metalloproteinase and tissue inhibitor of metalloproteinase expression in the murine strort model of osteoarthritis objective to study the temporal expression of matrix metalloproteinases and tissue inhibitors of metalloproteinases in the strort mouse model of osteoarthritis using in situ hybridization with oligonucleotide probes and specific antisera for each proteinmethods in situ hybridization and immunolocalization experiments were performed on serial cryosections of knee joints from strort and control cba mice the mrna was localized using digoxygeninlabeled probesresults mmp2 mmp3 mmp7 mmp9 mmp13 mt1mmp and timp2 mrna was detected in the tibial articular chondrocytes of strort mice at all ages 12 18 24 30 and 35 weeks levels were always higher than in agematched cba mice neither mmp8 nor timp1 mrna was detected in murine cartilage the location and distribution of each of the mmp mrna transcripts varied within the tibial plateau immunolocalization consistently detected mmp3 and mt1mmp in articular cartilage and mmp13 in calcified cartilage other proteases and their inhibitors were not detected in either of these cartilages but mmp2 and mmp9 were immunolocalized in bone marrow cells and growth cartilage respectivelyconclusion expression of all the detected mmps and timp2 is upregulated in strort mice at the mrna level however failure to detect protein expression for mmps 2 7 9 13 and timps 1 and 2 in murine chondrocytes by immunohistochemistry indicates that the changes in mrna levels in strort mice must be interpreted with caution