Time course of flow-induced smooth muscle cell proliferation and intimal thickening in endothelialized baboon vascular grafts

Abstract

Polytetrafluoroethylene (PTFE) grafts placed into the arterial circulation of baboons for 8 weeks under high blood flow (HF) conditions develop a thin intima composed of smooth muscle cells (SMCs) and extracellular matrix beneath an endothelial monolayer. When these grafts are returned abruptly to normal flow (NF), they develop marked intimai thickening within 1 month. The mechanisms underlying this thickening are unclear. We studied the SMC response to altered flow by placing bilateral aortoiliac PTFE grafts into baboons with bilateral femoral arteriovenous fistulas. After 8 weeks, one fistula was closed, returning the graft flow on that side to NF. The opposite graft remained under HF conditions. Flow differences were monitored with duplex ultrasound (for all grafts: NF, 135±21 [mean±SEM] mL/min; HF, 507±35 mL/min; P