Evaluation of the effectiveness of a bMSC and BMP-2 polymeric trilayer system in cartilage repair

In this study a poly(lactide-co-glycolide) acid (PLGA) tri-layer scaffold is proposed for cartilage repair. The trilayer system consists of a base layer formed by a tablet of PLGA microspheres, a second layer composed of a microsphere suspension placed on top of the tablet, and the third layer, which constitutes an external electrospun PLGA thin polymeric membrane. Combinations of bone morphogenetic protein-2 (BMP-2) encapsulated in the microspheres of the suspension layer, and bone marrow mesenchymal stem cells (bMSC) seeded on the electrospun membrane, are evaluated by histologic analyses and immunohistochemistry in a critical size osteochondral defect in rabbits. Five experimental groups, including a control group (empty defect), a blank group (blank scaffold), a bMSC treated group, two groups treated with 2.5 μg or 8.5 μg of BMP-2 and another two groups implanted with bMSC-BMP-2 combination are evaluated. The repair area increases throughout the experimental time (24 weeks). The repair observed in the treated groups is statistically higher than in control and blank groups. However, the bMSC-BMP-2 combination does not enhance the BMP-2 response. In conclusion, BMP-2 and bMSC repaired effectively the osteochondral defect in the rabbits. The bMSC-BMP-2 combination did not produce synergism.