Ectopia of epidermal stem cells on wound edge during wound healing process

To investigated the distribution of epidermal stem cells in rat full-thickness wound tissues during the wound healing process and to elucidate the roles of epidermal stem cells in wound repair in vivo.

Eighty circular full-thickness wounds were produced on both sides of the back in 20 male Wistar rats labeled with BrdU 60 days previously (4 wounds in each rat). BrdU, beta1 integrin and keratin 19 (K19) were employed to determine the epidermal stem cells with SP immunohistochemical methods, and the epithelialization was determined with routine histological methods of HE staining on the 3rd, 7th, 14th, and 21st days after operation.

No cells with positive immunostaining for beta1 integrin, K19 and BrdU were found in granulation tissue of wound in both groups during the healing process. However, a few scattered beta1 integrin and K19 positive cells were found within the stratum spinosum and stratum granulosum of the epidermis on the wound edges on the 3rd day post-injury. And these positive cells gradually became more and more in number, and mostly concentrated on the border of wound edges till the wounds healed. In addition, the number of positive cells for beta1 integrin and K19 in the infected wounds was less than that in non-infected wounds. These positive cells for beta1 integrin and K19 staining on the wound edge were also positively stained with BrdU in the cellular nuclei.

The above results indicate that ectopia of epidermal stem cells present a major function during wound epithelialization.