ther. 2010 Apr;10(4):495-503 Authors: Yang JA, Chung HM, Won CH, Sung JH IMPORTANCE OF THE FIELD: Adipose tissue is one of the richest sources of mesenchymal stem cells. Even more interesting is the fact that adipose-derived stem cells (ASCs) show an outstanding ability to regenerate damaged skin. Thus, ASCs are a popular and feasible treatment in clinical dermatology. AREAS COVERED IN THIS REVIEW: This review discusses the potential applications of ASCs and conditioned medium of ASC (ASC-CM) to skin, and briefly touches on the mechanisms by which ASCs promote skin regeneration. WHAT THE READER WILL GAIN: Clinically, processed lipo-aspirated (PLA) cells are commonly used for treatment of aged skin; however, the use of PLA cells for cosmetic purposes is not convenient, because PLA cells are prepared from patients. Alternatively, cosmetics that contain ASC-CM can be pre-made from healthy volunteers such that they are immediately available for clinical treatment of aged skin. Cell-based therapies are adequate for improvement of wrinkles or for soft tissue augmentation, whereas ASC-CM has merit for amelioration of skin tone. When culturing ASCs for the production of cosmetic raw materials, hypoxic culture conditions and transduction of specific genes into ASCs may increase the regenerative protein content of the conditioned medium. TAKE HOME MESSAGE: Application of ASCs and ASC-CM to dermatology shows promising results for skin regeneration. PMID: 20218919 [PubMed - indexed for MEDLINE] | | |
| Visualization of the cellulose biosynthesis and cell integration into cellulose scaffolds.
July 28, 2010 at 3:01 AM
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| | Visualization of the cellulose biosynthesis and cell integration into cellulose scaffolds. Biomacromolecules. 2010 Mar 8;11(3):542-8 Authors: Brackmann C, Bodin A, Akeson M, Gatenholm P, Enejder A By controlling the microarchitecture of bioengineered scaffolds for artificial tissues, their material and cell-interaction properties can be designed to mimic native correspondents. Current understanding of this relationship is sparse and based on microscopy requiring harsh sample preparation and labeling, leaving it open to which extent the natural morphology is studied. This work introduces multimodal nonlinear microscopy for label-free imaging of tissue scaffolds, exemplified by bacterial cellulose. Unique three-dimensional images visualizing the formation of nanofiber networks throughout the biosynthesis, revealing that supra-structures (layered structures, cavities) are formed. Cell integration in compact scaffolds was visualized and compared with porous scaffolds. While the former showed distinct boundaries to the native tissue, gradual cell integration was observed for the porous material. Thus, the degree of cell integration can be controlled through scaffold supra-structures. This illustrates the potential of nonlinear microscopy for noninvasive imaging of the intriguing interaction mechanisms between scaffolds and cells. PMID: 20158282 [PubMed - indexed for MEDLINE] | | |
| Inverted colloidal crystal scaffolds for uniform cartilage regeneration.
July 28, 2010 at 3:01 AM
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| | Inverted colloidal crystal scaffolds for uniform cartilage regeneration. Biomacromolecules. 2010 Mar 8;11(3):731-9 Authors: Kuo YC, Tsai YT A uniform distribution of chondrocytes in 3D scaffolds is a critical challenge to cartilage regeneration. This study aims to resolve the problem by showing uniformly distributed chondrogenesis in chitin/chitosan matrix with pores of inverted colloidal crystal (ICC) structure. The results revealed that the effect of solvent on the regularity of colloidal crystal arrays was in the order of ethanol > ethylene glycol > acetone. When the concentration of chitin/chitosan gel was <2.5%, the porosity of ICC scaffolds with pure ethanol was approximately 84%. The highly porous freeform scaffolds produced random and unconnected pores, in general. The viability of bovine knee chondrocytes (BKCs) in ICC constructs was >92%. Over 4 weeks of cultivation, the percentage of biodegradation of ICC scaffolds with pure ethanol was approximately 34%. The order in the produced BKCs, glycosaminoglycans (GAGs), and collagen was freeform constructs > ICC constructs with pure ethanol > ICC constructs with 95% acetone. However, the spatial distribution of BKCs in ICC constructs was more uniform than that in freeform constructs. In addition, BKCs could secrete GAGs and type II collagen in the core of ICC constructs, indicating the maintenance of phenotypic chondrocytes and their metabolism. The ICC constructs with well-controlled pore regularity and unique topography can generate uniform tissue-engineered cartilage. PMID: 20158195 [PubMed - indexed for MEDLINE] | | |
| Microfluidic assays for DNA manipulation based on a block copolymer immobilization strategy.
July 28, 2010 at 3:01 AM
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| | Microfluidic assays for DNA manipulation based on a block copolymer immobilization strategy. Biomacromolecules. 2010 Mar 8;11(3):827-31 Authors: Vasdekis AE, O'Neil CP, Hubbell JA, Psaltis D Methods to manipulate and visualize isolated DNA and oligonucleotide strands are important for investigation of their biophysics as well as their interactions with proteins. Herein, we report such a method by combining a block copolymer surface functionalization strategy with microfluidics. The copolymer poly(l-lysine-graft-polyethylene glycol) (PLL-g-PEG) coated one surface of the microfluidic channels, rendering it passive to adsorption and thus minimizing any noise arising from nontargeted adsorbed molecules. Single lambda-phage DNA molecules were immobilized and were extended by molecular combing. Their extension did not exceed their contour length, which we attribute to the low surface tension of the coated surface. To demonstrate further the applicability of our method, the anchored DNA was extended by hydrodynamic flow. We propose this method for exploring DNA-protein interactions due to the copolymer's enhanced capacity for single-molecule detection, stability under wet or dry conditions, hydrophilicity, full compatibility with microfluidics and simplicity being a one-step process. PMID: 20158193 [PubMed - indexed for MEDLINE] | | |
| Endothelial progenitor cells--an evolving story.
July 28, 2010 at 3:01 AM
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| | Endothelial progenitor cells--an evolving story. Microvasc Res. 2010 May;79(3):162-8 Authors: Pearson JD The first description of endothelial progenitor cells (EPC) in 1997 led rapidly to substantial changes in our understanding of angiogenesis, and within 5 years to the first clinical studies in humans using bone marrow derived EPC to enhance coronary neovascularisation and cardiac function after myocardial ischemia. However, to improve the success of this therapy a clearer understanding of the biology of EPC is needed. This article summarises recent data indicating that most EPC are not, in fact, endothelial progenitors but can be better described as angiogenic monocytes, and explores the implications this has for their future therapeutic use. PMID: 20043930 [PubMed - indexed for MEDLINE] | | |
| Newly established cell lines from mouse oral epithelium regenerate teeth when combined with dental mesenchyme.
July 28, 2010 at 3:01 AM
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| | Newly established cell lines from mouse oral epithelium regenerate teeth when combined with dental mesenchyme. In Vitro Cell Dev Biol Anim. 2010 May;46(5):457-68 Authors: Takahashi C, Yoshida H, Komine A, Nakao K, Tsuji T, Tomooka Y The present study attempted to examine whether clonal cell lines of the oral epithelium can differentiate into ameloblasts and regenerate tooth when combined with dental germ mesenchyme. Clonal cell lines with a distinct morphology were established from the oral epithelium of p53-deficient fetal mice at embryonic day 18 (E18). The strain of mouse is shown to be a useful source for establishing clonal and immortalized cell lines from various tissues and at various stages of development. Tooth morphogenesis is almost completed and the oral epithelium is segregated from the dental epithelium at E18. In RT-PCR analysis of cell lines, mucosal epithelial markers (cytokeratin 14) were detected, but ameloblast markers such as amelogenin and ameloblastin were not detected when cells were cultured on plastic dish. They formed stratified epithelia and expressed a specific differentiation marker (CK13) in the upper layer when cultured on feeder layer or on collagen gel for 1-3 wk, demonstrating that they are of oral mucosa origin. Next, bioengineered tooth germs were prepared with cell lines and fetal molar mesenchymal tissues and implanted under kidney capsule for 2-3 wk. Five among six cell lines regenerated calcified structures as seen in natural tooth. Our results indicate that some oral epithelial cells at E18 possess the capability to differentiate into ameloblasts. Furthermore, cell lines established in the present study are useful models to study processes in tooth organogenesis and tooth regeneration. PMID: 20033791 [PubMed - indexed for MEDLINE] | | |
| Development of a scaffoldless three-dimensional engineered nerve using a nerve-fibroblast co-culture.
July 28, 2010 at 3:01 AM
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| | Development of a scaffoldless three-dimensional engineered nerve using a nerve-fibroblast co-culture. In Vitro Cell Dev Biol Anim. 2010 May;46(5):438-44 Authors: Baltich J, Hatch-Vallier L, Adams AM, Arruda EM, Larkin LM Nerve grafts are often required to replace tissue damaged by disease, surgery, or extensive trauma. Limitations such as graft availability, donor site morbidity, and immune rejection have led investigators to develop strategies to engineer nerve tissue. The goal of this study was to fabricate a scaffoldless three-dimensional (3D) nerve construct using a co-culture of fetal nerve cells with a fibroblast monolayer and allow the co-culture to remodel into a 3D construct with an external fibroblast layer and an internal core of interconnected neuronal cells. Primary fibroblasts were seeded on laminin-coated plates and allowed to form a confluent monolayer. Neural cells isolated from E-15 spinal cords were seeded on top of the fibroblast monolayer and allowed to form a networked monolayer across the monolayer of fibroblasts. Media shifts initiated contraction of the fibroblast monolayer and a remodeling of the co-culture into a 3D construct held statically in place by the two constraint pins. Immunohistochemistry using S100 (Schwann cell), beta3-tubulin, DAPI, and collagen I indicated an inner core of nerve cells surrounded by an external layer of fibroblasts. Conduction velocities of the 3D nerve and control (fibroblast-only) constructs were measured in vitro and compared to in vivo measures of neonatal sciatic nerve. The conduction velocities of the nerve constructs were comparable to 24-d-old neonatal nerve. The presence of Schwann cells and the ability to conduct neuronal signals in vitro suggest the scaffoldless 3D nerve constructs will be a viable option for nerve repair. PMID: 19997868 [PubMed - indexed for MEDLINE] | | |
| Industrial approach in developing an advanced therapy product for bone repair.
July 28, 2010 at 3:01 AM
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| | Industrial approach in developing an advanced therapy product for bone repair. J Tissue Eng Regen Med. 2010 Mar;4(3):194-204 Authors: Gindraux F, Obert L, Laganier L, Barnouin L Mesenchymal stem cells (MSCs) are multipotent cells with therapeutic applications. The aim of our work was to develop an advanced therapy product for bone repair, associating autologous human adipose-derived MSCs (ASCs) with human bone allograft (TBF; Phoenix). We drew up specifications that studied: (a) the influence of tissue collection procedures (elective liposuction or non-invasive resection) and patient age on cell number and function; (b) monolayer cell culture conditions and osteodifferentiation and particularly the possibility of reducing stages of culture; and (c) the bone construct preparation and especially the comparison between two types of cells seeded on bone allograft (number of cultured processed lipoaspirate (PLA) cells and monolayer-expanded ASCs) and cultured for 1, 2 and 3 weeks. The results showed that tissue harvesting techniques and patient age did not affect PLA cell number and ASC cloning efficiency. PLA cells can be directly osteodifferentiated (instead of culturing them in expansion medium first and then differentiating them) and these cells were able to mineralize when they were cultured in an osteogenic medium containing calcium chloride. PLA cells directly seeded on bone allograft for a minimum of 3 weeks of culture in this osteogenic medium expressed osteocalcin and colonized the matrix better than monolayer-expanded ASCs. This work detailed the specifications of a pharmaceutical laboratory to develop an advanced therapy product and this current approach is promising for bone repair. PMID: 19967743 [PubMed - indexed for MEDLINE] | | |
| Transcriptional and translational control of C/EBPs: The case for "deep" genetics to understand physiological function.
July 28, 2010 at 3:01 AM
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| | Transcriptional and translational control of C/EBPs: The case for "deep" genetics to understand physiological function. Bioessays. 2010 Aug;32(8):680-6 Authors: Nerlov C The complexity of organisms is not simply determined by the number of their genes, but to a large extent by how gene expression is controlled. In addition to transcriptional regulation, this involves several layers of post-transcriptional control, such as translational repression, microRNA-mediated mRNA degradation and translational inhibition, alternative splicing, and the regulated generation of functionally distinct gene products from a single mRNA through alternative use of translation initiation sites. Much progress has been made in describing the molecular basis for these gene regulatory mechanisms. However, it is now a major challenge to translate this knowledge into deeper understanding of the physiological processes, both normal and pathological, that they govern. Using the C/EBP family of transcription factors as an example, the present review describes recent genetic experiments addressing this general problem and discusses how the physiological importance of newly discovered regulatory mechanisms might be determined. PMID: 20658706 [PubMed - in process] | | |
| Application of induced pluripotent stem (iPS) cells in periodontal tissue regeneration.
July 28, 2010 at 3:01 AM
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| | Application of induced pluripotent stem (iPS) cells in periodontal tissue regeneration. J Cell Physiol. 2010 Jul 23; Authors: Duan X, Tu Q, Zhang J, Ye J, Sommer C, Mostoslavsky G, David K, Yang P, Chen J Tissue engineering provides a new paradigm for periodontal tissue regeneration in which proper stem cells and effective cellular factors are very important. The objective of this study was, for the first time, to investigate the capabilities and advantages of periodontal tissue regeneration using induced pluripotent stem (iPS) cells and enamel matrix derivatives (EMD). In this study the effect of EMD gel on iPS cells in vitro was first determined, and then tissue engineering technique was performed to repair periodontal defects in three groups: silk scaffold only; silk scaffold + EMD; and silk scaffold + EMD + iPS cells. EMD greatly enhanced the mRNA expression of Runx2, but inhibited the mRNA expression of OC and mineralization nodule formation in vitro. Transplantation of iPS cells showed higher expression levels of OC, Osx, and Runx2 genes, both 12 and 24 days post-surgery. At 24 days post-surgery in the iPS cell group, histological analysis showed much more new alveolar bone and cementum formation with regenerated periodontal ligament between them. The results showed the commitment role that EMD contributes in mesenchymal progenitors to early cells in the osteogenic lineage. iPS cells combined with EMD provide a valuable tool for periodontal tissue engineering, by promoting the formation of new cementum, alveolar bone, and normal periodontal ligament. J. Cell. Physiol. (c) 2010 Wiley-Liss, Inc. PMID: 20658533 [PubMed - as supplied by publisher] | | | | 
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