OBJECTIVETo investigate the different location and the expression characteristics of epidermal stem cells in normal adult skin and scar tissue.

METHODSSkin tissue specimens were harvested from the corresponding sites from 6 healthy volunteers and from scar tissue of 6 patients 1 year after major deep burn. beta1 integrin and keratin 19 (K19) were employed as the biochemical markers for stem cells and transit amplifying cells identification and keratin 14 (K14) and keratin 10 (K10) as markers for post-mitotic cells and terminally differentiated cells respectively. Integrin and keratin were determined by Elivision two-step immunohistochemistry.

RESULTSThe expression of beta1 integrin and the K19 positive cell count in the epithelial basal layers of scar tissue were evidently decreased and weakened than those in normal adult healthy skin. Furthermore, the positive cells expressing K14 in epidermis of scar tissue were only located in 2 - 3 layers of basal epidermis, and their number was much less than that in normal adult skin. Whereas the cells positively expressing K10 were distributed wider in area than that in normal healthy skin. The epidermal stem cells and transit amplifying cells in scar epidermis were much less in number than that in normal skin. The differentiation process of scar epidermal stem cells was different from that of normal skin. And the proportions of post-mitotic cells and terminally differentiated cells were abnormal.

CONCLUSIONThe results indicated that the self-renewal ability of the scar epidermis was decreased, and the differentiation process of it was in disorder, which may be a reason for the abnormality of structure and function of the epidermis in scar, and a reason for the decreased ability of wound healing of scar tissue.