SDF-1α CXCR4Axis Is Crucial In Neointimal Formation And Recruitment Of Smooth Muscle Progenitor Cells In A Rat Model Of Vein Graft

Background and Aims：Ischemic heart disease is the major diseases which affect human health.Coronary artery bypass graft (CABG) surgery is a more important method oftreatment of such diseases, which can significantly improve the symptoms ofmyocardial ischemia. The great saphenous vein is one of the graft materials ofcoronary artery bypass grafting. However, occlusions in such grafts are common,resulting in patency rates of only50%after10years. Vein graft stenosis orocclusion can lead to serious clinical events such as angina or heart failure. It isreported that stromal cell derived factor-1α (SDF-1α) involved in neointimalthickening after arterial injury. The role of SDF-1α in the vein graft is stillunclear.This study is designed to establish a rat mold of vein graft and observe therole of SDF-1α/CXCR4and SPCs and the effect of AMD3100in vein graft neointimal hyperplasia which can lay the basis for exploring SDF-1α/CXCR4mechanism of vein graft neointimal thickening.MethodsPartⅠ：Rat vein graft model.1. Autologous vein graft model: Exciseexternal jugulars and grafted them, with end-to-side anastomosis, into carotidarteries；2. all the rats are examined with ultrasonography before the vein graftsare harvested.3. Frozen sections are stained with hematoxylin and eosin andthen examine microscopically. The thickness of graft is defined as the sum ofneointimal and media thickness.PartⅡ：The expression of SDF-1α/CXCR4in vein graft and the effectiveof AMD3100in vein graft neointimal hyperplasia.1. SDF-1α/CXCR4weredetected by immunofluorescence at various stage of neointima formation aftertransplantation.2. Double-immunofluorescence was used to detect theexpression of SDF-1α and CD68and the expression of SDF-1α and α-smoothmuscle actin.3. In isograft AMD3100group, recipient rats received AMD3100intraperitoneally after transplantation. Frozen sections are stained withhematoxylin and eosin and then examine microscopically.PartⅢ：The number of Sca-1＋cells and the expression of SPCs in veingrafts after transplantation and the effect of AMD3100on Sca-1＋cells andSPCs.1. Sca-1was detected by immunofluorescence at various stage ofneointima formation after transplantation.2. Double-immunofluorescence wasused to detect the expression of Sca-1and α-smooth muscle actin.3. In isograftAMD3100group, recipient rats received AMD3100intraperitoneally aftertransplantation. Then Sca-1was detected by immunofluorescence anddouble-immunofluorescence was used to detect the expression of Sca-1andα-smooth muscle actin. PartⅣ Receptor origins of Sca-1~+cells and SMCs and the effect ofAMD3100on Sca-1~+cells and SMCs of receptor origins.1. Allogeneic veingraft model: Place the right vessels of external jugular from female rat asinterposition grafts into right carotid artery of congenic male rat.2.Double-immunofluorescence was used to detect the expression of SRY andSca-1and the expression of SRY and α-smooth muscle actin28days aftertransplantation.3. In allogeneic graft, recipient rats received AMD3100intraperitoneally after transplantation. Then double-immunofluorescence wasused to detect the expression of SRY and Sca-1and the expression of SRY andα-smooth muscle actin28days after transplantation.All data are expressed as mean±SEM. Data were statistically analyzed byANOVA, followed by a modified Student’s t-test. A probability value0.05wasconsidered significant.Results：1. We first examined whether our vein graft model of rat is successful; allthe rats were examined with ultrasonography before the vein grafts wereharvested.2. Neointimal thickness of vein graft progressed gradually aftertransplantation(P﹤0.01).3. SDF-1α was not detected in vein graft at0day after transplantation.However, the expression of SDF-1α was detected in3-day graft. A markedexpression of SDF-1α was observed in vein graft, especially at7days aftersurgery. At14and28days, the expression of SDF-1α was decreased.Immunofluorescence revealed that the expression was similar to those ofSDF-1α at3and7days. However CXCR4staining continued to express at14 and28days. Double immunofluorescence staining indicated that macrophagesand SMCs served as a main source of SDF-1α. The growth of vessel walls inAMD3100group reduced compared with that in model group.4. we found that there were a lot of Sca-1＋cells in the adventitia of veingrafts at3days after surgery. Sca-1expression was mainly focus on the media at14days and was not detected at28days after surgery. Doubleimmunofluorescence staining for SMC marker α-actin and Sca-1in sections ofvein graft showed that a portion of SMCs were Sca-1-positive cells. AMD3100could reduce the number of Sca-1~+cells and SPCs in14-day vein graft.5. SRY~+Sca-1~+cells and SRY~+α-sma~+cells were detected separately invein graft at3days and28d after transplantation, and AMD3100could reducethe number of SRY~+Sca-1~+cells and SRY~+α-sma~+cells.Conclusion：1. SDF-1α/CXCR4axis involves in neointimal thickness of rat vein grafts.2. SPCs mediated by SDF-1α/CXCR4axis may involve in neointimalthickness of rat vein grafts.3. SDF-1α/CXCR4-mediated recipient-derived cells may involve in theprocess of neointimal thickness of rat vein grafts.