Bioengineering of cartilage in organ culture

Tissue Engineering of the TMJ disc: a review

The potential impact of a tissue-engineered temporomandibular joint (TMJ) disc is immense. Currently, patients suffering from a severely dysfunctional TMJ have few options. Facing the general lack of safe, effective TMJ disc implants, many patients undergo discectomy, a procedure that removes the injured TMJ disc in hopes of reducing debilitating symptoms associated with severe TMJ disorders. This procedure may not be ideal as the TMJ is left without an important functional component. Tissue engineering is a promising approach for the creation of viable, effective implants. The first attempt to investigate TMJ disc cells on a biomaterial was conducted in 1991. The first TMJ tissue-engineered constructs to be tested biochemically and biomechanically were formed in 1994; however, in examining this study in retrospect, it is clear how little TMJ knowledge was available at that time. Within the last 10 to 15 years, multiple studies have investigated critical TMJ disc characteristics, and while this characterization is not complete, these data have created a solid foundation for tissue-engineering research. Thus, the last 5 years have yielded core studies investigating the principal elements of tissue engineering: scaffold, cell source, and biological/biomechanical stimuli. Although TMJ disc tissue engineering is still in its formative years, its future is quite promising. Key studies are now being conducted that will assist in the establishment of a solid TMJ disc tissue-engineering approach. As the challenges of tissue engineering are faced and met, the ultimate goal of creating a functional biological implant nears.

In vitro synthesis and characterization of a cartilaginous meniscus grown from isolated temporomandibular chondroprogenitor cells

Internal derangement of the temporomandibularjoint can lead to perforation of the intra-articular meniscus and osteoarthritic degeneration. Current methods of repairing damaged menisci are limited by lack of biological compatibility of graft materials. This project aimed to synthesise and characterise a primate cartilaginous meniscus in vitro from harvested mandibular chondroprogenitor cells. Isolated cells from the mandibular cartilage of 12 young adult marmosets, aged 9-12 months, were grown in monolayer culture. After 21 days confluent colonies were resuspended and dispersed into a unpolymerised solution of type I collagen and fibrinogen. The resultant cell suspension was infiltrated into a resorbable type I collagen sponge carrier and allowed to polymerise. Aliquots of the cell-infiltrated sponge were maintained in organ culture for a further 14 days. Cultures were characterised using histochemical and immunocytochemical localisation of collagen and proteoglycan species. Two-thirds of cells in confluent 21-day monolayers expressed cartilage-specific type II collagen and chondroitin-4-sulphate. After 35 days organ cultures had formed a viable, organised, three-dimensional tissue mass consisting of mature chondrocytic cells interspersed in a dense cartilaginous matrix. The cartilaginous tissue generated in vitro may have potential application in the repair or replacement of damaged menisci in vivo.