The role of platelet derived growth factor in endomyocardial biopsies shortly after heart transplantation in relation to postoperative course

OBJECTIVE: Platelet-derived growth factor (PDGF) plays an important role in structural alterations of blood vessels after heart transplantation (HTx). The aim of this study was to clarify the effect of peritransplant injury and postoperative complications on the expression of PDGF ligand and receptor. METHODS: Right ventricular endomyocardial biopsies were collected from 46 patients before implantation, and then 1 and 2 weeks after HTx. According to the clinical course in the first postoperative year and to histopathological evaluation (based on the standardised 'International Society for Heart and Lung Transplantation' grading system) three groups were formed: (a) clinical uneventful course; (b) histologically and/or serologically proven cardiac or systemic infections; and (c) acute rejection episodes > or =grade 3A. Both, infections and rejections were detectable after the second postoperative week. The expression of PDGF AA/BB and PDGF receptors alpha/beta was examined immunohistochemically. The infiltrating cells were characterised by using monoclonal antibodies against CD3, CD4, CD8, CD57 and CD68. RESULTS: Only endothelial cells revealed a relevant expression of PDGF ligand and receptor. Prior to implantation there was no or only weak reactivity of single cells for all PDGF factors. One week after HTx a significantly increased immunoreactivity of all PDGF factors was observed in all groups. Two weeks after HTx the expression of PDGF AA in the infection group and the expression of all four PDGF factors in the rejection group remained significantly elevated. In contrast, in the group with an uneventful course there was no statistical difference in the expression of all the four PDGF factors. Compared with the uneventful group, there were significantly more CD3+ cells in the infection and rejection group at all three time points. Two weeks after HTx, the rejection group showed a significantly elevated number of CD3+ cells compared to the values before implantation. Two weeks after HTx there were significant more CD68+ cells in the infection and rejection group compared with before implantation. CONCLUSIONS: One week after HTx the peritransplant injury predominantly influences the endothelial expression of PDGF ligand and receptor. In the first postoperative week, expression of PDGF could be detected. The persistence of evaluated PDGF expression might be of prognostic value in terms of a risk for either infection or rejection. These patients should be carefully monitored.