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

Objective: The aim was to test the hypothesis that platelet derived growth 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 transplant recipients were cultured in serum-free media for 24 h. Tissue viability was assessed by ATP concentration. Cell proliferation was determined by incorporation of [H-3] thymidine, autoradiography, and proliferating cell nuclear antigen (PCNA) immunostaining. Coronary artery conditioned media were tested for mitogenic activity using a fibroblast proliferation bioassay. Reverse transcription polymerase chain reaction (RT-PCR) for PDGF A and B was subsequently performed in order to confirm the endogenous nature and isoform of this mitogen. Results: Tissue viability remained unchanged during culture, and cell proliferation was detected by incorporation of [H-3] thymidine. Autoradiography and PCNA immunostaining showed proliferating cells within the intimal and medial layers. Coronary artery conditioned media produced significant stimulation 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 endogenous 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 amplified products confirmed by DNA sequencing. Conclusions: The data provide evidence for active PDGF production and gene expression within cells of the vessel wall. They also suggest that endogenously produced PDGF may play a role in controlling vascular smooth muscle cell proliferation in human coronary arteries.