| Background and ObjectivesAt present, percutaneous transluminal angioplasty (PTA) has been widely applied in clinical practice. Compared with traditional open surgery, PTA has advantages of less trauma, fewer complications, quicker recovery, etc. Thereby, this procedure has become an important treatment of cardiovascular disease and obtains satisfactory results. However, PTA can also lead to endothelial injury, an important pathophysiological basis of restenosis after endovascular treatment. Restenosis is the most serious complication after PTA, which will endanger patient’s health and life again. So, how to prevent restenosis has become one of the problems to be solved in the field of surgery currently. Injured endothelium is the triggering factor of restenosis. Surgical injury and hemodynamic changes cause endothelial cells degeneration and stripping. Endothelial cells damage is an important pathophysiological step of restenosis after PTA. Pathological characteristic is that matrix underneath intima exposes to blood, resulting in accumulation of platelet. Platelet releases mitogen which induces aggregation of platelet and granulocytes and stimulates smooth muscle cells proliferation, migration, secretion and vessel remodeling. Meanwhile, the destruction of endothelial integrity leads to decreasing of auto-secreted protective mediators and increasing of contractive mediators and growth stimulating factors. Interaction of various factors contributes to the occurrence of restenosis. Therefore, endothelial cells become one of the targets of preventing restenosis after PTA and protection of endothelial cells, repair of endothelial injury and restoration of endothelial function become one of the key strategies.Endothelial progenitor cells (EPCs) derive from bone marrow, entering into circulation after mobilization, homing to injured site, differentiating to endothelial cells and replacing dysfunctional endothelium. Many studies have shown EPCs plays an important role in postnatal neovascularization and endothelial repair after vascular injury.In the present study, we established an acute vascular endothelial injury model using a balloon catheter to damage the endothelium of the rat common carotid artery, and then transplanted human fetal aorta-derived EPCs to investigate whether can repair endothelial injury. The aim of this study is to provide experimental basis for the clinical application of EPCs derived from human fetal aorta.Methods1. An acute vascular injury model was established using a balloon catheter to damage the endothelium of the rat common carotid artery. HE staining verified the establishment of the vascular injury model and Evans blue staining observed the carotid artery endothelial denudation.2. EPCs labelled by BCECF-AM fluorescent dye were injected into the injured carotid artery. At 24 hours later, rat was sacrificed and target vessel was harvested. Then green fluorescence(?)labeled EPCs were identified by fluorescent stereoscopic microscopy.3. The rats were randomly divided into transplantation group and control group, each group had 10 rats. After balloon injury, the cell suspension (1×106 EPCs in 40 β1) was injected locally into the arterial lumen of the transplantation group, and the same amount of normal saline was injected into the arterial lumen of the control group.4. Rats were sacrificed at 2 and 4 weeks after arterial injury and target vessels were harvested. HE staining assessed vascular neointimal thickness. The survival and differentiation of transplanted cells were identified by immunohistochemical staining with anti(?)human vWF, anti(?)human CD31 and anti(?)human mitochondria antibodies.Results1. The rat carotid artery balloon injury model was established successfully. HE staining showed the uninjured vessel was covered with the integrated monolayer of endothelial cells manifesting blue(?)stained nuclei on the endovascular surface. However, the intima of injured vessel was stripped and the monolayer of endothelial cells was absent. Evans blue staining showed the uninjured vessel was not stained due to the intimal integrity. However, the injured vessel was stained blue, indicating the endothelium was denuded.2. At 24 hours after transplantation of fluorescence(?)labeled EPCs, scattered green fluorescence could be seen on the endovascular surface of balloon(?)injured vessel under fluorescent stereoscopic microscopy, which suggested that injected EPCs could adhere to the intimal injury site and survive.3. At 2 and 4 weeks after balloon injury, the blood vessels from EPC(?)transplanted and control groups showed intimal hyperplasia, disordered and narrowed lumen. The intimal area (IA) and intimal/medial area (I/M) ratio were lower in the transplanted group than in the control (P< 0.05), indicating transplanted EPCs inhibited neointimal hyperplasia. Immunohistochemical staining found that human vWF-positive cells distributed on the neointimal surface in the transplantation group, further indicating transplanted EPCs could mediate the re-endothelialization of injured vessels.4. Immunohistochemical staining revealed human CD310 and mitochondria(?)positive cells distributed in the re-endothelialized endothelium in the transplantation group. However, the control group showed no positive expression. These suggested that transplanted EPCs could survive, differentiate into endothelial cells and form complete vascular endothelial layer in the injured vessels.ConclusionEPCs derived from human fetal aorta were successfully transplanted into injured vessels. The transplanted EPCs inhibited neointimal hyperplasia and repaired endothelial injury after vascular injury. |
