FIBRONECTIN AND CELL RECRUITMENT

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DESCRIPTION: (Adapted from the applicant's abstract) - The central hypothesis of this proposal is that specific integrins are required for fibroblast migration and granulation tissue organization in cutaneous wounds. A three day delay intervenes between cutaneous wounding and granulation tissue accumulation. During this delay fibroblasts increase their provisional matrix receptors and decrease their collagen receptors. The authors propose that the fibrin/fibronectin-rich provisional matrix is part of the induction mechanism controlling fibroblast expression of provisional matrix integrins, a regulatory mechanism that is essential for the early wound healing response. To test this hypothesis, Aim 1 proposes to determine the expression and function of fibroblasts integrins during granulation tissue development of cutaneous wounds using porcine excisional wound paradigms as well as human cutaneous wounds. To prove the requirement for the modulation of integrins during granulation tissue development, integrin expression will be experimentally regulated by addition of specific anti-integrin antibodies or cyclic peptide integrin antagonists to the wound site or by introducing exogenous fibroblasts to the wound site after in vitro modulation of their specific integrins. In Aim 2, the regulatory control of human skin fibroblast integrins in the context of provisional matrix vs collagen matrix will be determined at the molecular level utilizing in vitro systems that simulate cutaneous wound environments. This aim will include a study of cytokine and extracellular matrix enhancer elements in specific integrin promoters, and identification of transactivating factors that stimulate these integrin enhancer elements. Aim 3 proposes to determine which integrins are required for fibroblast movement over provisional matrix fibrils, and for fibroblast transmigration from collagen gels into fibrin clots, using in vitro conditions that simulate selective events in the early wound environment. To this end, integrins will be modulated by antibody and cyclic peptide antagonists, by culture conditions, and by molecular biological manipulations. In addition, it is proposed to investigate how integrins promote cell movement by modulation of fibroblast second messenger pathways using specific inhibitors and antisense oligonucleotides.