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| Weight Loss in Obese C57BL/6 Mice Limits Adventitial Expansion of Established Angiotensin II-induced Abdominal Aortic Aneurysms.
March 23, 2010 at 6:22 AM
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| | Weight Loss in Obese C57BL/6 Mice Limits Adventitial Expansion of Established Angiotensin II-induced Abdominal Aortic Aneurysms. Am J Physiol Heart Circ Physiol. 2010 Mar 19; Authors: Police SB, Putnam K, Thatcher SE, Batifoulier-Yiannikouris F, Daugherty A, Cassis LA Previous studies demonstrated that obesity increases inflammation in periaortic adipose tissue and promotes angiotensin II (AngII)-induced AAAs. We sought to determine if weight loss of obese C57BL/6 mice would influence the progression of established AAAs. Male C57BL/6 mice were fed a high fat diet (HF) for 4 months, and then infused with either saline or AngII (1,000 ng/kg/min) for 3 months. Mice with dilated suprarenal aortas at 28 days of AngII infusion were designated to groups fed the HF (HF/HF) or a low fat diet (LF, 10% kcal as fat; HF/LF) to induce weight loss for the last 2 months of infusions. Suprarenal aortic lumen diameters of obese mice were increased by AngII infusion at day 28 (day 0: 1.03 +/- 0.02; day 28: 1.86 +/- 0.14 mm; P < 0.05), but did not progress with continued infusion in HF/HF mice. Moreover, aortic lumen diameters were not different between groups (HF/HF: 1.89 +/- 0.15; HF/LF: 1.79 +/- 0.18 mm). However, maximal diameters of excise! d AAAs were decreased with weight loss (HF/HF: 2.00 +/- 0.11; HF/LF: 1.55 +/- 0.13; P < 0.05) and had reduced adventitial areas (HF/HF: 1.18 +/- 0.10 ; HF/LF: 0.54 +/- 0.02 mm2; P<0.05). Neovascularization of aortic adventitias was strikingly decreased in HF/LF mice (HF/HF: 43 +/- 5; HF/LF: 12 +/- 2 endothelial cells/adventitial area; P< 0.05). AngII-induced elevations in adipose mRNA expression of CD105, a stromal stem cell marker, were abolished with weight loss. These results demonstrate that weight loss limits adventitial expansion of AngII-induced AAAs. Reduced neovascularization from weight loss may limit progression of AAAs. Key words: weight loss, neovascularization, aneurysms. PMID: 20304811 [PubMed - as supplied by publisher] | | |
| Regenerative medicine for neurological disorders.
March 23, 2010 at 6:21 AM
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| | Regenerative medicine for neurological disorders. ScientificWorldJournal. 2010;10:470-89 Authors: Park DH, Eve DJ, Chung YG, Sanberg PR The annual meeting of the American Society for Neural Therapy and Repair (ASNTR) has always introduced us to top-notch and up-to-date approaches for regenerative medicine related to neuroscience, ranging from stem cell-based therapy to novel drugs. The 16th ASNTR meeting focused on a variety of different topics, including the unknown pathogenesis or mechanisms of specific neurodegenerative diseases, stem cell biology, and development of novel alternative medicines or devices. Newly developed stem cells, such as amniotic epithelial stem cells and induced pluripotent stem cells, as well as well-known traditional stem cells, such as neural, embryonic, bone marrow mesenchymal, and human umbilical cord blood-derived stem cells, were reported. A number of commercialized stem cells were also covered at this meeting. Fetal neural tissues, such as ventral mesencephalon, striatum, and Schwann cells, were investigated for neurodegenerative diseases or spinal cord injury. A n! umber of studies focused on novel methods for drug monitoring or graft tracking, and combination therapy with stem cells and medicine, such as cytokines or trophic factors. Finally, the National Institutes of Health guidelines for human stem cell research, clinical trials of commercialized stem cells without larger animal testing, and prohibition of medical tourism were big controversial issues that led to heated discussion. PMID: 20305989 [PubMed - in process] | | |
| Epimorphin Regulates Bile Duct Formation via Effects on Mitosis Orientation in Rat Liver Epithelial Stem-Like Cells.
March 23, 2010 at 6:21 AM
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| | Epimorphin Regulates Bile Duct Formation via Effects on Mitosis Orientation in Rat Liver Epithelial Stem-Like Cells. PLoS One. 2010;5(3):e9732 Authors: Zhou J, Zhao L, Qin L, Wang J, Jia Y, Yao H, Sang C, Hu Q, Shi S, Nan X, Yue W, Zhuang F, Yang C, Wang Y, Pei X Understanding how hepatic precursor cells can generate differentiated bile ducts is crucial for studies on epithelial morphogenesis and for development of cell therapies for hepatobiliary diseases. Epimorphin (EPM) is a key morphogen for duct morphogenesis in various epithelial organs. The role of EPM in bile duct formation (DF) from hepatic precursor cells, however, is not known. To address this issue, we used WB-F344 rat epithelial stem-like cells as model for bile duct formation. A micropattern and a uniaxial static stretch device was used to investigate the effects of EPM and stress fiber bundles on the mitosis orientation (MO) of WB cells. Immunohistochemistry of liver tissue sections demonstrated high EPM expression around bile ducts in vivo. In vitro, recombinant EPM selectively induced DF through upregulation of CK19 expression and suppression of HNF3alpha and HNF6, with no effects on other hepatocytic genes investigated. Our data provide evidence that EPM! guides MO of WB-F344 cells via effects on stress fiber bundles and focal adhesion assembly, as supported by blockade EPM, beta1 integrin, and F-actin assembly. These blockers can also inhibit EPM-induced DF. These results demonstrate a new biophysical action of EPM in bile duct formation, during which determination of MO plays a crucial role. PMID: 20305811 [PubMed - in process] | | |
| Bone progenitor dysfunction induces myelodysplasia and secondary leukaemia.
March 23, 2010 at 6:21 AM
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| | Bone progenitor dysfunction induces myelodysplasia and secondary leukaemia. Nature. 2010 Mar 21; Authors: Raaijmakers MH, Mukherjee S, Guo S, Zhang S, Kobayashi T, Schoonmaker JA, Ebert BL, Al-Shahrour F, Hasserjian RP, Scadden EO, Aung Z, Matza M, Merkenschlager M, Lin C, Rommens JM, Scadden DT Mesenchymal cells contribute to the 'stroma' of most normal and malignant tissues, with specific mesenchymal cells participating in the regulatory niches of stem cells. By examining how mesenchymal osteolineage cells modulate haematopoiesis, here we show that deletion of Dicer1 specifically in mouse osteoprogenitors, but not in mature osteoblasts, disrupts the integrity of haematopoiesis. Myelodysplasia resulted and acute myelogenous leukaemia emerged that had acquired several genetic abnormalities while having intact Dicer1. Examining gene expression altered in osteoprogenitors as a result of Dicer1 deletion showed reduced expression of Sbds, the gene mutated in Schwachman-Bodian-Diamond syndrome-a human bone marrow failure and leukaemia pre-disposition condition. Deletion of Sbds in mouse osteoprogenitors induced bone marrow dysfunction with myelodysplasia. Therefore, perturbation of specific mesenchymal subsets of stromal cells can disorder differentiation, pro! liferation and apoptosis of heterologous cells, and disrupt tissue homeostasis. Furthermore, primary stromal dysfunction can result in secondary neoplastic disease, supporting the concept of niche-induced oncogenesis. PMID: 20305640 [PubMed - as supplied by publisher] | | |
| Firefly Luciferase-Based Dynamic Bioluminescence Imaging: A Noninvasive Technique to Assess Tumor Angiogenesis.
March 23, 2010 at 6:21 AM
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| | Firefly Luciferase-Based Dynamic Bioluminescence Imaging: A Noninvasive Technique to Assess Tumor Angiogenesis. Neurosurgery. 2010 Apr;66(4):751-757 Authors: Sun A, Hou L, Prugpichailers T, Dunkel J, Kalani MA, Chen X, Kalani MY, Tse V OBJECTIVE: Bioluminescence imaging (BLI) is emerging as a cost-effective, high-throughput, noninvasive, and sensitive imaging modality to monitor cell growth and trafficking. We describe the use of dynamic BLI as a noninvasive method of assessing vessel permeability during brain tumor growth. METHODS: With the use of stereotactic technique, 10 firefly luciferase-transfected GL26 mouse glioblastoma multiforme cells were injected into the brains of C57BL/6 mice (n = 80). After intraperitoneal injection of D-luciferin (150 mg/kg), serial dynamic BLI was performed at 1-minute intervals (30 seconds exposure) every 2 to 3 days until death of the animals. The maximum intensity was used as an indirect measurement of tumor growth. The adjusted slope of initial intensity (I90/Im) was used as a proxy to monitor the flow rate of blood into the vascular tree. Using a modified Evans blue perfusion protocol, we calculated the relative permeability of the vascular tree at various! time points. RESULTS: Daily maximum intensity correlated strongly with tumor volume. At postinjection day 23, histology and BLI demonstrated an exponential growth of the tumor mass. Slopes were calculated to reflect the flow in the vessels feeding the tumor (adjusted slope = I90/Im). The increase in BLI intensity was correlated with a decrease in adjusted slope, reflecting a decrease in the rate of blood flow as tumor volume increased (y = 93.8e, R = 0.63). Examination of calculated slopes revealed a peak in permeability around postinjection day 20 (n = 42, P < .02 by 1-way analysis of variance) and showed a downward trend in relation to both postinjection day and maximum intensity observed; as angiogenesis progressed, tumor vessel caliber increased dramatically, resulting in sluggish but increased flow. This trend was correlated with Evans blue histology, revealing an increase in Evans blue dye uptake into the tumor, as slope calculated by BLI increases. CONCLUSION: Dy! namic BLI is a practical, noninvasive technique that can semiq! uantitat ively monitor changes in vascular permeability and therefore facilitate the study of tumor angiogenesis in animal models of disease. PMID: 20305496 [PubMed - as supplied by publisher] | | |
| Therapeutic Potential of Proteasome Inhibition in Duchenne and Becker Muscular Dystrophies.
March 23, 2010 at 6:21 AM
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| | Therapeutic Potential of Proteasome Inhibition in Duchenne and Becker Muscular Dystrophies. Am J Pathol. 2010 Mar 19; Authors: Gazzerro E, Assereto S, Bonetto A, Sotgia F, Scarfì S, Pistorio A, Bonuccelli G, Cilli M, Bruno C, Zara F, Lisanti MP, Minetti C Duchenne muscular dystrophy (DMD) and its milder allelic variant, Becker muscular dystrophy (BMD), result from mutations of the dystrophin gene and lead to progressive muscle deterioration. Enhanced activation of proteasomal degradation underlies critical steps in the pathogenesis of the DMD/BMD dystrophic process. Previously, we demonstrated that treatment with the proteasome inhibitor MG-132 rescues the cell membrane localization of dystrophin and the dystrophin glycoprotein complex in mdx mice, a natural genetic mouse model of DMD. The current work aims to thoroughly define the therapeutic potential in dystrophinopathies of Velcade, a drug that selectively blocks the ubiquitin-proteasome pathway. Velcade is particularly intriguing since it has been approved for the treatment of multiple myeloma. Therefore, its side effects in humans have been explored. Velcade effects were analyzed through two independent methodological approaches. First, we administered the dr! ug systemically in mdx mice over a 2-week period. In this system, Velcade restores the membrane expression of dystrophin and dystrophin glycoprotein complex members and improves the dystrophic phenotype. In a second approach, we treated with the compound explants from muscle biopsies of DMD or BMD patients. We show that the inhibition of the proteasome pathway up-regulates dystrophin, alpha-sarcoglycan, and beta-dystroglycan protein levels in explants from BMD patients, whereas it increases the proteins of the dystrophin glycoprotein complex in DMD cases. PMID: 20304949 [PubMed - as supplied by publisher] | | |
| Regenerative medicine for retinal diseases: activating endogenous repair mechanisms.
March 23, 2010 at 6:21 AM
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| | Regenerative medicine for retinal diseases: activating endogenous repair mechanisms. Trends Mol Med. 2010 Mar 18; Authors: Karl MO, Reh TA The retina is subject to degenerative diseases that often lead to significant visual impairment. Non-mammalian vertebrates have the remarkable ability to replace neurons lost through damage. Fish, and to a limited extent birds, replace lost neurons by the dedifferentiation of Müller glia to a progenitor state followed by the replication of these neuronal progenitor cells. Over the past five years, studies have investigated whether regeneration can be stimulated in the mouse and rat retina. Several groups have reported that at least some types of neurons can be regenerated in the mammalian retina in vivo or in vitro, and that the regeneration of neurons can be stimulated using growth factors, transcription factors or subtoxic levels of excitatory amino acids. These recent results suggest that some part of the regenerative program that occurs in non-mammalian vertebrates remains in the mammalian retina, and could provide a basis to develop new strategies for retina! l repair in patients with retinal degenerations. PMID: 20303826 [PubMed - as supplied by publisher] | | |
| Vascular differentiation of bone marrow stem cells is directed by a tunable 3D matrix.
March 23, 2010 at 6:21 AM
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| | Vascular differentiation of bone marrow stem cells is directed by a tunable 3D matrix. Acta Biomater. 2010 Mar 16; Authors: Zhang G, Drinnan CT, Geuss LR, Suggs LJ Microenvironmental cues are critical for regulating cell behavior and fate. The roles that matrix mechanical signals play in regulating cell behavior have recently been elucidated. An artificial matrix that can maintain appropriate characteristics for transplanted stem cells is therefore needed to achieve a desired cell phenotype. The objective of this study was to develop a 3D matrix with tunable physical and mechanical properties and investigate their effects on mesenchymal stem cell (MSC) differentiation towards vascular cell types. In this study, we developed an extracellular (ECM) microenvironment by modifying fibrinogen with various polyethylene glycol (PEG) derivatives. We hypothesized that adjusting the type of PEG derivative to modify the resultant physical and mechanical characteristics of fibrin would allow for a tunable system for use in culture or in vivo in conjunction with a regenerative medicine strategy. Human MSCs (hMSCs) were entrapped into PEGy! lated fibrin matrices at a density of 50,000 cells/ml, and cell phenotypes were confirmed by immunofluorescent staining as well as oligonucleotide arrays. Vascular phenotypes were correlated to measured mechanical properties and fiber diameters of the PEGylated fibrin matrices. Blocking studies were performed to identify mechanistic factors controlling MSC differentiation through selected blocking of matrix degradation or cell contraction. The cell-matrix interactions were examined in vivo as well. Our results demonstrate that transdifferentiation of MSCs towards an endothelial cell phenotype is profoundly affected by the 3D matrix microenvironment. Our work provides a predictive roadmap for the creation of fibrin-based matrices that support robust endothelial cell gene expression and tubulogenesis. PMID: 20302976 [PubMed - as supplied by publisher] | | |
| Exercise training reduces circulating adiponectin levels in patients with chronic heart failure.
March 23, 2010 at 6:21 AM
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| | Exercise training reduces circulating adiponectin levels in patients with chronic heart failure. Clin Sci (Lond). 2010 Feb;118(4):281-9 Authors: Van Berendoncks AM, Beckers P, Hoymans VY, Possemiers N, Wuytss FL, Vrints CJ, Conraads VM High adiponectin concentrations have emerged as an independent risk factor of outcome inpatients with CHF (chronic heart failure); however, modification of adiponectin in CHF patients has not been assessed to date. The aim of the present study was to investigate the effect of exercise training on adiponectin levels in CHF patients. A total of 80 patients with CHF due to systolic dysfunction were included. The effect of 4 months exercise training was studied in 46 patients,whereas the remaining 34 untrained CHF patients served as a sedentary control group. Circulating adiponectin concentrations, exercise capacity, anthropometric data and NT-proBNP (N-terminal pro-brain natriuretic peptide) levels were assessed. Adiponectin levels were significantly higher in CHF patients compared with healthy subjects [9.3 (7.1-16.1) and 4.9 (3.9-8.6) mg/l respectively;P=0.015]. Stratification of CHF patients according to tertiles of NT-proBNP revealed an increase in adiponectin wi! th disease severity (P<0.0001). Exercise training reduced circulating adiponectin levels in CHF patients [10.7 (7.2-17.6) mg/l before training to 9.4 (5.9-14.8) mg/l after training;P=0.013], whereas no changes were observed in the sedentary CHF group [9.0 (7.0-13.5) mg/l before training and 10.1 (6.0-15.7) mg/l after a similar time interval]. A significant time x group interaction (P=0.008) was observed for the mean change in adiponectin between the trained and untrained CHF patients. Adiponectin concentrations were positively associated with NT-proBNP and HDL (high-density lipoprotein)-cholesterol and negatively correlated with BMI (body mass index), triacylglycerols and exercise capacity. In conclusion, circulating adiponectin concentrations are higher in CHF patients compared with healthy subjects and increase with disease severity.Exercise training for 4 months lowers circulating adiponectin levels. PMID: 19656085 [PubMed - indexed for MEDLINE] | | |
| Tissue-engineered cartilage of porcine and human origin as in vitro test system in arthritis research.
March 23, 2010 at 6:04 AM
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| | Tissue-engineered cartilage of porcine and human origin as in vitro test system in arthritis research. Biotechnol Prog. 2010 Feb 16; Authors: Göhring AR, Lübke C, Andreas K, Kaps C, Häupl T, Pruss A, Perka C, Sittinger M, Ringe J The increasing prevalence of cartilage destruction during arthritis has entailed an intensified amount for in vitro cartilage models to analyze pathophysiological processes and to screen for antirheumatic drugs. Tissue engineering offers the opportunity to establish highly organized 3D cell cultures facilitating the formation of in vitro models that reflect the human situation. We report the comparison of porcine chondrocyte pellet and alginate bead cultures as model systems for human cartilage and the further development into a human system that was applied in an arthritis model. In porcine pellet and alginate cultures, formation of cartilage matrix similar to human matrix was verified by histology and PCR. As alginate beads could be cultivated batch-wise in one well of a multiwell plate, we further developed this setting into a human system. In contrast, each pellet had to be cultivated individually in one well of a multiwell plate, which is time consuming. Foll! owing stimulation of human chondrocyte alginate cultures with conditioned media from human synovial fibroblasts derived from arthritis patients, microarray analysis verified the induction of genes related to cartilage destruction (like MMP10, -12) and inflammation (like IL6, -8 and chemokines). Several genes are coding for proteins that are members of inflammatory and catabolic pathways. Belonging to the most affected pathways, we identified the focal adhesion, cytokine-cytokine receptor interaction, ECM-receptor signalling, Jak-STAT signalling, and toll-like receptor signalling pathways, all relevant in arthritis. Therefore, we demonstrate that engineered cartilage of porcine and human origin represents a powerful in vitro model for cartilage in vivo. (c) 2010 American Institute of Chemical Engineers Biotechnol. Prog., 2010. PMID: 20306542 [PubMed - as supplied by publisher] | | |
| Synthesis and characterization of a laminated hydroxyapatite/gelatin nanocomposite scaffold with controlled pore structure for bone tissue engineering.
March 23, 2010 at 6:04 AM
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| | Synthesis and characterization of a laminated hydroxyapatite/gelatin nanocomposite scaffold with controlled pore structure for bone tissue engineering. Int J Artif Organs. 2010 Feb;33(2):86-95 Authors: Azami M, Samadikuchaksaraei A, Poursamar SA In this study, a nanostructured scaffold was designed for bone repair using hydroxyapatite (HA) and gelatin (GEL) as its main components. Nanopowders of HA were synthesized, and together with GEL, used to engineer a 3-dimensional nanocomposite combining 3 techniques of layer solvent casting, freeze-drying, and lamination. The results show that the scaffold possesses a 3-dimensional interconnected homogenous porous structure with a porosity of 82% and pore sizes ranging from 300 to 500 mum. It has also been shown that mechanical indices are in the range of spongy bones. Cultured osteoblast-like cells (SaOS-2) have shown an excellent level of cell attachment, migration, and penetration into the porosities of the nanocomposite scaffold. Here, we have shown that by a combination of widely available methods with simple experimental operations, nano-HA powders can be synthesi- zed and used to make 3-dimensional HA/GEL nanocomposites in any desired shape, with mechanical! properties comparable to spongy bone. PMID: 20306435 [PubMed - in process] | | |
| Comparative study of different techniques for the sterilization of poly-L-lactide electrospun microfibers: effectiveness vs. material degradation.
March 23, 2010 at 6:04 AM
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| | Comparative study of different techniques for the sterilization of poly-L-lactide electrospun microfibers: effectiveness vs. material degradation. Int J Artif Organs. 2010 Feb;33(2):76-85 Authors: Rainer A, Centola M, Spadaccio C, Gherardi G, Genovese JA, Licoccia S, Trombetta M Electrospinning of biopolymeric scaffolds is a new and effective approach for creating replacement tissues to repair defects and/or damaged tissues with direct clinical application. However, many hurdles and technical concerns regarding biological issues, such as cell retention and the ability to grow, still need to be overcome to gain full access to the clinical arena. Interaction with the host human tissues, immunogenicity, pathogen transmission as well as production costs, technical expertise, and good manufacturing and laboratory practice requirements call for careful consideration when aiming at the production of a material that is available off-the-shelf, to be used immediately in operative settings. The issue of sterilization is one of the most important steps for the clinical application of these scaffolds. Nevertheless, relatively few studies have been performed to systematically investigate how sterilization treatments may affect the properties of electr! ospun polymers for tissue engineering. This paper presents the results of a comparative study of different sterilization techniques applied to an electrospun poly-L-lactide scaffold: soaking in absolute ethanol, dry oven and autoclave treatments, UV irradiation, and hydrogen peroxide gas plasma treatment. Morphological and chemical characterization was coupled with microbiological sterility assay to validate the examined sterilization techniques in terms of effectiveness and modifications to the scaffold. The results of this study reveal that UV irradiation and hydrogen peroxide gas plasma are the most effective sterilization techniques, as they ensure sterility of the electrospun scaffolds without affecting their chemical and morphological features. PMID: 20306434 [PubMed - in process] | | |
| Applications of quorum sensing in biotechnology.
March 23, 2010 at 6:04 AM
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| | Applications of quorum sensing in biotechnology. Appl Microbiol Biotechnol. 2010 Mar 20; Authors: Choudhary S, Schmidt-Dannert C Many unicellular microorganisms use small signaling molecules to determine their local concentration. The processes involved in the production and recognition of these signals are collectively known as quorum sensing (QS). This form of cell-cell communication is used by unicellular microorganisms to co-ordinate their activities, which allows them to function as multi-cellular systems. Recently, several groups have demonstrated artificial intra-species and inter-species communication through synthetic circuits which incorporate components of bacterial QS systems. Engineered QS-based circuits have a wide range of applications such as production of biochemicals, tissue engineering, and mixed-species fermentations. They are also highly useful in designing microbial biosensors to identify bacterial species present in the environment and within living organisms. In this review, we first provide an overview of bacterial QS systems and the mechanisms developed by bacteria! and higher organisms to obstruct QS communications. Next, we describe the different ways in which researchers have designed QS-based circuits and their applications in biotechnology. Finally, disruption of quorum sensing is discussed as a viable strategy for preventing the formation of harmful biofilms in membrane bioreactors and marine transportation. PMID: 20306190 [PubMed - as supplied by publisher] | | |
| Modulation of gene expression and collagen production of anterior cruciate ligament cells through cell shape changes on polycaprolactone/chitosan blends.
March 23, 2010 at 6:04 AM
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| | Modulation of gene expression and collagen production of anterior cruciate ligament cells through cell shape changes on polycaprolactone/chitosan blends. Biomaterials. 2010 Mar 19; Authors: Shao HJ, Lee YT, Chen CS, Wang JH, Young TH Our previous study has illustrated that chitosan could enhance human anterior cruciate ligament (ACL) cells to exhibit a dramatic effect on increasing the gene expression of transforming growth factor beta1 (TGF-beta1), which is a specific gene for wound healing and collagen synthesis. However, human ACL cells could not adhere and proliferate well on chitosan. In order to overcome this drawback, we introduced polycaprolactone (PCL) into chitosan by the method of blending in this study. It was found that the morphology, viability and gene expression of human ACL cells on the chitosan/PCL blends could be effectively regulated. With the increase of PCL content in blends, human ACL cells presented more flatten shape, well-organized cytoskeleton, and higher proliferated ability. Compared to flatten shape, human ACL cells with round shape exhibited higher levels of mRNA expression of TGF-beta1 and collagen type III through 3-day culture period. Furthermore, these blende! d materials could upregulate protein synthesis of human ACL cells, which corresponded to their gene expressions. Therefore, it is possible to combine the advantages of chitosan and PCL to create a new blended material, which could control cellular morphologies specifically, and further to regulate the gene expression and protein production of cells for specific applications. We expected this concept, controlling the cell shape through biomaterial to modulate the behavior of cells, could provide a new vision for the material selection of ligament tissue engineering. PMID: 20304482 [PubMed - as supplied by publisher] | | |
| The use of decellularized adipose tissue to provide an inductive microenvironment for the adipogenic differentiation of human adipose-derived stem cells.
March 23, 2010 at 6:04 AM
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| | The use of decellularized adipose tissue to provide an inductive microenvironment for the adipogenic differentiation of human adipose-derived stem cells. Biomaterials. 2010 Mar 19; Authors: Flynn LE The development of an engineered adipose tissue substitute, capable of supporting reliable, predictable, and complete fat tissue formation, would be of significant value in the fields of plastic and reconstructive surgery. Towards the goal of engineering an optimized microenvironment for adipogenesis, a decellularization strategy was developed for adipose tissue, which yielded 3-D scaffolds with preserved extracellular matrix architecture. A significant volume of scaffolding material could be obtained from a human tissue source that is commonly discarded. Histology, immunohistochemistry, and scanning electron microscopy confirmed the efficacy and reproducibility of the approach, and also indicated that the basement membrane was conserved in the processed matrix, including laminin and collagen type IV. Seeding experiments with human adipose-derived stem cells indicated that the decellularized adipose tissue (DAT) provided an inductive microenvironment for adipogene! sis, supporting the expression of the master regulators PPARgamma and CEBPalpha, without the need for exogenous differentiation factors. High levels of adipogenic gene expression and glycerol-3-phosphate dehydrogenase activity were observed in the induced DAT scaffolds, as compared to cells grown in monolayer or cell aggregate culture. The protein data emphasized the importance of the cell donor source in the development of tissue-engineering strategies for large-volume soft tissue regeneration. PMID: 20304481 [PubMed - as supplied by publisher] | | |
| Tissue engineering and biotechnology in general thoracic surgery.
March 23, 2010 at 6:04 AM
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| | Tissue engineering and biotechnology in general thoracic surgery. Eur J Cardiothorac Surg. 2010 Mar 18; Authors: Molnar TF, Pongracz JE Public interest in the recent progress of tissue engineering, a special line of biotechnology, makes the current review on thoracic surgery highly relevant. In this article, techniques, materials and cellular processes are discussed alongside their potential applications in tissue repair. Different applications of tissue engineering in tracheo-bronchial replacement, lung tissue cultures and chest-wall reconstruction are also summarised in the article. Potential tissue engineering-based solutions for destructive, chronic lung-injury-related conditions and replacement of tubular structures in the central airways are also examined. PMID: 20303776 [PubMed - as supplied by publisher] | | |
| The synergistic effects of 3-D porous silk fibroin matrix scaffold properties and hydrodynamic environment in cartilage tissue regeneration.
March 23, 2010 at 6:04 AM
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| | The synergistic effects of 3-D porous silk fibroin matrix scaffold properties and hydrodynamic environment in cartilage tissue regeneration. Biomaterials. 2010 Mar 18; Authors: Wang Y, Bella E, Lee CS, Migliaresi C, Pelcastre L, Schwartz Z, Boyan BD, Motta A Autologous cell-based tissue engineering using three-dimensional porous scaffolds has provided a good option for the repair of cartilage defects. Silk fibroin-based scaffolds are naturally degradable materials with excellent biocompatibility and robust mechanical properties, indicating potential applications in cartilage tissue engineering. In this study, silk fibroin scaffolds prepared by freeze-drying (FD) and salt-leaching (SL300 and SL500) were fully characterized and used to study the effects of silk fibroin scaffold properties on chondrocyte attachment, proliferation and differentiation. The synergistic effects of scaffold properties and hydrodynamic environment generated by in vitro rocking culture were also investigated using static cultures as control. FD scaffolds with small pore size and lower porosity increased cell attachment but inhibited cell penetration and limited cell proliferation and differentiation. In contrast, SL scaffolds displaying a bigge! r pore size, higher porosity and crystallinity resulted in homogenous cell distribution, increasing cell proliferation and advanced chondrocyte differentiation in terms of their spherical morphology, predominant chondrogenic gene expression and abundant cartilaginous extracellular matrix production. A hydrodynamic environment was beneficial to chondrocyte proliferation, differentiation, and integrin gene expression in a pore size dependent manner with superior cartilage matrix production but limited hypertrophic differentiation obtained using chondrocyte-seeded SL500 scaffolds. Integrin alpha5beta1 might mediate these effects. Chondrocyte/SL500 silk fibroin constructs obtained under in vitro rocking culture might serve as an excellent implant for in vivo cartilage defect reparation. PMID: 20303584 [PubMed - as supplied by publisher] | | |
| The effect of a laminin-5-derived peptide coated onto chitin microfibers on re-epithelialization in early-stage wound healing.
March 23, 2010 at 6:04 AM
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| | The effect of a laminin-5-derived peptide coated onto chitin microfibers on re-epithelialization in early-stage wound healing. Biomaterials. 2010 Mar 18; Authors: Min SK, Lee SC, Hong SD, Chung CP, Park WH, Min BM Considerable effort has been directed towards regenerating defective tissues using tissue-engineering methods. Recently, peptides have been recognized as a valuable scientific tool in the field of tissue-engineering. The PPFLMLLKGSTR motif of the human laminin-5 alpha3 chain has been previously reported to promote keratinocyte survival; however, the in vivo effects of the PPFLMLLKGSTR motif have not yet been studied. These studies raised the hypothesis that a laminin-5-derived peptide can promote wound healing by accelerating re-epithelialization in vivo. To examine this hypothesis, we applied chitin microfibrous matrices coated with the PPFLMLLKGSTR motif in both rat and rabbit full-thickness cutaneous wound models. Compared with vehicle-treated and peptide-treated cutaneous wounds, the application significantly promoted early-stage wound healing by accelerating re-epithelialization, notably reduced inflammatory cell infiltration, and prominently enhanced fibrobl! ast proliferation. These findings support our hypothesis that the PPFLMLLKGSTR motif acts as a very effective wound healing accelerator by enhancing re-epithelialization. PMID: 20303583 [PubMed - as supplied by publisher] | | |
| Hydroxyapatite nucleation and growth mechanism on electrospun fibers functionalized with different chemical groups and their combinations.
March 23, 2010 at 6:04 AM
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| | Hydroxyapatite nucleation and growth mechanism on electrospun fibers functionalized with different chemical groups and their combinations. Biomaterials. 2010 Mar 18; Authors: Cui W, Li X, Xie C, Zhuang H, Zhou S, Weng J Controlled nucleation and growth of hydroxyapatite (HA) crystals on electrospun fibers should play important roles in fabrication of composite scaffolds for bone tissue engineering, but no attempt has been made to clarify the effects of chemical group densities and the cooperation of two and more groups on the biomineralization process. The aim of the current study was to investigate into HA nucleation and growth on electrospun poly(dl-lactide) fibers functionalized with carboxyl, hydroxyl and amino groups and their combinations. Electrospun fibers with higher densities of carboxyl groups, combination of hydroxyl and carboxyl groups with the ratio of 3/7, and combination of amino, hydroxyl and carboxyl groups with the ratio of 2/3/5 were favorable for HA nucleation and growth, resulting in higher content and lower crystal size of formed HA. Carboxyl groups were initially combined with calcium ions through electrostatic attraction, and the introduction of hydroxyl ! groups could modulate the distance between carboxyl groups. The introduction of amino groups may lead to the inner ionic bonding with carboxyl groups, but can accelerate phosphate ions to form HA through a chelate ring with the calcium ion and carbonyl oxygen. The biological evaluation indicated that the mineralized scaffolds acted as an excellent cell support to maintain desirable cell-substrate interactions, to provide favorable conditions for cell proliferation and to stimulate the osteogenic differentiation. PMID: 20303582 [PubMed - as supplied by publisher] | | |
| Identification of light and dark hypertrophic chondrocytes in mouse and rat chondrocyte pellet cultures.
March 23, 2010 at 6:04 AM
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| | Identification of light and dark hypertrophic chondrocytes in mouse and rat chondrocyte pellet cultures. Tissue Cell. 2010 Mar 18; Authors: Chen KS, Tatarczuch L, Ahmed Y, Huang HH, Mirams M, Pagel CN, Mackie EJ Hypertrophic "light" and "dark" chondrocytes have been reported as morphologically distinct cell types in growth cartilage during endochondral ossification in many species, but functional differences between the two cell types have not been described. The aim of the current study was to develop a pellet culture system using chondrocytes isolated from epiphyseal cartilage of neonatal mice and rats, for the study of functional differences between these two cell types. Hypertrophic chondrocytes resembling those described in vivo were observed by light and electron microscopy in sections of pellets treated with triiodothyronine, 1% fetal calf or mouse serum, 10% fetal calf serum or 1.7MPa centrifugal pressure at day 14, and in pellets cultured with insulin or 0.1% fetal calf or mouse serum at day 21. A mixed population of light and dark chondrocytes was found in all conditions leading to induction of chondrocyte hypertrophy. This rodent culture system allows the diffe! rentiation of light and dark chondrocytes under various conditions in vitro and will be useful for future studies on tissue engineering and mechanisms of chondrocyte hypertrophy. PMID: 20303561 [PubMed - as supplied by publisher] | | | | 
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