Light-Switched Mesenchymal Stem Cells for In Situ Exosome Amplification in Craniofacial Bone Defect Reconstruction

Area of Science:

• Biomaterials Science
• Regenerative Medicine
• Nanotechnology

Background:

• Mesenchymal stem cell (MSC) therapies show potential for tissue regeneration.
• Precise spatiotemporal control of MSC bioactivity is a significant challenge.
• Exosomes derived from MSCs play a crucial role in their regenerative functions.

Purpose of the Study:

• To develop a light-switchable MSC system for controlled exosome biogenesis and regenerative function.
• To investigate the mechanism of light-induced exosome production.
• To evaluate the efficacy of the system in promoting bone regeneration.

Main Methods:

• Intracellular upconversion nanoparticles (UCNPs) were introduced into MSCs.
• Near-infrared (NIR) irradiation triggered localized ultraviolet (UVA) light emission.
• The effect of UVA on exosome production and signaling pathways was analyzed.
• An injectable hydrogel was used for localized delivery of MSC-UCNPs.
• PET-CT imaging was employed for in vivo tracking.

Main Results:

• UVA light emission from UCNPs enhanced exosome production by 2.7-fold without affecting MSC viability.
• Activated signaling cascade (ROS/HEXB/LAMP1) suppressed lysosome-multivesicular body fusion.
• MSC-derived exosomes promoted MSC proliferation, osteogenic differentiation, and osteoblast maturation via Wnt/β-catenin pathway.
• Injectable hydrogel facilitated localized delivery and on-demand exosome release.
• In vivo studies showed robust cranial bone regeneration with a 3.2-fold increase in bone volume.

Conclusions:

• The developed light-switchable MSC-UCNP system allows remote, precise control over exosome biogenesis and release.
• This platform significantly enhances bone regeneration through synergistic effects of MSCs and their exosomes.
• The findings present a promising strategy for advanced regenerative therapies.