Abstract
Abstract: :
Purpose: Stem cells currently being used in clinical practice to treat certain ocular surface diseases, are typically isolated from the limbal basal epithelium. They are usually isolated from donor tissue derived from the host itself (autograft), or from a living related or cadaver donor (allograft). The major limitation to the use of retinal stem cell allografts has been the resulting high immunogenic stimulus that ultimately leads to rejection. As a result alternative donor sites need to be investigated. Since the bone marrow is the primary site where self-renewal and differentiation of stem cells occur, the aim of the present study is to assess whether stem cells isolated from the bone marrow (MSC's) may hold potential therapeutic application of ocular diseases. Methods: MSC's were extracted from the femur and tibia of 7-9 week old RCS rats according to an established method and maintained in a basal medium solution. The effects of mechanical cell sorting on MSC's were investigated by labelling cells with CD11b, CD45 and CD90, and then putting them through a FACSVanatge Cell Sorter. MSC's solely expressing CD90 were then sorted out and cell viability, number and morphology assessed. Population profile studies were then performed on primary and subsequent cultures of MSC's, whereby harvested cells were incubated with CD11b, CD45 and CD90 for 1h @4OC. Cells were then washed, filtered and analysed by flow cytometry. Finally, the plasticity of stem cells was assessed with their differentiation into defined cell lineages. Results: Results showed that MSC's were heterogenous in nature, expressing CD90 (74-94%) and CD11b(2-6.3%). Continual passage of marrow stromal cells results in a loss of CD90 expression with no expression evident at p20. Stromal cells of early passage can be easily sorted and results in a primarily pure CD90 culture (95%), without any significant effect on cell viability or morphology. Cultures of CD90+ stem cells can then be successfully induced into the adipocytic and chondrocytic cell lineage when exposed to specifically defined medium. Conclusion: Results obtained in the present study show that MSC's can easily be isolated, cultured and sorted into an almost pure undifferentiated population of cells, though with continual passage their CD90 expression diminishes. These stem cells can then be induced to differentiate into specific cell lineages under strict conditions in vitro and hence hold potential for cell-based therapeutic treatment including ocular diseases.
Keywords: 561 retinal degenerations: cell biology • 517 photoreceptors