"This has significant ramifications because we are now beginning to talk, for the first time, about the potential treatment of entire arthritic joints and not just small defects," said lead researcher and lab director Kyriacos Athanasiou, the Karl F. Hasselmann Professor of Bioengineering.
Athanasiou's new self-assembly method involves a break from conventional wisdom in bioengineering; almost all previous attempts to grow replacement transplant tissues involved the use of biodegradable implants that are seeded with donor cells and growth factors. These implants, which engineers refer to as scaffolds, foster the tissue growth process by acting as a template for new growth, but they always present a risk of toxicity due to the fact that they are made of materials that aren't naturally found in the body.
In the newly reported findings, Athanasiou and postdoctoral researcher Jerry Hu, using nothing but donor cells, grew dime-sized disks of cartilage with properties approaching those of native tissue. In a follow-up study due for publication soon, graduate student Christopher Revell refined the process to produce disks that are virtually identical to native tissue in terms of both mechanical and biochemical makeup. In a third, and perhaps most impressive breakthrough, Athanasiou and Hu used the self-assembly approach to grow the entire articular surface of the distal femur. Each of these unbroken samples were tailored three-dimensionally to fit a specific rabbit femur.