EXPRESSION OF ANGIOGENIC GROWTH FACTORS IN KERATINOCYTES

The goal of these studies is to provide a genetically-improved cultered skin substitute product for use in the treatment of burns and chronic wounds. The current products include wild-type keratinocytes or fibroblasts in collagen-based or artificial matrixes. Genetic analysis of the wound healing process revealing specific growth factors that promote angiogenesis during wound healing. Temporally-regulated expression of these factors may promote vascularization and may facilitate the vascularization of skin grafts. Our working hypothesis is that human keratinocytes that express angiogenic growth factors will provide improved healing of burns and wounds of humans keratinocytes that express angiogenic growth factors will provide improved healing of burns and wounds on humans in the context of a cultured skin substitute. A key technology to test this hypothesis is the availability of a human cell line called NIKS(TM) that forms fully stratified skin equivalents in culture that are indistinguishable from those formed with primary human keratinocytes. We propose to inducibly express angiogenic growth factors in NIKS(TM) keratinocytes and demonstrate that NIKS(TM) cells expressing these factors can form fully stratified organotypic cultures that secrete these factors in biologically-active forms. In Phase II, we will test the genetically-modified NIKS(TM) organotypic cultures for enhanced vascularization in animal models of wound healing. PROPOSED COMMERCIAL APPLICATIONS: In the United States it is estimated the 1.25 million people need medical care for burns each year. Approximately 51,000 people are hospitalized for burns and 13,000 require skin grafts. Of these, 1,500 are severely burned and require extensive grafting. With respect to skin ulcers, it is estimated that 800,000 diabetics in the United States suffer from chronic, non-healing diabetic foot ulcers. In addition to diabetic ulcers, new products are needed for venous ulcers, and pressure ulcers (bedsores). Several products employ bioengineered skin substitutes; Genzyme's Epicel, Advanced Tissue Science's Transcyte and Dermagraft, LifeCell's Alloderm and Organogenesis' Apligraft. These products currently are not as effective as split thickness autologous grafts, which remain the method of choice for the treatment of full-thickness skin loss.