Ultrastructure observation of rhesus bone marrow mesenchymal stem cell after transplantation of cornea / 中华实验眼科杂志

ABSTRACT

BackgroundThe quest to look for seed cells is a hot spot of cornea transplant research in solving the problem of the lack of donor. Bone marrow mesenchymal stem cells(BMSCs) have been successfully induced into retinal ganglion cells(RGCs) in vivo,but the successful induction of BMSCs into corneal endothelial cells has not been reported.Objective This experiment was to study the transplantation of BMSCs on corneal endothelial surface using the splitting Descemet's membrane. MethodsFour healthy adult rhesus monkeys were divided into the experimental group ( 3 monkeys) and control group ( 1 monkey). Mesenchymal stem cells (MSCs) were isolated from bone marrow by density gradient centrifugation combined with adhering means. The cultured cells were identified by flow cytometry and its ability to differentiate was determined by allowing them to differentiate into adipocytes in vitro and labeled by 5-bromodeoxyuridine ( BrdU ) for subsequent identification. Corneal grafts of 7 mm in size with tearing of the Descemet' s membrane were prepared in the experimental group and control group. After labeling by 5-bromodeoxyuridine( BrdU ) ,cultured cells were transplanted onto the endothelial surface of cornea grafts in the experimental group, but no cultured cells were seeded in the graft of the control group. The corneal grafts were then sutured in situ, and were removed 1,2 or 3 months after operation to examine the distribution and connection between transplanted cells and their morphologic changes under the electron microscope. Results High purity MSCs were harvested by density gradient centrifugation combined with adhering method. Cultured cells reached confluency after 12 to 16 days, presenting with a spindle shape and parallel or swirling arrangement. Flow cytometry analysis showed that 94.26％ of cells were positive for CD29,7. 51％ for CD34 and 4. 02％ for CD45. Larger nuclei filled with plastosomes, golgiosomes and rough endoplasmic reticula were found on the graft under the transmission electron microscope( TEM ). After 3 weeks, MSCs were differentiated into adipocytes where Oil Red O staining resulted in an orange-red staining in the cytoplasm and blue staining in the nuclei. The transplanted cells attached loosely on the endothelial surface of the corneal graft and came in contact with each other in one month. The shape of the cells appeared as spindle-shaped and polygonal after 2 months and became tightly packed after 3 months. The positive cells retained the BrdU label and presented with brown nuclei. No endothelia cells grew in the cornea graft in the control group, with an absence of BrdU labeling. Conclusions Mesenchymal stem cells can be transplanted onto the corneal endothelial surface successfully and form a monolayer using the centrifugation method, and present with good survival and proliferation ability.