Drug-free extracellular vesicles: A spatiotemporally controlled release engineering strategy for osteogenesis and anti-inflammatory niches in rotator cuff regeneration

Natural small-molecule drugs have promising potential to promote tissue regeneration in various fields. Therefore, maximizing drug efficiency while minimizing potential side effects is imperative. Peiminine, a natural product extracted from natural Fritillaria, is one of small-molecule drugs in the field of bone regeneration due to its good bone-promoting and anti-inflammatory abilities. However, its application is limited by a lack of biological activity, poor biocompatibility at high concentrations, and difficulty in achieving long-term slow-release and therapeutic effects. Extracellular vesicles (EVs) produced by preconditioned cells are considered to have special biological functions, and their potential to further retain, buffer, and transmit drug effects and expand the therapeutic effect has been widely studied. Thus, our study provides a drug-free bioengineering strategy by preconditioning bone marrow mesenchymal stem cells (BMSC) with Peiminine, then EVs, secreted as Peim-EVs, were extracted and combined with a decellularized extracellular matrix (dECM). The final EVs-dECM system with a spatiotemporally controlled release system was formed. In vitro studies demonstrated that Peim-EVs solved the problem of Peiminine biocompatibility and exhibited osteogenic and anti-inflammatory effects, which may be related to PI3K/AKT, MAPK/NF-κB, and Hippo signaling pathways. An in vivo model of rotator cuff injury in rats also showed that EVs-dECM had a good effect on rotator cuff repair. Combined with engineering strategy, this study provides verification and scenario expansion for drug application, especially for drug-free strategies that retain the biological effects of drugs, and has broad significance.