PARENCHYMAL CYTOKINE EXPRESSION PRECEDES CLINICALLY OBSERVED ISCHEMIAIN DORSAL FLAPS IN THE RAT

Cytokines have been implicated as pivotal mediators of the wound-heali ng process. An understanding of the production and interaction of cyto kines may lead to a better appreciation of the complex mechanisms of f lap ischemia. The potential would then exist for novel diagnostic and therapeutic approaches to prevent and reverse damage to the endangered flap. The goal of this study was to determine the expression of paren chymal cytokines at various time points during flap ischemia. Punch bi opsies were obtained from McFarlane dorsal flaps in the Sprague-Dawley murine model. We examined cytokine mRNA profiles for interleukin 1 al pha (IL-1 alpha), IL-2, IL-6, basic fibroblast growth factor (b-FGF), gamma-interferon (gamma IFN), transforming growth factor beta (TGF-bet a), and platelet-derived growth factor A chain (PDGF-alpha) using in s itu hybridization. Samples were taken from 0 to 48 hours postoperative ly, with n = 3 for each time point. Eight hours postoperatively there was an abrupt peak of parenchymal cytokine expression at the bases of the flaps. Clinically at this time the flaps appeared completely viabl e without evidence of ischemic change. Leukocyte cytokine production p eaked at 16 hours, when distal flap ischemia was evident clinically. T hese findings demonstrate an early peak of cytokine expression prior t o clinical evidence of ischemia.