The authors acknowledge the use of instruments at the Shared Instrumentation Core Facility at the Institute of Basic Medicine and Cancer (IBMC), Chinese Academy of Sciences. This study was supported by the National Natural Science Foundation of China (NSFC; 82172598), the Natural Science Foundation of Zhejiang Province, China (LZ22H310001), the 551 Health Talent Training Project of Health Commission of Zhejiang Province, China, the Agricultural and Social Development Research Project of Hangzhou Municipal Science and Technology Bureau (2022ZDSJ0474) and Qiantang Interdisciplinary Research Grant.

NOTE: A schematic of the method is shown in Figure 1.
1. EM preparation and isolation
<ol>
	<li>Cell internalization of MNPs
	<ol>
		<li>Cell culture
		<ol>
			<li>Suspend 1 &#215; 106 rat bone marrow mesenchymal stem cells (BMSC), 293T cells, or Mouse ovarian epithelial cancer cells (ID8) in DMEM complete medium with 10% fetal bovine serum (FBS) and 5% penicillin-streptomycin solution (P/S) in 2 mL per six-well plate (see Tab...

Optimized Magnetic High-Yield Production of Endosome-Derived Nanovesicles

<ol>
	<li>Kalluri, R., LeBleu, V. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+biology,+function,+and+biomedical+applications+of+exosomes.">The biology, function, and biomedical applications of exosomes.</a> Science. 367 (6478), eaau6977 (2020).</li><li>Hyenne, V., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=RAL-1+controls+multivesicular+body+biogenesis+and+exosome+secretion.">RAL-1 controls multivesicular body biogenesis and exosome secretion.</a> J Cell Biol. 211 (1), 27-37 (2015).</li><li>Farooqi, A. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Exosome+biogenesis,+bioactivities+and+functions+as+new+delivery+systems+of+natural+compounds.">Exosome biogenesis, bioactivities and functions as new delivery systems of natural compounds.</a> Biotechnol Adv. 36 (1), 328-334 (2018).</li><li>Gatti, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microvesicles+derived+from+human+adult+mesenchymal+stem+cells+protect+against+ischaemia-reperfusion-induced+acute+and+chronic+kidney+injury.">Microvesicles derived from human adult mesenchymal stem cells protect against ischaemia-reperfusion-induced acute and chronic kidney injury.</a> Nephrol Dial Transplant. 26 (5), 1474-1483 (2011).</li><li>Zhang, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Exosome:+A+review+of+its+classification,+isolation+techniques,+storage,+diagnostic+and+targeted+therapy+applications.">Exosome: A review of its classification, isolation techniques, storage, diagnostic and targeted therapy applications.</a> Int J Nanomedicine. 15, 6917-6934 (2020).</li><li>Yang, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Progress,+opportunity,+and+perspective+on+exosome+isolation+-+efforts+for+efficient+exosome-based+theranostics.">Progress, opportunity, and perspective on exosome isolation - efforts for efficient exosome-based theranostics.</a> Theranostics. 10 (8), 3684-3707 (2020).</li><li>Castilletti, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Coordinate+induction+of+IFN-alpha+and+-gamma+by+SARS-CoV+also+in+the+absence+of+virus+replication.">Coordinate induction of IFN-alpha and -gamma by SARS-CoV also in the absence of virus replication.</a> Virology. 341 (1), 163-169 (2005).</li><li>Guo, P., Huang, J., Moses, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cancer+nanomedicines+in+an+evolving+oncology+landscape.">Cancer nanomedicines in an evolving oncology landscape.</a> Trends Pharmacol Sci. 41 (10), 730-742 (2020).</li><li>Jo, W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Large-scale+generation+of+cell-derived+nanovesicles.">Large-scale generation of cell-derived nanovesicles.</a> Nanoscale. 6 (20), 12056-12064 (2014).</li><li>Yoon, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Generation+of+nanovesicles+with+sliced+cellular+membrane+fragments+for+exogenous+material+delivery.">Generation of nanovesicles with sliced cellular membrane fragments for exogenous material delivery.</a> Biomaterials. 59, 12-20 (2015).</li><li>Li, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Exosome+mimetics+derived+from+bone+marrow+mesenchymal+stem+cells+ablate+neuroblastoma+tumor+in+vitro+and+in+vivo.">Exosome mimetics derived from bone marrow mesenchymal stem cells ablate neuroblastoma tumor in vitro and in vivo.</a> Biomater Adv. 142, 213161 (2022).</li><li>Wang, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Exosome+mimetics+derived+from+bone+marrow+mesenchymal+stem+cells+deliver+doxorubicin+to+osteosarcoma+in+vitro+and+in+vivo.">Exosome mimetics derived from bone marrow mesenchymal stem cells deliver doxorubicin to osteosarcoma in vitro and in vivo.</a> Drug Deliv. 29 (1), 3291-3303 (2022).</li><li>Zhang, Z., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comprehensive+proteomic+analysis+of+exosome+mimetic+vesicles+and+exosomes+derived+from+human+umbilical+cord+mesenchymal+stem+cells.">Comprehensive proteomic analysis of exosome mimetic vesicles and exosomes derived from human umbilical cord mesenchymal stem cells.</a> Stem Cell Res Ther. 13 (1), 312 (2022).</li><li>Li, Y. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Artificial+exosomes+for+translational+nanomedicine.">Artificial exosomes for translational nanomedicine.</a> J Nanobiotechnology. 19 (1), 242 (2021).</li><li>Yang, W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Clinical+characteristics+of+310+SARS-CoV-2+Omicron+variant+patients+and+comparison+with+Delta+and+Beta+variant+patients+in+China.">Clinical characteristics of 310 SARS-CoV-2 Omicron variant patients and comparison with Delta and Beta variant patients in China.</a> Virol Sin. 37 (5), 12 (2022).</li><li>Shapira, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+novel+platform+for+attenuating+immune+hyperactivity+using+EXO-CD24+in+COVID-19+and+beyond.">A novel platform for attenuating immune hyperactivity using EXO-CD24 in COVID-19 and beyond.</a> EMBO Mol Med. 14 (9), 15997 (2022).</li><li>Jang, S. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bioinspired+exosome-mimetic+nanovesicles+for+targeted+delivery+of+chemotherapeutics+to+malignant+tumors.">Bioinspired exosome-mimetic nanovesicles for targeted delivery of chemotherapeutics to malignant tumors.</a> ACS Nano. 7 (9), 7698-7710 (2013).</li><li>Le, T. S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quick+and+mild+isolation+of+intact+lysosomes+using+magnetic-plasmonic+hybrid+nanoparticles.">Quick and mild isolation of intact lysosomes using magnetic-plasmonic hybrid nanoparticles.</a> ACS Nano. 16 (1), 885-896 (2022).</li><li>Jeong, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nanovesicles+engineered+from+ES+cells+for+enhanced+cell+proliferation.">Nanovesicles engineered from ES cells for enhanced cell proliferation.</a> Biomaterials. 35 (34), 9302-9310 (2014).</li><li>Kooijmans, S. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Display+of+GPI-anchored+anti-EGFR+nanobodies+on+extracellular+vesicles+promotes+tumour+cell+targeting.">Display of GPI-anchored anti-EGFR nanobodies on extracellular vesicles promotes tumour cell targeting.</a> J Extracell Vesicles. 5, 31053 (2016).</li></ol>

As a surrogate of cell-free therapy and a nanoscale drug delivery system, EVs have yet to meet their clinical expectations, and a main obstacle is the lack of scalable and reproducible production and purification methods6. Therefore, various types of EMs have been developed as EV analogs with similar biological complexity14. To date, the most commonly used EM example is cell plasma membrane-derived nanovesicles. The preparation of such nanovesicles is relatively easy and st...

Extracellular vesicles (EVs) are small vesicles secreted by almost all cells with a size range of 30-150 nm, containing abundant bioactive substances. Depending on the cell of origin, EVs show high heterogeneity, possessing multiple components specific to parent cells1. EVs are released into body fluids and transported to distant sites where they are taken up by target cells for action2, which can be utilized to deliver a wide range of bioactive molecules and drugs for tissue repairing, tumor diagnosis and treatment, and immune modulation3,4. However, other biological nanoparticles (e.g., lipoproteins) and nanovesicles (e.g., EVs derived from non-endosomal pathways) with similar biophysical properties in body fluids inevitably affect EV isolation and purification. To date, ultracentrifugation remains the gold standard for EV isolation, and other isolation methods, including sucrose density gradient centrifugation, ultrafiltration, polyethylene glycol precipitation, chromatography, and immunomagnetic bead isolation, have been developed5. The current bottleneck limiting clinical translation and commercialization of EV therapeutics is the severe lack of isolation techniques that allow for highly scalable and reproducible isolation of EVs6,7,8. Traditional EV isolation techniques (e.g., ultracentrifugation and size exclusion chromatography) suffer from low yield (1 x 107-1 x 108/1 x 106 cells), long production cycle (24-48 h), poor reproducibility of product quality, and require expensive and energy-intensive production equipment that cannot meet the current clinical demand for EVs6.
Exosome mimics (EMs), synthetic surrogates of native EVs, have attracted important attention due to their highly similar structure, function, and scalability in production. The main source of EMs is from the direct extrusion of whole parental cells with continuous sectioning9,10, demonstrating potent biological functions as native EVs11,12. For instance, EMs derived from human umbilical cord mesenchymal stem cells (hUCMSCs) exert similar wound-healing effects as native EVs and are richer in protein composition13. Though EMs derived from whole cells have the biological complexity of EVs, their main drawback is the heterogeneity of products because they are inevitably contaminated by various cellular organelles and cell debris. Protein localization analysis further revealed that EMs derived from whole-cell extrusion contain many non-EVs-specific proteins from mitochondria and the endoplasmic reticulum13. Moreover, most methods for manufacturing EMs still require ultracentrifugation, a highly time and energy-consuming process14. Considering the fact that exosomes are exclusively derived from cellular endosomes, we hypothesized that bioengineered endosome-derived nanovesicles may better recapitulate the biological homology between exosomes and EMs in comparison with the well-established cell membrane-derived EMs produced by whole cell extrusion method14. Nevertheless, the manufacture of endosome-derived nanovesicles is difficult due to the lack of viable approaches.
Clinical studies have been carried out by utilizing EVs as a surrogate of cell-free therapy and a nanoscale drug delivery system for the treatment of various diseases. For instance, EVs derived from bone marrow mesenchymal stem cells have been used to treat severe pneumonia caused by COVID-19 and have achieved promising results. Recently, genetically engineered EVs carrying CD24 proteins have also demonstrated potent therapeutic benefits for treating COVID-19 patients15,16. However, the clinical requirement of EV therapy still cannot be met with traditional isolation methods because of the low yield and cost. This study reports the large-scale production of endosome-derived nanovesicles via a magnetic separation-assisted high-speed homogenization approach. It takes advantage of the endocytosis pathway of MNPs to isolate MNP-loaded endosomes via magnetic separation, followed by high-speed homogenization to formulate endosomes into monodisperse nanovesicles. Since the types of endosomes collected by this protocol are diverse, further in-depth research is still required to establish good manufacturing practices (GMP) in the industry. This novel EM preparation approach is more time efficient (5 min of high-speed homogenization) to obtain nanovesicles homologous to native EVs. It produces exponentially more vesicles from the same amounts of cells than ultracentrifugation, which can be generally applied to various cell types.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Annexin antibody</td>
			<td>ABclonal</td>
			<td>A11235</td>
			<td>Western blotting</td>
		</tr>
		<tr>
			<td>BCA assay kit</td>
			<td>Beyotime</td>
			<td>P0012</td>
			<td>Protein concentration assay</td>
		</tr>
		<tr>
			<td>Calnexin</td>
			<td>GeneTex</td>
			<td>HL1598</td>
			<td>Western blotting</td>
		</tr>
		<tr>
			<td>CD63 antibody</td>
			<td>ABclonal</td>
			<td>A19023</td>
			<td>Western blotting</td>
		</tr>
		<tr>
			<td>Cell lysis buffer for Western and IP</td>
			<td>Beyotime</td>
			<td>P0013</td>
			<td>Western blotting</td>
		</tr>
		<tr>
			<td>Centrifuge</td>
			<td>Beckman</td>
			<td>Allegra X-30R</td>
			<td>Cell centrifuge</td>
		</tr>
		<tr>
			<td>CO2 incubator</td>
			<td>Thermo</td>
			<td></td>
			<td>Cell culture</td>
		</tr>
		<tr>
			<td>Confocal laser scanning fluorescence microscopy</td>
			<td>NIKON</td>
			<td>A1 HD25</td>
			<td>Photo the fluorescence picture</td>
		</tr>
		<tr>
			<td>DMEM basic (1x)</td>
			<td>GIBCO</td>
			<td>C11995500BT</td>
			<td>Cell culture</td>
		</tr>
		<tr>
			<td>Dynamic light scattering (DLS)</td>
			<td>Malvern</td>
			<td>Zetasizer Nano ZS ZEN3600</td>
			<td>Diameter analysis</td>
		</tr>
		<tr>
			<td>Electric glass homogenizer</td>
			<td>SCIENTZ(Ningbo, China)</td>
			<td>DY89-II</td>
			<td>Low-speed homogenization</td>
		</tr>
		<tr>
			<td>Exosome-depleted FBS</td>
			<td>system Bioscience</td>
			<td>EXO-FBS-50A-1</td>
			<td>Cell culture</td>
		</tr>
		<tr>
			<td>High-speed homogenizer</td>
			<td>SCIENTZ(Ningbo, China)</td>
			<td>XHF-DY</td>
			<td>High-speed homogenization</td>
		</tr>
		<tr>
			<td>Magnetic grate</td>
			<td>Tuohe Electromechanical Technology (Shanghai, China)</td>
			<td>NA</td>
			<td>Magnetic separation</td>
		</tr>
		<tr>
			<td>PKH26 Red Fluorescent Cell Linker Kit for General Cell Membrane Labeling</td>
			<td>Sigma-Aldrich</td>
			<td>PKH26GL-1KT</td>
			<td>The kit contains PKH26 cell linker in ethanol and Diluent C</td>
		</tr>
		<tr>
			<td>Polylysine-modified iron oxide nanoparticles (IONPs)</td>
			<td>Zhongke Leiming Technology (Beijing, China)</td>
			<td>Mag1100-10</td>
			<td>Cell culture</td>
		</tr>
		<tr>
			<td>Potassium chloride</td>
			<td>Aladdin</td>
			<td>7447-40-7</td>
			<td>Cell hypotonic treatment</td>
		</tr>
		<tr>
			<td>Protease inhibitor cocktail</td>
			<td>Beyotime</td>
			<td>P1030</td>
			<td>Proteinase inhibitor</td>
		</tr>
		<tr>
			<td>Sodium citrate</td>
			<td>Aladdin</td>
			<td>7447-40-7</td>
			<td>Cell hypotonic treatment</td>
		</tr>
		<tr>
			<td>Transmission electron microscopy (TEM)</td>
			<td>JEOL</td>
			<td>JEM-2100plus</td>
			<td>Morphology image</td>
		</tr>
		<tr>
			<td>Ultracentrifuge</td>
			<td>Beckman</td>
			<td>Optima XPN-100</td>
			<td>Exosome centrifuge</td>
		</tr>
		<tr>
			<td>ZetaView nanoparticle&#160; tracking analyzers</td>
			<td>Particle Metrix</td>
			<td>PMX120</td>
			<td>Nanoparticle tracking analysis</td>
		</tr>
	</tbody>
</table>

a magnetic separation-assisted high-speed homogenization method for large-scale production of endosome-derived vesicles

Extracellular vesicles (EVs) have attracted significant attention in physiological and pathological research, disease diagnosis, and treatment; however, their clinical translation has been limited by the lack of scale-up manufacturing approaches. Therefore, this protocol provides a magnetic separation-assisted high-speed homogenization method for the large-scale production of endosome-derived nanovesicles as a new type of exosome mimics (EMs) derived from the endosomes, which have about 100-time higher yield than conventional ultracentrifugation method. In this method, magnetic nanoparticles (MNPs) were internalized by parental cells via endocytosis and were subsequently accumulated within their endosomes. Then, MNPs-loaded endosomes were collected and purified by hypotonic treatment and magnetic separation. A high-speed homogenizer was utilized to break MNP-loaded endosomes into monodisperse nanovesicles. The resulting endosome-derived vesicles feature the same biological origin and structure, characterized by nanoparticle tracking analysis, transmission electron microscope, and western blotting. Their morphology and protein composition are similar to native EVs, indicating that EMs may potentially serve as a low-cost and high-yield surrogate of native EVs for clinical translations.

Author Spotlight: Development of a Large-Scale, Reproducible Production Method for Exosome Mimetics Using Magnetic Nanoparticles 

A Magnetic Separation-Assisted High-Speed Homogenization Method for Large-Scale Production of Endosome-Derived Vesicles

In this study, we try to address a critical unmet need in exosome research, which is developing a large-scale and reproducible production method for exosome mimetics. Due to the notion of native evades, exosome mimetics, EMS, has been produced as surrogates by methods such as real exclusion and ultracentrifugation based filtration. Certainly most exosome mimetics are from the direct exclusion of whole cells, which demonstrates minimal biologic functions, but are inevitable contaminated by cell debris and organelles.Extracellular vesicles have attracted significant attention in biomedical research, especially in disease treatment. However, traditional EV isolation techniques like ultrasensitive filtration, inside exclusion, catamental glyphic start from low-yield poor productibility of plow down quality and require expensive and engineer intensive production equipment that cannot meet the clinical demand for EVs. Our study provided a simple and no cost method for scan up production of exosomes mimetics.We take advantage of unique biological finding that magnetic nanoparticles can be only endonized within cell endosomes, not other organelles. Thus, we can formulate the endosomes into uniform nanosescose. This method effectively improve EME and reduces cost.

The workflow of EM preparation by magnetic separation-assisted high-speed homogenization is shown in Figure 1. Cells internalize 10 nm polylysine-modified IONPs, which are specifically accumulated in endosomes via endocytosis (Figure 3A). After being treated with hypotonic buffer and homogenized, the IONP-loaded endosomes are released from the cells and subsequently collected by magnetic separation. The isolated endosomes are further reconstituted into monodispe...

Watch this Scientific Journal Video about Development of a Large-Scale, Reproducible Production Method for Exosome Mimetics Using Magnetic Nanoparticles at JoVE.com

Here, we describe a magnetic separation-assisted high-speed homogenization method for large-scale production of endosome-derived nanovesicles as a new type of exosome mimics (EMs) that share the same biological origin and similar structure, morphology, and protein composition of native extracellular vesicles (EVs).

Extracellular vesicles (EVs) have attracted significant attention in physiological and pathological research, disease diagnosis, and treatment; however, ...

a-magnetic-separation-assisted-high-speed-homogenization-method-for