Isolation and Therapeutic Application of Extracellular Vesicles Derived from Self-Assembled Mesenchymal Stem Cell Aggregates

Summary

This protocol details the efficient isolation of large extracellular vesicles (LEVs) from self-assembled stem cell aggregates and their therapeutic application for mandibular bone regeneration.

Abstract

Extracellular vesicles (EVs) are vital mediators of intercellular communication and promising cell-free agents for regenerative medicine. Among EV subpopulations, large extracellular vesicles (LEVs) are particularly suited for tissue repair due to their enriched pro-regenerative cargo. However, standardized and reproducible methods to generate functional dental stem cell-derived LEVs for downstream characterization and therapeutic evaluation remain limited. Utilizing the exceptional osteogenic potential of stem cells from the apical papilla (SCAPs), we developed a 3D culture model under low-adhesion conditions to induce self-assembled SCAP aggregates. This model mimics physiological mesenchymal condensation, significantly enhancing cell-cell interactions and boosting LEV secretion. Key culture parameters and handling notes are provided to improve aggregate consistency and maximize LEV output while maintaining cell viability. Here, we present a standardized protocol for the efficient production of functional SCAP-derived LEVs, encompassing 3D aggregate generation, isolation via differential centrifugation, nanoparticle tracking analysis (NTA)-based particle size distribution and concentration analysis, and therapeutic delivery using a thermally crosslinked hydrogel for mandibular bone defect repair. This approach streamlines LEV production for downstream mechanistic studies and preclinical evaluation in craniofacial regeneration. This optimized workflow ensures the reproducible preparation of bioactive LEVs with consistent yields and enriched pro-osteogenic cargo, facilitating fundamental research and accelerating the clinical translation of EV-mediated craniofacial reconstruction. In representative applications, hydrogel-loaded LEVs provide a localized depot at defect sites and facilitate convenient handling during implantation. Collectively, this method provides a scalable platform to prepare SCAP-derived LEVs and highlights key considerations for standardized reporting and translational study design. This approach supports broader adoption across craniofacial EV laboratories.

Introduction

Extracellular vesicles (EVs) are membrane-bound nanoparticles released by cells that mediate intercellular communication through the transfer of bioactive cargoes such as proteins, miRNAs, and lipids^1,2,3. Among EV subpopulations, large extracellular vesicles (LEVs) are distinctive for their direct release from the cell membrane and inherent enrichment of pro-regenerative molecules, making them well-suited for tissue repair and regeneration demands^4,5. In regenerative medicine, EVs derived from mesenchymal stem cells ....

Protocol

All animal experiments were approved by the Animal Care and Use Committee of the Fourth Military Medical University and were conducted in compliance with the ARRIVE guidelines. The collection and use of human samples were approved by the Ethics Committee of the Fourth Military Medical University (approval no. IRB-REV-2022187). Written informed consent was obtained from all donors prior to sample collection; for donors who were minors or otherwise unable to provide consent, written informed consent was obtained from their legal guardians. All reagents were sterile-filtered, and cell culture procedures were conducted in a biosafety cabinet to maintain sterility (see

Results

According to the experimental workflow, key steps including SCAP isolation, aggregate formation, LEVs extraction, and therapeutic implantation were successfully executed (Figure 1). Clinical impacted third molars from donors exhibited immature apices with intact apical papilla tissue attached around the open root canal orifices, confirming the suitable source of SCAP (Figure 2A). When cultured in vitro, spindle-shaped SCAPs with abundant cellular proces.......

Discussion

The growing interest in cell-free regenerative therapies has positioned mesenchymal stem cell-derived LEVs as promising alternatives to whole-cell transplantation, owing to their ability to deliver bioactive molecules without the risks associated with cell-based approaches. However, the clinical translation of LEV-based therapies has been hampered by the lack of physiologically relevant culture systems that can fully preserve and enhance LEVs functionality. Conventional 2D monolayer cultures significantly diverge from th.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
1 mL Syringe with Needle	BD	300841	Anesthetization
10 cm Cell Culture Dish	Corning	353003	Cell culture
15 mL Polystyrene Centrifuge Tube	Corning	352095	Cell culture
75% Ethanol Disinfectant	Hai Shi Hai Nuo	HS-750	Operation
Absorbable Suture 4-0	Jinhuan Medical	R413	Operation
Benchtop centrifuge	WIGGENS	CE187	EV isolation
CO2 Incubator, 150 L, Universal Type	ThermoFisher	51032874	Cell culture
Collagenase Type I	ThermoFisher	17100017	Cell culture
Cotton Balls	Deroyal	30-033	Operation
Curved Operating Scissor	JZ Surgical Instrument	J21040	Operation
Dental Mobile Turbine Unit	KaVo	S609C	Operation
Electronic Balance	Zhi Ke	ZK-DST	Cell culture
Eppendorf Tube	Eppendorf	3810X	EV isolation
Forcep,fine	JZ Surgical Instrument	JD1020	Operation
Hair Removal Cream	Veet	1.00097E+11	Operation
High-speed Ball Bur	Dentsply Sirona	E0123	Operation
High-speed Handpiece	KaVo	KV-1-008-1644	Operation
Inverted Microscope	Mshot	MF53-N	Cell culture
MEM α (Minimum Essential Medium α)	ThermoFisher	12561056	Cell culture
Nanoparticle Tracking Video Microscope PMX-120	Particle Metrix	ZetaView PMX120	Nanoparticle tracking analysis
Penicillin-Streptomycin (P/S)	ThermoFisher	15140122	Cell culture
Pentobarbital sodium	Sigma-Aldrich	57-33-0	Anesthetization
Phosphate-Buffered Saline (PBS)	ThermoFisher	10010023	Cell culture
Pluronic F-127	Sigma-Aldrich	P2443	EV implantation
Povidone Iodine Solution	Baxter	PROSL500	Operation
Specialty Fetal Bovine Serum (FBS)	ThermoFisher	12664025	Cell culture
Sterile Gauze Block	Winning	10-000-681	Operation
Tabletop High-Speed Micro Centrifuge	Hitachi	CT15E	EV isolation
Trephine Drill	Biomet Microfixation	01-9182	Operation
Trypsin-EDTA	ThermoFisher	25200072	Cell culture
Ultra-Low Attachment 24-Well Plate	Corning	3473	Cell culture
Vortex Mixer Genie	Scientific Industries	SI0425	EV implantation