[ 14 KDa wound-healing peptide from the skin of the Frog Rana esculenta]

ABSTRACT

Contrary to organ regeneration which does not occur in nature, wound healing or tissue regeneration is a widespread event among all organisms. Wound healing in mammals is a multistep phenomenon. It consists of an inflammatory phase involving scavengering of damaged cells by macrophages and phagocytes whose recruitments to the site is induced by cytokines secreted by cells of wounded tissues. In the reparation phase, some differentiated cells [keratinocytes, granular cells, and fibroblasts] in the G0 phase of the cell cycle dedifferentiate, returning, along with local stem cells, to G1 phase; start dividing to ensure the needed number of differentiated cells. This mitotic activity is also regulated by specific growth factors, and a host of regulatory molecules of the immune system. These cells seem to secret a network of collagen fibers which guide their migration. The healing phase involves the formation of keratinized and apoptosing cells, forming a deciduous crust. In human, normal wound healing requires 7-8 days; in articulated regions twice this time. Here we report the purification and partial characterization of previously unknown peptide having a wound healing activity, from the dorsal skin of Rana esculenta. Isolation was carried out on column of CM-Sephadex C25. Skin proteins were eluted to peak A, B, C, and D. Peak C only has wound healing activity as demonstrated by the healing of experimental wounds made on the inner side of the rabbit's ear, covered by a thin layer of lyophilized peak C mixed with vaseline codex in ratio of 1 to 1000. The application of the ointment was done at the time of incision once only. Wound healing essays were also made on open ulcerated wounds induced on the back of rabbits injected by a mixture of known antigen with Freund adjuvant. Furthermore, wound healing essays also carried out on accidental wounds on human hands. All these wounds were treated as mentioned earlier. Further purification of peak C was carried out by FPLC on mono-Q column, and by SDS-PAGE electrophoresis. It was found that peak C consisted of two subpeaks Ca and Cb. Ca was found to have the highest wound healing activity; banded at 14 KDa. In all wound healing essays, treated wounds by the C fraction or Ca 14 KDa peptide healed at half time compared to wound controls which did not show any apparent infection