Urinary-derived stem cells protect osteoarthritic chondrocytes by inhibiting the PI3K/AKT pathway
Objective To explore whether the effect of urine-derived stem cells(USCs)on chondro-cytes in osteoarthritis(OA)is related to the PI3K/AKT pathway.Methods Human urine was collected aseptically,and primary USCs were isolated and cultured through specific steps.Meanwhile,chondro-cytes were extracted from the knee joints of Sprague-Dawley rats to establish the OA model.USCs were co-cultured with OA chondrocytes by using Transwell co-culture system,and the transcriptome changes of chondrocytes before and after co-culture were analyzed by using the high-throughput RNA sequencing.Moreover,the phosphorylation levels of key proteins of the PI3K/AKT/mTOR pathway were detected using protein immunoblotting,and the PI3K agonist 740 Y-P was employed to further vali-date the relationship between the protective effect of USCs on OA chondrocytes,as well as its possi-ble relationship to the PI3K/AKT pathway and the possible mechanism.Results Transcriptomic analysis showed that the protective effect of USCs on OA chondrocytes might be related to the'PI3K-Akt sig-naling pathway'.Protein level analysis confirmed that USCs significantly inhibited the PI3K/AKT/mTOR pathway in OA chondrocytes.Moreover,protein immunoblotting and immunofluorescence showed that USCs improved the expression of OA-related proteins and autophagy-related proteins in OA chondro-cytes.What's more,the inhibitory effect of USCs on the PI3K/AKT/mTOR pathway was partially re-versed by using the PI3K agonist 740 Y-P,while the protective and autophagy-promoting effects of USCs on OA chondrocytes were down-regulated.Conclusion This study reveals the potential protective effect of USCs on OA chondrocytes through inhibition of the PI3K/AKT/mTOR signalling pathway and its close correlation with improved autophagy.Therefore,it provides a research basis and theoretical support for the future application of USCs in the treatment of OA.