Figure 1.

Biological obstacles associated with cell-based approaches to cartilage tissue engineering. Formation of hyaline neocartilage can be hindered due to loss of transplanted chondrogenic cells by cellular efflux, apoptosis or necrosis, differentiation insufficiencies, including fibroblastic, hypertrophic or osteogenic differentiation (red arrows), matrix destruction by mechanical, oxidative and/or inflammatory stressors (red flashes), as well as integration failures within the cartilage and/or bone compartment (green arrows) of the defect.