Abstract 722: Treatment of Acute and Chronic Limb Ischemia with Intermedin (IMD) in Mouse Models

Abstract

Objectives: This experiment proposes a novel mouse model to simulate long-term chronic ischemia caused by peripheral artery disease (PAD) using a partial ligation method to narrow down the femoral artery lumen in C57Bl/6 mice. This model will be compared to the typical occlusion model while testing Intermedin (IMD) as a possible treatment for ischemia. Methods: Partial hindlimb ligation technique: we use a strand of 11-0 nylon sutures to pierce the middle of the artery and suture half of the artery shut at both the proximal and distal end of the femoral artery. The typical occlusion model: we use a 7-0 silk suture to completely ligate the distal and proximal femoral artery. Hindlimb blood flow was monitored daily by Laser Doppler perfusion monitor before and after the surgery. IMD was administered at 150 μg/kg, ip, immediately following ligation and twice daily afterwards for up to one week, while in the control group saline was injected instead of IMD. Gastrocnemius muscle samples were collected at day 3 and day 7 for histology and molecular biology study. Results: Ischemic/non-ischemic leg blood perfusion ratio in the partial ligation model is significantly higher than in the typical model. It is also significantly increased in IMD-treated groups in both models. Compared to the tissue in complete ligation models, it is apparent that partial ligation model tissue is less severely affected upon initial ligation but maintains ischemia over the one week testing period as would be expected. Compared to the untreated ischemia groups in acute and chronic hindlimb ischemia models, IMD-treated animals had less severe ischemic injuries. Conclusion: Our study indicates that our chronic hindlimb ischemia model was successful with expected less ischemia status than complete occlusion. The partial occlusion model presented here more closely mimics human PAD, where atherosclerotic plaque builds up slowly, resulting in a lower pressure difference between the proximal and distal artery preventing adequate shunting of the blood into collateral circulation. Moreover, our study suggests that IMD has promise as a therapeutic treatment in acute and chronic hindlimb ischemia models to prevent necrosis in muscle tissue following ischemic events.