Low molecular‐weight fucoidan protects against hindlimb ischemic injury in type 2 diabetic mice through enhancing endothelial nitric oxide synthase phosphorylation

Background Diabetes mellitus (DM) complications are associated with ischemic injury. Angiogenesis is a therapeutic strategy for diabetic foot. The aim of this study was to investigate the possible angiogenic effect of low molecular weight fucoidan (LMWF) in diabetic peripheral arterial disease (PAD). Methods Diabetic db/db mice and age‐matched C57BL/6 mice underwent femoral artery ligation followed by LMWF (30, 60, 80 mg/kg per day, p.o.) or cilostazol (30 mg/kg/day, p.o.) treatment for 6 weeks. Endothelium‐dependent vasodilation and blood flow of the hindlimb were measured. Histological and western blot analyses of CD34, vascular endothelial growth factor (VEGF), eNOS, and inflammatory factors in the gastrocnemius were performed. The effects of LMWF were confirmed in human umbilical vein endothelial cells (HUVEC). Results Diabetic mice with ligation exhibited hindlimb ulceration, hydrosarca, and necrosis, increased expression of inflammatory factors, and decreased levels of VEGF and eNOS phosphorylation. Treatment with LMWF markedly ameliorated foot lesions, suppressed expression of inflammatory factors, and improved plantar perfusion by promoting endothelium‐dependent vasodilation and revascularization in diabetic PAD mice. In high‐glucose treated HUVEC, LMWF (40 μg/mL) reversed blunted endothelial cell proliferation, migration, and tube formation, and promoted eNOS phosphorylation and VEGF expression, whereas HUVEC pretreatment with 100 μmol/L N G ‐nitro‐ l ‐arginine methyl ester, an eNOS antagonist, markedly inhibited the effects of LMWF. Conclusion This study demonstrates that LMWF alleviates hindlimb ischemic damage, at least in part by promoting eNOS phosphorylation, nitric oxide production, and VEGF expression, resulting in enhanced angiogenesis in the ischemic region.