Morphologic Observation And The Expression Of TGF-β1 And Its TypeⅡ Receptor In Experimental Ascending Aortic Aneurysm Of Rat Model

ObjectiveAneurysm expansion is characterized by inflammation,loss of elastin,and increased turnover of collagen in the aortic wall.The reason of aortic aneurysm expansion is interplay of inflammation,genetic,proteolysis and other factor.Transforming growth factor-beta 1(TGF-β1)is a multifunctional growth factor that is capable of inducing a spectrum of cellular events including proliferation,cell cycle arrest,differentiation,programmed cell death and matrix deposition.The objective of this study is to investigate the Morphologic change of arterial wall and the expression and signification of TGF-β1 and its typeⅡReceptor (TGF-βRⅡ)in experimental ascending aortic aneurysm of rat model.MethodTwenty young female Wistar rats(100-110g)were divided into two groups,the operated group(aneurysmal group,10 rats)and the sham operated group(control group, 10 rats).Opened the chest under sterile condition,segregated the thymus and isolated the ascending aorta.According the diameter of the ascending aorta,Banded a ring which was made by a plastic soft tube(diameter 1mm,length 6-8mm)in the ascending aorta over the aortic valve 1cm.Than closed the chest.Sham operated group only isolated the ascending aorta,didn't band the ring.Four months later,the rat of operated group may growth an aneurysm over the ring,and harvested the ascending aorta.Using methods of HE stain,Masson's stain,Uana's orcein stain and Van Gieson's stain observed the network structure of collagen,elastin and vascular smooth muscle cells in wall of both group.Using Immunohistochemical stain investigated the expression of TGF-β1 and TGF-βRⅡin the aneurysms and control group,and located the positive position.Using Western Blotting investigated the expression of TGF-β1 and TGF-βRⅡin the wall of the both group.The semi-quantitative analysis between the two groups was done by Scion Image software.SPSS 13.0 statistical software was applied for data analysis.ResultHE stain showed that most of the aneurysm contained thrombosis,part of the tunica intima hyperplasyed prominently.A lot of inflammatory cells infiltrated in the adventitia and thrombosis.The structure of artery wall in control group was normal.Masson's stain and Van Gieson's stain showed that hyperplastic vascular smooth muscle cells arranged disorderly,some part even didn't have vascular smooth muscle cell.Most part of the aneurysm increased in collagen and the structure was disorder.Uana's orcein stain showed that half of the aneurysmal wall didn't have elastic fiber,the other part had nearly normal tunica media elastic lamellae.The control group had normal collagen and elastin.Immunohistochemical stain results showed that TGF-β1 expressed in all layers of the aortic aneurysm and control.TGF-βRⅡprimary located in the hyperplastic intima and tunica media smooth muscle cells in the aortic aneurysm,but there had only a little positive stain in control group.Western blotting results indicated that the expression levels of TGF-β1 and TGF-βRⅡin the aortic aneurysm were stronger than control,P＜0.05 and P＜0.01 respectively.ConclusionExperimental ascending aortic aneurysm of rat have tunica intima hyperplasia, most of the aneurysm contained thrombosis,Lots of Inflammatory cells infiltrate in the adventitia and thrombosis.The structure of vascular smooth muscle cells arrange disorderly.The wall of ascending aortic aneurysm reconstruct obviously.The expressions of TGF-β1 and TGF-βRⅡin ascending aortic aneurysm are stronger than control.The TGF-βsignaling increases in the ascending aortic aneurysm.