RELEASE OF PLATELET-DERIVED GROWTH-FACTOR IN SERUM-FREE ORGAN-CULTUREOF HUMAN CORONARY-ARTERY

Objective: The aim was to test the hypothesis that platelet derived gr owth factor (PDGF) is synthesised in intact coronary arteries and that it is associated with cell proliferation in atherosclerotic plaques. Methods: Segments of human coronary artery obtained from heart transpl ant recipients were cultured in serum-free media for 24 h. Tissue viab ility was assessed by ATP concentration. Cell proliferation was determ ined by incorporation of [H-3] thymidine, autoradiography, and prolife rating cell nuclear antigen (PCNA) immunostaining. Coronary artery con ditioned media were tested for mitogenic activity using a fibroblast p roliferation bioassay. Reverse transcription polymerase chain reaction (RT-PCR) for PDGF A and B was subsequently performed in order to conf irm the endogenous nature and isoform of this mitogen. Results: Tissue viability remained unchanged during culture, and cell proliferation w as detected by incorporation of [H-3] thymidine. Autoradiography and P CNA immunostaining showed proliferating cells within the intimal and m edial layers. Coronary artery conditioned media produced significant s timulation of cell growth [127(SEM 29)%, n = 15] above that caused by culture medium alone. This mitogenic activity was inhibited by 42(8)% (n = 8) with a polyclonal neutralising antibody to PDGF. The endogenou s nature of this mitogenic activity was confirmed by detection of PDCF -A and PDGF-B mRNA expression using RT-PCR and the identity of the amp lified products confirmed by DNA sequencing. Conclusions: The data pro vide evidence for active PDGF production and gene expression within ce lls of the vessel wall. They also suggest that endogenously produced P DGF may play a role in controlling vascular smooth muscle cell prolife ration in human coronary arteries.