Unlike cartilage, most tissues in our bodies ?including skin, blood vessels and bone ?regenerate themselves constantly. Tissue engineers try to capitalize on the body's own regenerative powers to grow replacement tissues that can be transplanted without risk of rejection. Donor cells from the patient are used as a starting place to eliminate rejection risks.
Most tissue engineering involves honeycombed plastic templates or hydrogels called scaffolds that are used to guide colonies of donor cells. Donor cells can be either adult stem cells or other immature cells. Athanasiou's latest work was done using chondrocytes, or cartilage cells.
Athanasiou, a former president of the international Biomedical Engineering Society, helped pioneer the development of coin-sized scaffolds in the early 1990s that are now the state-of-the-art clinical option for repairing small defects in articular knee cartilage.
His lab is also working on techniques to grow replacement knee menisci, the kidney shaped wedges of cartilage that sit between the femur and tibia and absorb the compressive shock that the bones undergo during walking and running. Over the past 18 months, he and his students Adam Aufderheide and Gwen Hoben have perfected methods of growing meniscus-shaped pieces of cartilage, but they are still trying to perfect the mechanical strength of the engineered meniscus tissue, which must be able to withstand up to an astounding 2,400 pounds per square inch of compressive pressure.