| Acoustic tweezers can position tiny objects
August 28, 2009 at 2:28 pm
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| Bioluminescent Imaging Demonstrates Transplanted Human Embryonic Stem Cell-derived Cd34(+) Cells Preferentially Develop into Endothelial Cells.
August 28, 2009 at 12:03 pm
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| | Bioluminescent Imaging Demonstrates Transplanted Human Embryonic Stem Cell-derived Cd34(+) Cells Preferentially Develop into Endothelial Cells. Stem Cells. 2009 Aug 26; Authors: Tian X, Hexum MK, Penchev VR, Taylor RJ, Shultz LD, Kaufman DS Human embryonic stem cells (hESCs) provide an important resource for novel regenerative medicine therapies and have been used to derive diverse cell populations, including hematopoietic and endothelial cells. However, it remains a challenge to achieve significant engraftment of hESC-derived blood cells when transplanted into animal models. To better understand mechanisms that enhance or limit the in vivo developmental potential of hESC-derived cells, we utilized hESCs that express firefly luciferase (luc) to allow non-invasive, real-time bioluminescent imaging of hESC-derived CD34(+) cells transplanted into the liver of neonatal immunodeficient mice. Serial imaging demonstrated stable engraftment and expansion of the luc(+) hESC-derived cells in vivo over several months. While we found that these hESC-derived CD34(+) cells have bipotential ability to generate both hematopoietic and endothelial lineages in vitro, these studies demonstrate preferential differentiation into endothelial cells in vivo, with only low levels of hematopoietic cell engraftment. Therefore, these studies reveal key differences in the developmental potential of hESC-derived cells using in vitro and in vivo analyses. While transplanted hESC-derived CD34(+) cells are well suited for revascularization therapies, additional measures are needed to provide higher levels of long-term hematopoietic engraftment. PMID: 19711457 [PubMed - as supplied by publisher] |
| Clone and Gene Specific Aberrations of Parental Imprinting in Human Induced Pluripotent Stem Cells.
August 28, 2009 at 12:03 pm
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| | Clone and Gene Specific Aberrations of Parental Imprinting in Human Induced Pluripotent Stem Cells. Stem Cells. 2009 Aug 26; Authors: Pick M, Stelzer Y, Bar-Nur O, Mayshar Y, Eden A, Benvenisty N Genomic imprinting is an epigenetic phenomenon whereby genes are expressed in a mono-allelic manner, which is inherited either maternally or paternally. Expression of imprinted genes has been examined in human embryonic stem (ES) cells, and the cells show a substantial degree of genomic imprinting stability. Recently, human somatic cells were reprogrammed to a pluripotent state using various defined factors. These induced pluripotent stem (iPS) cells are thought to have a great potential for studying genetic diseases and to be a source of patient specific stem cells. Thus studying the expression of imprinted genes in these cells is important. We examined the allelic expression of various imprinted genes in several iPS cell lines and found polymorphisms in four genes. After analyzing parent-specific expression of these genes we observed overall normal monoallelic expression in the iPS cell lines. However, we found biallelic expression of the H19 gene in one iPS cell line and biallelic expression of KCNQ10T1 gene in another iPS cell line. We further analyzed the DNA methylation levels of the promoter region of the H19 gene and found that the cell line that showed biallelic expression had undergone extensive DNA demethylation. Additionally we studied the imprinting gene expression pattern of multiple human iPS cell lines via DNA microarray analyses and divided the pattern of expression into three groups: 1) Genes which showed significantly stable levels of expression in iPS cells, 2) Genes which showed a substantial degree of variability of expression both in human ES and iPS cells and 3) Genes which showed aberrant expression levels in some human iPS cell lines as compared to human ES cells. In general, iPS cells have a rather stable expression of their imprinted genes. However, we found a significant number of cell lines with abnormal expression of imprinted genes, and thus we believe that imprinted genes should be examined for each cell line if it is to be used for studying genetic diseases or for the purpose of regenerative medicine. PMID: 19711451 [PubMed - as supplied by publisher] |
| Regenerative medicine in the treatment of peripheral arterial disease.
August 28, 2009 at 12:03 pm
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| | Regenerative medicine in the treatment of peripheral arterial disease. J Cell Biochem. 2009 Aug 26; Authors: Sneider EB, Nowicki PT, Messina LM The last decade has witnessed a dramatic increase in the mechanistic understanding of angiogenesis and arteriogenesis, the two processes by which the body responds to obstruction of large conduit arteries. This knowledge has been translated into novel therapeutic approaches to the treatment of peripheral arterial disease, a condition characterized by progressive narrowing of lower extremity arteries and heretofore solely amenable to surgical revascularization. Clinical trials of molecular, genetic, and cell-based treatments for peripheral artery obstruction have generally provided encouraging results. J. Cell. Biochem. (c) 2009 Wiley-Liss, Inc. PMID: 19711369 [PubMed - as supplied by publisher] |
| Efficient expansion of mesenchymal stromal cells from umbilical cord under low serum conditions.
August 28, 2009 at 12:03 pm
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| | Efficient expansion of mesenchymal stromal cells from umbilical cord under low serum conditions. Cytotherapy. 2009 Aug 26;:1-11 Authors: Girdlestone J, Limbani VA, Cutler AJ, Navarrete CV Background aims Mesenchymal stromal cells (MSC) are of clinical interest for their potential use in regenerative medicine and immunotherapy. Originally derived from bone marrow (BM), MSC have now been isolated from most tissues, including umbilical cord (UC) and UC blood (UCB). If MSC from UC are biologically equivalent to those from BM, they would be attractive as a readily available and non-invasive source for cellular therapies. Methods Sections of UC were separated into vascular and Wharton's jelly (WJ) fractions, which were then digested individually to release MSC that were isolated by plastic adherence in a 10% fetal calf serum (FCS) medium, or a low serum medium designed for multipotent adult progenitor cells (MAPC). The resulting perivascular (PV) and WJ MSC lines were assayed for expression of characteristic markers, and differentiation and immunosuppressive properties. Results MSC lines were readily derived from most UC tested. Cells grown in MAPC medium (MM) tended to be smaller and more elongated and expressed more nestin, but did not differ substantially in their growth rate, expression of other markers, or differentiation capacity. All UC lines tested were adipogenic but poorly osteogenic, and were equivalent in their ability to suppress T-cell proliferation induced by phytohemagglutinin (PHA), activation beads and allostimulation. Conclusions UC is a convenient, efficient source of MSC that can be expanded under low serum conditions for application to future studies of tissue regeneration and immunosuppression. PMID: 19711214 [PubMed - as supplied by publisher] |
| Osteogenic properties of late adherent subpopulations of human bone marrow stromal cells.
August 28, 2009 at 12:03 pm
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| | Osteogenic properties of late adherent subpopulations of human bone marrow stromal cells. Histochem Cell Biol. 2009 Aug 27; Authors: Leonardi E, Ciapetti G, Baglìo SR, Devescovi V, Baldini N, Granchi D The nonadherent (NA) population of bone-marrow-derived mononuclear cells (MNC) has been demonstrated to be a source of osteogenic precursors in addition to the plastic-adherent mesenchymal stromal cells (MSC). In the current study, two subpopulations of late adherent (LA) osteoprogenitors were obtained by subsequent replating of NA cells, and their phenotypic, functional, and molecular properties were compared with those of early adherent (EA) MSC. Approximately 35% of MNC were LA cells, and they acquired a homogeneous expression of MSC antigens later than EA cells. In EA-MSC, the alkaline phosphatase (ALP) activity increased significantly from time of seeding to the first confluence, whereas in LA cells it raised later, after the addition of mineralization medium. All subpopulations were able to produce type I collagen and to deposit extracellular matrix with organized collagen fibrils. The proportion of large colonies with more than 50% of ALP positive cells as well as the calcium content was higher in LA than in EA cells. Molecular analysis highlighted the upregulation of bone-related genes in LA-MSC, especially after the addition of mineralization medium. Our results confirm that bone marrow contains LA osteoprogenitors which exhibit a delay in the differentiation process, despite an osteogenic potential similar to or better than EA-MSC. LA cells represent a reservoir of osteoprogenitors to be recruited to gain an adequate bone tissue repair and regeneration when a depletion of the most differentiated component occurs. Bone tissue engineering and cell therapy strategies could take advantage of LA cells, since an adequate amount of osteogenic MSCs may be obtained while avoiding bone marrow manipulation and cell culture expansion. PMID: 19711092 [PubMed - as supplied by publisher] |
| Mesenchymal stem cells promote oligodendroglial differentiation in hippocampal slice cultures.
August 28, 2009 at 12:03 pm
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| | Mesenchymal stem cells promote oligodendroglial differentiation in hippocampal slice cultures. Cell Physiol Biochem. 2009;24(3-4):317-24 Authors: Rivera FJ, Siebzehnrubl FA, Kandasamy M, Couillard-Despres S, Caioni M, Poehler AM, Berninger B, Sandner B, Bogdahn U, Goetz M, Bluemcke I, Weidner N, Aigner L We have previously shown that soluble factors derived from mesenchymal stem cells (MSCs) induce oligodendrogenic fate and differentiation in adult rat neural progenitors (NPCs) in vitro. Here, we investigated if this pro-oligodendrogenic effect is maintained after cells have been transplanted onto rat hippocampal slice cultures, a CNS-organotypic environment. We first tested whether NPCs, that were pre-differentiated in vitro by MSC-derived conditioned medium, would generate oligodendrocytes after transplantation. This approach resulted in the loss of grafted NPCs, suggesting that oligodendroglial pre-differentiated cells could not integrate in the tissue and therefore did not survive grafting. However, when NPCs together with MSCs were transplanted in situ into hippocampal slice cultures, the grafted NPCs survived and the majority of them differentiated into oligodendrocytes. In contrast to the prevalent oligodendroglial differentiation in case of the NPC/MSC co-transplantation, naïve NPCs transplanted in the absence of MSCs differentiated predominantly into astrocytes. In summary, the pro-oligodendrogenic activity of MSCs was maintained only after co-transplantation into hippocampal slice cultures. Therefore, in the otherwise astrogenic milieu, MSCs established an oligodendrogenic niche for transplanted NPCs, and thus, co-transplantation of MSCs with NPCs might provide an attractive approach to re-myelinate the various regions of the diseased CNS. PMID: 19710546 [PubMed - in process] |
| Small Molecule Induction of Neural Crest-like Cells Derived from Human Neural Progenitors.
August 28, 2009 at 10:36 am
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| | Small Molecule Induction of Neural Crest-like Cells Derived from Human Neural Progenitors. Stem Cells. 2009 Aug 26; Authors: Hotta R, Pepdjonovic L, Anderson RB, Zhang D, Bergner AJ, Leung J, Pébay A, Young HM, Newgreen DF, Dottori M Neural crest (NC) cells are stem cells that are specified within the embryonic neuroectodermal epithelium, and migrate to stereotyped peripheral sites for differentiation into many cell types. Several neurocristopathies involve a deficit of NC-derived cells, raising the possibility of stem cell therapy. In Hirschsprung's Disease the distal bowel lacks an enteric nervous system due to a failure of colonisation by NC-derived cells. We have developed a robust method of producing migrating NC-like cells from human embryonic stem cell-derived neural progenitors using a co-culture system of mouse embryonic fibroblasts. Significantly, subsequent exposure to Y27632, a small molecule inhibitor of the Rho effectors ROCKI/II, dramatically increased the efficiency of differentiation into NC-like cells, identified by marker expression in vitro. NC-like cells derived by this method were able to migrate along NC pathways in avian embryos in ovo and within explants of murine bowel, and to differentiate into cells with neuronal and glial markers. This is the first study to report the use of a small molecule to induce cells with NC characteristics from embryonic stem cells that can migrate and generate neurons and support cells in complex tissue. Furthermore, this study demonstrates that small molecule regulators of ROCKI/II signalling may be valuable tools for stem cell research aimed at treatment of neurocristopathies. PMID: 19711454 [PubMed - as supplied by publisher] |
| Osteogenic properties of late adherent subpopulations of human bone marrow stromal cells.
August 28, 2009 at 9:42 am
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| | Osteogenic properties of late adherent subpopulations of human bone marrow stromal cells. Histochem Cell Biol. 2009 Aug 27; Authors: Leonardi E, Ciapetti G, Baglìo SR, Devescovi V, Baldini N, Granchi D The nonadherent (NA) population of bone-marrow-derived mononuclear cells (MNC) has been demonstrated to be a source of osteogenic precursors in addition to the plastic-adherent mesenchymal stromal cells (MSC). In the current study, two subpopulations of late adherent (LA) osteoprogenitors were obtained by subsequent replating of NA cells, and their phenotypic, functional, and molecular properties were compared with those of early adherent (EA) MSC. Approximately 35% of MNC were LA cells, and they acquired a homogeneous expression of MSC antigens later than EA cells. In EA-MSC, the alkaline phosphatase (ALP) activity increased significantly from time of seeding to the first confluence, whereas in LA cells it raised later, after the addition of mineralization medium. All subpopulations were able to produce type I collagen and to deposit extracellular matrix with organized collagen fibrils. The proportion of large colonies with more than 50% of ALP positive cells as well as the calcium content was higher in LA than in EA cells. Molecular analysis highlighted the upregulation of bone-related genes in LA-MSC, especially after the addition of mineralization medium. Our results confirm that bone marrow contains LA osteoprogenitors which exhibit a delay in the differentiation process, despite an osteogenic potential similar to or better than EA-MSC. LA cells represent a reservoir of osteoprogenitors to be recruited to gain an adequate bone tissue repair and regeneration when a depletion of the most differentiated component occurs. Bone tissue engineering and cell therapy strategies could take advantage of LA cells, since an adequate amount of osteogenic MSCs may be obtained while avoiding bone marrow manipulation and cell culture expansion. PMID: 19711092 [PubMed - as supplied by publisher] |
| Reversible mitotic and metabolic inhibition following the encapsulation of fibroblasts in alginate hydrogels.
August 28, 2009 at 9:42 am
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| | Reversible mitotic and metabolic inhibition following the encapsulation of fibroblasts in alginate hydrogels. Biomaterials. 2009 Aug 24; Authors: Hunt NC, Shelton RM, Grover LM Limiting cell proliferation without reducing cell viability for in vivo tissue engineering applications is important in co-culture applications where the growth of one cell type must be inhibited to prevent overgrowth of the scaffold at the expense of another cell type. Also, it is vital for maintaining viability of cells in large constructs before vascularisation occurs. In this study we have shown by means of the Thiazolyl blue (MTT) assay and immuno-staining for proliferating cell nuclear antigen (PCNA) that encapsulating fibroblasts in 2% and 5%w/v calcium-alginate at a density of 7.5x10(5)cells/ml as uniformly dispersed entities, enabled cells to maintain viability and caused a reversible mitotic inhibition. Alginate encapsulation also caused reversible metabolic inhibition as demonstrated by the MTT assay and fluorescent staining for mitochondrial membrane potential. Histological evaluation of the alginate constructs containing fibroblasts showed that mitotic and metabolic inhibition was possibly due to cell isolation during the first five weeks of culture. The alginate scaffold degraded with time releasing encapsulated fibroblasts. Upon implantation to a wound site this should ensure that encapsulated cells are able to replace the damaged tissue after sufficient proliferation of the co-cultured cell type or sufficient vascularisation of the construct. PMID: 19709739 [PubMed - as supplied by publisher] |
| Chemically crosslinkable thermosensitive polyphosphazene gels as injectable materials for biomedical applications.
August 28, 2009 at 9:42 am
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| | Chemically crosslinkable thermosensitive polyphosphazene gels as injectable materials for biomedical applications. Biomaterials. 2009 Aug 24; Authors: Potta T, Chun C, Song SC Chemically crosslinkable and thermosensitive poly(organophosphazenes) containing multiple thiol (-SH) groups along with hydrophobic isoleucine ethyl ester and hydrophilic alpha-amino-omega-methoxy-poly(ethylene glycol) of the molecular weight 550 have been synthesized and characterized as an injectable biomaterial. The aqueous solutions of these polymers were transformed into hydrogel with desired gel strength at body temperature via hydrophobic interactions, and the gel strength was further improved by the cross-linking of thiol groups with crosslinkers, divinyl sulfone (VS) and PEG divinyl sulfone (PEGVS) under physiological conditions. The kinetics of cross-linking behavior of polymer thiol groups with crosslinkers was studied in both in vitro and in vivo conditions. Field Emission-Scanning Electron Microscopy (FE-SEM), swelling experiments, and rheology study of present polymers revealed that the inner three-dimensional hydrogel networks depended on the degree of thiol units in the polymer network. From the in vivo (in mice) degradation studies, the dual cross-linked gels showed to have a controlled degradation. These results demonstrate that the inner network of the hydrogels can be tuned, gel strength and degradation rate can be controlled, and the chemically crosslinkable and thermosensitive poly(organophosphazenes) hold promises for uses as injectable systems for biomedical applications including tissue engineering and protein delivery. PMID: 19709738 [PubMed - as supplied by publisher] |
| Maxillary sinus floor elevation using a tissue-engineered bone complex with beta-TCP and BMP-2 gene-modified bMSCs in rabbits.
August 28, 2009 at 9:42 am
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| | Maxillary sinus floor elevation using a tissue-engineered bone complex with beta-TCP and BMP-2 gene-modified bMSCs in rabbits. Clin Oral Implants Res. 2009 Aug 25; Authors: Jiang XQ, Sun XJ, Lai HC, Zhao J, Wang SY, Zhang ZY Abstract Objectives: To study the effects of maxillary sinus floor elevation by a tissue-engineered bone complex with beta tricalcium phosphate (beta-TCP) and bone morphogenetic protein-2 (BMP-2) gene-modified bone marrow stromal cells (bMSCs) in rabbits. Material and methods: bMSCs derived from New Zealand rabbit bone marrow were cultured and transduced with the adenovirus with BMP-2 (AdBMP-2), adenovirus with enhanced green fluorescent protein gene (AdEGFP) in vitro. Gene transfer efficiency was detected by EGFP expression. These gene-modified autologous bMSCs were then combined with a beta-TCP granule scaffold at a concentration of 2 x 10(7) cells/ml and used to elevate the maxillary sinus floor in rabbits. Twenty rabbits were randomly allocated into groups and sacrificed at weeks 2 and 8. For each time point, 20 maxillary sinus floor elevation surgeries were made bilaterally in 10 rabbits for the following groups (n=5 per group): group A (beta-TCP alone), group B (untransduced bMSCs/beta-TCP), group C (AdEGFP-bMSCs/beta-TCP), and group D (AdBMP-2-bMSCs/beta-TCP). All samples were evaluated by histology and histomorphometric analysis. The fate of implanted bMSCs was traced initially by a confocol fluorescent microscope in the AdEGFP group. Results: Gene transfer efficiency reached up to 60-80% with 50 PFU/cell transduction as demonstrated by fluorescent microscopic analysis in the AdEGFP group. The augmented maxillary sinus height was maintained for the four groups till 8 weeks post-surgery, while new bone area increased over the time. At week 2, bone areas in groups B-D were significantly larger than those in group A, while at week 8, in group D, the BMP-2 gene-enhanced tissue-engineered bone had the largest bone area among the groups (P<0.05, ANOVA). In that group, a mature bone structure was detected in the center of the elevated space. Under a confocal microscope, green fluorescence in newly formed bone was observed for the EGFP group, which suggested that those implanted bMSCs might have contributed to the new bone formation. Conclusion: bMSCs modified with the AdBMP-2 gene can promote new bone formation and maturation in the rabbit maxillary sinus. BMP-2 regional gene therapy and a tissue engineering technique could be effectively used in maxillary sinus elevation and bone regeneration. To cite this article: Jiang X-Q, Sun X-J, Lai H-C, Zhao J, Wang S-Y, Zhang Z-Y. Maxillary sinus floor elevation using a tissue-engineered bone complex with beta-TCP and BMP-2 gene-modified bMSCs in rabbits. Clin. Oral Impl. Res. xx, 2009; 000-000. PMID: 19709061 [PubMed - as supplied by publisher] |
| Controllable Expansion of Primary Cardiomyocytes by Reversible Immortalization.
August 28, 2009 at 9:42 am
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| | Controllable Expansion of Primary Cardiomyocytes by Reversible Immortalization. Hum Gene Ther. 2009 Aug 26; Authors: Vunjak-Novakovic G, Zhang Y, Nuglozeh E, Toure F, Schmidt AM Cardiac tissue engineering will remain only a prospect unless large numbers of therapeutic cells can be provided, either from small samples of cardiac cells or from stem cell sources. In contrast to most adult cells, cardiomyocytes are terminally differentiated and cannot be expanded in culture. We explored the feasibility of enabling the in vitro expansion of primary neonatal rat cardiomyocytes by lentivector-mediated cell immortalization, and then reverting the phenotype of the expanded cells back to cardiomyocytes state. Primary rat cardiomyocytes were transduced with SV40 large T Antigen (TAg) or Bmi-1 followed by human telomerase (hTERT) gene, the cells were expanded, and the transduced genes were removed by adenovirus vector expressing Cre recombinase. The TAg gene was more efficient in cell transduction than Bmi-1/hTERT gene, based on the rate of cells proliferation. Immortalized cells exhibited the morphological features of dedifferentiation (increased vimentin expression, reduced expression of troponin I and Nkx2.5) along with the continued expression of cardiac markers (alpha-actin, connexin 43 (Cx-43), calcium transients). After the immortalization was reversed, cells returned to their differentiated state. This strategy for controlled expansion of primary cardiomyocytes by gene transfer has potential for providing large amounts of patient's own cardiomyocytes for cell therapy, and the cardiomyocytes derived by this method could be a useful cellular model to study cardiogenesis. PMID: 19708763 [PubMed - as supplied by publisher] |
| Patellofemoral full-thickness chondral defects treated with second-generation autologous chondrocyte implantation: results at 5 years' follow-up.
August 28, 2009 at 9:42 am
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| | Patellofemoral full-thickness chondral defects treated with second-generation autologous chondrocyte implantation: results at 5 years' follow-up. Am J Sports Med. 2009 Jun;37(6):1083-92 Authors: Gobbi A, Kon E, Berruto M, Filardo G, Delcogliano M, Boldrini L, Bathan L, Marcacci M BACKGROUND: Patellofemoral lesions represent a very troublesome condition to treat for orthopaedic surgeons; however, second-generation autologous chondrocyte implantation (ACI) seems to offer an interesting treatment option with satisfactory results at short-term follow-up. HYPOTHESIS: Hyaluronan-based scaffold seeded with autologous chondrocytes is a viable treatment for the damaged articular surface of the patellofemoral joint. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Among a group of 38 patients treated for full-thickness patellofemoral chondral lesions with second-generation ACI, we investigated 34 who were available for final follow-up at 5 years. These 34 had chondral lesions with a mean size of 4.45 cm(2). Twenty-one lesions were located on the patella, 9 on the trochlea, and 4 patients had multiple lesions: 3 had patellar and trochlear lesions, and 1 had patellar and lateral femoral condyle lesions. Twenty-six lesions (76.47%) were classified as International Cartilage Repair Society (ICRS) grade IV A or B, 5 lesions (14.70%) were grade IIIC, and 3 (8.82%) were lesions secondary to osteochondritis dissecans (OCD). Results were evaluated using the International Knee Documentation Committee (IKDC) 2000 subjective and objective scores, EuroQol (EQ) visual analog scale (VAS), and Tegner scores at 2 and 5 years. Eight patients had second-look arthroscopy and biopsies. RESULTS: All the scores used demonstrated a statistically significant improvement (P < .0005) at 2 and 5 years' follow-up. Objective preoperative data improved from 8 of 34 (23.52%) normal or nearly normal knees to 32 of 34 (94.12%) at 2 years and 31 of 34 (91.17%) at 5 years after transplantation. Mean subjective scores improved from 46.09 points preoperatively to 77.06 points 2 years after implantation and 70.39 at 5 years. The Tegner score improved from 2.56 to 4.94 and 4.68, and the EQ VAS improved from 56.76 to 81.47 and 78.23 at 2 and 5 years' follow-up, respectively. A significant decline of IKDC subjective and Tegner scores was found in patients with multiple and patellar lesions from 2 to 5 years' follow-up. Second-look arthroscopies in 8 cases revealed the repaired surface to be nearly normal with biopsy samples characterized as hyaline-like in appearance. CONCLUSION: Hyaluronan-based scaffold seeded with autologous chondrocytes can be a viable treatment for patellofemoral chondral lesions. PMID: 19465733 [PubMed - indexed for MEDLINE] |
| In vitro organogenesis from undifferentiated cells in Xenopus.
August 28, 2009 at 9:42 am
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| | In vitro organogenesis from undifferentiated cells in Xenopus. Dev Dyn. 2009 Jun;238(6):1309-20 Authors: Asashima M, Ito Y, Chan T, Michiue T, Nakanishi M, Suzuki K, Hitachi K, Okabayashi K, Kondow A, Ariizumi T Amphibians have been used for over a century as experimental animals. In the field of developmental biology in particular, much knowledge has been accumulated from studies on amphibians, mainly because they are easy to observe and handle. Xenopus laevis is one of the most intensely investigated amphibians in developmental biology at the molecular level. Thus, Xenopus is highly suitable for studies on the mechanisms of organ differentiation from not only a single fertilized egg, as in normal development, but also from undifferentiated cells, as in the case of in vitro organogenesis. Based on the established in vitro organogenesis methods, we have identified many genes that are indispensable for normal development in various organs. These experimental systems are useful for investigations of embryonic development and for advancing regenerative medicine. Developmental Dynamics 238:1309-1320, 2009. (c) 2009 Wiley-Liss, Inc. PMID: 19441056 [PubMed - indexed for MEDLINE] |
| The effect of porosity and mechanical property of a synthetic polymer scaffold on repair of osteochondral defects.
August 28, 2009 at 9:42 am
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| | The effect of porosity and mechanical property of a synthetic polymer scaffold on repair of osteochondral defects. Int Orthop. 2009 Jun;33(3):821-8 Authors: Ikeda R, Fujioka H, Nagura I, Kokubu T, Toyokawa N, Inui A, Makino T, Kaneko H, Doita M, Kurosaka M We have made three types of poly (DL-lactide-co-glycolide) (PLG) scaffolds (porosity: scaffold I 80 +/- 0.9%, II 85 +/- 0.8%, III 92 +/- 0.7%; compression module determined with 10% strain: scaffold I 0.26 MPa, II 0.091 MPa, III 0.0047 MPa). Osteochondral defects made in the femoral condyle of rabbits were treated with these scaffolds and the possibilities of cartilage repair were investigated histologically. At post-operative weeks 6 and 12, histological scores in the groups of scaffolds II and III were significantly higher than the score in the group of scaffold I. Scaffolds II and III, which have higher porosity than scaffold I, allow better migration of bone marrow cells and better replacement of the scaffold with bone and cartilage than scaffold I. This study suggests that higher porosity allowing bone marrow cells to migrate to the scaffold is important in repairing osteochondral defects. PMID: 18415099 [PubMed - indexed for MEDLINE] | | | 
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