Do Matrix Metalloproteases and Tissue Inhibitors of Metalloproteases in Tenocytes of the Rotator Cuff Differ with Varying Donor Characteristics?

An imbalance between matrix metalloproteases (MMPs) and the tissue inhibitors of metalloproteases (TIMPs) may have a negative impact on the healing of rotator cuff tears. The aim of the project was to assess a possible relationship between clinical and radiographic characteristics of patients such as the age, sex, as well as the degenerative status of the tendon and the MMPs and TIMPs in their tenocyte-like cells (TLCs). TLCs were isolated from ruptured supraspinatus tendons and quantitative Real-Time PCR and ELISA was performed to analyze the expression and secretion of MMPs and TIMPs. In the present study, MMPs, mostly gelatinases and collagenases such as MMP-2, -9 and -13 showed an increased expression and protein secretion in TLCs of donors with higher age or degenerative status of the tendon. Furthermore, the expression and secretion of TIMP-1, -2 and -3 was enhanced with age, muscle fatty infiltration and tear size. The interaction between MMPs and TIMPs is a complex process, since TIMPs are not only inhibitors, but also activators of MMPs. This study shows that MMPs and TIMPs might play an important role in degenerative tendon pathologies.

Influence of prophylactic antibiotics on tissue integration versus bacterial colonization on poly(methyl methacrylate).

PURPOSE: Biomaterial-associated infections (BAI) remain a major concern in modern health care. BAI is difficult to treat and often results in implant replacement or removal. Pathogens can be introduced on implant surfaces during surgery and compete with host cells attempting to integrate the implant. Here we studied the influence of prophylactically given cephatholin in the competition between highly virulent Staphylococcus aureus and human osteoblast-like cells (U-2 OS, ATCC HTB-94) for a poly(methyl methacrylate) surface in vitro using a peri-operative contamination model. METHOD: S. aureus was seeded on the acrylic surface in a parallel plate flow chamber prior to adhesion of U-2 OS cells. Next, S. aureus and U-2 OS cells were allowed to grow simultaneously under shear (0.14 1/s) in a modified culture medium containing cephatholin for 8 h, the time period this drug is supposed to be active in situ. Subsequently, the flow was continued with modified culture medium for another 64 h. RESULTS: In the absence of cephatholin, highly virulent S. aureus caused U-2 OS cell death within 18 h. In contrast, the presence of cephatholin for 8 h resulted in survival of U-2 OS cell up to 72 h during simultaneous growth of U-2 OS cells and bacteria. Not all adhering bacteria were killed however, but they showed a delayed growth. CONCLUSIONS: These findings are in line with the recalcitrance of biofilms against antibiotic treatment observed clinically, and represent another support for the use of in vitro co-culture models in mimicking the clinical situation.