Chondrogenic capacities of outer or inner meniscus cells in co-culture with mesenchymal stromal cells (MSCs) are similar. Biochemical analysis was used to evaluate the chondrogenic differentiation capacities (GAG/DNA) and the chondrogenic differentiation indices of the pellets from MSCs, MCI/MSCs, MCI, MCO/MSCs, and MCO after 3 weeks of culture in chondrogenic medium (transforming growth factor-beta 1, dexamethasone, and ascorbate). Chondrogenic induction index was calculated with equations 1 and 2 in the Biochemical analysis subsection of Materials and methods. If the chondro-induction index was greater than 1, an enhancement in chondrogenic matrix formation was considered to have occurred. Data are presented as mean ± standard error of mean of four donor pairs. One-way analysis of variance with Tukey's multiple comparison post tests: *significance when compared with mono-cultures of meniscus cells - outer meniscus cells (MCO) or inner meniscus cells (MCI) - and MSC pellet controls (P <0.05); **significance when compared with MCO or MCI and MSC pellet controls (P <0.0001). Paired two-tailed Student t statistics: no significance (n.s.) (P >0.05) between chondro-induction indices of co-cultures of MCO or MCI and MSCs. GAG, glycosaminoglycan; MCI, meniscus cells from inner meniscus region; MCO, meniscus cells from the outer meniscus region.