OBJECTIVETo investigate the biological characteristics of human keloid-derived stem cells (KDSC) in order to further research its role in keloid pathogenesis.

METHODSHuman keloid specimens were harvested to isolate and select KDSC by enzyme digestion and subculturing. Primary and (or) the third generation of KDSC were collected for identification of biological characteristics as follows. (1) After addition of mouse anti-human monoclonal fluorescent antibodies (CD29-PE, CD34-PE, CD44-FITC, CD90-FITC, CD45-PerCP), the expression of cell surface antigen phenotype (CD29, CD34, CD44, CD45, CD90) as well as cell cycle was analyzed by flow cytometry. (2) After addition of mouse anti-human cell keratin (CK19) monoclonal antibody and mouse anti-human vimentin monoclonal antibody, the expression level of CK19 and vimentin was respectively determined with immunocytochemical method. RT-PCR was used to detect the expression of Oct4. The multipotent differentiation capacity of the first generation KDSC was observed with osteogenic, chondrogenic and adipogenic nutrient media.

RESULTSAfter being subcultured, the sizes of cells were similar, and the majority of them were spindle-shaped with disorderly arrangement. The cells highly expressed typical surface markers of mesenchymal stem cells (such as CD29, CD44, and CD90, etc.) with low expression of hematopoietic stem cell surface markers (such as CD34, CD45, etc.). 67.66% of cells were in G0/G1 phase, 26.24% of cells were in G2/M phase, and 6.11% of cells were in S phase. Vimentin was positively expressed in KDSC while CK19 was negatively expressed. The expression of Oct4 was also positive. After being cultured in inducing differentiation media, the cells could differentiate into osteoblasts, chondrocytes, and adipocytes.

CONCLUSIONSStem cells existing in human keloid, which are similar to mesenchymal stem cells, may play an important role in keloid pathogenesis.