Restenosis remains a significant clinical problem associated with mechanical interventional procedures for arterial revascularization or repair, including coronary angioplasty and stenting. Studies with rodents have established that
platelet-derived growth factor (
PDGF), a potent chemotactic and mitogenic agent for vascular smooth muscle cells, is a key mediator of lesion formation after
vascular injury. To further explore this hypothesis in a more clinically relevant model, neutralizing
monoclonal antibodies (mAbs) were used to examine the effect of selective inhibition of alpha or beta
PDGF receptor (PDGFR) on
neointima formation in nonhuman primates. Carotid arteries were injured by surgical
endarterectomy and femoral arteries by balloon
catheter dilatation. Immunostaining revealed that both
injuries induced cell proliferation and the upregulation of
beta PDGFR but not alpha PDGFR. By 7 days after injury,
beta PDGFR staining was limited to the
luminal region of the media, the small areas of
neointima, and the adventitia. Nearly all
bromodeoxyuridine-positive cells were found in these regions as well. After 30 days, a concentric
neointima that stained strongly for
beta PDGFR had formed in the carotid and femoral arteries. Treatment of baboons with anti-
beta PDGFR mAb 2A1E2 for 6 days after injury reduced the carotid artery and femoral artery lesion sizes by 37% (P<0.05) and 48% (P<0.005), respectively, when measured at 30 days. Under the same conditions, treatment with anti-alpha PDGFR mAb 2H7C5 had no effect. These findings suggest that PDGF mediates
neointima formation through the
beta PDGFR, and that antagonism of this pathway may be a promising therapeutic strategy for reducing clinical restenosis.