| Neurodegenerative diseases of the retina are major causes of blindness worldwide. These include the glaucomas, which primarily affect retina ganglion cells, and ischemic retinopathies (including diabetic and hypertensive retinopathies) that affect other populations of retinal neurons are largely retardant and are not sufficient to restore visual function after severe impairment of retinal circuitry. Numerous neuroprotective strategies have been used in an effort to prolong the survival of retinal neurons damaged in models of retinal degeneration. Therapeutic strategies in these models have included delivery of growth factors or cytokines to retard ganglion cell loss or transplantation of retinal or optic nerve glion cells to enhance optic nerve axon regrowth or myelination. These experimental models also often result in degeneration of cells and retinal circuitry is still problematic. Recent advances in stem cell biology have invigorated the potential for achieving partial restoration of visual function after retinal neurodegeneration by augmenting the remaining retinal circuitry. It has been demonstrated that neural progenitor cells, retinal neural progenitor, embryonic retinal progenitor cells can be transplanted to the vitreous chamber and subretina. Recent studies show that bone marrow mesenchymal stem cells are multipotential adult stem cells that contribute to the regeneration of tissues such as bone, cartilage, fat, and muscle. Data suggest that BMMSCs can also be induced to differentiate into neural cells in vivo. Since BMMSCs are adult derived and could potentially be used for autologous transplantation, their use in central nervous system replacement therapy is currently being investigated mainly by either in vivo transplantation studies or in vitro evaluation of differentiation. As we all known, retina is a part of central nervous. However there was little study on differentiation BMMSCs into retinal cells and structures. We separate and purify the BMMSCs by density gradient centrifugation and by adhering to the culture plastic, select suitable culture medium and concentration of serum. Cell surface antigens were examined by immuncytochemistry technique and flow cytometry technique. Alkaline phosphatase (ALPase) was detected by enzyme cytochemistry technique. We also implant BMMSCs into nude mice to examine their pluripotentiality. In vitro BMMSCs were cultivated in the medium containing chemical induction, NGF and BDNF, brain cells-conditioned medium, retinal cells-conditioned medium respectively. Additionally, BMMSCs were incubated with retinal cells-conditioned medium. The morphological changes of the cells we observed under phase contrast microscope, the cells were stained with antiNestin, NSE, NF, GFAP, and Thy1.1. BMMSCs in vitro were transplanted into the eyes of nude mice. Mophological and immunohistochemical examinations were implemented. The morphology and alignment of some differentiated cells were similar to those of the retina of nude mice .Herein in an effort to gain a better understanding of the behavior of transplanted BMMSCs; we used a model of transient ischemia-reperfusion and transplantation of BMMSCs into rat subretina. We detect engraftment, migration and differentiation of Brdu labeled BMMSCs by immunocytofluorescent staining. The cultured cells were characterized by spindle-shaped appearance. Positive expression of CD29, CD44 were detected while CD34, CD45, collagenâ…¡ were negative. Enzyme cyotchemistry evaluation showed that the cultured cells were negative for ALPase. This resulted showed that the cultured cells were not hemopoietic stem cells or fibroblasts but the BMMSCs that had not differentiated. Subcutaneous implantation of BMMSCs into nude mice was performed to observe their differentiation potential to 4 weeks after the implantation. BMMSCs showed the differentiate into such tissue cells as of the bone, cartilage, adipose, skeletal muscle and tendon-like tissue. BMMSCs were cultivated in a medium containing different induction medium. Microscopical... |
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