[Epidermal growth factor induce the epithelial stem cell island formation in the regenerated epidermis]

To explore the cell reversion and epithelial stem cell distribution in skins from different developed stages and regenerated epidermis treated with rhEGF.

Tissue biopsies from 8 regenerated ulcer skins treated with recombinant human epidermal growth factor (rhEGF) were used to evaluate the cell reversion and stem cell distribution in epidermis. The expression of beta1 integrin, keratin 19 (K19), keratin 14 (K14) and keratin 10 (K10) in skin was detected with Streptavidin/Peroxidase (SP) immunohistochemical methods. Another 15 biopsies including 7 cases from the regenerated epidermis treated with SD-Ag, 3 cases from fetus (24 weeks), 3 cases from children and 2 cases from adults were used as the controls.

Immunohistochemical stain from beta1 integrin and keratin 19 showed that there were some stem cell islands in epidermis treated with rhEGF. These cells were small and exhibiting positive expression with beta1 integrin and K19 stain. They were isolated, bearing no anatomic relation with the epithelial stem cells in the basal layer. The serial identification experiments indicated that there were no similar stem cell islands in skins from normal adult skin, fetus or child's skin and the regenerated epidermis treated with SD-Ag. All of these results supported that these beta1 integrin and K19 positive stain cells were the stem cells.

The results indicated that these stem cell islands were the specific and individual cell structures in rhEGF treated wounds. There is a possibility that these cells come from the cell reversion from differentiated cells to undifferentiated stem cells.