Efficacy of fragmin/protamine microparticles containing fibroblast growth factor-2 (F/P MPs/FGF-2) to induce collateral vessels in a rabbit model of hindlimb ischemia

ObjectivesThe localized delivery of exogenous, angiogenic growth factors such as fibroblast growth factor (FGF)-2 has become a promising alternative treatment of peripheral artery disease (PAD) and critical limb ischemia (CLI). The present study describes the efficacy of fragmin/protamine microparticles containing FGF-2 (F/P-MPs/FGF-2) to promote vessel growth in a rabbit model of hindlimb ischemia.MethodsA total of 24 rabbits were used to construct a model of hindlimb ischemia by resection of the left femoral artery. The rabbits were randomly divided into four groups 10 days after surgery (day 0); group A: control (non-treated; 1 mL of phosphate-buffered saline [PBS]); group B: FGF-2 (100 μg FGF-2 in 1 mL PBS)-treated; group C: F/P-MPs (12 mg dried F/P MPs in 1 mL PBS)-treated; and group D; F/P MPs/FGF-2 (100 μg FGF-2 and 12 mg dried F/P MPs in 1 mL PBS)-treated (n = 6 each). The drugs were administered intramuscularly to each group. Blood flow and blood pressure were measured in each group on days 0, 14, and 28. Angiography was performed to assess arteriogenesis on day 28. The number of capillaries on day 28 was determined by direct counting CD31− and α-smooth muscle antibody (α-SMA)-positive vessels.ResultsNeither death nor wound infection was observed throughout the experiment. The F/P MPs/FGF-2-treated group showed marked improvement in the blood flow ratio, blood pressure ratio, and capillary number in comparison to the control group, FGF-2-treated group, and F/P MPs-treated group. The F/P MPs-treated group showed intermediate improvement in blood flow ratio and capillary number in comparison to the control group and FGF-2-treated group.ConclusionsThe F/P MPs/FGF-2-treated group strongly induced functional collateral vessels in the rabbit model of hindlimb ischemia, indicating a possible therapy for PAD.

Clinical RelevancePAD due to atherosclerotic vascular disease is a major health problem. Despite recent advances in surgical and radiologic vascular techniques, certain patients with CLI are not suitable for revascularization. A variety of strategies have been tried to promote development of collateral vessels. F/P MPs can act as carriers for controlled release of FGF-2. The purpose of this study was to evaluate the efficacy of F/P MPs/FGF-2 to induce functional collateral vessels in a rabbit model of hindlimb ischemia. This study will lead to F/P MPs/FGF-2-therapy which is an effective therapeutic strategy for treating PAD patients in clinic.