TRANSPLANTATION OF CRYOPRESERVED CULTURED EPIDERMAL ALLOGRAFTS

Objective: To optimize cryopreservation methods for cultured epidermal allografts (CEAs) for transplantation onto wounds, Design: Conditions were determined to optimize the cryopreservation of CEAs, Cryopreserv ed CEAs were then grafted onto 16 donor sites in a double blind random ized trial, Materials and Methods: CEAs were grown in culture, Viabili ty of cryopreserved CEAs was determined by: 1) trypan blue dye exclusi on; 2) histology; 3) flow cytometry; and 4) acid lipase activity, Cryo preserved CEAs were grafted onto 16 donor sites. Wound healing assessm ents included 1) visual assessment of healing; 2) histologic assessmen t of re-epithelialization and differentiation; and 3) visual scar asse ssment, Measurements and Main Results: CEAs were cryopreserved using a controlled rate freezer with an experimentally determined setting of -7 degrees C for the CEA freezing point. Such freezing conditions resu lted in retention of approximately 92% of the original viability, no l oss in basal keratinocytes as determined by now cytometry, and no chan ge in acid lipase activity, CEAs cryopreserved according to this metho d were grafted onto 16 donor sites in a double blind randomized trial, All donor sites underwent complete healing. Histologic examination of biopsies taken hom the center of the wound beds showed that CEA-treat ed wounds significantly accelerated the rate of re-epithelialization ( 7.8 +/- 0.6 days vs, 9.2 +/- 0.9 days for CEA- and control-treated wou nds, respectively; p = 0.039) and epithelial differentiation (p = 0.02 3) compared with control sites, Longterm results showed that CEA-treat ed wounds were comparable to control sites with regard to: 1) pigmenta tion; 2) scar height; 3) scar pliability; 4) vascularity; and 5) pain, Wounds treated with cryopreserved CEAs remained durable and not prone to blistering after healing, Conclusions: CEAs can be successfully cr yopreserved for long-term storage, Upon retrieval from storage, CEAs m ay be used to treat partial thickness wounds.