engleski

Osteogenic potential of muscle tissue in ACL reconstruction

Introduction In recent years there have been many improvements in the operating technique of anterior cruciate ligament (ACL) reconstruction with semitendinosus and gracilis tendons. Tendon to bone healing within the tunnels still remains a problem with a certain dose of unpredictability. Usually a surgeon takes two tendons with an instrument that harvests muscle tissue and not only the tendon itself. Next step during graft preparation is to “clean” the tendon from muscle tissue. Muscle tissue is rich with mesenchymal stem cells and can be used in order to enhance tendon to bone healing. Materials and methods The purpose of this research is to enable and stimulate differentiation of the pluripotent mesenchymal stem cells (MSC) isolated from the muscles and tendons harvested as an autograft. Further objective is to enhance tendon ingrowths in the bone tunnels with the use of MSCs gained from muscle tissue that is usually treated as waste after harvesting. At the time of surgery both tendons are separated from residual muscle tissue and sized to 22 cm in length. The remaining length of the muscles is being processed within the study. Four study groups are formed: gracilis muscle tissue, gracilis tendon tissue, semitendinosus muscle tissue and semitendinosus tendon tissue. Osteogenic potential of both tissues (muscle and tendon) was measured first day after harvesting and 14 days afterwards. Results Tissue cultures were stained histochemically for (Alkaline phosphatases) ALP and mineralized matrix was visualized with von Koss method. Activity of ALP was measured 14 days after beginning of differentiation of mesenchymal stem cells isolated from semitendinosus and gracilis muscles, semitendinosus and gracilis tendons. Purple intense color was gained in cells differed from muscle tissue which shows significantly larger activity of ALP comparing to the cells differed from tendons. Visualization of mineralized matrix with von Koss citochemic method showed more intense black color gained in cells differed from muscle tissue comparing to the cells differed from tendons. Discussion In this study we compared osteogenic potential of mesenchimal stem cells isolated from semitendinosus and gracilis muscles, semitendinosus and gracilis tendons through expression of pluripotential markers and markers of osteogenesis . Activity of ALP measured 14 days after beginning of differentiation of mesenchymal stem cells schow significantly larger activity of ALP comparing to the cells differed from tendons. Expression of pluripotential markers Oct4, Sox2 and Nanong (relative expression of mRNA) decreases after induction of osteogenesis in differentiated MSC cells isolated from muscles (which is in accordance with the role of these gens) while expression of this markers in semitendinosus , gracilis tendons is not so clearly decreased. Conclusion The present study showed that muscle tissue is rich with mesenchymal stem cells. In future cleaning the tendons should not be performed cause osteogenic potential of MSC stem cells isolated from muscles can enhance tendon to bone healing within the tunnels in ACL reconstruction.

Muscle-derived mesenchimal stem cells; Oct4; Sox2; Nanog

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