ALTERNATIVE DELIVERY OF KERATINOCYTES USING A POLYURETHANE MEMBRANE AND THE IMPLICATIONS FOR ITS USE IN THE TREATMENT OF FULL-THICKNESS BURN INJURY

The Epicel ASAProgram(SM) service generates autologous keratinocyte gr afts used for the closure of full-thickness wounds in moderately and s everely burned patients. The manufacturing process used to generate Ep icel(SM) service autografts (ESA) is based upon the keratinocyte co-cu lture technique described by Rheinwald and Green which employs murine Swiss 373/J2 fibroblasts as feeder cells. Recently, a technique has be en described that employs a polyurethane wound dressing, HydroDerm(TM) (HD, Innovative Technologies, Ltd), as a delivery vehicle for culture d keratinocytes intended for autologous grafting. We have examined the practical feasibility of this technique and report on testing the abi lity of HD to support keratinocyte growth and epithelium formation in vitro, at the air-liquid interface (ALI), and in vivo, after grafting to full-thickness wounds created on the backs of athymic (Swiss Nu/Nu) mice. The results demonstrate that keratinocytes grow on the HD dress ing in Gibco SFM at a rate that is approximately 15 per cent of that o bserved when cells are cultivated on tissue culture (TC) plastic using standard techniques, yet the cells retain their proliferative capacit y and form an epithelium in vitro when cultivated at the ALI on a derm al substrate. Keratinocyte-seeded HD membranes were also transferred t o full-thickness wounds in athymic mice. Animals grafted with cells se eded to HD developed human epithelium, as revealed by species-specific detection of involucrin and evolved a normal attachment to the wound substratum, as demonstrated through the expression of dermally opposed laminin and alpha 6 beta 4 integrin. The ability of keratinocytes to maintain proliferative potential after seeding onto HD and their abili ty to form a properly oriented epithelium in vitro and in vivo suggest s that this wound dressing may be useful as a vehicle for autologous k eratinocyte grafting and help to provide earlier epithelial coverage t o the burned patient. However, because of the slow proliferation rate of keratinocytes on HydroDerm, timely graft delivery would be best ach ieved by combining cell expansion via the Rheinwald and Green culture system, followed by the seeding of cells onto HydroDerm in a reduced c alcium medium for subsequent autologous granting. (C) 1998 Elsevier Sc ience Ltd for ISBI. All rights reserved.