This work was supported by grants from the National Natural Science Foundation of China (32000974, 81930025, and 82170988) and the China Postdoctoral Science Foundation (2019M663986 and BX20190380). We are grateful for the assistance of the National Experimental Teaching Demonstration Center for Basic Medicine (AMFU) and the Analytical and Testing Central Laboratory of Military Medical Innovation Center of Air Force Medical University.

All animal procedures were approved by the Animal Care and Use Committee of the Fourth Military Medical University and performed in accordance with the National Institutes of Health Guide for the Care and Use of Laboratory Animals. Eight-week-old C57Bl/6 mice (no preference for either females or males) were used. Cryopreserved human umbilical cord-derived MSCs (UCMSCs), used for the present study, were obtained from a commercial source (see Table of Materials). The use of human cells was approved by the Ethics Committee of Fourth Military Medical University.
1. Culture of human mesenchymal stem cells (hMSCs)
<ol>
	<li>Prepare the accessories and solutions required for the experimental work, including pipettes, pipette tips, 10 cm Petri dish, thermostatic equipment (water bath), rubber gloves, 75% alcohol, culture medium (incubated at 37 &#176;C), fatal bovine serum (FBS), and 100x penicillin-streptomycin (P/S) solution (see Table of Materials).</li>
	<li>Prepare commercially available alpha-Minimum Essential Medium (&#945;-MEM) by supplementing with 20% FBS and 1% P/S. 
	NOTE: Dilute all the solutions used for isolation and analysis of EVs in ultrapure filtered water made by the ultrapure filtered water purification system (see Table of Materials).</li>
	<li>Recover the cryopreserved human umbilical cord-derived MSCs (UCMSCs) from the liquid nitrogen by melting them in a 37 &#176;C water bath.</li>
	<li>Quickly and gently transfer the melted cell suspension into a 15 mL tube with 5 mL of culture medium (step 1.2). Centrifuge at 4 &#176;C, 500 x g for 5 min.</li>
	<li>Remove the supernatant with a sterile pipette and retain the cell precipitate. Add 2 mL of culture medium into the centrifuge tube and gently resuspend the cells.</li>
	<li>Seed the cells in a 10 cm Petri dish, and add 8 mL of culture medium to a total of 10 mL.</li>
	<li>Culture MSCs at 37 &#176;C in 5% CO2 in the cell incubator.</li>
</ol>
2. Differential centrifugation for isolation of Exos and MVs
<ol>
	<li>When MSCs grow to &#62;90% confluence, replace the culture medium with &#945;-MEM supplemented with 20% EV-depleted FBS and 1% P/S for 8 mL of each dish. 
	NOTE: Centrifuge FBS at 4 &#176;C, 1,50,000 x g overnight to remove EVs and other impurities.</li>
	<li>After 48 h of culture, collect the culture medium (step 2.1) into 50 mL centrifuge tubes.</li>
	<li>Centrifuge the MSC culture medium at 4 &#176;C, 800 x g for 10 min.</li>
	<li>Remove the cell fragments and cellular debris by transferring the supernatant to clean 1.5 mL conical tubes. 
	NOTE: Using 1.5 mL conical tubes is necessary to increase EV yield.</li>
	<li>Centrifuge the supernatant at 4 &#176;C, 16,000 x g for 30 min. The pellet is MVs. MVs from each dish of cells were resuspended with 50 &#181;L of PBS.</li>
	<li>Transfer the supernatant obtained by centrifugation in step 2.5 by pipette to clean ultracentrifuge tubes. Centrifuge at 1,50,000 x g for 2 h at 4 &#176;C.</li>
	<li>Discard the supernatant and collect the residue, which is Exos. Resuspend Exos from seven dishes of cells in 50 &#181;L of PBS. 
	NOTE: The sixth-passaged UCMSCs are used for EV isolation. To get enough MVs and Exos for experimental use, 7-8 dishes of cultured cells are usually needed. The EV samples are used immediately for the following characterization steps or for therapeutic application, which is better not stored. 
	CAUTION: Avoid repeated freezing and thawing of EVs, and it is best to store EVs at 4 &#176;C in the short term and not at -80 &#176;C.</li>
</ol>
3. Detection of particle numbers and size distribution of EVs from MSCs
NOTE: For size distribution evaluation, nanoparticle tracking analysis (NTA) is performed by a commercially available nanoparticle tracking analyzer (see Table of Materials).
<ol>
	<li>Dilute 1 &#181;L of EVs (from step 2.5 and step 2.7) in 1,499 &#181;L of PBS and mix enough in a 15 mL tube.</li>
	<li>Operate the tracking analyzer following the manufacturer&#39;s instructions. Firstly, start the compatible software (see Table of Materials).</li>
	<li>Fill the sample cell with distilled water, and then allow the instrument to start the cell check.</li>
	<li>Calibrate the instrument with a prepared standard solution. Ensure that the particle number displayed on the software detection interface is between 50-400 (preferably around 200). Click OK. 
	NOTE: Prepare the standard solution by reconstituting 1 &#181;L of calibration solution (see Table of Materials) in 1 mL of distilled water to generate a primary solution, and then take 100 &#181;L of the primary solution and add 25 mL of distilled water to prepare a standard solution (1:250,000). Store this working reagent at 4 &#176;C for a week.</li>
	<li>Rinse the sample cell with 5 mL of distilled water.</li>
	<li>Before sample analysis, flush the channel with 1 mL of distilled water. Ensure that the particle number displayed on the software detection interface is less than 10.</li>
	<li>Inject 1 mL of the EV sample prepared in step 3.1. Perform vesicle test according to the operating instructions of the instrument. 
	CAUTION: The sample and distilled water are injected with a 1 mL syringe at a constant speed of 0.5 mL/s under careful manual control.</li>
</ol>
4. Characterization of EV morphology by transmission electron microscope (TEM)
<ol>
	<li>Dilute 1 &#181;L of EVs from step 2.7 in 199 &#181;L of PBS and mix enough. Add 20 &#181;L of EV suspension drops to the formvar/carbon-coated square mesh (see Table of Materials), and let it stay for 3 min.</li>
	<li>Remove excess liquid by a small filter paper, and let it stay for 15 s to slightly dry the surface.</li>
	<li>Negatively stain EV samples with 1.5% phosphotungstic acid droplets for 40 s.</li>
	<li>Remove the excess phosphotungstic acid and allow it to stand for 15 s to slightly dry the surface.</li>
	<li>Put the sample containing formvar/carbon-coated square mesh into a clean dish covered with filter papers. Observe and capture images with a transmission electron microscope. 
	NOTE: In this process, Exos are taken as an example.</li>
</ol>
5. Labeling of MSCs-derived EVs
<ol>
	<li>After EVs extraction (step 2.5), resuspend with 250 &#181;L of PBS in a 1.5 mL conical tube.</li>
	<li>Use another 1.5 mL conical tube for preparing the working solution of the PKH26 dye; use 1 &#181;L of PKH26 labeling reagent diluted with 250 &#181;L of Diluent C (a component of the commercially available EV labeling kit used for the present study, see Table of Materials). 
	NOTE: Prepare the working solution immediately before use. 
	CAUTION: Excessive PKH26 dye or labeling without pre-dilution is at risk of damaging the EVs.</li>
	<li>Mix the resuspended EVs with the working solution. Allow it to stand at room temperature for 5 min, and then add 500 &#181;L of EV-depleted FBS to stop the reaction.</li>
	<li>For MVs, centrifuge at 4 &#176;C, 16,000 x g for 30 min, and discard the supernatant by a pipette. Add 1 mL of PBS to rinse the residue.</li>
	<li>Centrifuge at 4 &#176;C, 16,000 x g for 30 min, and discard the supernatant to remove the unbound dye.</li>
	<li>Resuspend the residue with 200 &#181;L of PBS. Drop 20 &#181;L of suspension on the slide and observe it under a fluorescence microscope. 
	NOTE: In this process, MVs are taken as an example.</li>
</ol>
6. Local transplantation and systemic injection of MSC-EVs
NOTE: For the following procedures, place the EVs on ice before injection.
<ol>
	<li>Perform local transplantation following the steps below.
	<ol>
		<li>Anesthetize the mice with 4% (vol/vol) isoflurane.&#160;Maintain anesthesia at 1%-3% isoflurane during the procedure.</li>
		<li>Before the surgery, administer 5 mg/kg carprofen (IP) for analgesia to minimize postprocedural pain.</li>
		<li>Before wound excision, shave the dorsal hair and sterilize the dorsal surface by applying 3 alternating rounds of 10% povidone-iodine and 75% ethanol.&#160;</li>
		<li>Using a biopsy punch (see Table of Materials), create a full-thickness wound of 1 cm in diameter on the dorsal skin.</li>
		<li>Resuspend the MSC-derived EVs from two dishes in 100 &#181;L of PBS and administer the injection in the subcutaneous layer of the wound bed, around each wound with four sites. 
		NOTE: An average of 100 &#181;g of EVs per mouse (EVs from two 10 cm dishes of cells) is injected. Ten 10 cm dishes of MSCs are needed to yield enough EVs to set up an experiment of n = 5 in a murine model.</li>
		<li>After treatment, wrap the mice with sterile gauze and place them on heat insulation pads (see Table of Materials) until they wake up.</li>
		<li>Ensure that the mice are not left unattended until they have regained sufficient consciousness. Do not return the mice to the company of other animals until they have fully recovered.</li>
		<li>Administer additional doses of analgesia on day 2 and day 3 post-surgery as required.&#160;</li>
	</ol>
	</li>
	<li>Perform systemic injection.
	<ol>
		<li>Resuspend MSC-derived EVs in 200 &#181;L of PBS, and then mix with heparin solution at a 10:1 volume ratio.</li>
		<li>Place the mice into the caudal vein imaging system (see Table of Materials). Press the switch to lift the lever.</li>
		<li>Disinfect the tail vein using an alcohol pad before the IV injection. Then, inject the mice systematically with suspension prepared in step 6.2.1 through the tail vein. The procedure is helped by a tail vein illustrator. 
		NOTE: Inject EV suspension immediately after mixing with heparin. An average of 100 &#181;g EVs per mouse (EVs from two 10 cm dishes of cells) is injected. Ten 10 cm dishes of MSCs are needed to yield enough EVs to set up an experiment of n = 5 in a murine model. 
		CAUTION: Mouse tail vein injection is usually limited to 200 &#181;l of volume. The injection should go slowly and stop if you see a bump or resistance, which suggests the needle is out of the vein. If the mice show&#160;adverse clinical signs like curling and trembling, this could be a shock response to high-volume injection, fast injection, or toxicity/anaphylaxis.</li>
	</ol>
	</li>
</ol>

<ol>
	<li>Liu, 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=The+application+of+MSCs-derived+extracellular+vesicles+in+bone+disorders:+Novel+cell-free+therapeutic+strategy.">The application of MSCs-derived extracellular vesicles in bone disorders: Novel cell-free therapeutic strategy.</a> Frontiers in Cell and Developmental Biology. 8, 619 (2020).</li><li>Arthur, A., Zannettino, A., Gronthos, 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+therapeutic+applications+of+multipotential+mesenchymal/stromal+stem+cells+in+skeletal+tissue+repair.">The therapeutic applications of multipotential mesenchymal/stromal stem cells in skeletal tissue repair.</a> Journal of Cellular Physiology. 218 (2), 237-245 (2009).</li><li>Zhou, Y., Yamamoto, Y., Xiao, Z., Ochiya, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+immunomodulatory+functions+of+mesenchymal+stromal/stem+cells+mediated+via+paracrine+activity.">The immunomodulatory functions of mesenchymal stromal/stem cells mediated via paracrine activity.</a> Journal of Clinical Medicine. 8 (7), 1025 (2019).</li><li>Mathieu, M., Martin-Jaular, L., Lavieu, G., Thery, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Specificities+of+secretion+and+uptake+of+exosomes+and+other+extracellular+vesicles+for+cell-to-cell+communication.">Specificities of secretion and uptake of exosomes and other extracellular vesicles for cell-to-cell communication.</a> Nature Cell Biology. 21 (1), 9-17 (2019).</li><li>Mori, M. A., Ludwig, R. G., Garcia-Martin, R., Brandao, B. B., Kahn, C. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Extracellular+miRNAs:+From+Biomarkers+to+Mediators+of+Physiology+and+Disease.">Extracellular miRNAs: From Biomarkers to Mediators of Physiology and Disease.</a> Cell Metabolism. 30 (4), 656-673 (2019).</li><li>Lei, L. 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=Exosomes+and+Obesity-Related+Insulin+Resistance.">Exosomes and Obesity-Related Insulin Resistance.</a> Frontiers in Cell and Developmental Biology. 9, 651996 (2021).</li><li>Isaac, R., Reis, F. C. G., Ying, W., Olefsky, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Exosomes+as+mediators+of+intercellular+crosstalk+in+metabolism.">Exosomes as mediators of intercellular crosstalk in metabolism.</a> Cell Metabolism. 33 (9), 1744-1762 (2021).</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> Nephrology Dialysis Transplantation. 26 (5), 1474-1483 (2011).</li><li>Thery, C., Amigorena, S., Raposo, G., Clayton, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+and+characterization+of+exosomes+from+cell+culture+supernatants+and+biological+fluids.">Isolation and characterization of exosomes from cell culture supernatants and biological fluids.</a> Current Protocols In Cell Biology. , 22 (2006).</li><li>Cheruvanky, 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=Rapid+isolation+of+urinary+exosomal+biomarkers+using+a+nanomembrane+ultrafiltration+concentrator.">Rapid isolation of urinary exosomal biomarkers using a nanomembrane ultrafiltration concentrator.</a> American Journal of Physiology-Renal Physiology. 292 (5), 1657-1661 (2007).</li><li>Zarovni, N., 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=Integrated+isolation+and+quantitative+analysis+of+exosome+shuttled+proteins+and+nucleic+acids+using+immunocapture+approaches.">Integrated isolation and quantitative analysis of exosome shuttled proteins and nucleic acids using immunocapture approaches.</a> Methods. 87, 46-58 (2015).</li><li>Boing, A. N., 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=Single-step+isolation+of+extracellular+vesicles+by+size-exclusion+chromatography.">Single-step isolation of extracellular vesicles by size-exclusion chromatography.</a> Journal of Extracellular Vesicles. 3, (2014).</li><li>Chen, I. H., 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=Phosphoproteins+in+extracellular+vesicles+as+candidate+markers+for+breast+cancer.">Phosphoproteins in extracellular vesicles as candidate markers for breast cancer.</a> Proceedings of the National Academy of Sciences of the United States of America. 114 (12), 3175-3180 (2017).</li><li>Li, P., Kaslan, M., Lee, S. H., Yao, J., Gao, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Progress+in+exosome+isolation+techniques.">Progress in exosome isolation techniques.</a> Theranostics. 7 (3), 789-804 (2017).</li><li>Lobb, R. 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=Optimized+exosome+isolation+protocol+for+cell+culture+supernatant+and+human+plasma.">Optimized exosome isolation protocol for cell culture supernatant and human plasma.</a> Journal of Extracellular Vesicles. 4, 27031 (2015).</li><li>Liu, 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=MSC+Transplantation+Improves+Osteopenia+via+Epigenetic+Regulation+of+Notch+Signaling+in+Lupus.">MSC Transplantation Improves Osteopenia via Epigenetic Regulation of Notch Signaling in Lupus.</a> Cell Metabolism. 22 (4), 606-618 (2015).</li><li>Deng, C. L., 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=Photoreceptor+protection+by+mesenchymal+stem+cell+transplantation+identifies+exosomal+MiR-21+as+a+therapeutic+for+retinal+degeneration.">Photoreceptor protection by mesenchymal stem cell transplantation identifies exosomal MiR-21 as a therapeutic for retinal degeneration.</a> Cell Death and Differentiation. 28 (3), 1041-1061 (2021).</li><li>Wu, 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=SHED+aggregate+exosomes+shuttled+miR-26a+promote+angiogenesis+in+pulp+regeneration+via+TGF-beta/SMAD2/3+signalling.">SHED aggregate exosomes shuttled miR-26a promote angiogenesis in pulp regeneration via TGF-beta/SMAD2/3 signalling.</a> Cell Proliferation. 54 (7), 13074 (2021).</li><li>Qiu, X., 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=Exosomes+released+from+educated+mesenchymal+stem+cells+accelerate+cutaneous+wound+healing+via+promoting+angiogenesis.">Exosomes released from educated mesenchymal stem cells accelerate cutaneous wound healing via promoting angiogenesis.</a> Cell Proliferation. 53 (8), 12830 (2020).</li><li>He, X., 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=MSC-derived+exosome+promotes+M2+polarization+and+enhances+cutaneous+wound+healing.">MSC-derived exosome promotes M2 polarization and enhances cutaneous wound healing.</a> Stem Cells International. 2019, 7132708 (2019).</li><li>Cheng, L., Hill, A. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Therapeutically+harnessing+extracellular+vesicles.">Therapeutically harnessing extracellular vesicles.</a> Nature Reviews Drug Discovery. 21 (5), 379-399 (2022).</li><li>Th&#233;ry, 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=Minimal+information+for+studies+of+extracellular+vesicles+2018+(MISEV2018):+a+position+statement+of+the+International+Society+for+Extracellular+Vesicles+and+update+of+the+MISEV2014+guidelines.">Minimal information for studies of extracellular vesicles 2018 (MISEV2018): a position statement of the International Society for Extracellular Vesicles and update of the MISEV2014 guidelines.</a> Journal of Extracellular Vesicles. 7 (1), 1535750 (2018).</li><li>Nielsen, T., 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=Extracellular+vesicle-associated+procoagulant+phospholipid+and+tissue+factor+activity+in+multiple+myeloma.">Extracellular vesicle-associated procoagulant phospholipid and tissue factor activity in multiple myeloma.</a> PLoS One. 14 (1), 0210835 (2019).</li><li>Zheng, 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=Apoptotic+vesicles+restore+liver+macrophage+homeostasis+to+counteract+type+2+diabetes.">Apoptotic vesicles restore liver macrophage homeostasis to counteract type 2 diabetes.</a> Journal of Extracellular Vesicles. 10 (7), 12109 (2021).</li><li>Gelibter, 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=The+impact+of+storage+on+extracellular+vesicles:+A+systematic+study.">The impact of storage on extracellular vesicles: A systematic study.</a> Journal of Extracellular Vesicles. 11 (2), 12162 (2022).</li><li>Dehghani, M., Gulvin, S. M., Flax, J., Gaborski, T. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Systematic+evaluation+of+PKH+labelling+on+extracellular+vesicle+size+by+nanoparticle+tracking+analysis.">Systematic evaluation of PKH labelling on extracellular vesicle size by nanoparticle tracking analysis.</a> Scientific Reports. 10 (1), 9533 (2020).</li><li>Zeringer, E., Barta, T., Li, M., Vlassov, A. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Strategies+for+isolation+of+exosomes.">Strategies for isolation of exosomes.</a> Cold Spring Harbor Protocols. 2015 (4), 319-323 (2015).</li><li>Bosch, 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=Trehalose+prevents+aggregation+of+exosomes+and+cryodamage.">Trehalose prevents aggregation of exosomes and cryodamage.</a> Scientific Reports. 6, 36162 (2016).</li><li>Williams, A. 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=Mesenchymal+stem+cell-derived+exosomes+provide+neuroprotection+and+improve+long-term+neurologic+outcomes+in+a+swine+model+of+traumatic+brain+injury+and+hemorrhagic+shock.">Mesenchymal stem cell-derived exosomes provide neuroprotection and improve long-term neurologic outcomes in a swine model of traumatic brain injury and hemorrhagic shock.</a> Journal of Neurotrauma. 36 (1), 54-60 (2019).</li><li>Li, 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=Apoptotic+vesicles+activate+autophagy+in+recipient+cells+to+induce+angiogenesis+and+dental+pulp+regeneration.">Apoptotic vesicles activate autophagy in recipient cells to induce angiogenesis and dental pulp regeneration.</a> Molecular Therapy: The Journal of the American Society of Gene Therapy. 1525 (22), 00304-00305 (2022).</li><li>Nozaki, T., 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=Significance+of+a+multiple+biomarkers+strategy+including+endothelial+dysfunction+to+improve+risk+stratification+for+cardiovascular+events+in+patients+at+high+risk+for+coronary+heart+disease.">Significance of a multiple biomarkers strategy including endothelial dysfunction to improve risk stratification for cardiovascular events in patients at high risk for coronary heart disease.</a> Journal of the American College of Cardiology. 54 (7), 601-608 (2009).</li><li>Qi, Y., Ma, J., Li, S., Liu, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Applicability+of+adipose-derived+mesenchymal+stem+cells+in+treatment+of+patients+with+type+2+diabetes.">Applicability of adipose-derived mesenchymal stem cells in treatment of patients with type 2 diabetes.</a> Stem Cell Research and Therapy. 10 (1), 274 (2019).</li><li>Kumar, 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=High-fat+diet-induced+upregulation+of+exosomal+phosphatidylcholine+contributes+to+insulin+resistance.">High-fat diet-induced upregulation of exosomal phosphatidylcholine contributes to insulin resistance.</a> Nature Communications. 12 (1), 213 (2021).</li></ol>

The authors have no conflicts of interest to disclose.

EVs are emerging to play an important role in diverse biological activities, including antigen presentation, genetic material transport, cell microenvironment modification, and others. Furthermore, their wide application brings new approaches and opportunities for diagnosing and treating diseases21. Implementation of therapeutic applications of EVs is based on successful isolation and characterization. However, due to the lack of standardized isolation and purification methods and the low extracti...

Stem cells are undifferentiated pluripotent cells with self-renewal capability and translational potential1. Mesenchymal stem cells (MSCs) are easily isolated, cultured, expanded, and purified in the laboratory, which remains characteristic of stem cells after multiple passages. In recent years, increasing evidence has supported the view that MSCs act in a paracrine mode in therapeutic use2,3. Especially the secretion of extracellular vesicles (EVs) plays a crucial role in mediating the biological functions of MSCs. As heterogeneous membranous nanoparticles released from most cell types, EVs consist of subcategories termed exosomes (Exos), microvesicles (MVs), and even larger apoptotic bodies4,5. Among them, Exos is the most widely studied EV with a size of 40-150 nm, which is of an endosomal origin and actively secreted in physiological conditions. MVs are formed by shedding directly from the surface of the cell plasma membrane with a diameter of 100-1,000 nm, which are characterized by high expression of phosphatidylserine and expression of surface markers of donor cells6. EVs contain RNA, proteins, and other bioactive molecules, which have similar functions to the parent cells and play a significant role in cell communication, immune response, and tissue damage repair7. MSC-EVs have been widely investigated as a powerful cell-free therapeutic tool in regenerative medicine8.
Isolation and purification of MSC-derived EVs is a common issue in the field of research and application. At present, differential and density gradient ultracentrifugation9, ultrafiltration process10, immunomagnetic separation11, molecular exclusion chromatograph12, and microfluidic chip13 are widely employed methods in the isolation and purification of EVs. With the advantages and disadvantages of each approach, the quantity, purity, and activity of collected EVs cannot be satisfied at the same time14,15. In the present study, the differential centrifugation protocol of isolation and characterization of EVs from cultured MSCs is shown in detail, which has supported efficient therapeutic use16,17,18,19,20. The adaptability of this method for a series of downstream approaches, such as fluorescent labeling, local transplantation, and systemic injection, has further been exampled. Implementing this procedure will address the need for simple and reliable collection and application of MSC-EVs in translational research.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>10% povidone-iodine (Betadine)</td>
			<td>Weizhenyuan</td>
			<td>10053956954292</td>
			<td>Wound disinfection</td>
		</tr>
		<tr>
			<td>Calibration solution</td>
			<td>Particle Metrix</td>
			<td>110-0020</td>
			<td>Calibrate the NTA instrument</td>
		</tr>
		<tr>
			<td>Carprofen</td>
			<td>Sigma</td>
			<td>53716-49-7</td>
			<td>Analgesic medicine</td>
		</tr>
		<tr>
			<td>Caudal vein imager&#160;</td>
			<td>KEW Life Science</td>
			<td>KW-XXY</td>
			<td>Caudal vein imager</td>
		</tr>
		<tr>
			<td>Centrifuge</td>
			<td>Eppendorf</td>
			<td>5418R</td>
			<td>Centrifugation</td>
		</tr>
		<tr>
			<td>Fatal bovine serum</td>
			<td>Corning</td>
			<td>35-081-CV</td>
			<td>Culture of UCMSCs</td>
		</tr>
		<tr>
			<td>Formvar/carbon-coated square mesh</td>
			<td>PBL Assay Science&#160;</td>
			<td>24916-25</td>
			<td>Transmission electron microscope</td>
		</tr>
		<tr>
			<td>Heating pad</td>
			<td>Zhongke Life Science</td>
			<td>Z8G5JBMz</td>
			<td>Post-treatment care of animals</td>
		</tr>
		<tr>
			<td>Heparin Solution</td>
			<td>StemCell</td>
			<td>7980</td>
			<td>Systemic injection</td>
		</tr>
		<tr>
			<td>Isoflurane</td>
			<td>RWD Life Science</td>
			<td>R510-22</td>
			<td>Animal anesthesia</td>
		</tr>
		<tr>
			<td>Minimum Essential Medium Alpha basic (1x)</td>
			<td>Gibco</td>
			<td>C12571500BT</td>
			<td>Culture of UCMSCs</td>
		</tr>
		<tr>
			<td>Nanoparticle tracking analyzer</td>
			<td>Particle Metrix</td>
			<td>ZetaView PMX120</td>
			<td>Nanoparticle tracking analysis</td>
		</tr>
		<tr>
			<td>PBS (1x)</td>
			<td>Meilunbio</td>
			<td>MA0015</td>
			<td>Resuspend EVs</td>
		</tr>
		<tr>
			<td>Penicillin/Streptomycin</td>
			<td>Procell Life Science</td>
			<td>PB180120</td>
			<td>Culture of UCMSCs</td>
		</tr>
		<tr>
			<td>Phosphotungstic acid</td>
			<td>Solarbio</td>
			<td>12501-23-4</td>
			<td>Transmission electron microscope</td>
		</tr>
		<tr>
			<td>Pipette</td>
			<td>Eppendorf</td>
			<td>3120000224</td>
			<td></td>
		</tr>
		<tr>
			<td>PKH26 Red Fluorescent Cell Linker Kit</td>
			<td>Sigma-Aldrich</td>
			<td>MINI26</td>
			<td>Labeling EVs</td>
		</tr>
		<tr>
			<td>Skin biopsy punch</td>
			<td>Acuderm</td>
			<td>69038-10-50</td>
			<td>Skin defects</td>
		</tr>
		<tr>
			<td>Software ZetaView</td>
			<td>Particle Metrix</td>
			<td>Version 8.05.14 SP7&#160;</td>
			<td></td>
		</tr>
		<tr>
			<td>Thermostatic equipment</td>
			<td>Grant</td>
			<td>v-0001-0005</td>
			<td>Water bath</td>
		</tr>
		<tr>
			<td>Transmission electron microscope</td>
			<td>HITACHI</td>
			<td>HT7800</td>
			<td>Transmission electron microscope</td>
		</tr>
		<tr>
			<td>UCMSCs</td>
			<td>Bai&#39;ao&#160;</td>
			<td>UKK220201</td>
			<td>Commercially UCMSCs</td>
		</tr>
		<tr>
			<td>Ultracentrifuge</td>
			<td>Beckman</td>
			<td>XPN-100</td>
			<td>Centrifugation</td>
		</tr>
		<tr>
			<td>Ultrapure filtered water purification system</td>
			<td>Milli-Q</td>
			<td>IQ 7000</td>
			<td>Preparation of ultrapure water</td>
		</tr>
	</tbody>
</table>

isolation, characterization, and therapeutic application of extracellular vesicles from cultured human mesenchymal stem cells

Extracellular vesicles (EVs) are heterogeneous membrane nanoparticles released by most cell types, and they are increasingly recognized as physiological regulators of organismal homeostasis and important indicators of pathologies; in the meantime, their immense potential to establish accessible and controllable disease therapeutics is emerging. Mesenchymal stem cells (MSCs) can release large amounts of EVs in culture, which have shown promise to jumpstart effective tissue regeneration and facilitate extensive therapeutic applications with good scalability and reproducibility. There is a growing demand for simple and effective protocols for collecting and applying MSC-EVs. Here, a detailed protocol is provided based on differential centrifugation to isolate and characterize representative EVs from cultured human MSCs, exosomes, and microvesicles for further applications. The adaptability of this method is shown for a series of downstream approaches, such as labeling, local transplantation, and systemic injection. The implementation of this procedure will address the need for simple and reliable MSC-EVs collection and application in translational research.

MVs and Exos from cultured human UCMSCs are isolated following the experimental workflow (Figure 1). The NTA results demonstrate that the size of Exos from human MSCs ranges from 40 nm to 335 nm with a peak size of about 100 nm, and the size of MVs ranges from 50 nm to 445 nm with a peak size of 150 nm (Figure 2). Morphological characterization of MSC-derived Exos exhibit a typical cup shape (Figure 3). EVs are efficiently labeled b...

Watch this Scientific Journal Video about Isolation, Characterization, and Therapeutic Application of Extracellular Vesicles from Cultured Human Mesenchymal Stem Cells at JoVE.com

Isolation, Characterization, and Therapeutic Application of Extracellular Vesicles from Cultured Human Mesenchymal Stem Cells

The present protocol describes the differential centrifugation for isolating and characterizing representative EVs (exosomes and microvesicles) from cultured human MSCs. Further applications of these EVs are also explained in this article.

Extracellular vesicles (EVs) are heterogeneous membrane nanoparticles released by most cell types, and they are increasingly recognized as physiological ...

isolation-characterization-therapeutic-application-extracellular

Research

JoVE Journal

Biology

1.8K Views.  Northwest University. The present protocol describes the differential centrifugation for isolating and characterizing representative EVs (exosomes and microvesicles) from cultured human MSCs. Further applications of these EVs are also explained in this article.

Video: Isolation, Characterization, and Therapeutic Application of Extracellular Vesicles from Cultured Human Mesenchymal Stem Cells

Isolation and Animal Serum Free Expansion of Human Umbilical Cord Derived Mesenchymal Stromal Cells (MSCs) and Endothelial Colony Forming Progenitor Cells (ECFCs)

The umbilical cord is a rich source for progenitor cells with high proliferative potential including mesenchymal stromal cells (also termed mesenchymal stem cells, MSCs) and endothelial colony forming progenitor cells (ECFCs). Both cell types are key players in maintaining the integrity of tissue and are probably also involved in regenerative processes and tumor formation.
To study their biology and function in a comparative manner it is important to have both cells types available from the same donor. It may also be beneficial for regenerative purposes to derive MSCs and ECFCs from the same tissue.
Because cellular therapeutics should eventually find their way from bench to bedside we established a new method to isolate and further expand progenitor cells without the use of animal protein. Pooled human platelet lysate (pHPL) replaced fetal bovine serum in all steps of our protocol to completely avoid contact of the cells to xenogeneic proteins.
This video demonstrates a methodology for the isolation and expansion of progenitor cells from one umbilical cord.
All materials and procedures will be described.

Isolation and Animal Serum Free Expansion of Human Umbilical Cord Derived Mesenchymal Stromal Cells MSCs and Endothelial Colony Forming Progenitor Cells ECFCs

This protocol describes the isolation and subsequent expansion of mesenchymal stromal cells and endothelial colony forming cells without the use of animal serum to generate autologous pairs for experimental transplantation purposes.

The umbilical cord is a rich source for progenitor cells with high proliferative potential including mesenchymal stromal cells (also termed mesenchymal ...

Isolation of Stem Cells from Human Pancreatic Cancer Xenografts

Cancer stem cells (CSCs) have been identified in a growing number of malignancies and are functionally defined by their ability to undergo self-renewal and produce differentiated progeny1. These properties allow CSCs to recapitulate the original tumor when injected into immunocompromised mice. CSCs within an epithelial malignancy were first described in breast cancer and found to display specific cell surface antigen expression (CD44+CD24low/-)2. Since then, CSCs have been identified in an increasing number of other human malignancies using CD44 and CD24 as well as a number of other surface antigens. Physiologic properties, including aldehyde dehydrogenase (ALDH) activity, have also been used to isolate CSCs from malignant tissues3-5.
Recently, we and others identified CSCs from pancreatic adenocarcinoma based on
ALDH activity and the expression of the cell surface antigens CD44 and CD24, and CD1336-8. These highly tumorigenic populations may or may not be overlapping and display other functions. We found that ALDH+ and CD44+CD24+ pancreatic CSCs are similarly tumorigenic, but ALDH+ cells are relatively more invasive8. In this protocol we describe a method to isolate viable pancreatic CSCs from low-passage human
xenografts9. Xenografted tumors are harvested from mice and made into a single-cell suspension. Tissue debris and dead cells are separated from live cells and then stained using antibodies against CD44 and CD24 and using the ALDEFLUOR reagent,
a fluorescent substrate of ALDH10. CSCs are then isolated by fluorescence activated cell sorting. Isolated CSCs can then be used for analytical or functional assays requiring viable cells.

Cancer stem cells (CSCs) have been identified in a number of malignancies. In this protocol we describe a flow cytometric method utilizing aldehyde dehydrogenase activity and CD44 and CD24 expression to isolate CSCs from human pancreatic adenocarcinoma xenografts. These viable cells can then be used in functional and analytical studies.

Cancer stem cells (CSCs) have been identified in a growing number of malignancies and are functionally defined by their ability to undergo self-renewal ...

Isolation and Culture of Adult Epithelial Stem Cells from Human Skin

The homeostasis of all self-renewing tissues is dependent on adult stem cells. As undifferentiated stem cells undergo asymmetric divisions, they generate daughter cells that retain the stem cell phenotype and transit-amplifying cells (TA cells) that migrate from the stem cell niche, undergo rapid proliferation and terminally differentiate to repopulate the tissue.
Epithelial stem cells have been identified in the epidermis, hair follicle, and intestine as cells with a high in vitro proliferative potential and as slow-cycling label-retaining cells in vivo 1-3. Adult, tissue-specific stem cells are responsible for the regeneration of the tissues in which they reside during normal physiologic turnover as well as during times of stress 4-5. Moreover, stem cells are generally considered to be multi-potent, possessing the capacity to give rise to multiple cell types within the tissue 6. For example, rodent hair follicle stem cells can generate epidermis, sebaceous glands, and hair follicles 7-9. We have shown that stem cells from the human hair follicle bulge region exhibit multi-potentiality 10.
Stem cells have become a valuable tool in biomedical research, due to their utility as an in vitro system for studying developmental biology, differentiation, tumorigenesis and for their possible therapeutic utility. It is likely that adult epithelial stem cells will be useful in the treatment of diseases such as ectodermal dysplasias, monilethrix, Netherton syndrome, Menkes disease, hereditary epidermolysis bullosa and alopecias 11-13. Additionally, other skin problems such as burn wounds, chronic wounds and ulcers will benefit from stem cell related therapies 14,15. Given the potential for reprogramming of adult cells into a pluripotent state (iPS cells)16,17, the readily accessible and expandable adult stem cells in human skin may provide a valuable source of cells for induction and downstream therapy for a wide range of disease including diabetes and Parkinson's disease.

A rapid, robust way of isolating viable adult epithelial stem cells from human skin is described. The method utilizes enzymatic digestion of skin collagen matrix , followed by plucking of hair follicles and isolation of single cell suspensions or tissue fragments for cell culture.

The homeostasis of all self-renewing tissues is dependent on adult stem cells. As undifferentiated stem cells undergo asymmetric divisions, they generate ...

Isolation &#38; Characterization of Hoechstlow CD45negative Mouse Lung Mesenchymal Stem Cells

Tissue resident mesenchymal stem cells (MSC) are important regulators of tissue repair or regeneration, fibrosis, inflammation, angiogenesis and tumor formation. Taken together these studies suggest that resident lung MSC play a role during pulmonary tissue homeostasis, injury and repair during diseases such as pulmonary fibrosis (PF) and arterial hypertension (PAH). Here we describe a technology to define a population of resident lung MSC. The definition of this population in vivo pulmonary tissue using a define set of markers facilitates the repeated isolation of a well-characterized stem cell population by flow cytometry and the study of a specific cell type and function.

Isolation &amp; Characterization of Hoechstlow CD45negative Mouse Lung Mesenchymal Stem Cells

In this article we demonstrate the isolation of murine resident lung mesenchymal stem cells (lung MSC), their expansion, characterization and analysis of immunomodulatory properties.

Tissue resident mesenchymal stem cells (MSC) are important regulators of tissue repair or regeneration, fibrosis, inflammation, angiogenesis and tumor ...

Na&iuml;ve Adult Stem Cells Isolation from Primary Human Fibroblast Cultures

Over the last decade, several adult stem cell populations have been identified in human skin 1-4. The isolation of multipotent adult dermal precursors was first reported by Miller F. D laboratory 5, 6. These early studies described a multipotent precursor cell population from adult mammalian dermis 5. These cells--termed SKPs, for skin-derived precursors-- were isolated and expanded from rodent and human skin and differentiated into both neural and mesodermal progeny, including cell types never found in skin, such as neurons 5. Immunocytochemical studies on cultured SKPs revealed that cells expressed vimentin and nestin, an intermediate filament protein expressed in neural and skeletal muscle precursors, in addition to fibronectin and multipotent stem cell markers 6. Until now, the adult stem cells population SKPs have been isolated from freshly collected mammalian skin biopsies.
Recently, we have established and reported that a population of skin derived precursor cells could remain present in primary fibroblast cultures established from skin biopsies 7. The assumption that a few somatic stem cells might reside in primary fibroblast cultures at early population doublings was based upon the following observations: (1) SKPs and primary fibroblast cultures are derived from the dermis, and therefore a small number of SKP cells could remain present in primary dermal fibroblast cultures and (2) primary fibroblast cultures grown from frozen aliquots that have been subjected to unfavorable temperature during storage or transfer contained a small number of cells that remained viable 7. These rare cells were able to expand and could be passaged several times. This observation suggested that a small number of cells with high proliferation potency and resistance to stress were present in human fibroblast cultures 7.
We took advantage of these findings to establish a protocol for rapid isolation of adult stem cells from primary fibroblast cultures that are readily available from tissue banks around the world (Figure 1). This method has important significance as it allows the isolation of precursor cells when skin samples are not accessible while fibroblast cultures may be available from tissue banks, thus, opening new opportunities to dissect the molecular mechanisms underlying rare genetic diseases as well as modeling diseases in a dish.

Na&amp;#239;ve Adult Stem Cells Isolation from Primary Human Fibroblast Cultures

We report a method to isolate na&#239;ve multipotent skin-derived precursor (SKP) cells from primary human fibroblast cultures. We show that these SKPs derived from fibroblast cultures share similar stem cell properties to the ones derived directly from human skin biopsies. These cells express the neural crest marker, nestin, in addition to the multipotent markers such as OCT4 and Nanog.

Over the last decade, several adult stem cell  populations have been identified in human skin 1-4.  The isolation of multipotent adult dermal precursors ...

Induction and Analysis of Epithelial to Mesenchymal Transition

Epithelial to mesenchymal transition (EMT) is essential for proper morphogenesis during development. Misregulation of this process has been implicated as a key event in fibrosis and the progression of carcinomas to a metastatic state. Understanding the processes that underlie EMT is imperative for the early diagnosis and clinical control of these disease states. Reliable induction of EMT in vitro is a useful tool for drug discovery as well as to identify common gene expression signatures for diagnostic purposes. Here we demonstrate a straightforward method for the induction of EMT in a variety of cell types. Methods for the analysis of cells pre- and post-EMT induction by immunocytochemistry are also included. Additionally, we demonstrate the effectiveness of this method through antibody-based array analysis and migration/invasion assays.

A straightforward method is described for the induction of epithelial to mesenchymal transition (EMT) in a variety of cell types. Methods for the analysis of cells in EMT states by immunocytochemistry are included.

Epithelial  to mesenchymal transition (EMT) is essential for proper morphogenesis during  development. Misregulation of this  process has been implicated ...

Manual Isolation of Adipose-derived Stem Cells from Human Lipoaspirates

In 2001, researchers at the University of California, Los Angeles, described the isolation of a new population of adult stem cells from liposuctioned adipose tissue that they initially termed Processed Lipoaspirate Cells or PLA cells. Since then, these stem cells have been renamed as Adipose-derived Stem Cells or ASCs and have gone on to become one of the most popular adult stem cells populations in the fields of stem cell research and regenerative medicine. Thousands of articles now describe the use of ASCs in a variety of regenerative animal models, including bone regeneration, peripheral nerve repair and cardiovascular engineering. Recent articles have begun to describe the myriad of uses for ASCs in the clinic. The protocol shown in this article outlines the basic procedure for manually and enzymatically isolating ASCs from large amounts of lipoaspirates obtained from cosmetic procedures. This protocol can easily be scaled up or down to accommodate the volume of lipoaspirate and can be adapted to isolate ASCs from fat tissue obtained through abdominoplasties and other similar procedures.

In 2001, researchers at UCLA described the isolation of a population of adult stem cells, termed Adipose-derived Stem Cells or ASCs, from adipose tissue. This article outlines the isolation of ASCs from lipoaspirates using a manual, enzymatic digestion protocol using collagenase.

In 2001, researchers at the University of  California, Los Angeles, described the isolation of a new population of adult  stem cells from liposuctioned ...

Isolation and Culture of Dental Epithelial Stem Cells from the Adult Mouse Incisor

Understanding the cellular and molecular mechanisms that underlie tooth regeneration and renewal has become a topic of great interest1-4, and the mouse incisor provides a model for these processes. This remarkable organ grows continuously throughout the animal&#39;s life and generates all the necessary cell types from active pools of adult stem cells housed in the labial (toward the lip) and lingual (toward the tongue) cervical loop (CL) regions. Only the dental stem cells from the labial CL give rise to ameloblasts that generate enamel, the outer covering of teeth, on the labial surface. This asymmetric enamel formation allows abrasion at the incisor tip, and progenitors and stem cells in the proximal incisor ensure that the dental tissues are constantly replenished. The ability to isolate and grow these progenitor or stem cells in vitro allows their expansion and opens doors to numerous experiments not achievable in vivo, such as high throughput testing of potential stem cell regulatory factors. Here, we describe and demonstrate a reliable and consistent method to culture cells from the labial CL of the mouse incisor.

The continuously growing mouse incisor provides a model for studying renewal of dental tissues from dental epithelial stem cells (DESCs). A robust system for consistently and reliably obtaining these cells from the incisor and expanding them in vitro is reported here.

Understanding the cellular and molecular mechanisms that underlie tooth regeneration and renewal has become a topic of great interest1-4, and the mouse ...

Isolation, Characterization, And High Throughput Extracellular Flux Analysis of Mouse Primary Renal Tubular Epithelial Cells

Mitochondrial dysfunction in the renal tubular epithelial cells (TECs) can lead to renal fibrosis, a major cause of&#160;chronic kidney disease (CKD). Therefore, assessing mitochondrial function in primary TECs may provide valuable insight into the bioenergetic status of the cells, providing insight into the pathophysiology of CKD. While there are a number of complex protocols available for the isolation and purification of proximal tubules in different species, the field lacks a cost-effective method optimized for&#160;tubular cell isolation without the need for purification. Here, we provide an isolation protocol that allows for studies focusing on both primary mouse proximal and distal renal TECs. In addition to cost-effective reagents and minimal animal procedures required in this protocol, the isolated cells maintain high energy levels after isolation and can be sub-cultured up to four&#160;passages, allowing for continuous studies. Furthermore, using a high throughput extracellular flux analyzer, we assess the mitochondrial respiration directly in the isolated TECs in a 96-well plate for which we provide recommendations for the optimization of cell density and compound concentration. These observations suggest that this protocol can be used for renal tubular ex vivo studies with a consistent, well-standardized production of renal TECs. This protocol may have broader future applications to study mitochondrial dysfunction associated with renal disorders for drug discovery or drug characterization purposes.

This protocol provides a cost-effective approach to isolate and characterize mouse primary renal tubular cells that can subsequently be sub-cultured to assess renal biological functions ex vivo, including mitochondrial bioenergetics.

Mitochondrial dysfunction in the renal tubular epithelial cells (TECs) can lead to renal fibrosis, a major cause of&#160;chronic kidney disease (CKD). ...

Scalable Isolation and Purification of Extracellular Vesicles from Escherichia coli and Other Bacteria

Diverse bacterial species secrete ~20-300 nm extracellular vesicles (EVs), comprised of lipids, proteins, nucleic acids, glycans, and other molecules derived from the parental cells. EVs function as intra- and inter-species communication vectors while also contributing to the interaction between bacteria and host organisms in the context of infection and colonization. Given the multitude of functions attributed to EVs in health and disease, there is a growing interest in isolating EVs for in vitro and in vivo studies. It was hypothesized that the separation of EVs based on physical properties, namely size, would facilitate the isolation of vesicles from diverse bacterial cultures. 
The isolation workflow consists of centrifugation, filtration, ultrafiltration, and size-exclusion chromatography (SEC) for the isolation of EVs from bacterial cultures. A pump-driven tangential flow filtration (TFF) step was incorporated to enhance scalability, enabling the isolation of material from liters of starting cell culture. Escherichia coli was used as a model system expressing EV-associated nanoluciferase and non-EV-associated mCherry as reporter proteins. The nanoluciferase was targeted to the EVs by fusing its N-terminus with cytolysin A. Early chromatography fractions containing 20-100 nm EVs with associated cytolysin A - nanoLuc were distinct from the later fractions containing the free proteins. The presence of EV-associated nanoluciferase was confirmed by immunogold labeling and transmission electron microscopy. This EV isolation workflow is applicable to other human gut-associated gram-negative and gram-positive bacterial species. In conclusion, combining centrifugation, filtration, ultrafiltration/TFF, and SEC enables scalable isolation of EVs from diverse bacterial species. Employing a standardized isolation workflow will facilitate comparative studies of microbial EVs across species.

Scalable Isolation and Purification of Extracellular Vesicles from Escherichia coli and Other Bacteria

Bacteria secrete nanometer-sized extracellular vesicles (EVs) carrying bioactive biological molecules. EV research focuses on understanding their biogenesis, role in microbe-microbe and host-microbe interactions and disease, as well as their potential therapeutic applications. A workflow for scalable isolation of EVs from various bacteria is presented to facilitate standardization of EV research.

Diverse bacterial species secrete ~20-300 nm extracellular vesicles (EVs), comprised of lipids, proteins, nucleic acids, glycans, and other molecules ...