Differentiated Expression Patterns of Growth Factors in Routine Formalin-Fixed Endomyocardial Biopsies in the Early Postoperative Phase After Heart Transplantation

Abstract

Background Platelet-derived growth factor (PDGF) and fibroblast growth factor (FGF) seem to play a key role in immunological reactions shortly after heart transplantation (HTx). The aim of this study was to analyze the time course of the expression of PDGF A and B, PDGF-receptor α (PDGF-Rα) and β, aFGF, and bFGF on formalin-fixed routine endomyocardial biopsies. Patients and Methods Right ventricular endomyocardial biopsies were obtained from 36 heart transplant recipients up to 2 weeks after HTx. According to the clinical course in the first postoperative year, 3 groups were formed: (1) clinically uneventful course (n = 12); (2) cardiac/systemic infections (n = 12); (3) acute rejection (n = 12). The growth factor expression was examined immunohistochemically. Results In the early phase after HTx, PDGF A, PDGF B, PDGF-Rα, and PDGF-Rβ were predominantly expressed in endothelial cells. The main expression of PDGF-Rα and bFGF was found in cardiomyocytes, endothelial cells, and smooth muscle cells. During the first 2 postoperative weeks, PDGF A, PDGF B, and PDGF-Rβ showed a similar time course of expression: A significantly elevated expression in the first week was followed by a decrease in the second week. In the rejection group, PDGF A was significantly elevated after the first week. Conclusions The increased expression of PDGF in the first postoperative week can be interpreted as an unspecific reaction to peritransplant injury. The prolonged expression of PDGF A, PDGF B, and PDGF-Rβ showed that there were ongoing immunological reactions in the transplant during week 2. The persistence of elevated PDGF A expression might be of prognostic value in terms of a risk factor for either infection or rejection.