Mechanism underlying enhanced angiogenesis of PDE III inhibitor (Cilostazol) in limb ischemia of diabetes

Abstract

Cilostazol is used for peripheral arterial disease with evidence level A by AHA. Previous study suggested it may work even in diabetes, however, the mechanism was not fully proven. Methods 30 mice were divided into 3 groups (Control; C, Diabetes; D, and Diabetes with Cilostazol; L). After ligation of femoral artery, each 5 mice were sacrificed at 1 and 4 weeks postoperatively. Soleus muscle was resected. Evaluations were made by 1) distal arterial flow, 2) capillary density (CD), 3) expression of HIF1 alpha, VEGFR2 and eNOS by IHC and western blotting. Results At 1 week: As level of ischemia shown by flow (C: 90% of preoperative flow, D: 58%, L: 66%), HIF1 alpha expression was higher in D and L than C (p<0.001 and p<0.005). However, in VEGFR2 expression, there was no difference between C and D, whereas there was significant difference between C and L (p<0.05). There was no difference in eNOS expression and CD in 3 groups. At 4 weeks: CD decreased in D (p<0.05) whereas increased in L (p<0.01). Significant difference in VEGFR2 was only seen between D and L (p<0.05). On the other hand, in eNOS expression, D was significantly lower from C and L (p<0.005 and p<0.05). Conclusion 1. HIF1 alpha did not promote VEGFR2 expression in DM. 2. Cilostazol improved VEGFR2 expression in spite of HIF1 alpha dysfunction. 3. Mechanism of Cilostazol on ischemic diabetic angiogenesis was possibly due to enhancement of eNOS expression rather than VEGER2.