Delivery Of AICAR To Enhance The Endothelialization Of Small-diameter Vascular Grafts Via Energy Supply And Anti-inflammatory Mechanisms

Background:Small-diameter tissue-engineered vascular grafts are considered the most ideal grafts for replacing autologous blood vessels in bypass surgery.Tissue mechanical damage caused by the tissue engineering blood vessel transplantation process and the persistent inflammatory reaction caused by foreign body rejection often leads to poor endothelialization of tissue engineering vascular grafts,eventually leading to the failure of small diameter tissue engineering blood vessel transplantation.Amp-activated protein kinase(AMPK)is known as the "cell energy monitor" and plays a positive role in the anti-inflammatory effect.This study aims to explore the process and potential mechanism of AMPK agonist(AICAR)modification in small-diameter tissue-engineered vascular grafts.Methods:We successfully prepared AICAR-modified small-diameter tissue-engineered vascular grafts by electrospinning technology.The surface morphology,mechanical properties,drug release properties,and hydrophilicity of the tissue-engineered vascular grafts were evaluated by scanning electron microscopy,tensile strengthen test,drug release test,and static contact Angle detection.The biological properties of tissue-engineered vascular grafts in vitro were evaluated by scratch test,angiogenesis test,Western Blot(WB),ELISA,live or dead staining,JC-1 fluorescent probe,and RT-PCR.The tissue-engineered vascular grafts were transplanted into the common carotid artery of New Zealand white rabbits by end-to-end anastomosis.At the 6-week/12-week time point,Doppler ultrasound and digital subtraction angiography(DSA)were performed to evaluate the blood flow patency of the vascular grafts.Scanning electron microscopy,immunofluorescence,and immunohistochemical staining were used to evaluate the endothelialization and vascular remodeling process of tissue-engineered vascular grafts in vivo.Results:AICAR-modified small-diameter tissue engineering vascular grafts have suitable mechanical and degradation properties for transplantation.The in vitro results showed that AICAR could enhance the intracellular energy supply of endothelial cells and induce the differentiation of macrophages into M2 anti-inflammatory phenotype.Under the inflammatory condition,vascular endothelial cells co-culture with AICAR-modified tissue engineering vascular grafts can obtain better survival rate,migration ability,and angiogenesis ability.Moreover,in vivo experiments showed that AICAR-modified tissue-engineered vascular grafts exhibited better vascular remodeling and higher blood flow patency rate(92.9%and 85.7%,respectively)at different time points(6 weeks and 12 weeks),compared with the control group(11.1%and 0%,respectively).AICAR-modified small-diameter tissue-engineered vascular grafts can enhance the energy supply of vascular endothelial cells and induce the polarization of macrophages to M2 anti-inflammatory phenotype,thereby reducing the negative effects of inflammatory response.Conclusions:AICAR-modified small-diameter tissue-engineered vascular grafts have suitable mechanical and degradation properties for transplantation.The AICAR-modified tissue-engineered vascular grafts can induce AMPK phosphorylation in endothelial cells,increase the energy supply of endothelial cells,attenuate inflammatory damage,and promote the remodeling process of AICAR-modified tissue-engineered vascular grafts in vivo,enhance endothelialization,and improve vascular patency rate.