Arterial injury repair in nonhuman primates - The role of PDGF receptor-β

Background This study documents the time course of the response to injury of the saphenous artery in baboons and the role of the platelet-derived growth factor-β. Fundamental differences with the well-characterized rat arterial injury model have been found. Materials and methods Thirty-eight baboons received a unilateral balloon injury to the saphenous artery and were treated with a chimeric blocking antibody to PDGFR-β or vehicle control for 7, 14, or 28 days. The arteries were evaluated morphologically and for cell proliferation. Results Both medial and intimal smooth muscle cell proliferation were elevated 7 days after injury and were back close to baseline at 14 days. Unlike the rat, blockade of PDGFR-β inhibited medial proliferation over 80% at 7 and 14 days, while intimal proliferation was only inhibited at 14 days (>95%). Also, unlike the rat, the baboon arterial media, as well as the intima, increased in size by 14 days after injury. Blockade of PDGFR-β completely inhibited both intimal and medial growth at 14 days, but there was less of an effect on intimal growth at 28 days. Conclusion Blockade of PDGFR-β may be a clinical approach to inhibit intimal hyperplasia in humans, but this study raises concerns about the long-term efficacy of this treatment.