Transplantation of keratinocyte spore-like stem cells

Wound granulation tissue should be covered by epidermal cells migrating from the basal layer of the epidermis or hair "bulge" of the wound edge. However, new epidermal islands are frequently formed on the granulation tissue remote from the wound edge. Thus, current theory of "bulge"-originating stem cells does not necessarily correspond to the histological pictures of the healing wound. We took imprints of a leg ulcer surface and found single dispersed, large nucleated cells, some of them in mitosis. These cells resembled those from epidermal spinosum layer. The question arouse as to whether these cells might be the "spore-like" stem cells creating epidermal island. We found similarly shaped cells among the keratinocyte preserved in pulverized sodium chloride as the only surviving population in culture and revealing enzymatic activity. The aim of this work was to study whether the population of human keratinocytes surviving sodium chloride preservation and transplanted to SCID mice may form epidermis.

The 12-month sodium chloride-preserved and cultured keratinocytes (KC) were transplanted to the wound on the dorsum of SCID mice for 14 and 21 days.

Ninety-five percent of cultured KC were enzymatically active "large" cells; they did not express p63 and CD29 claimed as specific for stem cells, and they did not proliferate. Transplanted to the center of the wound, they formed small KC islands and became confluent after 14 days.

The "large" epidermal keratinocytes survived the 12-month preservation in anhydrous sodium chloride. Transplanted to the wound, they formed epidermal islands of human phenotype. These cells may be the so-called "spore-like" stem cells.