BIOLOGICAL AND PHYSICAL FACTORS INFLUENCING THE SUCCESSFUL ENGRAFTMENT OF A CULTURED HUMAN SKIN SUBSTITUTE

Skin tissue may be engineered in a variety of ways. Our cultured skin substitute (Graftskin, living skin equivalent or G-LSE), Apligraf(TM), is an organotypic culture of skin, containing both a ''dermis'' and ' 'epidermis.'' The epidermis is an important functional component of sk in, responsible for biologic wound closure. The epidermis possesses a stratum corneum which develops with time in culture. The stratum corne um provides barrier function properties and gives the LSE improved str ength and handling characteristics. Clinical experience indicated that the stratum corneum might play an important role in improving the cli nical utility of the LSE. Handling and physical characteristics improv ed with time in culture. We examined the LSE at different stages of ep idermal maturation for barrier function and ability to persist as a gr aft. LSE grafted onto athymic mice before significant development of b arrier function did not withstand bandage removal at 7 days postgraft. LSE grafted after barrier function had been established in vitro were able to with-stand bandage removal at day 7. Corneum lipid compositio n and structure are critical components for barrier function. Media mo difications were used in an attempt to improve the fatty acid composit ion of the stratum corneum. The barrier developed more rapidly and was improved in a serum-free, lipid-supplemented condition. Lipid lamella r structure was improved with 10% of the stratum corneum exhibiting br oad-narrow-broad lipid lamellar arrangements similar to human skin. Fa tty acid metabolism was not appreciably altered. Barrier function in v itro was 4- to 10-fold more permeable than human skin. Epidermal diffe rentiation does not compromise engraftment or the wound healing abilit y of the epidermis. The stratum corneum provides features beneficial f or engraftment and clinical use. (C) 1996 John Wiley & Sons, Inc.