| The healing process of injured anterior cruciate ligament (ACL) is always one ofthe most challenging and intractable clinical and scientific problems. The poor healingresponse of injured ACL and the low success rate of surgical repair will needresearchers to find new ways of regeneration the function of injured ACL. The ACLinjury and repair process is very complex, which including the old extracellular matrix(ECM) degradation and synthesis of ECM, and a variety of proteases involved in thisprocess. Such as, the balance between the degradative and the biosynthetic arms of thisprocess is controlled by the activities of matrix metalloproteinases (MMPs) and lysyloxidase (LOXs), which implicating their important fundamental roles in injuryhealing.Therefore, the molecular response mechanisms of MMPs and LOXs in normal/injury of ACL fibroblast cells could considered to be the main analysis way of injuredACL healing mechanism. There were lots of reasesrches in our group on the effection ofLOXs and MMPs on the ligament repair process, but their researches were based onmonolayer culture condition and had a big limitation. Anatomically, in knee joint,tissues of one particular type are not present in isolation, but exist in intimate structuraland functional interaction with tissues of other types. ACL is considered anintraarticular but extrasynovial structure surrounded by a thin layer of synovial tissuewithin an intraarticular environment. When this synovial tissue is ruptured, the ACL isexposed to synovial fluids, hemorrhagic breakdown products, and proteolytic enzymes.Thus, it has been postulated that it was considered necessary to establish coculturemodel which mimick the microenvironment in vivo and detected whether the co-culutreinfluence the cross-talking of ACL cells and synovial cells or not? The results shownthat the co-culture system not only maintained a better cell growth state but alsopromoted cell migration. Therefore, it is very important to explore the molecularmechanism of ACL injured and healing in co-culture system. The mRNA expressions ofLOXs and MMPs and the activity expressions of MMP-2in ACL fibroblasts co-culturedwith HS cells were analyzed by Semi-quantitative PCR, Quantitative real-time PCR andZymography. Our results shown:1）Compared with monolayer culture, co-culture system not only maintained abetter cell growth state but also promoted cell migration.2）In normal ACL fibroblasts, the results demonstrated that synovial cell co-culture significantly increased the mRNA expressions of LOXs and MMP-2, but the mRNAexpressions of MMP-1and MMP-3were decreased relatively compared to the controls.3) co-culture can promote the mRNA expressions of LOXs and MMP-1,2,3ininjured ACL fibroblast, particularly the expression of MMP-2. From gelatinzymography can be seen that the activity expression of MMP-2in the12%mechanicaltensile damage and co-culture was significantly higher than the other group.These results shown that the interactions of cell-cell plays a very important role inwound and healing process. The differential expressions of LOXs and MMP-1,2,3inco-cultured ACL indicate that ACL cells and synovial cells do exist interaction andcrosstalk either in normal state or wound state, imply that cell-cell interaction andcrosstalk are relationship with ACL wound healing and have potential significant valueand clinical usage for cure of injured ACL. It is hypothesized according to thecharacteristics of indirected co-culture that cells may secrete certain cytokines throughparacrine, which can induce another cells migration and regulate expressions of LOXsand MMP-1,2,3in co-culture environment. |
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