Partial replacement of chondrocytes by stem cells has been proposed to improve the performance of autologous chondrocyte implantation (ACI). Our previous studies showed that the increased cartilage production in pellet cocultures of chondrocytes and mesenchymal stem cells (MSCs) is due to a trophic role of the MSCs by stimulating chondrocyte proliferation and matrix production rather than MSCs actively undergoing chondrogenic differentiation. The aim of this study is to compare the trophic effects of stromal vascular fraction cells (SVF) and in vitro expanded adipose stem cells (ASC). SVF and culture-expanded ASC (n = 9) were cocultured with primary human chondrocytes in pellets. By glycosaminoglycan (GAG) and DNA assays, we showed that coculture pellets of SVF and chondrocytes have more GAG deposition than that of ASC and chondrocytes. Results of the short tandem repeats analysis indicated that the increase in the chondrocyte proportion in the coculture pellets is more pronounced in the SVF coculture group than in the ASC coculture group. Using flow cytometry and microarray, we demonstrated that SVF and ASC have different characteristics in cell surface markers and gene expression profiles. SVF is more heterogeneous than ASC, whereas ASC is more enriched in cells from the mesenchymal lineage than SVF. By subcutaneous implantation into nude mice, we showed that constructs of SVF and chondrocytes are better in depositing cartilage matrix than the mixture of ASC and chondrocytes. Taken together, SVF is better than ASC in terms of forming cartilage matrix in pellet coculture and in coimplantation models omitting the need for prior cell expansion. Our study suggests that the SVF in combination with primary human chondrocytes may be a good cell combination for one-stage cartilage repair.
