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| Transcriptional and translational control of C/EBPs: The case for "deep" genetics to understand physiological function.
July 27, 2010 at 9:28 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 27, 2010 at 9:28 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] | | |
| Identification of human placenta-derived mesenchymal stem cells involved in re-endothelialization.
July 27, 2010 at 9:28 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 27, 2010 at 9:28 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 27, 2010 at 9:28 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 27, 2010 at 9:28 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 27, 2010 at 9:28 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 27, 2010 at 9:28 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 27, 2010 at 9:28 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 27, 2010 at 9:28 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 27, 2010 at 9:28 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 27, 2010 at 9:28 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 27, 2010 at 9:28 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 27, 2010 at 9:28 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 27, 2010 at 9:28 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 27, 2010 at 9:28 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 27, 2010 at 9:28 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 27, 2010 at 9:28 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 27, 2010 at 9:28 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 27, 2010 at 9:28 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] | | |
| Visualization of the cellulose biosynthesis and cell integration into cellulose scaffolds.
July 27, 2010 at 9:28 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 27, 2010 at 9:28 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 27, 2010 at 9:28 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 27, 2010 at 9:28 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 27, 2010 at 9:28 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 27, 2010 at 9:28 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 27, 2010 at 9:28 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] | | | | 
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