Tissue engineering of hyaline cartilage

Cartilage injuries are frequent and lead to pain and disability. Unfortunately, articular cartilage shows a limited capacity for selfhealing and often goes on to osteoarthritis. Several surgical techniques have been developed to fill the cartilage defects , but so far none of them have been able to produce normal cartilage. Recently, our group published the first controlled, randomized study in this field. Our five year results comparing microfracture surgery with ACT did not find any difference between t he patients. Like other groups, we have found that chondrocytes in suspension implanted into a defect under a periosteal flap do not result in normal hyaline cartilage in biopsies from ACT patients and in our animal studies, but rather develops into fibro cartilage, which is expected to have a short lifespan. Our group, and others, have therefore started studies on mesenchymal stem cells (MSC) from the patients own bone marrow because basic studies suggest that these cells may be able to develop into a mor e normal cartilage type. To prevent the cells from producing fibrous tissue, the cells are expanded on plastic surfaces in vitro, and then transferred to three-dimensional (3D) scaffolds. Alginate, the scaffold chosen for the present project is extracted from seaweed. A considerable part of the alginate research has been performed by Norwegian research institutions, and a Norwegian company (NovaMatrix/FMC) has a patent on the production of alginate in ultra-pure form. In order to determine how to best mak e hyaline cartilage discs in vitro, we will be investigating the use of human articular chondrocytes and human BM-MSC in parallel. At the same time, our industry coworker will investigate the production of a biodegradable, malleable alginate implant. In t he next step we will test the implants in our well known animal model, and finally we will evaluate the implants in a randomized controlled human study similar to our previous designs.