Effects Of Osteoblast-Specific Knockout Of Wnt5a On OA Cratilage And Subchondral Bone In Mice

Objectives In osteoblast-specific knockout of Wnt5a mice,build type ? collagenase type induced osteoarthritis,observations in the model of Wnt5a knock out the effects of cartilage and subchondral bone.Methods Ocn-cre+;wnt5afl/fl(KO)and Wnt5afl/fl(WT)genotype were measured by PCR through mating OCN-Cre and Wnt5afl/fl mice.3-month-old KO and WT male mice produced in the same batch were randomly divided into four groups:Group vehicle+WT,Group vehicle+KO,group collagenase+WT and Group collagenase+KO(n=6 for each group).The right knee joints in the group collagenase+WT and collagenase+KO were injected with type VII collagenase(Sigma-Aldrich)from the patellar ligament with a microsyringe on days 0 and 2,as the same time,the left side of the knee joint injection dose normal saline treatment.All mice were sacrificed to harvest the entire knee joints after 6 weeks and the expression of Wnt5a in osteoblasts was observed by immunohistochemistry.Cartilage pathology was evaluated by gross visual,histology and immunohistochemical assessments.Micro-computed tomography was used to determine the bone mass and microstructure of subchondral bone.Results Gross observation and scoring showed that the vehicle+WT group and vehicle+KO group had smooth cartilage surface,rosy color and excellent luster.The cartilage surface in the collagenase+WT and collagenase+KO groups was uneven,with local pale color and poor glossiness.The gross score was no significant difference between any two groups.Histological results of toluidine blue showed that the articular cartilage was smooth and regular in vehicle+WT and vehicle+KO groups.The morphology and number of chondrocytes were normal.The cartilage extracellular matrix was stained uniformly without loss.The articular cartilage of mice in the collagenase+WT and collagenase+KO groups showed slight degeneration,with rough and irregular cartilage surface,local cartilage surface fracture,local reduction of chondrocytes,uneven staining of local extracellular matrix and local staining loss.OARSI score shows that compared with group vehicle+WT,group collagenase+WT scores significantly increased(p<0.05).Compared with group vehicle+KO,the score of group collagenase+KO significantly increased(p<0.05),and there was no significant difference between collagenase+KO group and collagenase+WT group.Morphological observation of HE showed that the articular cartilage of vehicle+WT and vehicle+KO group mice had normal structure,smooth and regular cartilage surface,and no wear and crack.The morphology and number of chondrocytes were normal.In the collagenase+WT and collagenase+KO groups,minor changes were observed in articular cartilage structure,local cartilage surface fracture,local reduction in the number of chondrocytes,and morphological changes.Micro-CT detection results showed that compared with group vehicle+WT,the BDM,BV/TV and Tb.Th in group collagenase+WT were significantly reduced(p<0.05).Compared with group vehicle+KO,BMD and BV/TV showed no significant difference in group collagenase+KO.Compared with group vehicle+WT,BMD,BV/TV and Tb.Th in group vehicle+KO increased significantly(p<0.05),while Tb.Sp decreased significantly(p<0.05).Compared with group collagenase+WT,BMD,BV/TV and Tb.N in group collagenase+KO were significantly increased(p<0.05),while SMI and Tb.Sp were significantly decreased(p<0.05).Conclusions In the group of collagenase+WT and collagenase+KO mice,inside the knee type ? collagenase injection can be successfully established early OA model,induced histology articular cartilage and subchondral bone lesion.Bone mass was significantly increased in mice with osteoblast-specific knockout of Wnt5a.Figure9;Table2;Reference 144.