ECM Protein CYR61 Promotes Migration and Osteoblastic Differentiation of Irradiation BMSCs via Migrasomes.

Osteoradionecrosis of the jaw (ORNJ) is a complication of radiation therapy that can lead to hard-to-repair bone defects. Bone marrow mesenchymal stem cells (BMSCs) have been identified as potential "seeds" for restoring bone defects. In this study, we reported extracellular matrix protein cysteine-rich angiogenic inducer 61 (CYR61) to enhance the migratory and osteogenic functions of irradiated BMSCs (IR BMSCs) by migrasomes. Various assays, including alkaline phosphatase (ALP) activity assay, Cell Counting Kit-8 (CCK-8), apoptosis analysis, qRT-PCR, western blot, ALP staining, alizarin red S (ARS) staining, wound healing assay, transwell assay, and co-immunoprecipitation (co-IP) were conducted to assess the optimal radiation dose for generating IR BMSCs and migrasome functionality. Proteomics, bioinformatics analysis, gene transfection, and molecular docking were employed to identify key molecules mediating migration and osteoblastic differentiation and its downstream mechanisms. Furthermore, confocal microscopy, transmission electron microscopy (TEM), and western blot were utilized to identify migrasomes. Results showed that a radiation dose of 2 Gy inhibited migratory and osteogenic abilities of cells without significantly affecting viability. CYR61 emerged as a pivotal molecule regulating BMSC migration and osteoblastic differentiation through binding to integrin αvβ3 at the 125th aspartic acid and activating the ERK signaling pathway. We discovered that migrasomes are the key vehicle effectively delivering CYR61 to restore migration and osteogenesis of IR BMSCs. In conclusion, migrasomes-secreted CYR61 facilitating a promotional effect can regulate the migration and osteogenesis of IR BMSCs. Thus, migrasomes-origin CYR61 may serve as potential therapeutic agents for repairing ORNJ-related bone defects.