Fig. 1.

The commonly used cell sources and obtaining the conditioned medium. CM for cartilage regeneration therapies may be obtained from stromal and stem cell populations such as BM-MSCs, SM-MSCs, AD-MSCs, placenta-derived-MSCs, amnion-derived-MSCs, UC-MSCs, UCB-MSCs, WJ-MSCs, DPSCs, SHED and iPSC (induced pluripotent stem cells). Isolated homogenic populations of cells are expanded in in vitro culture. After a reasonable period of time or when adequate cell confluence is achieved CM might be collected, precleared and stored for the future use. circRNA, circular RNA; CCL2, C–C motif chemokine ligand 2; DKK-1, dickkopf 1; ECM, extracellular matrix; FGF, fibroblast growth factor; HGF, hepatocyte growth factor; HIPK3, homeodomain interacting protein kinase 3; IFN-γ, interferon γ; IL-6 /-10, interleukin 6 /10; LIF, leukemia inhibitory factor; lncKLF3-AS1, KLF Transcription Factor 3 Antisense RNA 1; lncRNA, long-non coding RNA; LYRM4, LYR Motif-Containing Protein 4; miR, micro RNA; MMPs, matrix metalloproteinases; ncRNA, non-coding RNA; PDGF, platelet derived growth factor; PGE2, prostaglandin-E2; SDF-1, stromal cell-derived factor 1; SEA, N-stearoylethanolamide; SERPINE, serine proteinase inhibitor; TGF-β, transforming growth factor β; TIMPs, tissue inhibitor of metalloproteinases; VEGF, vascular endothelial growth factor; VIM, vimentin