Green Tea Polyphenols Affect Skin Preservation in Rats and Improve the Rate of Skin Grafts

Abstract

Green tea polyphenols have been recently reported to promote the preservation of tissues, such as blood vessels, corneas, nerves, islet cells, articular cartilage, and myocardium, at room temperature. These findings indicate the possibility of a new method of tissue banking without freezing. A main active ingredient of green tea, epigallocatechin-3-gallate (EGCG), is a polyphenol that possesses antioxidant, antimicrobial, antiproliferative, and free radical scavenging effects. This study examined the effects of EGCG regarding skin preservation. Skin sample biopsy specimens measuring 1 × 1 cm from GFP rats were held in sterile containers with 50 ml preserving solution at 4°C and 37°C for up to about 8 weeks. Periodically, some of the preserved skin specimens were directly examined histologically and others were transplanted into nude mice. Histological examinations of skin preserved at 4°C revealed a degeneration of the epidermal and dermal layers from 5 weeks in all groups. In the groups preserved at 37°C, degeneration and flakiness of the epidermal layer were demonstrated starting at 2 weeks preservation regardless of addition of EGCG. After 2–7 weeks of preservation the rat skin grafted to nude mice in the EGCG groups stored at 4°C showed successful engraftment. However, grafts preserved at 4°C without EGCG and at 37°C did not demonstrate GFP-positive keratinocyte or fibroblasts. In conclusion, the present findings suggest the future clinical usefulness of EGCG for skin preservation without freezing; however, the mechanism by which EGCG promotes skin preservation still remains unclear.