Skin epithelial cells in mice from umbilical cord blood mesenchymal stem cells

The purpose of this study was investigation of the potential to isolate mesenchymal stem cells (MSCs) from human umbilical cord blood (UCB) and differentiate them into epithelial cells in mouse skin tissues. Mononuclear cells (MNCs) from UCB (UCB-MNCs) were isolated and induced to MSCs in culture. UCB-MSCs were transfected with pEGFP and labeled with PKH26 dye. eGFP-transfected and PKH26-labeled UCB-derived MSCs were purified by flow cytometry to gate purified eGFP(+) PKH26(+) cells and transplanted at a single clone level into injured nude Balb/C mice by tail vein injection. The phenotype of cultured UCB-MSCs, the expression of human cytokeratins and the expression of eGFP(+) PKH26(+) cells in mouse skin tissues were examined by flow cytometry. Human HLA-1 antigen and cytokeratin 10 (CK10) were detected by direct immunofluorescence on mouse skin tissue sections and flow cytometry. Sry gene (sex-determining region of Y chromosome) was detected by PCR reaction. The results showed that MSCs were isolated from UCB and had heterogeneous morphology and growth potential. Moreover, UCB-derived MSCs localized into mouse skin tissues and differentiated into skin epithelial cells confirmed by in vivo cell tracking and human antigen detection. At two weeks after transplant, a number of eGFP(+) PKH26(+) cells were detected in recipient mouse skin tissues. The detection of sry gene and HLA-1 antigen further confirmed that the human UCB-derived cells were present in recipient mouse skin tissues. Human cells localizing to mouse skin and differentiating into skin epithelial cells were demonstrated by cytokeratins (CK) 8 and 10 expression during flow cytometry, and CK10 expression on injured skin tissue section by direct immunofluorescence.

UCB-derived MSCs localized to injured skin in vivo and differentiated into epithelial phenotypes. The results demonstrate that UCB-derived MSCs contribute to skin tissue regeneration in vivo and may be an ideal cell source for therapy of skin epithelial tissue injury, including burns.