Expression of VEGF-A Signaling Pathway in Cartilage of ACLT-Induced Osteoarthritis Mouse Model

Abstract

Background: The clear understanding of the underlying mechanism of Osteoarthritis(OA) remains elusive.Researches have shown that Vascular Endothelial Growth Factor(VEGF) induced angiogenesis and inflammation were important processes in the pathophysiology of OA.Now, Anterior Cruciate Ligament Transection surgery(ACLT) induced OA model was often used to invesgate the molecular mechanism of OA,but till now the angiogenesis and inflammation reaction in different pathological stages of ACLT-induced OA model has never been revealed.Methods:Moderate OA model was established by ACLT,and 1,2,4,8 and 12 weeks after surgery, Hematoxylin–eosin(HE) and Safranin-O(S-O) staining were used to detect the pathological changes in mouse knee cartilage,and the matrix biomarkers A Disintegrin and Metalloproteinase with Thrombospondin Motifs 5(ADAMTS5), Collagen II(COL-II) were detected using Immunohistochemistry (IHC),CD31 was detected by Immunofluorescence(IF) to show the vascular invasion in cartilage,and proteins expression of VEGF-A pathway were detected by Western blot(WB).Meanwhile the inflammatory biomarkers Cyclooxygenase-2 (COX-2) and inducible Nitric Oxide Synthase(Inos) in cartilage were detected by WB.Results:ACLT surgery can lead to degeneration of cartilage in mice,and the characteristics of the lesion were time dependent.The ADAMTS5 positive cells increased while COL-II decreased in OA cartilage with time,new blood vessel labeled by CD31 can been seen from 1 week in OA cartilage,and increased in 8 and 12 weeks.The expression of VEGF-A,VEGFR2,COX-2 and iNOS were higher than control groups,which were basically consistent with the degree of osteoarthritis.Conclusions:VEGF-A related signaling pathway played an irreplaceable role in the occurrence and development of ACLT model,and the underlying mechanism may be related to the angiogenesis and inflammation in cartilage.