Abstract: Objective To investigate whether human bone marrow mesenchymal stem cells（HMSCs） are able to differentiate, in vitro, into corneal epithelial-like cells. Methods The primary human corneal keratocytes (HCFs) were obtained from the corneal stromal pieces by tissue culture, and the HMSCs were isolated by density gradient centrifugalization. Both the HMSCs and HCFs were identified according to their morphological characterizes, and the protein expression of CD29 and vimentin were analyzed by immunocytochemistry. To induce cells differentiation, HMSCs were cultured by establishing epithelial culture microenvironment in a co-culture model. Cells were characterized by phase contrast microscopy observation. Using immunocytochemistry，we confirmed the protein presence of cornea-specific cytokeratin 12 (CK12) in differentiated cells. What is more, the CK12 mRNA in differentiated cells was analyzed by reverse transcriptasepolymerase chain reaction（RT-PCR）.Results Most of the adherent HCFs and HMSCs were in spindle-shape, and perfectly align in a certain direction of the whirlpool-like shape while cells were grown to near confluence. HMSCs positively stained for CD29 and HCFs expressed Vimentin. HMSCs changing shape toward irregular polygon morphology after co-culture with HCFs over time, and the differentiating cells formed cell clusters some of which resembled epithelial-like cells. The expression of CK12 was positive for immunocytochemistry staining in differentiated cells, and further confirmed by RT-PCR. These results indicated that the differentiated cells acquired characteristics similar to those of corneal epithelial. Conclusion HMSCs isolated from human bone marrow were capable of differentiating into epithe1ial-like cells and possess the phenotypical characteristics of corneal epithe1ial.

Key words: Mesenchymal stem cells, Cell culture, Differentiation, Cornea