['This study investigates the effect of cell seeding density on cartilage repair in matrix-assisted chondrocyte implantation in vitro and in vivo.', "In vitro: Four different cell seeding densities of human chondrocytes were seeded onto a porous methoxy-polyethylene glycol-polylactic-co-glycolic acid scaffold (MPEG-PLGA) polymer scaffold ASEED™ (1.2\xa0×\xa010(6), 4.0\xa0×\xa010(6), 1.2\xa0×\xa010(7) and 2.0\xa0×\xa010(7)\xa0cells/cm(3)). The cartilage repair response was evaluated by relative gene expression of the chondrogenic markers sox9, collagen types I, II and X, and aggrecan, total DNA content and sulphated glycosaminoglycan synthesis. In vivo: Using a New Zealand white rabbit intercondylar osteochondral defect model, three different cell seeding densities (1.2\xa0×\xa010(6), 4.0\xa0×\xa010(6) and 1.2\xa0×\xa010(7)\xa0cells/cm(3)) were tested with an empty scaffold as control. The cartilage repair response was evaluated using O'Driscoll score.", 'In vitro: A significant difference (p\xa0<\xa00.05) in total DNA content was found at day 2 but not at day 7. The low cell seeding densities yielded the highest GAG content (p\xa0<\xa00.001) at day 7. Collagen type I was highest (p\xa0<\xa00.01) at the lowest density at day 7. In vivo: No significant difference was found between the 4 groups.'] Does increased chondrocyte seeding density have no positive effect on cartilage repair in an MPEG-PLGA scaffold?