| Objective1. To present a novel pathogenesis of abdominal aortic aneurysm (AAA), that is to determine if heparanase might participate in AAA since heparan sulfate proteoglycan (HSPG) represents a critical component of non-structure proteins in aortic wall extracellular matrix (ECM), and endoglycosidase activity-heparanase could degrade the HS side chains of HSPG.2. To establish a new, steady and reliable rat model of AAA, not only laying a foundation for more AAA studies in vivo, but also for further understanding the relativity between immune inflammation damage and AAA formation and development. 3. To evaluate heparanase in vascular responses to xenografts and its correlation with the pathogenesis of AAA on the basis of the new model above; and with the therapy of PI-88(sulfated oligosaccharide phosphomannopentaose sulfate, one of the inhibitors of heparanase activity ), to prove the role of heparanase in AAA in back side and in vivo, which also provide a novel way for the prevention and cure of AAA.MethodsTissue samples of human infrarenal aneurysmal and normal aorta, and primary hepatocellular carcinoma were evaluated. Northern blot, immunohistochemistry and computer-assisted image analysis were used to evaluate the expression of heparanase and heparan sulfate proteoglycan (HSPG) protein and/or mRNA, and microvessel density by using heparanase cDNA probe and the antibodies of heparanase, HSPG and Von Willebrand Factor. At the same time, the correlations were compared between heparanase and HSPG, or heparanase and MVD, and their1. clinicopathological significance in AAA.2. According the principle of xenograft rejection, interspecies graft between guinea pig and SD rat abdominal aorta was performed by microvascular anastomosis. Macroscopic and microscopic morphologic changes, occurred in xenografts, were compared after implantation in rats using H&E and special pigmentation, immunohistochemistry,in situ end-labeling of DNA fragments (TUNAL) and computer-assisted image analysis by a computer-assisted technique. Besides, the novel model was compared with the conventional AAA model of elastinase perfusion in the morphology and so on.3. Using techniques of RT-PCR, immunohistochemistry and vascular special pigmentation, and before and after the therapy of PI-88,the guinea pig-to-SD rat transplant model of AAA was used for dynamic observation and comparison of the concomitant platelet aggregation, heparanase deposition, loss of HSPG and microvessel hyperplasia within the local vascular microenvironment, during vascular responses to xenotransplantation. We also take a further step to observe the morphologic changes of the grafts after administration of PI-88.Results1. Expression and clinicopathological significance of heparanase and HSPG in human AAA tissues. There was increased synthesis of heparanase mRNA in human AAA in comparison with the normal abdominal aortas(NA), and the level of heparanase mRNA were remarkably negative correlated with the inflammatory cells infiltration and reduce of smooth muscle cells(SMC) in media,and obviously positive correlated with MVD seen mostly within adventitia, but no correlation with the diameters of AAA. Upregulated heparanase proteins were mainly distributed in the tunica adventitia and intima, concomitant the loss of HSPG within local microenvironment. HSPG proteins within AAA walls were lower than that in NA.2. Morphologic characteristics of the xenografted AAA in rats. 88 percent of the grafts were gradually dilated within 4 weeks after transplantation, remarkable differences vs. the controls. There was correlation between the diameters with transverse areas of aneurysmal lumen in enlarged grafts. The sections of H&E, special pigmentation,TUNAL and immunohistochemistry have showed large numbers of inflammatory infiltration and microvessel hyperplasia within remarkable incrassated adventitia and intima, degradation of structral elastin and decreased density of SMC in media, and concomitant SMC apoptosis and MMP upr...
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