LOXs And MMPs Expressions Of The PCL Fibroblasts Cells Co-cultured With Synovial Cells

The healing process of injured posterior cruciate ligament (PCL) is one of the mostchallenging and intractable clinical problems. The poor healing response of injury PCLand the low success rate of surgical repair will need researchers to find new ways ofregeneration the function of injured PCL. The PCL injury and repair process is verycomplex, which including the degradation and synthesis of extracellular matrix (ECM).The balance between the degradative and the biosynthetic arms of this process iscontrolled by the activities of matrix metalloproteinases (MMPs) and lysyl oxidase(LOXs), which implicating their important fundamental roles in injury healing.Therefore, the molecular response mechanisms of MMPs and LOXs in normal/injury ofPCL fibroblast cells could considered to be the main analysis way of injured PCLhealing 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. PCL is considered an intraarticularbut extrasynovial structure surrounded by a thin layer of synovial tissue within anintraarticular environment. When this synovial tissue is ruptured, the PCL is exposed tosynovial fluids, hemorrhagic breakdown products, and proteolytic enzymes. Thus, it hasbeen postulated that it was considered necessary to establish coculture model whichmimick the in vivo microenvironment and detected whether the co-culutre influence thecross-talking of PCL cells and synovial cells or not? The results shown that theco-culture system not only maintained a better cell growth state but also promoted cellmigration. The migration rates of PCL cells and synovial cells in co-culture wereincreased by43.1%and76.2%, respectively, compared to monolayer culture (P <0.01). Therefore, it is very inmportant to explore the molecular mechanism of PCLinjured and healing in co-culture system. The mRNA expressions of LOXs and MMPsand the activity expressions of MMP-2in PCL fibroblasts co-cultured with HS cellswere analyzed by semi-quantitative PCR, quantitative real-time PCR and zymography.Our results shown that co-culture can regulate the mRNA expressions of LOXs andMMPs in the normal/injured PCL fibroblasts cells, and time-dependent change ofdifferent expression trends. These results shown that the interactions of cell-cell plays a very important role in wound and healing process. The differential expressions of LOXsand MMP-1,2,3in co-cultured PCL indicate that PCL cells and synovial cells do existinteraction and crosstalk either in normal state or wound state, imply that cell-cellinteraction and crosstalk are relationship with PCL wound healing and have potentialsignificant value and clinical usage for cure of injured PCL. It is hypothesizedaccording to the characteristics of indirected co-culture that cells may secrete certaincytokines through paracrine, which can induce another cells migration and regulateexpressions of LOXs and MMP-1,2,3in co-culture environment.