R. M. Lassance-Soares1, D. R. Hernandez1, M. T. Pinto3, C. D. Rodrigues2,3, Z. Liu1, R. I. Vazquez-Padron1, O. C. Velazquez1 1University Of Miami,DeWitt Daughtry Family Department Of Surgery,Miami, FL, USA 2University Of Miami,Molecular And Cellular Pharmacology,Miami, FL, USA 3University Of Miami,Interdisciplinary Stem Cell Institute,Miami, FL, USA
Introduction: Chronic limb ischemia is associated with high morbidity with approximately 200,000 major lower limb amputations annually in the USA. Despite the progress in bypass or endovascular procedures, 50% of affected patients are not eligible for these treatments. The spontaneous enlargement of native collaterals, called arteriogenesis, functions as a natural bypassing of a main occluded artery, recovering the blood flow distal to the occlusion. Despite significant efforts to understand the vascular process during arteriogenesis, the molecular mechanisms are not fully understood. c-kit is a tyrosine receptor and its pathway plays an important role during angiogenesis; however its role in arteriogenesis (collaterals remodeling) is poorly investigated. Hypothesis: c-kit signaling dictates proper arteriogenesis in the murine ischemic hindlimb.
Methods: c-kit mutant mice (W/Wv) and their littermates (controls) were subjected to femoral artery ligation. Laser Doppler assessed blood flow after hindlimb ischemia with time (days: 3, 7, 14, 21 and 28). Ischemic tissue and function of the foot were quantified postoperatively (days: 1, 3, 7, 14). Pressure myograph measured vascular function of mesenteric arteries in dose response to acetylcholine and sodium nitroprusside (NO donor).
Results: Blood flow recovery was impaired in c-kit mutant mice on days 7, 14, 21 and 28 (p<0.05; n=10). This data suggests dysfunction in collaterals remodeling and not anatomical differences (number and/or diameter of native collaterals), since blood flow was similar between groups immediately post and on day3. Foot ischemic damage was greater (on days 3, 7 and 14 p<0.05; n=10) and foot function was impaired (on days 1 and 14 p<0.05; n=11) in c-kit mutant mice compared to controls. These data support the blood flow recovery finding confirming the importance of c-kit in arteriogenesis. Vasodilatation of mesenteric arteries subjected to different doses of acetylcholine was not different between the groups (p>0.05; n=5). However, when subjected to different doses of sodium nitroprusside, c-kit mutant mesenteric arteries showed significant impairment in vasodilation (p<0.05; n=5). Because sodium nitroprusside acts in smooth muscle cells (SMCs) as an NO donor, these findings suggest SMCs dysfunction on c-kit mutant mice.
Conclusion: c-kit signaling is required to an appropriate blood flow recovery after hindlimb ischemia. The lack of c-kit impairs arteriogenesis and it is associated with SMCs dysfunction.