EFFECT OF KERATINOCYTE SEEDING OF COLLAGEN-GLYCOSAMINOGLYCAN MEMBRANES ON THE REGENERATION OF SKIN IN A PORCINE MODEL

A collagen-glycosaminoglycan matrix, impregnated with autologous kerat inocytes, was applied as island grafts onto full-thickness porcine wou nds to determine whether complete epidermal coverage could be achieved in a single grafting procedure. Twenty-four grafts with seeding densi ties ranging from 0 to 3,000,000 cells/cm(2) were used to determine th e kinetics of epidermal coverage. The time sequence of epidermal forma tion was then studied between days 14 and 28 using four additional gra fts, each seeded with a density of 500,000 cells/cm(2). Autologous ker atinocytes proliferated as the collagen-glycosaminoglycan matrix was v ascularized to form a confluent epidermis by 2 weeks in matrices seede d with at least 100,000 cells/cm(2). The epidermal thickness and the n umber of keratinocyte cysts observed in the neodermis at 2 weeks incre ased linearly with the logarithm of the seeding density. Sequential an alysis of neoepidermis showed the nascent epidermis to be hyperplastic , parakeratotic, and focally lacking in granular layer differentiation at 2 weeks. After 2 weeks, it underwent normal maturation and differe ntiation. Irrespective of seeding density at 2 weeks the collagen-glyc osaminoglycan matrix was well vascularized, contained a dense cellular infiltrate, and was almost completely degraded. These studies demonst rate that seeded keratinocytes proliferate and differentiate to form a confluent epidermis by 2 weeks in matrices seeded with at least 100,0 00 cells/cm(2).