This work was supported by grants from the National Health Research Institutes (05A1-CSPP16-014, H.J.L.) and from the Ministry of Science and Technology (MOST 103-2320-B-400-015-MY3, H.J.L).

All research involving animals complied with protocols approved by the Institutional Committee on Animal Care.
1. Extracellular Vesicle/exosome Isolation and Validation
<ol>
	<li>Culture mammary epithelial basal cells, NAMECs4, with fresh, serum-free medium made of 500 mL of MCDB 170, pH 7.4 + 500 mL of DMEM/F12 with sodium bicarbonate (0.2438%); EGF (5 ng/mL); hydrocoritisone (0.5 &#181;g/mL); insulin (5 &#181;g/mL); bovine pituitary extract (BPE; 35 &#181;g/mL); and...

<ol>
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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=PGE2+/EP4+Signaling+Controls+the+Transfer+of+the+Mammary+Stem+Cell+State+by+Lipid+Rafts+in+Extracellular+Vesicles.">PGE2 /EP4 Signaling Controls the Transfer of the Mammary Stem Cell State by Lipid Rafts in Extracellular Vesicles.</a> Stem Cells. , (2016).</li><li>Th&#233;ry, 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> Curr Protoc Cell Biol. , (2006).</li><li>Gy&#246;rgy, B., 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=Membrane+vesicles,+current+state-of-the-art:+emerging+role+of+extracellular+vesicles.">Membrane vesicles, current state-of-the-art: emerging role of extracellular vesicles.</a> Cell Mol Life Sci. 68 (16), 2667-2688 (2011).</li><li>Olver, C., Vidal, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Proteomic+analysis+of+secreted+exosomes.">Proteomic analysis of secreted exosomes.</a> Subcell Biochem. 43, 99-131 (2007).</li><li>Shackleton, 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=Generation+of+a+functional+mammary+gland+from+a+single+stem+cell.">Generation of a functional mammary gland from a single stem cell.</a> Nature. 439 (7072), 84-88 (2006).</li><li>Prater, M. 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=Mammary+stem+cells+have+myoepithelial+cell+properties.">Mammary stem cells have myoepithelial cell properties.</a> Nat Cell Biol. 16 (10), 942-950 (2014).</li><li>Stingl, 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=Purification+and+unique+properties+of+mammary+epithelial+stem+cells.">Purification and unique properties of mammary epithelial stem cells.</a> Nature. 439 (7079), 993-997 (2006).</li><li>Gardiner, C., Ferreira, Y. J., Dragovic, R. A., Redman, C. W., Sargent, I. L. <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+sizing+and+enumeration+by+nanoparticle+tracking+analysis.">Extracellular vesicle sizing and enumeration by nanoparticle tracking analysis.</a> J Extracell Vesicles. 2, (2013).</li><li>Shapiro, A. L., Vi&#241;uela, E., Maizel, J. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Molecular+weight+estimation+of+polypeptide+chains+by+electrophoresis+in+SDS-polyacrylamide+gels.">Molecular weight estimation of polypeptide chains by electrophoresis in SDS-polyacrylamide gels.</a> Biochem Biophys Res Commun. 28 (5), 815-820 (1967).</li><li>Riches, A., Campbell, E., Borger, E., Powis, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Regulation+of+exosome+release+from+mammary+epithelial+and+breast+cancer+cells+-+a+new+regulatory+pathway.">Regulation of exosome release from mammary epithelial and breast cancer cells - a new regulatory pathway.</a> Eur J Cancer. 50 (5), 1025-1034 (2014).</li><li>Witwer, K. 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=Standardization+of+sample+collection,+isolation+and+analysis+methods+in+extracellular+vesicle+research.">Standardization of sample collection, isolation and analysis methods in extracellular vesicle research.</a> J Extracell Vesicles. 2, (2013).</li><li>van der Vlist, E. J., Nolte-'t Hoen, E. N., Stoorvogel, W., Arkesteijn, G. J., Wauben, M. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fluorescent+labeling+of+nano-sized+vesicles+released+by+cells+and+subsequent+quantitative+and+qualitative+analysis+by+high-resolution+flow+cytometry.">Fluorescent labeling of nano-sized vesicles released by cells and subsequent quantitative and qualitative analysis by high-resolution flow cytometry.</a> Nat Protoc. 7 (7), 1311-1326 (2012).</li><li>Kowal, 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=Proteomic+comparison+defines+novel+markers+to+characterize+heterogeneous+populations+of+extracellular+vesicle+subtypes.">Proteomic comparison defines novel markers to characterize heterogeneous populations of extracellular vesicle subtypes.</a> Proc Natl Acad Sci U S A. 113 (8), E968-E977 (2016).</li><li>Li, 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=ADVANCED+IMAGING.+Extended-resolution+structured+illumination+imaging+of+endocytic+and+cytoskeletal+dynamics.">ADVANCED IMAGING. Extended-resolution structured illumination imaging of endocytic and cytoskeletal dynamics.</a> Science. 349 (6251), (2015).</li><li>Outzen, H. C., Custer, R. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Growth+of+human+normal+and+neoplastic+mammary+tissues+in+the+cleared+mammary+fat+pad+of+the+nude+mouse.">Growth of human normal and neoplastic mammary tissues in the cleared mammary fat pad of the nude mouse.</a> J Natl Cancer Inst. 55 (6), 1461-1466 (1975).</li><li>Sheffield, L. G., Welsch, C. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transplantation+of+human+breast+epithelia+to+mammary-gland-free+fat-pads+of+athymic+nude+mice:+influence+of+mammotrophic+hormones+on+growth+of+breast+epithelia.">Transplantation of human breast epithelia to mammary-gland-free fat-pads of athymic nude mice: influence of mammotrophic hormones on growth of breast epithelia.</a> Int J Cancer. 41 (5), 713-719 (1988).</li></ol>

The authors have nothing to disclose.

Exosomes often carry characteristics of the cells that released them, and the amount of released exosomes can be induced by stimuli4. The culture medium of cells can be collected and subjected to differential ultracentrifugation for EV/exosome collection (Figure 1). There is currently no general agreement on an ideal method to isolate EVs/exosomes. The optimal method used here has been determined by the downstream application14. Ultracentrifuga...

Exosomes can mediate cellular communication by transferring membrane and cytosolic proteins, lipids, and RNAs between cells1. Exosome-mediated communication has been demonstrated to be involved in many physiological and pathological processes (i.e., antigen presentation, development of tolerance2, and tumor progression3). Exosomes often have contents similar to those of the source cells releasing them. Thus, the exosomes can carry specific cell properties from the source cells and transfer these properties to the cells ingesting them4.
Exosomes are 50- to 150-nm double-layer membrane vesicles and present specific markers (e.g., CD9, CD81, CD63, HSP70, Alix, and TSG101). Thus, exosomes must be characterized by various methods for different aspects. Transmission electron microscopy can be used to visualize membrane vesicles such as exosomes4,5. Nanoparticle tracking analysis (NTA) and dynamic light scattering analysis (DLS) are used for measuring the size and number of purified exosomes4. The lipid membrane content of exosomes can be verified by density gradient. Exosomal markers, such as CD9, CD81, CD63, HSP70, Alix, and TSG1016,7, can be measured by Western blotting.
Mammary basal cells have the ability to generate mammary glands when implanted into fat pads, while luminal cells cannot8,9,10. Thus, mammary basal cells are also referred to as mammary repopulating units. By using the model of mammary basal and luminal cells, the ability of EVs/exosomes to transfer cell characteristics between different cell populations can be examined. This work demonstrates the method of transferring gland-forming ability from mammary basal epithelial cells to mammary luminal epithelial cells by using EVs/exosomes derived from mammary basal epithelial cells. Luminal mammary epithelial cells acquired basal cell properties following the ingestion of EVs/exosomes secreted from basal cells and can then form mammary glands4.

<table>
	<tbody>
		<tr>
			<td>MCDB 170&#160;</td>
			<td>USBiological</td>
			<td>M2162</td>
			<td></td>
		</tr>
		<tr>
			<td>DMEM/F12</td>
			<td>Thermo</td>
			<td>1250062</td>
			<td></td>
		</tr>
		<tr>
			<td>Optima L-100K ultracentrifuge</td>
			<td>Beckman</td>
			<td>393253</td>
			<td></td>
		</tr>
		<tr>
			<td>SW28 Ti Rotor</td>
			<td>Beckman</td>
			<td>342204</td>
			<td></td>
		</tr>
		<tr>
			<td>SW41 Rotor</td>
			<td>Beckman</td>
			<td>331306</td>
			<td></td>
		</tr>
		<tr>
			<td>NANOSIGHT LM10</td>
			<td>Malvern</td>
			<td>NANOSIGHT LM10</td>
			<td>for nanoparticle tracking analysis (NTA)</td>
		</tr>
		<tr>
			<td>Optiprep&#160;</td>
			<td>Sigma-Aldrich</td>
			<td>D1556</td>
			<td>60% (w/v) solution of iodixanol in water (sterile).</td>
		</tr>
		<tr>
			<td>CD81 antibody</td>
			<td>GeneTex</td>
			<td>GTX101766</td>
			<td>1:1000 in 5% w/v nonfat dry milk, 1X TBS, 0.1% Tween 20 at 4&#176;C, overnight&#160;</td>
		</tr>
		<tr>
			<td>CD9 antibody</td>
			<td>GeneTex</td>
			<td>GTX100912</td>
			<td>1:1000 in 5% w/v nonfat dry milk, 1X TBS, 0.1% Tween 20 at 4&#176;C, overnight&#160;</td>
		</tr>
		<tr>
			<td>CD63 antibody</td>
			<td>Abcam</td>
			<td>Ab59479</td>
			<td>1:1000 in 5% w/v nonfat dry milk, 1X TBS, 0.1% Tween 20 at 4&#176;C, overnight&#160;</td>
		</tr>
		<tr>
			<td>TSG101 antibody</td>
			<td>GeneTex</td>
			<td>GTX118736</td>
			<td>1:1000 in 5% w/v nonfat dry milk, 1X TBS, 0.1% Tween 20 at 4&#176;C, overnight&#160;</td>
		</tr>
		<tr>
			<td>GAPDH</td>
			<td>GeneTex</td>
			<td>GTX100118</td>
			<td>1:6000 in 5% w/v nonfat dry milk, 1X TBS, 0.1% Tween 20 at 4&#176;C, overnight&#160;</td>
		</tr>
		<tr>
			<td>CFSE (carboxyfluorescein succinimidyl diacetate ester)</td>
			<td>Thermo</td>
			<td>V12883</td>
			<td></td>
		</tr>
		<tr>
			<td>FACSCalibur</td>
			<td>BD Biosciences</td>
			<td></td>
			<td>fluorescence cell analyzer</td>
		</tr>
		<tr>
			<td>collagenase Type IV&#160;</td>
			<td>Thermo</td>
			<td>17104019</td>
			<td></td>
		</tr>
		<tr>
			<td>trypsin</td>
			<td>Thermo</td>
			<td>27250018</td>
			<td></td>
		</tr>
		<tr>
			<td>&#160;ITS</td>
			<td>Sigma-Aldrich</td>
			<td>I3146</td>
			<td>a mixture of recombinant human insulin, human transferrin, and sodium selenite</td>
		</tr>
		<tr>
			<td>accutase</td>
			<td>ebioscience</td>
			<td>00-4555-56</td>
			<td>a natural enzyme mixture with proteolytic and collagenolytic enzyme activity</td>
		</tr>
		<tr>
			<td>dispase&#160;</td>
			<td>STEMCELL</td>
			<td>7913</td>
			<td>5 mg/ml = 5 U/ml</td>
		</tr>
		<tr>
			<td>anti-CD49f antibody</td>
			<td>Biolegend</td>
			<td>313611</td>
			<td>1:50</td>
		</tr>
		<tr>
			<td>anti-EpCAM antibody</td>
			<td>Biolegend</td>
			<td>118213</td>
			<td>1:200</td>
		</tr>
		<tr>
			<td>FACSAria</td>
			<td>BD Biosciences</td>
			<td></td>
			<td>cell sorter</td>
		</tr>
		<tr>
			<td>carmine alum</td>
			<td>Sigma-Aldrich</td>
			<td>C1022</td>
			<td></td>
		</tr>
		<tr>
			<td>human mammary epithelial cells (HMLE cells, NAMECs)</td>
			<td></td>
			<td></td>
			<td>gifts from Dr. Robert Weinberg</td>
		</tr>
		<tr>
			<td>permount</td>
			<td>Thermo Fisher Scientific&#160;</td>
			<td>SP15-500</td>
			<td></td>
		</tr>
		<tr>
			<td>sodium bicarbonate</td>
			<td>Zymeset&#160;</td>
			<td>BSB101</td>
			<td></td>
		</tr>
		<tr>
			<td>EGF</td>
			<td>Peprotech</td>
			<td>AF-100-015</td>
			<td></td>
		</tr>
		<tr>
			<td>Hydrocoritisone</td>
			<td>Sigma-Aldrich</td>
			<td>SI-H0888</td>
			<td></td>
		</tr>
		<tr>
			<td>Insulin&#160;</td>
			<td>Sigma-Aldrich</td>
			<td>SI-I9278</td>
			<td></td>
		</tr>
		<tr>
			<td>BPE (bovine pituitary extract)</td>
			<td>Hammod Cell Tech&#160;</td>
			<td>1078-NZ</td>
			<td></td>
		</tr>
		<tr>
			<td>GW627368X&#160;</td>
			<td>Cayman</td>
			<td>10009162</td>
			<td></td>
		</tr>
		<tr>
			<td>15-cm culture dish</td>
			<td>Falcon&#160;</td>
			<td>353025</td>
			<td></td>
		</tr>
		<tr>
			<td>table-top centrifuge</td>
			<td>Eppendrof&#160;</td>
			<td>Centrifuge 3415R</td>
			<td></td>
		</tr>
		<tr>
			<td>ultracentrifuge tube</td>
			<td>Beckman</td>
			<td>344058</td>
			<td></td>
		</tr>
		<tr>
			<td>PBS (Phosphate-buffered saline)&#160;</td>
			<td>Corning</td>
			<td>46-013-CM</td>
			<td></td>
		</tr>
		<tr>
			<td>BCA Protein Assay</td>
			<td>Thermo Fisher Scientific&#160;</td>
			<td>23228</td>
			<td></td>
		</tr>
		<tr>
			<td>Transmission Electron Microscopy</td>
			<td>Hitachi</td>
			<td>HT7700</td>
			<td></td>
		</tr>
		<tr>
			<td>gelatin&#160;</td>
			<td>STEMCELL</td>
			<td>7903</td>
			<td></td>
		</tr>
		<tr>
			<td>10-cm culture dish</td>
			<td>Falcon&#160;</td>
			<td>353003</td>
			<td></td>
		</tr>
		<tr>
			<td>6-well culture dish</td>
			<td>Corning</td>
			<td>3516</td>
			<td></td>
		</tr>
		<tr>
			<td>female C57BL/6 mice</td>
			<td>NLAC (National Laboratory Animal Center</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>FBS (Fetal Bovine Serum)</td>
			<td>BioWest&#160;</td>
			<td>S01520</td>
			<td></td>
		</tr>
		<tr>
			<td>gentamycin</td>
			<td>Thermo Fisher Scientific&#160;</td>
			<td>15710072</td>
			<td></td>
		</tr>
		<tr>
			<td>Pen/Strep</td>
			<td>Corning</td>
			<td>30-002-Cl</td>
			<td></td>
		</tr>
		<tr>
			<td>DNase I</td>
			<td>5PRIMER</td>
			<td>2500120</td>
			<td></td>
		</tr>
		<tr>
			<td>isofluorane&#160;</td>
			<td>Halocarbon</td>
			<td>NPC12164-002-25</td>
			<td></td>
		</tr>
		<tr>
			<td>formaldehyde</td>
			<td>MACRON</td>
			<td>H121-08</td>
			<td></td>
		</tr>
		<tr>
			<td>EtOH (Ethanol)</td>
			<td>J.T. Baker</td>
			<td>800605</td>
			<td></td>
		</tr>
		<tr>
			<td>glacial acetic acid</td>
			<td>Panreac</td>
			<td>131008.1611</td>
			<td></td>
		</tr>
		<tr>
			<td>aluminum potassium sulfate</td>
			<td>Sigma-Aldrich</td>
			<td>12625</td>
			<td></td>
		</tr>
		<tr>
			<td>Xylene&#160;</td>
			<td>Leica</td>
			<td>3803665</td>
			<td></td>
		</tr>
		<tr>
			<td>0.22 &#956;m membranes</td>
			<td>Merck Millipore</td>
			<td>Millex-GP</td>
			<td></td>
		</tr>
		<tr>
			<td>AUTOCLIP Wound Clips, 9 mm</td>
			<td>BD Biosciences</td>
			<td>427631</td>
			<td></td>
		</tr>
		<tr>
			<td>AUTOCLIP Wound Clip Applier</td>
			<td>BD Biosciences</td>
			<td>427630</td>
			<td></td>
		</tr>
		<tr>
			<td>CellMask&#8482; Deep Red</td>
			<td>Thermo Fisher Scientific&#160;</td>
			<td>C10046</td>
			<td>plasma membrane stain</td>
		</tr>
	</tbody>
</table>

transfer of mammary gland-forming ability between mammary basal epithelial cells and mammary luminal cells via extracellular vesicles/exosomes

Cells can communicate via exosomes, ~100-nm extracellular vesicles (EVs) that contain proteins, lipids, and nucleic acids. Non-adherent/mesenchymal mammary epithelial cell (NAMEC)-derived extracellular vesicles can be isolated from NAMEC medium via differential ultracentrifugation. Based on their density, EVs can be purified via ultracentrifugation at 110,000 x g. The EV preparation from ultracentrifugation can be further separated using a continuous density gradient to prevent contamination with soluble proteins. The purified EVs can then be further evaluated using nanoparticle-tracking analysis, which measures the size and number of vesicles in the preparation. The extracellular vesicles with a size ranging from 50 to 150 nm are exosomes. The NAMEC-derived EVs/exosomes can be ingested by mammary epithelial cells, which can be measured by flow cytometry and confocal microscopy. Some mammary stem cell properties (e.g., mammary gland-forming ability) can be transferred from the stem-like NAMECs to mammary epithelial cells via the NAMEC-derived EVs/exosomes. Isolated primary EpCAMhi/CD49flo luminal mammary epithelial cells cannot form mammary glands after being transplanted into mouse fat pads, while EpCAMlo/CD49fhi basal mammary epithelial cells form mammary glands after transplantation. Uptake of NAMEC-derived EVs/exosomes by EpCAMhi/CD49flo luminal mammary epithelial cells allows them to generate mammary glands after being transplanted into fat pads. The EVs/exosomes derived from stem-like mammary epithelial cells transfer mammary gland-forming ability to EpCAMhi/CD49flo luminal mammary epithelial cells.

Since it has been shown that blocking PGE2/EP4 signaling triggers EV/exosome release from mammary basal-like stem cells4, this work presents a method of isolating the induced EVs/exosomes from mammary epithelial basal cell (NAMEC) culture. Since NAMECs are cultured in serum-free medium, there are no pre-existing EVs/exosomes derived from serum13. For cells cultured in serum-containing medium, pre-existing exosomes in th...

Watch this Scientific Journal Video about Transfer of Mammary Gland-forming Ability Between Mammary Basal Epithelial Cells and Mammary Luminal Cells via Extracellular Vesicles/Exosomes at JoVE.com

Transfer of Mammary Gland-forming Ability Between Mammary Basal Epithelial Cells and Mammary Luminal Cells via Extracellular Vesicles/Exosomes

This protocol describes methods for purifying, quantitating, and characterizing extracellular vesicles (EVs)/exosomes from non-adherent/mesenchymal mammary epithelial cells and for using them to transfer mammary gland-forming ability to luminal mammary epithelial cells. EVs/exosomes derived from stem-like mammary epithelial cells can transfer this cell property to cells that ingest the EVs/exosomes.

Cells can communicate via exosomes, ~100-nm extracellular vesicles (EVs) that contain proteins, lipids, and nucleic acids. Non-adherent/mesenchymal ...

The overall goals of this procedure are to isolate stem ness transferring extra cellular vesicles and exosomes from stem cells. And to assess the stem ness transferring ability of these nano-particles. The meso can answer key questions in the stem cell field about weather stem cell derive in trans cell or vesicle.Or exosome can transfer stem cell property to non stem cell. The main advantage of this technique is that the induced stem cell derive in trans cell vesicle. And the exosome can be used to directly reprogramming non stem cell into stem cell.Demonstrating the procedure will be postal researcher LeMonsier, with surgical assistant, Pei-Ling, Wen-Tin, and Shih-Yin, all from my laboratory. Begin by seeding one point two times ten to the sixth non-adherent/mesenchymal mammary epithelial cells, or NAMECs in 12 milliliters of medium per 15 centimeter dish for a four day culture in a cell culture incubator. On day four, harvest the culture medium for table top centrufigation.Then transfer the supernatent into a conical tube for a second table top centrifugation. Next, transfer the supernatent into a new ultra-centrifuge and perform ultracentrifugation for 30 minutes. At the end of the spin, transfer the supernatent into a new ultra-centrifuge tube and ultra-centrifuge the supernatent again.Remove the supernatent and re-suspend the extra-cellular vesicle exosome palate in PBS for a third ultracentrifugation. Then, re-suspend the palate in fresh PBS and ultra-centrifuge the cell particles one final time. Remove the supernatent and re-suspend the extra cellular vesicle exosome palate in 100 microliters of PBS.Then, measure the protein concentration of the extra cellular vesicle suspension by bicinchoninic acid assay. The concentration should be approximately 20 to 40 micrograms per 100 microliters. To measure the concentration and the size of the extra cellular vesicles and exosomes, dilute the cell particles to two micrograms of protein per 100 milliliters of PBS.And analyze the particles by nanoparticle tracking analysis. To purify the exosomes by density gradient, after the third ultracentrifugation, resuspend the palate in two milliliters of 40 percent iodixanol in PBS. And overlay the cell suspension with sequential two milliliter volumes of 30 percent, 20 percent, 10 percent and five percent iodixanol.Separate the cell fraction by density gradient ultracentrifugation using a pipette to harvest each of the ten gradient layers at the end of the centrifugation. Then, analyze the presence of exosome markers in each fraction by SDS page and western blot according to standard protocols. Using antibodies against the appropriate exosome markers of interest.To treat mammary epithelial cells with the extra cellular vesicles and exosomes first, seed two times tent to the fifth flow sorted epcam hi-CD 49F low luminal mammary epithelial cells per plate onto gelatine coated six well plates. Then, treat each cellular culture with two micrograms per milliliter of the NAMEC derived extra cellular vesicles and exsomes. Replacing the cultured medium with fresh extra cellular vesicles and exosomes every two days for ten days.At the end of the treatment period, place a three week old female anesthetized 57 BL6 mouse in the supine position, and remove the fur on the mid-abdomen. Disinfect the surgery site with three alternating cycles of 70 percent alcohol and povodone iodine. And make a one point five centimeter vertical incision through the skin, along the ventral thorassic inguinal region.Alternately expose the right and left fourth mammary fat pads. Locate the lymph node in each fat pad and remove the whole gland perancama below the lymph node. Next, use a natural enzyme with prodialitic and cologenalitic activity to detach the extra cellular vesical and exsome treated luminal mammary epithelial cells.Neutralizing the enzyme activity, with five percent FBS in PBS after ten minutes. Collect the cells by centrifugation and discard the supernatent. After counting, dilute the cells to one times ten to the second to one times ten to the fourth cells per 15 microliters of PBS concentration.And use a 100 liter microliter glass syringe equipped with a 27 gauge needle to inject 15 microliters of the mammary epithelial cell suspension into each fat pad. Then, close the skin with wound clips. Eight weeks after the injection, make a vertical incision through the skin from the thorassic region to the ingrinal region and expose both the right and left fourth mammary fat pads.Remove the fourth mammary glans and spread the fat pads onto individual glass microscope slides. Then, transfer the slides to a chemical hood, and fix the pads with collies fixatives overnight at room temperature. The next morning, wash the samples in 250 milliliters of 70 percent ethanol for 15 minutes.Followed by 250 milliliters of distilled water for five minutes. After the distilled water wash, stain the fat pads with carmine alum overnight at room temperature. Followed by dehydration in ascending 15 minute ethanol incubations.After the last dehydration, transfer the samples into zylene in a chemical hood until the fat pads become transparent. Then, mount the slides with mounting medium, and use a digital slide scanner to image the fat pads at 2, 400 dots per inch. The size of the isolated vesicles and the ultracentrifuge palate are typically approximately 100 nanometers, as measured by nano particle tracking analysis.Further, transmission electron microscopy analysis of ultracentrifuge fractions of NAMEC conditioned medium reveals the presences of abundant membrane vesicles. After density gradient separation as just demonstrated, exosome markers can be detected in the 20 percent iodixonal fraction. Flow side emetric analysis of human luminal mammary epithelial cells traded with CFSE labeled namic derived, extra cellular vesicles and exsomes reveals a ten fold higher CFSE signal in the exosome treated cultures.Indicating the specific uptake of CFSE labeled extra cellular vesicles and exosomes, by the mammary epithelial cells. Further, while the negative control, PBS treated mammary epithelial cells do not exhibit a CFSE singnal, evidence of namic derived extra cellular vesical and exosome uptake by the exosome treated cells can also be observed by confocal microscopy. Notably, the fat pads of mice injected with flow sorted epCAMhi/CD49Flo luminal mammary epithelial cells treated with NAMEC derived extra cellular vesicles and exosomes for ten days acquired the ability to form mammary glands.After it's development, this tech paved the way for our researcher in the field of stem cell biology. To explore in the usage of the stem cell derived trans cell and vesicle and exosome in regeneration medicine and direct cell reprogramming.

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JoVE Journal

Developmental Biology

11.5K visualizações.  National Health Research Institutes. The overall goals of this procedure are to isolate stem ness transferring extra cellular vesicles and exosomes from stem cells. And to assess the stem ness transferring ability of these nano-particles. The meso can answer key questions in the stem cell field about weather stem cell derive in trans cell or vesicle.Or exosome can transfer stem cell property to non stem cell. The main advantage of this technique is that the induced stem cell derive in trans cell vesicle. And the exosome c...