Cartilage is one of the more challenging tissues to regenerate - it's comparatively easy to grow something that's more or less like cartilage, but it's proven hard to reproduce the necessary small-scale structure and mechanical properties of the real thing. So work continues in laboratory animals:
[Researchers] have suggested that articular cartilage defects can be repaired by a novel thermo-sensitive injectable hydrogel engineered with gene modified bone marrow mesenchymal stromal cells (BMSCs). The chitosan and polyvinyl alcohol composite hydrogel containing hTGFβ-1 gene modified BMSCs was injected into rabbits with defective articular cartilage. Sixteen weeks later the defected cartilage regenerated.
No reliable approach is currently available for complete restoration of damaged articular cartilage. Tissue engineering combined with gene therapy technology has the potential to manage the repair of defective articular cartilage. CS/PVA gel can be applied to the repair of articular cartilage defects as an injectable material in tissue engineering, and the regenerated cartilage can secrete cartilage matrix and perform the functions of hyaline cartilage. Use of this gel for cartilage repair has advantages such as the minor surgical procedure required, tight bonding with the damaged tissue and lack of rejection.