The Committed Differentiation And Its Mechanism Of Rhesus Bone Marrow Mesenchymal Stem Cells

The repair of lacerated tendon is a common problem of surgery, and no methods to treat it are good enough. With the development of tendon tissue engineering, new methods of healing lacerated tendon are emerging. Tenocytes are high-differentiated cells, and have the limited potential of replication. In Vitro proliferation of it could not provide enough seed cells to tendon tissue engineering. Bone marrow mesenchymal stem cells (MSCs) are thought to be self-renewing and multilineage potential cells, which are present in bone marrow stroma. MSCs have the potential of differentiation into the tissue from mesenchymal, ectoderm, and even from endoderm. In addition, MSCs do not elicit alloreactive lymphocyte proliferative response and modulate immune response. It can be transplantable between HLA-incompatible individuals. Therefore, MSCs could serve as seed cells in tendon tissue engineering.To establish a method for isolation and culture of MSCs, MSCs were isolated from non-sapient primate rhesus bone marrow aspirate, and cultured in mesenchymal stem cells growth medium (MSCGM). MSCs were separated by their adherent ability. To identify the features of the isolated cells, the ALPase activity and the features of surface antigen and cell stroma protein were measured by immunocytochemistry and flow cytometry. The results indicated the-3-isolated cells were not hemopoietic stem cells or fibroblasts, but undifferentiated MSCs, and the purity of the cells was high. The cell cycle analysis of MSCs showed its high potential of proliferation. Multipotent differentiation ability of the cultured MSCs was confirmed in nude mouse in vivo experiment. The telomerase activity of MSCs detected by In situ hybridization was positive. The committed differentiation of MSCs into tenocyte induced by bone morphogenetic protein (BMP) 12 gene transfer. The phenotypic features of transfected cells, which were different from parent MSCs, were similar to tenocytes; and these changes were determined by morphological observation, RT-PCR and flow cytometry. Cell cycle analysis showed the transfected cells maintained active proliferation ability resembling with parent MSCs. Western blotting for Smad4 was performed on transfected MSCs extracts, and it showed Smad pathway involved in the process of the committed differentiation of MSCs into tenocytes.To sum up, bone marrow MSCs were optional seed cells applying to tendon tissue engineering.