Work

Exosome-packaged ILK from healthy female serum stimulate osteogenesis via the MAPK signaling pathway

Year: 2026

Type: article

Abstract: The pathogenesis of osteoporosis (OP) is multifactorial, with impaired osteogenic differentiation of bone marrow stromal cells (BMSCs) serving as a fundamental pathological basis. Enhancing osteogenesis is a key strategy for OP therapy. Exosomes are recognized as promising cell-free therapeutic agents. Here, we demonstrate that serum exosomes derived from healthy females (Exo-HF) exhibit superior pro-osteogenic potential and identify underlying mechanisms through proteomics and RNA sequencing. Exo-HF was isolated and characterized. Subsequently, we established an ovariectomized (OVX) mouse model to evaluate the in vivo therapeutic efficacy of Exo-HF. A series of in vitro functional assays was conducted to assess the impact of Exo-HF on osteogenesis and proliferation of BMSCs from postmenopausal osteoporosis (PMOP) patients. The candidate molecule integrin-linked kinase (ILK), identified through proteomic analysis as a major mediator of Exo-HF function, was validated using a specific inhibitor (QLT0267), lentivirus, and AAV9 vectors. Furthermore, RNA sequencing (RNA-seq) analysis was conducted to explore the signaling pathways involved in ILK-mediated osteogenesis. Finally, a comparative study of peptide versus aptamer modification was performed for systemic bone targeting. Exo-HF exhibits cross-species therapeutic effects by significantly improving bone microstructure and bone strength in OVX mice. Exo-HF also enhanced the osteogenesis of PMOP-derived BMSCs. Proteomics analysis identified that Exo-HF was enriched with ILK. Functionally, blocking ILK with targeted inhibitors partially attenuated the osteogenic activity of Exo-HF both in vitro and in vivo, whereas overexpression of ILK promoted osteogenesis both in vitro and in vivo. RNA-seq linked this process to the MAPK signaling pathway, and MAPK inhibition abolished ILK-induced osteogenesis. Preliminary systemic tracking revealed that, compared to the peptide strategy, the Apt-19s modification exhibited superior bone-targeting efficiency. Exo-HF serves as a safe and efficient vehicle for OP treatment. Furthermore, the robust osteogenic stimulation by Exo-HF is centrally driven by the ILK/MAPK signaling axis. While ILK acts as a major, but not exclusive, mediator in this process, other exosomal proteins may also exert synergistic effects. Apt-19s modification successfully achieved systemic bone targeting, paving the way for non-invasive clinical applications.

Source: Stem Cell Research & Therapy

DOI: 10.1186/s13287-026-05277-x