**4.1 Cartilage tissue regeneration**

Cartilage is a flexible, connective tissue in which chondrocytes are sparsely distributed in the extracellular matrixes rich in proteoglycans (PGs) and collagen fibers. Cartilage has a limited capacity for self-repair due to its avascular nature and low mitotic activity of chondrocytes. In articular cartilage, chondrocytes are the only cell type and responsible for the synthesis and maintenance of resilient extracellular matrix. Chondrocytes may undergo a dedifferentiation process during monolayer culturing and lose their phenotype. However, once cultured in hydrogels, dedifferentiated chondrocytes are able to redifferentiate (Benya & Shaffer, 1982), as indicated by their rounded morphology and the production of ECM molecules such as type II collagen and sulfated glycosaminoglycans.
