Angiogenesis Effect Of Astragalus Polysaccharide Combined With Endothelial Progenitor Cells In Diabetic Male Rat Following Experimental Hind Limb Ischemia

ObjectiveIn the present study,we aimed to evaluate the effect of APS and EPCs on enhancing angiogenesis after experimental hind limb ischemia caused by femoral artery ligation in rat with streptozotocin(STZ)-induced diabetes.And to observe whether the APS and EPCs are involved in neovasculogenesis and maintenance of vascular integrity following hind limb ischemia,through enhancing the expression of VEGF and its receptor system.Thereby,to provide evidence for the future therapeutic strategy.Methods1.Rat model of type 2 diabetes was performed by high-fat chow feeding and low dose STZ injection.Rats were considered in type 2 diabetic only if they developed FBG?16.7mmol/L for two times.2.Type 2 diabetic rats were randomly assigned into 5 groups:Sham group,Ischemia group,Ischemia+APS group,Ischemia+EPCs group and Ischemia+APS+EPCs group.The Rat model of hind limb ischemia was established by excising the femoral arteries of the type 2 diabetic rat.Hind limb blood flow was measured by a laser Doppler perfusion system before and after the surgery to observe damage degree.3.APS(2g/Kg),EPCs(106/ml)or an equal volume of vehicle was administered intramuscularly after hind limb ischemia induction to treat the type 2 diabetic rat with hind limb ischemia.4.The type 2 diabetic rats were assessed by angiography at 28 days after induction of hind limb ischemia.The microvessel density(MVD)was detected by angiography and immunohistochemistry.Angiogenesis related proteins(VEGF?Flt-1?Flk-1?Ang-1?Tie-2)were evaluated by Western blot analysis and RT-PCR.Results1.Western blot analysis showed that ischemia tissue resulted increasing the expression of VEGF?Flt-1?Flk-1?Ang-1?Tie-2 levels(P<0.05),the mRNA of related proteins were also increased(P<0.05).VEGF?Flt-1?Flk-1 immuoreactivity is located mainly in vascular endothelial cells and few found in vascular smooth muscle cells.2.Astragalus Polysaccharide induced an increase in the expression of VEGF(36.61%Vs 61.59%),Flt-1(35.50%Vs 57.33%),Flk-1(31.75%Vs 41.89%),Ang-1(37.57%Vs 64.66%),Tie-2(42.55%Vs 76.94%),as well as EPCs transplantation.Angiography showed microvessel density(MVD)increasing after injection APS,which means the APS could improve neovascularization and flow recovery.The expression of angiogenesis related proteins has no significantly different with injection APS or EPCs.3.The combined therapy of Astragalus Polysaccharide and EPCs therapy enhanced the effort of angiogenesis through increasing the expression of VEGF(99.67%),Flt-1(105.33%),Flk-1(72.05%),Ang-1(114.30%),Tie-2(111.87%)after induction of hind limb ischemia in diabetic rat(P<0.001),the mRNA of related proteins were also increased(P<0.001).Angiography showed the significant improving in microvessel density(MVD)and abundant new vessel networks founds in the ischemic limbs.Conclusions1.Angiogenesis related factors are activated after induction of hind limb ischemia in type 2 diabetic rats,which suggests that angiogenesis related factors may play a key role to reconstruction of microcirculation in ischemia limb of type 2 diabetic rats.2.Astragalus Polysaccharide enhance angiogenesis through increasing expression of angiogenesis related proteins(VEGF?Flt-1?Flk-1?Ang-1?Tie-2),thereby to reconstructing the microcirculation and repairing the ischemia limb tissue.3.Astragalus Polysaccharide enhance reconstruction of microcirculation by increasing expression of angiogenesis related proteins(VEGF?Flt-1?Flk-1?Ang-1?Tie-2).This angiogenesis effect is significantly increased with EPCs injection which is likely exerted by involving angiogenesis directly via VEGF and Ang-1/Tie-2 signaling.