Targeted synergistic therapy for bone and brain disorders using hydrogel microneedles loaded with exosomes and drugs

This review highlights an innovative co-delivery system using hydrogel microneedles (MNs) to encapsulate exosomes and drugs, presenting a transformative strategy for treating interconnected bone and brain disorders. By offering potential strategies to address the blood-brain barrier, MNs enable minimally invasive delivery of exosomes, natural vesicles rich in microRNAs and cytokines, facilitating spatiotemporal control over therapeutic release. This system enhances regenerative outcomes in diabetic wounds, myocardial infarction, osteochondral defects, and neurological conditions via multi-mechanistic actions including immunomodulation, angiogenesis, and tissue repair. However, clinical translation remains challenging due to issues in exosome standardization, microneedle mechanical properties, and long-term biosafety.