ZO-1 Participates In The Recovery Of Endothelial Barrier Function After PLLA Stent Implantation And Its Relationship With ISR

Bioabsorbable scaffolds are one of the hot topics in the research of vascular scaffolds.After the completion of dilatation/support of arterial stenosis and partial revascularization,they can gradually degrade into harmless small molecules in the body.In particular,polymers have become one of the main research materials due to their good histocompatibility and biodegradability.However,polymer scaffolds are thicker than traditional metal scaffolds,which can significantly affect the hemodynamics of the implanted site and delay the repair process after endothelial injury.With the degradation of scaffolds,the local mechanical environment of scaffolds becomes more complex,which is easy to cause late vascular complications such as atherosclerosis.Besides,mechanical stimulations like friction,tensile stress,oppression caused by endovascular stenting and balloon expansion destroy the integrity of the vascular endothelial damage,easily to adhere and activate platelet blood components,and then form thrombosis.In addition,the injury leads to the activation of the inflammatory response,producing a series of growth factors and cytokines,leading to the proliferation of vascular smooth muscle cells in the blood vessel wall.During this process,vascular smooth muscle cells undergo a phenotypic transition,secreting a large amount of extracellular matrix,increasing the thickness of the intima,and causing restenosis.Therefore,change of various factors(such as hemodynamic,inflammatory factor,mechanical damage)caused by vascular endothelial injury,is not only a link in the development of atherosclerotic plaque,and restenosis after stent implantation and thrombosis of the key factors,how to quickly endothelial,as soon as possible to restore the damaged parts of the endothelial function,is the key link in solving many problems after stentingEndothelial cells are the barrier between blood and vascular walls.After injury,the ability of proliferation and repair is weakened,which leads to increased permeability of the intima.Endothelial dysfunction can lead to the invasion of harmful lipids and inflammatory cells into the vascular walls,as well as the activation of platelets,leading to a cascade reaction.The structure of TJs(tight junctions,TJs)is an important participant of the endothelial barrier,when TJs are destroyed,it directly causes the leakage of large molecules in the liquid,even cells,which affects the steady state of blood vessels,tissues,and organs.In addition,ZO-1(Zonula Occludens-1,ZO-1)to constitute the endothelial connect closely,maintain vascular permeability and protect endothelial barrier function plays an important role,such as damage,the structure and function of the TJs complex changes,so the ZO-1 is often used as determine various epithelial or endothelium signature molecules,the TJs barrier function and ZO-1 is a mechanical signal sensors,signal can convert mechanical signals into the nucleus.In this study,SD rat abdominal aortic stent implantation was used as an animal model,and 3D printed poly-L-lactic acid(PLLA)scaffolds were implanted to study the restenosis of blood vessels under persistent mechanical injury after stent implantation,reendothelialization,repair of endothelial barrier function and the expression of tight junction protein ZO-1 at different time points.In addition,the effects of mechanical loading on the expression and distribution of ZO-1 in vascular endothelial cells in vitro were further studied.Finally,the effects of ZO-1 on the repair of endothelial barrier function in SD rats with sustained vascular mechanical injury and transient vascular mechanical injury by balloon were compared.Its main contents and results are as follows:(1)Intimal hyperplasia and restenosis after PLLA scaffold implantation in abdominal aorta of SD rats.After PLLA scaffold implantation,the degree of intimal hyperplasia and restenosis increased and then stabilized.(2)Re-endothelialization and changes of endothelial barrier function after the implantation of fully degradable PLLA scaffold.1 month after implantation,CD31 was specifically expressed on the surface of the neointima and completely reendothelialized.Scanning electron microscopy showed complete reendothelialization.In the extracellular matrix of neointima and mesenchyme,collagen fibers were increased and then decreased,elastic fibers were decreased and then increased,collagen and proteoglycan were increased and then decreased.In vivo evanlan staining showed that the permeability of vascular intima increased significantly at 1week and gradually decreased later,and the endothelial barrier function was well repaired at 3 months.(3)Changes in the expression of tight junction protein after the implantation of fully degradable PLLA scaffold.After PLLA stent implantation,the expression of ZO-1increased with the time of implantation,and the barrier function of neointima was well repaired.In prophase,the expression of Occludin,Claudin-5 and Tricellulin was enhanced,which promoted repair of newborn endothelial layer.Additionally,Piezo1 and KLF2 increase and then decrease in response to mechanical microenvironment changes,which is conducive to the repair of neointima.(4)Expression and distribution of tight junction protein ZO-1 in vascular cells under different mechanical loading conditions.Changes in high and low shear stress can cause the expression of zo-1 and f-actin on the cell membrane to decrease and be incomplete,and close connections between cells are destroyed.After static pressure,the expression of zo-1 can be increased gradually with the extension of time.(5)Expression of tight junction protein ZO-1 and its relationship with the change of endothelial barrier function after balloon injury in abdominal aorta of SD rats.The intimal hyperplasia was severe in 1 month after balloon injury,and restenosis reached its maximum.Vascular permeability increased first and then decreased.After balloon injury for 3 months,ZO-1 expression was enhanced and located on the cell membrane,and the barrier function was well repaired.In summary,in this study,SD rat abdominal aorta PLLA scaffold implantation and balloon injury were used as animal models of vascular persistent and transient mechanical injury to detect intimal hyperplasia and re-endothelialization at different time points after vascular injury,changes in permeability,permeability,barrier function,etc.,explored the relationship between tight junction protein ZO-1 and endothelial barrier function repair,and combined with in vitro cell mechanical loading experiments,preliminary studied the tight junction protein ZO-1 and its involvement in endothelial barrier function after vascular mechanical injury.