In vitro Zellkultur-Studie über die Signifikanz von Bone Morphogenetic Protein-2 (BMP-2) im Prozess der Knochen-Sehnen-Integration

Ligament ruptures are the most common sports injuries worldwide. With about 50% the ACL-rupture is the most common ligament injury of the knee joint. Currently, more than 100.000 reconstructions of the anterior cruciate ligament (ACL) are performed annually, in the USA only. The integration of the tendon graft into the bone continues to be a critical factor in ligament surgery. Bone morphogenetic proteins are often topics in scientific publications. Their osteoinductive potential is shown in many articles and reviews. But there is yet to be any broad in vitro-studies concerning the use of BMP in ACL-surgery. The aim of our study was to demonstrate in which extend BMP-2 has an influence on the tendon-bone-integration and to prove if external application of BMP-2 leads to a better and faster calcification of tendons. In doing so, we established an in vitro-cell culture model based on a bone stem cell culture. With the help of this model we were able to cultivate bovine tendons for a period of 3 months. To measure calcification, the results have been analysed microscopically (scanning electorn microscopy, light microscopy), as well as histologically and biochemically by determining specific analytes such as alkaline phosphatase (ALP) and osteocalcin (OCN). Our cell culture model demonstrates ideal conditions for cell culture experiments over a prolonged period of time. With our analysing techniques we were able to examine the calcification process from the early stages (biochemically) and the late stages(histology). The cultivation time and the population size can be extendet at will. In our experiments we found details about the triggering effect of BMP-2 in the mineralization process. BMP-2 seems to accelerate and optimize the process of tendonbone-integraton. Besides the influence of BMP-2 on Osteoblasts, we assume, that an effect of BMP-2 on the Fibroblasts plays an important role as well. Though the definite mechanism is not completely understood. According to our findings, we assume that BMP-2 triggers an ossification that is carried by osteoblasts and by fibroblasts as well. Therefore the tendon could play an important role in the process of bone-tendonintegration, so that the tendon takes an active role growing into the bone. In conclusion we can say, that we confirmed the well known effects of BMP-2 in our experiments and additionally we identified some new effects of this group of proteins. Further studies are needed to utilize the whole potential of BMP-2 in the future.