Experimental Pathological Study Of CD31 In The Formation Of Aortic Dissection And Its Mechanism

Objective: Through experimental pathological study,to observe the pathological changes of CD31 molecule in the formation of aortic dissection and its potential mechanism.Method: By collecting 10 cases of sudden unexpected cardiac death(aortic dissection)in Forensic Identification Center of Wannan Medical College and fifteen patients with aortic dissection who underwent aortic vascular repair or replacement were admitted to the Department of Cardiovascular surgery of Yijishan Hospital,the first affiliated Hospital of Wannan Medical College from March 2018 to December 2020 as the experimental group.At the same time,the cause of death of Anhui Medical Forensic Identification Center in the same period was sudden unexpected cardiac death(coronary heart disease,hypertension and other cases of non-aortic dissection)as a negative control group.The causes of death were mechanical injury,traffic accident and high fall as a blank control study.Routine histological staining(HE staining),special staining(Masson trichrome staining,Verh(?)eff elastic fiber staining)and immunohistochemical staining were used to observe the histopathological changes of aortic wall in different groups.At the same time,molecular biological methods(Western Blot)and immunohistochemical staining(IHC staining)were used to observe the changes of CD31 expression in aortic wall in different groups,and statistical analysis of the observed results.Results:The results of HE staining showed that:(1)Blank control group: The structure of each layer of aortic wall is normal,the arterial smooth muscle is arranged regularly,the intima is smooth,there is no fibrous thickening,and there is no atherosclerotic plaque.(2)Negative control group: Local thickening of vascular intima,proliferation of a large number of smooth muscle under intima,degeneration and necrosis of foam cells at the bottom of plaque,degeneration,fracture and disintegration of internal elastic layer and middle elastic plate,necrotic smooth muscle cells,nuclear pyknosis,nuclear staining deepened,atherosclerotic plaque and inflammatory cell infiltration appeared in intima and media,connective tissue hyperplasia and vitreous degeneration occurred on the surface of plaque.(3)Experimental group: The intima and adventitia were obviously thickened,the vascular smooth muscle cells in the media layer were obviously atrophied,decreased and disarranged,the fiber structure of the vascular wall was disordered,broken and discontinuous,the intima was damaged and broken,and the false lumen could be seen in the media.There are a large number of red blood cells and inflammatory cells infiltration in the false cavity,and thrombus attachment can be seen at the same time.2.The results of Verh(?)eff elastic fiber staining showed that:(1)Blank control group: The structure of elastic fibers in aortic tissue was intact,arranged neatly in the shape of cable,no deformation or fracture occurred,and no obvious morphological changes were observed.(2)Negative control group: The intima thickened significantly,the tissue structure of elastic fibers was disordered in the media,and the morphology of some elastic fibers changed,but there was no obvious fracture and destruction,and the number of elastic fibers decrease.(3)Experimental group: The structure of middle elastic fibers was completely disordered,with obvious morphological changes,continuous interruption and a significant decrease in number.3.The results of Masson trichrome staining showed that:(1)Blank control group: The intima is smooth and blue,the collagen fibers are evenly distributed,and the smooth muscle fibers are scattered among them.(2)Negative control group: It can be seen that the deposition of collagen fibers in the media is obvious,showing a flaky distribution.A large number of collagen fibers proliferated,smooth muscle fibers decreased significantly,and a large number of smooth muscle fibers were replaced by collagen fibers.(3)Experimental group: Smooth muscle fibers decreased significantly,collagen fibers proliferated obviously,a large number of smooth muscle fibers were replaced by collagen fibers,collagen fibers arranged disorderly and loose,and the structure was discontinuous.4.The results of immunohistochemical staining showed that:(1)CD31 is mainly located in the cytoplasm of vascular endothelial cells and the junction between endothelial cells and endothelial cells in aortic tissue.(2)In the blank control group,there were a large number of brown granules deposited in the intima of the aorta,and the expression of CD31 was strongly positive.(3)Compared with the blank control group,there were fewer brown granules in the intima of the negative control group,and no expression of CD31 was found in the formation of atherosclerotic plaque,and the difference was statistically significant(P <0.05).(4)The brown granules in the intima of the experimental group were rare and the expression of CD31 was significantly lower than that of the blank control group(P <0.05).5.The results of CD31 expression detected by Western Blot showed that:(1)Compared with the blank control group,the expression of CD31 in the negative control group decreased,and the protein expression decreased gradually with the increase of age and the aggravation of atherosclerotic symptoms(P <0.05).(2)The expression of CD31 protein in the experimental group was significantly lower than that in the control group(P <0.05).(3)The expression of CD31 protein in experimental group was lower than that in negative control group.Conclusions: 1、The changes in the structure and content of collagen and elastic fibers will lead to the destruction of the structure and function of aortic wall,which may play a potential role in the progression of aortic atherosclerosis and aortic dissection.2、The expression of CD31 decreased in aortic dissection and aortic atherosclerosis.3、CD31 may be involved in the formation of aortic dissection by affecting the connection between endothelial cells and cells.