Osteochondral Grafts
In vitro optimization of tissue engineered osteochondral grafts
In osteochondral defects inside living joints, cartilage and the underlying bone are damaged. These defects do not heal in adults, and lead to arthritis. Many methods have been used to treat diseased cartilage; among these areautologous chondrocyte transplantation, arthroscopic surgery, and ultimately, prosthetic joint replacement. All such treatments have serious limitations related to donor site morbidity, immunological reaction, long-term durability,and other variables. The concept of replacing deficient cartilage with host stem cells seeded into synthetic grafts is an experimental approach that has generated considerable interest and research. Dr Bal (Associate Professor of Orthopaedic Surgery, PI) and Dr Jayabalan (Co-PI) have previously investigated the in vivo performance of synthetic osteochondral grafts in a live animal model. These grafts were based on a Tantalum metal or bioactive glass osseous support material bonded to poly(ethylene) glycol chondral layer. Our collaborator Dr Rahaman (Professor of Ceramics, Missouri University of Science and Technology) and Dr Bal have fabricated this glass into complex geometries with precise control of pore dimensions and overall porosity, including the shape of a proximal human tibia. Our related work has also shown that bioactive glasses can be shaped into anatomic configurations; pore orientation within bioactive glasses can be controlled by freeze-casting; and that bioactive glass adhesion and bioreactivity vary by glass composition. The advantage of bioactive glass is that it forms an interfacial bond with tissues upon implantation, and promotes bone formation as a result of surface modification when exposed to biological fluids.
Currently we are collaborating with Dr Clark Hung (Associate Professor of Biomedical Engineering, Columbia University) to identify the optimal materials for the osseous (including bioactive glass) and cartilaginous phases of osteochondral grafts. By combining respective osseous and cartilage phases, we will synthesize osteochondral grafts and culture them to different time points with multiple outcome measurements being determined. In so doing, we hope to identify the best combination of gel/porous materials for tissue-engineering cartilage in a functional animal model, with the eventual goal of using such techniques to address osteoarthritic joints in human patients. (This work is funded by the MU Research Council).