Small extracellular vesicles originating from TNFAIP6-ADSCs subpopoulation identified by single-cell RNA sequencing promote tendon healing

Background Small extracellular vesicles originating from adipose-derived mesenchymal stromal cells (ADSC-sEVs) have excellent therapeutic value in tendon injury healing, but its mechanism and effect have not been fully elucidated. This study aimed to identify the key subsets and mechanisms involved in ADSC-sEVs contributing to tendon healing. Methods Based on our previous research of ADSC-sEVs improving the quality of tendon healing, we utilizing second-generation sequencing and bioinformatics methods to predict the key role of the TNFAIP6 ⁻ ADSCs subgroup in the treatment of tendon injury. We constructed different ADSC-sEVs through transfection ADSCs and treated to tendon stem cells (TSCs) for further exploration. The EdU, cell scratch, and transwell assays were used for proliferation proliferation and migration assays. Western blot and qRT-PCR analyses were used for qualitative analysis. Histopathological, immunohistochemical and, biomechanical testing were used for in vitro validation. Results TNFAIP6 ⁻ ADSC-sEVs significantly improves the therapeutic effect of ADSC-sEVs on tendon injury, which is related to the high expression of let-7c-5p. Based on application of different ADSC-sEVs in vitro and vivo, we identified CRCT1/JAK2/STAT3 as a key downstream signaling pathway regulated by let-7c-5p. Conclusions Our findings contributed to deeper understanding of how TNFAIP6 ⁻ ADSC-sEVs promote tendon healing through the let-7c-5p/CRCT1/JAK2/STAT3 signaling pathway. Furthermore, this study proposes a concept for constructing conditional ADSC-sEVs to enhance its inherent therapeutic effect.