Effects of platelet-rich plasma-containing fragmin/protamine microparticles in enhancing endothelial and smooth muscle cell growth and inducing collateral vessels in a rabbit model of hindlimb ischemia.

The purpose of the study was to evaluate the effects of isogenous platelet-rich plasma (PRP)-containing fragmin/protamine microparticles (F/P MPs) as a delivery system for proteins in PRP on growth of endothelial and smooth muscle cells (SMCs) in vitro and as an alternative treatment for peripheral arterial disease (PAD) and critical limb ischemia. Frozen and thawed PRP contains high concentrations of growth factors that are adsorbed by F/P MPs. Human aorta endothelial cells (AECs) and SMCs were grown in a medium with PRP. Addition of F/P MPs significantly enhanced the proliferative effects of PRP on AECs and SMCs at 37 °C for >10 days. Intramuscular administration of phosphate-buffered saline (PBS; 2 mL, control), F/P MPs (12 mg in 2 mL PBS), PRP (2 mL), or PRP (2 mL) containing F/P MPs (12 mg) was then performed in a rabbit model of hindlimb ischemia prepared by resection of the left femoral artery. Blood flow and pressure were measured on days 0, 14, and 28, and angiography to assess arteriogenesis was performed on day 28. PRP-containing F/P MPs strongly induced functional collateral vessels in the rabbit model of hindlimb ischemia, indicating possible use of these microparticles in therapy for PAD.