No abstract

Sarcopenia is a geriatric disease characterized by reduced muscle function and mass. The capacity to self-renew and myogenesis of satellite cells (SCs) declines with age, resulting in age-related sarcopenia. MicroRNAs (miRNAs) can regulate the proliferation and myogenesis of SCs. In this study, it is identified that miR-467a-3p and miR-874-5p could respectively mediate the stemness and myogenesis of SCs by performing bioinformatics analysis. AntagomiR-467a-3p (ant-467a) and antagomiR-874-5p (ant-874) improve the stemness and myogenesis of SCs, respectively. SC-targeting extracellular vesicles (EVs) are constructed by overexpressing TSG101 on the surface of EVs isolated from bone marrow mesenchymal stem cells. Ant-467a loaded EVs (EVs-467a) and ant-874 loaded EVs (EVs-874) are prepared by transferring ant-467a and ant-874 into SC-targeting EVs. EVs-467a and EVs-874 are more effective than ant-467a and ant-874 in promoting the stemness and myogenesis of SCs. Sequentially intermuscular injection of EVs-467a and EVs-874 significantly improve sarcopenia in ovariectomy mice. The effects of multiple injections of EVs-467a and EVs-874 in the treatment of sarcopenia could be achieved by using a hierarchically injectable hydrogel to sustainedly release EVs-467a and EVs-874 in vivo. The findings provide an EV-based SC-targeting antagomiRNAs controlled release strategy as a novel therapy against sarcopenia.

Osteoporotic fracture is a major health problem plaguing the ageing society, and improving its treatment is an urgent challenge. How to ameliorate bone loss determines the recovery of such fractures. Extracellular vesicle (EV)‐loaded hydrogel has the capacity to treat osteoporotic fractures due to its pro‐osteogenic property. And balancing proliferation and maturation of osteoblast precursors (OBPs) is of great significance to avoid OBP depletion, which is lacking in current treatment. Based on osteoblastogenic miRNAs, this study aimed to explore the efficacies of the combination of hierarchical hydrogel and EVs altering functional miRNAs level in bone loss. Through bioinformatics analyses, we screened out proliferative gene‐targeting miR‐200b‐3p and osteogenic gene‐targeting miR‐130b‐3p. And antagomiR‐200b‐3p (ant‐200b) enhanced OBP proliferation, and antagomiR‐130b‐3p (ant‐130b) promoted OBP differentiation. After confirming the directional effect of Fibronectin (Fn1) on OBPs, we prepared OBP‐targeting EVs. Furthermore, encapsulation of two antagomiRNAs in EVs enhanced the respective effect of ant‐200b and ant‐130b. Notably, hierarchically injectable hydrogel exerted an effective function in promoting the sequential delivery of EVs‐200b and EVs‐130b. Importantly, hierarchical hydrogel containing dual EVs effectively ameliorated bone loss. Overall, hierarchical hydrogel based on two antagomiRNAs effectively improves bone loss in vivo due to its role in promoting OBP proliferation and maturation sequentially.