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[Redistribution of epidermal stem cells in wound edge in the process of re-epithelialization].

OBJECTIVE
To study the redistribution of epidermal stem cells in regenerating wound tissues, and to elucidate the role of epidermal stem cells during wound repair.


METHODS
80 circular full-thickness wounds were produced on both sides of the back in 20 male Wistar rats (4 wounds in each animal). Then the 80 wounds were randomly divided into 2 groups: group A (treated with sulfadiazine silver- sulfadiazine zinc cream, n = 40) and group B (without any treatment, n = 40). The infection and healing process of the wounds were observed with naked eyes. Five mice were killed one time 3, 7, 14, and 21 days after the wounding. Two wounds with surrounding normal skin tissues were collected from each mouse. Routine histological examination was conducted with HE staining. Beta(1) integrin and keratin19 (K19), markers of epidermal stem cells, were employed to determine the distribution of epidermal stem cells with streptavidin-peroxidase (SP) immunohistochemical method.


RESULTS
The healing rate of wounds was 80% (32/40) in group A, and 60% (24/40) in group B. No beta(1) integrin and K19 positive cells was found in the granulation tissue of all wounds in these 2 groups at any time point during the healing process. However, a few beta1 integrin and K19 positive cells, bearing no anatomic relation with the epidermal stem cells in the basal layer, were found scattering in the stratum spinosum and stratum granulosum of the epidermis on the wound edges. The closer to the wound the more concentrated the beta(1) integrin and keratin19 positive cells. Their numbers increased gradually along with the shrinking of the wound surface until the wound completely healed. The numbers of the beta(1) integrin and keratin19 positive cells decreased gradually after epithelialization. The numbers of the beta(1) integrin and keratin19 positive cells were obviously lower in the infected wounds than in the uninfected wounds.


CONCLUSION
Epidermal stem cells participated in the healing of wound. The function of redistribution of epidermal stem cells in wound edges seems to promote the re-epithelialization of granulating wounds.