Functionalized osteogenic extracellular vesicles derived from BMP9-stimulated mesenchymal stem cells (MSCs)...

Area of Science:

• Biomaterials and Regenerative Medicine
• Stem Cell Biology
• Molecular Biology

Background:

• Large bone defects present significant clinical challenges for effective healing.
• Extracellular vesicle (EV)-mediated therapy offers promise for bone regeneration, but unmodified EVs have limited osteogenic potential.
• Bone morphogenetic protein 9 (BMP9) is a potent osteogenic cytokine.

Purpose of the Study:

• To develop and evaluate modified EVs (B9-EVs) loaded with BMP9 for enhanced bone defect repair.
• To investigate the immunogenicity and osteogenic capacity of B9-EVs in vitro and in vivo.
• To elucidate the molecular mechanisms underlying B9-EV-mediated osteogenesis.

Main Methods:

• Adipose-derived mesenchymal stem cells (iMAD) were stimulated with BMP9 to produce modified EVs (B9-EVs).
• In vitro assays assessed osteogenic marker induction. In vivo studies involved subcutaneous injections in mice and cranial defect repair models.
• miRNA sequencing (miRNA-seq) and RNA sequencing (RNA-seq) were performed on B9-EVs and stimulated cells, followed by bioinformatic analysis to construct an miRNA-mRNA network.

Main Results:

• Subcutaneous injection of B9-EVs did not elicit a detectable immune response in mice.
• B9-EVs effectively induced osteogenic markers in vitro and promoted subcutaneous bone formation and cranial defect repair in vivo.
• miRNA-seq identified unique osteogenesis-related miRNAs in B9-EVs, and RNA-seq revealed distinct transcriptomic regulation compared to direct BMP9 stimulation.

Conclusions:

• Functionalized B9-EVs are non-immunogenic and possess significant osteogenic potential for bone tissue engineering.
• B9-EVs promote bone regeneration through EV-mediated paracrine signaling, involving unique miRNA and mRNA interactions.
• These cell-free, engineered EVs represent a promising therapeutic strategy for treating large bone defects.