Exosomes Derived from Tanshinone IIA-Pretreated Umbilical Cord Mesenchymal Stem Cells Repair Traumatic Spinal Cord Injury by miR-223–5p/USP8/NLRP3 Axis
Guoqiang Shen, Minhao Liu, Juan Wang, Zhiqiang Qi, Yaoqi Cao, Zhengshuai Jin, Sheng Chen, Bowen Wan, Jun Gu
Abstract
Spinal cord injury (SCI) lacks effective therapies, and umbilical cord mesenchymal stem cell (UCMSC)-derived exosomes show promise but require efficacy optimization. This study explored tanshinone IIA (TSA)-pretreated UCMSC exosomes (T-Exos) to enhance neuroprotection and functional recovery post-SCI. T-Exos were isolated from the TSA-treated UCMSCs. SCI mice received T-Exos, with motor function assessed behaviorally. In vitro and in vivo, microglial NLRP3 inflammasome activity, polarization (M1/M2), and cytokine release were analyzed. miRNA profiling identified key miRNAs in T-Exos; miR-223-5p's role was validated via inhibition. Mechanistic studies linked miR-223-5p to USP8/NLRP3 using Western blot, qPCR, and co-IP assays. T-Exos improved motor recovery in SCI mice by suppressing NLRP3 inflammasome activation, shifting microglia to anti-inflammatory M2 phenotypes, reducing the level of IL-1β/IL-18, and alleviating oxidative stress. miR-223-5p was highly enriched in T-Exos, and its inhibition reversed therapeutic effects. Mechanistically, miR-223-5p targeted USP8, a deubiquitinase stabilizing NLRP3. By inhibiting USP8, T-Exos reduced NLRP3 levels, dampening neuroinflammation. TSA pretreatment enhances exosomal miR-223-5p, which blocks USP8-mediated NLRP3 stabilization, driving microglial M2 polarization and neuroprotection. These findings highlight T-Exos as a targeted therapy for SCI, offering insights into the exosome-mediated modulation of inflammatory microenvironments for neural repair.