Expression of Platelet-Derived Growth Factor and Fibroblast Growth Factor in Cryopreserved Endomyocardial Biopsies Early and Late After Heart Transplant

Background Growth factors such as platelet-derived growth factor (PDGF) and fibroblast growth factor (FGF) appear to play a key role in immunologic reactions in the long-term course after heart transplant. Their expression in the early phase after transplant has been recently described. The aim of the present study was, therefore, to examine the growth factor expression in the early and later periods, up to three years after transplant in the same patient cohort. Methods Right ventricular endomyocardial biopsies were obtained from 29 heart transplant recipients before implantation, after one and two weeks, and after one, two, and three years after heart transplant, and immediately frozen in liquid nitrogen. The growth factor expression was examined immunohistochemically. Results The PDGFs were mainly expressed in vascular structures and they were less pronounced in cardiomyocytes. Especially after the first week, a significant increase was found in the expression of PDGF A and B as well as PDGF-receptors α and β. In the yearly biopsies, PDGF expression was rarely found. The bFGF expression was merely weak in the later period three years after transplant and the aFGF was only expressed in the early phase. A comparison of recipients with short and long ischemic time did not reveal any significant differences in the intensity of expression. Conclusions The increased expression of PDGF and FGF in the first postoperative week can be interpreted as an unspecific reaction to peritransplant injury. This might be related to important reparative, angioprotective, and wound-healing processes shortly after the heart transplant had taken place. The weak expression in the later period appears to be linked to a stable transplant function and a direct influence by the immunosuppressive therapy.