Structural barrier principle for growth factor-based articular cartilage repair

A growth factor-based strategy recently has been shown to induce the intrin sic repair of partial-thickness articular cartilage lesions, thereby obviat ing the need for transplanting cells or tissue. It was the purpose of the c urrent study to ascertain whether this principle could be applied to full-t hickness articular cartilage defects created in adult rabbits and mature mi niature pigs. The transforming growth factor-beta1 contained within the aut hors' chondrogenic matrix-complex proved to be potent in its osteogenic cap acity when liberated into the bone compartment of such lesions, inducing th e rapid upgrowth of osseous tissue and vascular buds into the cartilage com partment. This is an unwanted response that must be prevented. A cell and b lood vessel-excluding membrane (Millipore (R) in rabbits and Goretex (R) in miniature pigs) was inserted at the interface between cartilage and bone c ompartments, both of which were filled at the appropriate juncture with the chondrogenic matrix-complex. These structural barriers were effective in o bstructing the upgrowth of blood vessels into the cartilage compartment and in preventing the osteogenic tissue differentiation attributable to the pr esence of a vasculature.