The authors acknowledge support from the Queenie Victorina Neri Research Scholar Award (D.J.) and the Hung-Ching Liu Research Scholar Award (L.M.). N.L.G is supported by the NYSTEM Stem Cell and Regenerative Medicine postdoctoral training grant.

All procedures involving mice were approved by the Institutional Animal Care and Use Committee (IACUC) at Weill Cornell Medicine. All xenotransplantation experiments using ovarian tissue were performed in accordance with relevant guidelines and regulations. Both ovaries were isolated from a 14-year-old brain-dead organ donor with no history of radio/chemotherapy and no documented history of endocrine or reproductive conditions. The institutional review board (IRB) Committee of Weill Cornell Medicine approved the collection of tissue, and approval from the family of the organ donor was obtained following informed consent regarding the use of tissue.
1. Ovarian tissue collection and handling
<ol>
	<li>Collect whole ovaries and the associated tissue, and rinse in sterile saline solution.</li>
	<li>Using sterile tweezers, place the ovaries in a sterile container. Pour sterile, buffered, cold solution (e.g., Leibovitz&#39;s L-15 medium) into the container. Ensure that the tissue is completely covered with the liquid.</li>
	<li>Close the container and double-bag it using sterile plastic bags. Transport the container on ice within an isolated box (e.g., Styrofoam). Transfer the specimens to the lab that will process the ovaries as soon as possible, preferably in a time not exceeding 5 h3,4.</li>
</ol>
2. Processing the ovarian tissue
NOTE: Make sure all the reagents and tools are prepared before the tissue arrives in the lab to reduce the ischemic interval as much as possible. The buffers can be prepared up to 1 week prior to freezing and refrigerated until use.
<ol>
	<li>Preparations for the ovarian processing and freezing
	<ol>
		<li>Set sterilized surgical tools in the biosafety cabinet in preparation for tissue processing: one number 21 scalpel; one number 11 scalpel; sharp fine curved scissors; one long forceps (~150 mm length); and two medium forceps (~110 mm length).</li>
		<li>Prepare 100 mL of tissue processing medium (see the Table of Materials): Leibovitz&#39;s L-15 medium containing antibiotic-antimycotic solution and filtered using a 0.2 &#956;m filter. Keep the medium chilled.</li>
		<li>Label the cryovials, add 1.5 mL of freezing solution (see the Table of Materials) to each vial, and store it at 4 &#176;C.</li>
		<li>Have available a 6-well plate on hand for use.</li>
	</ol>
	</li>
	<li>Upon arrival of the tissue
	<ol>
		<li>Spray the container with 70% ethanol solution, wipe thoroughly, and place it within the biosafety cabinet.</li>
		<li>Wearing sterile gloves, open the container. Place the ovary in a sterile Petri dish, and pour chilled medium (from step 2.1.2) to hydrate the tissue. Ensure that the ovary is half-submerged in the medium.</li>
		<li>Remove any sutures or other material and dissect the residual surrounding tissue away from the ovary.</li>
	</ol>
	</li>
</ol>
3. Isolation of antral follicles
<ol>
	<li>Identify individual follicles for isolation. In choosing healthy follicles, exclude any blood-filled, dark, or non-symmetric follicles, as those are likely to be atretic.</li>
	<li>Isolate the chosen antral follicles from the whole ovary using scalpels, keeping the antrum intact by excising the cortical tissue encompassing the follicle.</li>
	<li>Place each excised intact antral follicle in one well of the 6-well plate. If needed for descriptive purposes, use a ruler placed underneath the dish to determine the follicle diameter.</li>
	<li>Using a scalpel, bisect the intact antral follicle to gain access to the antral cavity, and add 4 mL of enzymatic cell detachment medium. Incubate the plate in a humidified incubator at 5% CO2 and 37 &#176;C for 10 min.</li>
	<li>Repeat the extraction of additional antral follicles as needed.</li>
</ol>
4. Isolation of follicle resident cells
<ol>
	<li>Following incubation, add 4 mL of available medium containing 20% FBS, and flush by repeated, vigorous pipetting of the medium over the bisected follicles with a P1,000 micropipette.</li>
	<li>Collect the medium, and pass it through a 100 &#956;m&#160;filter.</li>
	<li>Centrifuge the filtered supernatant at 300 &#215; g and 4 &#176;C for 3 min. Aspirate the supernatant, and reserve the cell pellet (enriched with GCs) on ice for labeling and fluorescence-activated cell sorting (FACS).</li>
	<li>Place the remaining tissue in a mixture of collagenase (100 U/mL) and dispase (1 U/mL) diluted in a balanced saline solution (e.g., Hanks), and incubate for 30 min at 5% CO2 and 37 &#176;C, mechanically disrupting the tissue by trituration and vigorous pipetting (i.e., 10-15 passes through the pipet tip) twice after 10 min and 20 min.</li>
	<li>Recover media containing the tissue, flush via pipetting through a P1,000 micropipette tip, and strain through a 100 &#956;m&#160;filter.</li>
	<li>Centrifuge at 300 &#215; g and 4 &#176;C for 3 min. Aspirate the supernatant, and put aside the cell pellet (enriched with TCs and stroma cells) on ice for labeling and FACS.</li>
</ol>
5. Fluorescence-activated cell sorting
<ol>
	<li>Resuspend the cell pellets in blocking solution (PBS + 0.1% FBS), and incubate for 10 min at 4 &#176;C.</li>
	<li>Centrifuge at 300 &#215; g and 4 &#176;C for 3 min, and aspirate the supernatant.</li>
	<li>Resuspend the cell pellets in blocking solution containing directly conjugated antibodies (see Table 1 for appropriate antibody combinations to identify GCs and TCs), and incubate on ice for 10 min.</li>
	<li>Wash and centrifuge the cells at 300 &#215; g and 4 &#176;C for 3 min. Resuspend the cells in FACS buffer containing 4&#8242;,6-diamidino-2-phenylindole (DAPI), and run the cell suspension through a FACS instrument to capture a small population of the cells (500-1,000) using the fluorescence intensity of fluorophore-conjugated antibodies for gating.</li>
	<li>For the identification of unique subpopulations, utilize the following gating strategies:
	<ol>
		<li>For the purification of GCs, draw a gate around the CD45+ cells (Figure 1B), and exclude this population from the CD99+ population (Figure 1A and Figure 1C); then, further subdivide the remaining CD99+ fraction into PVRL+/- fractions (Figure 1A and Figure 1C).</li>
		<li>For the purification of TCs and stroma, gate the total ENG+ (Figure 1A) or CD55+ (Figure 1D) population to exclude the CD34+ endothelial fraction (Figure 1E) and distinguish the steroidogenic (ANPEP+) and non-steroidogenic (ANPEP-) cells. Be careful to compensate for bleed-through between fluorophores that are close in the emission spectra.</li>
	</ol>
	</li>
	<li>To validate the purity of the sorted cell fraction, run 5% of the total captured volume through the FACS instrument, and ensure that cells populate the expected gates and are present at &#62;95% purity.</li>
</ol>
6. Processing of the ovarian cortical tissue
<ol>
	<li>Bisect the remainder of the ovary, and excise the medulla using curved fine scissors and scalpels, being careful to avoid damage to the ovarian cortex.</li>
	<li>Continue processing and thinning the ovarian cortex by gentle scraping until minimal medulla remains. Ensure to use the minimum force needed. 
	NOTE: The cortical tissue thickness should be between 1 mm and 1.5 mm.</li>
	<li>Divide the cortical tissue into 2-3 mm wide strips along the length of the ovary.</li>
</ol>
7. Ovarian tissue slow freezing
<ol>
	<li>Preparation for freezing
	<ol>
		<li>Place one cortical strip into each chilled cryogenic vial containing freezing solution.</li>
		<li>Shake the cryogenic vials containing the cortical strips on a rotating plate for 20 min at 4 &#176;C.</li>
	</ol>
	</li>
	<li>Slow freezing of the ovarian tissue5
	<ol>
		<li>Place the cryovials containing ovarian tissue into a programmable freezer set to start at 0 &#176;C.</li>
		<li>Cool at a rate of 2 &#176;C/min until &#8722;7 &#176;C.</li>
		<li>Maintain the cryovials at this temperature for 10 min.</li>
		<li>Nucleate ice crystal formation by touching each cryovial with a cotton tip that has been briefly immersed in liquid nitrogen (LN2).</li>
		<li>Cool at a rate of 0.3 &#176;C/min until the sample temperature reaches &#8722;40&#176;C.</li>
		<li>Increase the rate of cooling to 10 &#176;C/min until the sample temperature reaches &#8722;140 &#176;C.</li>
		<li>Transfer the cryovials for storage in LN2.</li>
	</ol>
	</li>
</ol>

<ol>
	<li>Aghadavod, E., 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=Isolation+of+granulosa+cells+from+follicular+fluid;+Applications+in+biomedical+and+molecular+biology+experiments.">Isolation of granulosa cells from follicular fluid; Applications in biomedical and molecular biology experiments.</a> Advanced Biomedical Research. 4, 250 (2015).</li><li>Man, 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=Comparison+of+human+antral+follicles+of+xenograft+versus+ovarian+origin+reveals+disparate+molecular+signatures.">Comparison of human antral follicles of xenograft versus ovarian origin reveals disparate molecular signatures.</a> Cell Reports. 32 (6), 108027 (2020).</li><li>Schmidt, K. L., Ernst, E., Byskov, A. G., Nyboe Andersen, A., Yding Andersen, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Survival+of+primordial+follicles+following+prolonged+transportation+of+ovarian+tissue+prior+to+cryopreservation.">Survival of primordial follicles following prolonged transportation of ovarian tissue prior to cryopreservation.</a> Human Reproduction. 18 (12), 2654-2659 (2003).</li><li>Jensen, A. K., 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=Outcomes+of+transplantations+of+cryopreserved+ovarian+tissue+to+41+women+in+Denmark.">Outcomes of transplantations of cryopreserved ovarian tissue to 41 women in Denmark.</a> Human Reproduction. 30 (12), 2838-2845 (2015).</li><li>Newton, H., Aubard, Y., Rutherford, A., Sharma, V., Gosden, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Low+temperature+storage+and+grafting+of+human+ovarian+tissue.">Low temperature storage and grafting of human ovarian tissue.</a> Human Reproduction. 11 (7), 1487-1491 (1996).</li><li>Man, 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=Chronic+superphysiologic+AMH+promotes+premature+luteinization+of+antral+follicles+in+human+ovarian+xenografts.">Chronic superphysiologic AMH promotes premature luteinization of antral follicles in human ovarian xenografts.</a> Science Advances. 8 (9), 7315 (2022).</li><li>Gougeon, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dynamics+of+follicular+growth+in+the+human:+A+model+from+preliminary+results.">Dynamics of follicular growth in the human: A model from preliminary results.</a> Human Reproduction. 1 (2), 81-87 (1986).</li><li>Richards, J. S., Ren, Y. A., Candelaria, N., Adams, J. E., Rajkovic, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ovarian+follicular+theca+cell+recruitment,+differentiation,+and+impact+on+fertility:+2017+update.">Ovarian follicular theca cell recruitment, differentiation, and impact on fertility: 2017 update.</a> Endocr Rev. 39 (1), 1-20 (2018).</li><li>Asiabi, P., Dolmans, M. M., Ambroise, J., Camboni, A., Amorim, C. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vitro+differentiation+of+theca+cells+from+ovarian+cells+isolated+from+postmenopausal+women.">In vitro differentiation of theca cells from ovarian cells isolated from postmenopausal women.</a> Human Reproduction. 35 (12), 2793-2807 (2020).</li><li>Dalman, A., Totonchi, M., Valojerdi, M. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Establishment+and+characterization+of+human+theca+stem+cells+and+their+differentiation+into+theca+progenitor+cells.">Establishment and characterization of human theca stem cells and their differentiation into theca progenitor cells.</a> Journal of Cellular Biochemistry. 119 (12), 9853-9865 (2018).</li></ol>

All authors declare they have no competing interests.

Better resolution of the cellular diversity within the ovarian follicles is clinically important for several reasons. In applying the above protocol to the isolation of the unique phenotypic subtypes that reside within antral stage follicles, several factors should be considered. First, the health and viability of the ovarian tissue from which the antral follicle is derived is critical in determining the quality of the cells and the success of downstream applications. This can be optimized by minimizing the ischemic inte...

The primary functional elements of the human ovary are the follicles, which govern the growth and development of oocytes. Protocols for the isolation of follicular cells have been well established in the context of in vitro fertilization, but these are appropriate only for the collection of cells from luteinized follicles at the point of oocyte retrieval1. We have developed a protocol that enables the isolation of discrete cell populations from antral follicles at different developmental stages that arise from native ovaries or xenotransplanted ovarian tissue2. Although there is consensus that the contributions of follicle resident cells to the cultivation of the oocyte are highly important, few studies have prospectively identified and extracted the unique phenotypic subtypes present in antral-stage follicles. A deeper understanding of the differentiation hierarchy and signal transduction between specialized cells during the different developmental stages could broaden our understanding of ovarian physiology under homeostatic and pathological conditions. Moreover, the discrimination of discrete cellular subtypes and their molecular contributions to follicle growth/maturation may provide a means of generating ex vivo surrogates that reconstruct ovarian function to foster oocyte maturation and/or treat endocrine dysfunction. 
Each unique cell type within the ovary contributes to the complex function of the follicle, which effectively functions as a discrete mini-organ to foster the growth and maturation of the oocyte it contains. The oocyte, the centerpiece of the follicle, is directly enveloped by a continuous layer of granulosa cells (GCs), with the theca cells (TCs) forming a secondary layer of cells that combine with the oocyte and GCs to compose the follicular unit. Although classified into two groups, GCs and TCs contain numerous subtypes. GCs are classified according to their position within the follicle; GCs that surround the oocyte versus those that are adjacent to the basement membrane are designated as oophorous and mural GCs, respectively, and these subtypes display unique transcriptomic signatures. TCs have numerous subtypes that function to provide steroidogenic, metabolic, and structural support. Endothelial, perivascular, and immune cells play a central role in maintaining normal ovarian physiology. The ovarian stroma serves not only as a substrate for follicle growth but also likely provides a source of progenitors that give rise to TCs. This multilayered complex of cellular subtypes within the ovary is what enables its function as both an endocrine and a reproductive organ.
This paper presents a protocol for the identification and purification of granulosa, theca, stromal, endothelial, and hematopoietic cells from antral follicles. We have utilized this protocol to isolate these ovarian cells and analyze them using single-cell sequencing, followed by specific staining in follicles of different developmental stages. The protocol provides a straightforward methodology that is replicable and will enable the high-resolution analysis of both the physiology and pathology of the ovary.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Chemicals, reagents</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Antibiotic-Antimycotic 100x</td>
			<td>Thermo Fisher Scientific</td>
			<td>15240062</td>
			<td>Anti-Anti</td>
		</tr>
		<tr>
			<td>Antifade Mountant solution</td>
			<td>Thermo Fisher Scientific</td>
			<td>&#160;P36930</td>
			<td>ProLong Gold</td>
		</tr>
		<tr>
			<td>Collagenase from&#160;Clostridium histolyticum</td>
			<td>Millipore Sigma</td>
			<td>C 2674</td>
			<td></td>
		</tr>
		<tr>
			<td>DAPI</td>
			<td>Thermo Fisher Scientific</td>
			<td>D1306</td>
			<td></td>
		</tr>
		<tr>
			<td>Dispase II, powder</td>
			<td>Thermo Fisher Scientific</td>
			<td>17105041</td>
			<td></td>
		</tr>
		<tr>
			<td>DMSO</td>
			<td>Millipore Sigma</td>
			<td>D 2650</td>
			<td>Dimethyl sulfoxide</td>
		</tr>
		<tr>
			<td>DPBS, no calcium, no magnesium</td>
			<td>Thermo Fisher Scientific</td>
			<td>14190144</td>
			<td></td>
		</tr>
		<tr>
			<td>Enzyme Cell Detachment Medium&#160;</td>
			<td>Thermo Fisher Scientific</td>
			<td>00-4555-56</td>
			<td>Accutase</td>
		</tr>
		<tr>
			<td>Fetal Bovine Serum, heat-inactivated</td>
			<td>Thermo Fisher Scientific</td>
			<td>10438026</td>
			<td></td>
		</tr>
		<tr>
			<td>Hanks&#8242; Balanced Salt solution</td>
			<td>Thermo Fisher Scientific</td>
			<td>14175079</td>
			<td>no calcium, no magnesium, no phenol red</td>
		</tr>
		<tr>
			<td>Leibovitz&#8217;s L-15 medium&#160;</td>
			<td>Thermo Fisher Scientific</td>
			<td>11415064</td>
			<td></td>
		</tr>
		<tr>
			<td>Normal Saline</td>
			<td>Quality Biological</td>
			<td>114-055-101</td>
			<td></td>
		</tr>
		<tr>
			<td>Sucrose</td>
			<td>Millipore Sigma</td>
			<td>S 1888</td>
			<td></td>
		</tr>
		<tr>
			<td>Freezing Medium (100 mL, filtered through a 0.2 micron filter)</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>- 69.64 mL of Leibovitz&#39;s L-15</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>- 17.66 mL of fetal bovine serum</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>- 3.42 g of sucrose</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>- 10.65 mL of DMSO</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>- 1 mL of antibiotic-antimycotic</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Lab Plasticware and Supplies</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>6-well Clear Flat Bottom Not Treated&#160;</td>
			<td>Corning</td>
			<td>351146</td>
			<td>Falcon</td>
		</tr>
		<tr>
			<td>Cell Strainer 100 &#181;m</td>
			<td>Fisher scientific</td>
			<td>352360</td>
			<td>Corning, Falcon</td>
		</tr>
		<tr>
			<td>Cryovials</td>
			<td>Thermo Fisher Scientific</td>
			<td>377267</td>
			<td>CryoTube 1.8 mL</td>
		</tr>
		<tr>
			<td>Petri dish, D x H 150 mm x 25 mm&#160;</td>
			<td>Millipore Sigma</td>
			<td>CLS430599</td>
			<td>60EA</td>
		</tr>
		<tr>
			<td>Round-Bottom Polystyrene Test Tubes with Cell Strainer Snap Cap, 5 mL</td>
			<td>Fisher scientific</td>
			<td>352235</td>
			<td>Corning, Falcon</td>
		</tr>
		<tr>
			<td>Vacuum Filter/Storage Bottle System, 0.22 &#181;m</td>
			<td>Corning</td>
			<td>431154</td>
			<td></td>
		</tr>
		<tr>
			<td>Antibodies</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>ANPEP</td>
			<td>BioLegend</td>
			<td>301703</td>
			<td></td>
		</tr>
		<tr>
			<td>CD34</td>
			<td>R&#38;D Systems</td>
			<td>FAB7227A</td>
			<td></td>
		</tr>
		<tr>
			<td>CD45</td>
			<td>BioLegend</td>
			<td>304019</td>
			<td></td>
		</tr>
		<tr>
			<td>CD55</td>
			<td>BioLegend</td>
			<td>311306</td>
			<td></td>
		</tr>
		<tr>
			<td>CD 99</td>
			<td>BioLegend</td>
			<td>371308</td>
			<td></td>
		</tr>
		<tr>
			<td>PVRL</td>
			<td>BioLegend</td>
			<td>340404</td>
			<td></td>
		</tr>
		<tr>
			<td>Surgical tools</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>long forceps (~150 mm length)</td>
			<td>Fisherbrand</td>
			<td>12-000-128</td>
			<td>Fisher Scientific</td>
		</tr>
		<tr>
			<td>medium forceps (~110 mm length)</td>
			<td>Fisherbrand</td>
			<td>12-000-157</td>
			<td>Fisher Scientific</td>
		</tr>
		<tr>
			<td>number 21 scalpel</td>
			<td>Andwin Scientific&#160;</td>
			<td>EF7281H</td>
			<td>Fisher Scientific</td>
		</tr>
		<tr>
			<td>number 11 scalpel</td>
			<td>Andwin Scientific</td>
			<td>&#160;FH/CX7281A</td>
			<td>Fisher Scientific</td>
		</tr>
		<tr>
			<td>sharp fine curved scissors</td>
			<td>Roboz Surgical</td>
			<td>RS-5881</td>
			<td></td>
		</tr>
		<tr>
			<td>Instruments</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>FACSJazz Flourescence activated cell sorter</td>
			<td>BD</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>LSM 710 META Confocal microscope</td>
			<td>Zeiss</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

extraction, labeling, and purification of lineage-specific cells from human antral follicles

The activation, growth, development, and maturation of oocytes is a complex process that is coordinated not just between multiple cell types of the ovary but also across multiple points of control within the hypothalamic/pituitary/ovarian circuit. Within the ovary, multiple specialized cell types grow in close association with the oocyte within the ovarian follicles. The biology of these cells has been well described at the later stages, when they are easily recovered as byproducts of assisted reproductive treatments. However, the in-depth analysis of small antral follicles isolated directly from the ovary is not commonly carried out due to the scarcity of human ovarian tissue and the limited access to the ovary in patients undergoing assisted reproductive treatments. 
These methods for processing whole ovaries for the cryopreservation of cortical strips with the concurrent identification/isolation of ovary resident cells enable the high-resolution analysis of the early stages of antral follicle development. We demonstrate protocols for isolating discrete cell types by treating antral follicles enzymatically and separating the granulosa, theca, endothelial, hematopoietic, and stromal cells. The isolation of cells from the antral follicles at various sizes and developmental stages enables the comprehensive analysis of the cellular and molecular mechanisms that drive follicle growth and ovarian physiology and provides a source of viable cells that can be cultured in vitro to recapitulate the follicle microenvironment.

We isolated follicles from the surface of the ovary and enzymatically treated them to isolate the GCs as well as theca and stroma cells surrounding the antral cavity. The cells were collected, and the cell fractions were sorted from the antral follicles (diameters ranging between 0.5 mm and 4 mm) by FACS to &#62;95% purity (Figure 1).
To label and purify unique cellular fractions within the human antral follicles, we combined enzymatic digestion with flow cytometr...

Watch this Scientific Journal Video about Extraction, Labeling, and Purification of Lineage-Specific Cells from Human Antral Follicles at JoVE.com

Extraction, Labeling, and Purification of Lineage-Specific Cells from Human Antral Follicles

Here, we present protocols for the identification and purification of ovarian cells from antral follicles. We elaborate on methods for processing whole ovaries for the cryopreservation of cortical strips while also harvesting intact antral follicles that are treated enzymatically to liberate multiple follicle resident cell types, including granulosa, theca, endothelial, hematopoietic, and stromal cells.

The activation, growth, development, and maturation of oocytes is a complex process that is coordinated not just between multiple cell types of the ovary ...

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1.1K Views.  Weill Cornell Medical College. Here, we present protocols for the identification and purification of ovarian cells from antral follicles. We elaborate on methods for processing whole ovaries for the cryopreservation of cortical strips while also harvesting intact antral follicles that are treated enzymatically to liberate multiple follicle resident cell types, including granulosa, theca, endothelial, hematopoietic, and stromal cells.

Video: Extraction, Labeling, and Purification of Lineage-Specific Cells from Human Antral Follicles

Human ES cells: Starting Culture from Frozen Cells

Here we demonstrate how our lab begins a HuES human embryonic stem cell line culture from a frozen stock.  First, a one to two day old ten cm plate of  approximately one (to two) million irradiated mouse embryonic fibroblast feeder cells is rinsed with HuES media to remove residual serum and cell debris, and then HuES media added and left to equilibrate in the cell culture incubator.  A frozen vial of cells from long term liquid nitrogen storage or a -80C freezer is sourced and quickly submerged in a 37C water bath for quick thawing.  Cells in freezing media are then removed from the vial and placed in a large volume of HuES media.  The large volume of HuES media facilitates removal of excess serum and DMSO, which can cause HuES human embryonic stem cells to differentiate.  Cells are gently spun out of suspension, and then re-suspended in a small volume of fresh HuES media that is then used to seed the MEF plate.  It is considered important to seed the MEF plate by gently adding the HuES cells in a drop wise fashion to evenly disperse them throughout the plate.  The newly established HuES culture plate is returned to the incubator for 48 hrs before media is replaced, then is fed every 24 hours thereafter.

Here we demonstrate how our lab begins a HuES human embryonic stem cell line culture from a frozen stock.

Here we demonstrate how our lab begins a HuES human embryonic stem cell line culture from a frozen stock.  First, a one to two day old ten cm plate of  ...

In vitro Labeling of Human Embryonic Stem Cells for Magnetic Resonance Imaging

Human embryonic stem cells (hESC) have demonstrated the ability to restore the injured myocardium. Magnetic resonance imaging (MRI) has emerged as one of the predominant imaging modalities to assess the restoration of the injured myocardium. Furthermore, ex-vivo labeling agents, such as iron-oxide nanoparticles, have been employed to track and localize the transplanted stem cells. However, this method does not monitor a fundamental cellular biology property regarding the viability of transplanted cells. It has been known that manganese chloride (MnCl2) enters the cells via voltage-gated calcium (Ca2+) channels when the cells are biologically active, and accumulates intracellularly to generate T1 shortening effect. Therefore, we suggest that manganese-guided MRI can be useful to monitor cell viability after the transplantation of hESC into the myocardium.
In this video, we will show how to label hESC with MnCl2 and how those cells can be clearly seen by using MRI in vitro. At the same time, biological activity of Ca2+-channels will be modulated utilizing both Ca2+-channel agonist and antagonist to evaluate concomitant signal changes.

In this video, we are showing how to label human embryonic stem cells (hESC) with manganese chloride (MnCl2) which can enter cells via voltage-gated calcium channels when the cells are biologically active. Additionally, we show the use of MnCl2 as cellular MRI contrast agent to determine the in vitro viability of hESC.

Human embryonic stem cells (hESC) have demonstrated the ability to restore the injured myocardium. Magnetic resonance imaging (MRI) has emerged as one of ...

Staining of Proteins in Gels with Coomassie G-250 without Organic Solvent and Acetic Acid

In classical protein staining protocols using Coomassie Brilliant Blue (CBB), solutions with high contents of toxic and flammable organic solvents (Methanol, Ethanol or 2-Propanol) and acetic acid are used for fixation, staining and destaining of proteins in a gel after SDS-PAGE. To speed up the procedure, heating the staining solution in the microwave oven for a short time is frequently used. This usually results in evaporation of toxic or hazardous Methanol, Ethanol or 2-Propanol and a strong smell of acetic acid in the lab which should be avoided due to safety considerations. In a protocol originally published in two patent applications by E.M. Wondrak (US2001046709 (A1), US6319720 (B1)), an alternative composition of the staining solution is described in which no organic solvent or acid is used. The CBB is dissolved in bidistilled water (60-80mg of CBB G-250 per liter) and 35 mM HCl is added as the only other compound in the staining solution. The CBB staning of the gel is done after SDS-PAGE and thorough washing of the gel in bidistilled water. By heating the gel during the washing and staining steps, the process can be finished faster and no toxic or hazardous compunds are evaporating. The staining of proteins occurs already within 1 minute after heating the gel in staining solution and is fully developed after 15-30 min with a slightly blue background that is destained completely by prolonged washing of the stained gel in bidistilled water, without affecting the stained protein bands.

A short protocol for protein staining with Coomassie Brilliant Blue (CBB) G-250 in polyacrylamide gels is described without using organic solvents or acetic acid as in the classical staining procedures with CBB.

In classical protein staining protocols using Coomassie Brilliant Blue (CBB), solutions with high contents of toxic and flammable organic solvents ...

Purification of Mitochondria from Yeast Cells

Mitochondria are the main site of ATP production during aerobic metabolism in eukaryotic non-photosynthetic cells1. These complex organelles also play essential roles in apoptotic cell death2, cell survival3, mammalian development4, neuronal development and function4, intracellular signalling5, and longevity regulation6. Our understanding of these complex biological processes controlled by mitochondria relies on robust methods for assessing their morphology, their protein and lipid composition, the integrity of their DNA, and their numerous vital functions. The budding yeast Saccharomyces cerevisiae, a genetically and biochemically manipulable unicellular eukaryote with annotated genome and well-defined proteome, is a valuable model for studying the molecular and cellular mechanisms underlying essential biological functions of mitochondria. For these types of studies, it is crucial to have highly pure mitochondria. Here we present a detailed description of a rapid and effective method for purification of yeast mitochondria. This method enables the isolation of highly pure mitochondria that are essentially free of contamination by other organelles and retain their structural and functional integrity after their purification. Mitochondria purified by this method are suitable for cell-free reconstitution of essential mitochondrial processes and can be used for the analysis of mitochondrial structure and functions, mitochondrial proteome and lipidome, and mitochondrial DNA.

We describe a rapid and effective method for purification of mitochondria from the yeast Saccharomyces cerevisiae. This method enables the high-yield isolation of pure mitochondria that are essentially free of contamination by other organelles and retain their structural and functional integrity after their purification.

Mitochondria are the main site of ATP production during aerobic metabolism in eukaryotic non-photosynthetic cells1. These complex organelles also play ...

Extraction and Analysis of Cortisol from Human and Monkey Hair

The stress hormone cortisol (CORT) is slowly incorporated into the growing hair shaft of humans, nonhuman primates, and other mammals. We developed and validated a method for CORT extraction and analysis from rhesus monkey hair and subsequently adapted this method for use with human scalp hair. In contrast to CORT &#34;point samples&#34; obtained from plasma or saliva, hair CORT provides an integrated measure of hypothalamic-pituitary-adrenocortical (HPA) system activity, and thus physiological stress, during the period of hormone incorporation. Because human scalp hair grows at an average rate of 1 cm/month, CORT levels obtained from hair segments several cm in length can potentially serve as a biomarker of stress experienced over a number of months.
In our method, each hair sample is first washed twice in isopropanol to remove any CORT from the outside of the hair shaft that has been deposited from sweat or sebum. After drying, the sample is ground to a fine powder to break up the hair&#39;s protein matrix and increase the surface area for extraction. CORT from the interior of the hair shaft is extracted into methanol, the methanol is evaporated, and the extract is reconstituted in assay buffer. Extracted CORT, along with standards and quality controls, is then analyzed by means of a sensitive and specific commercially available enzyme immunoassay (EIA) kit. Readout from the EIA is converted to pg CORT per mg powdered hair weight. This method has been used in our laboratory to analyze hair CORT in humans, several species of macaque monkeys, marmosets, dogs, and polar bears. Many studies both from our lab and from other research groups have demonstrated the broad applicability of hair CORT for assessing chronic stress exposure in natural as well as laboratory settings.

Cortisol (CORT) accumulates in the growing hair shaft of humans and nonhuman primates. We describe methods for extracting and analyzing hair CORT with high precision and sensitivity. Measurement of hair CORT is particularly well-suited for assessing chronic stress over periods of weeks to months.

The stress hormone cortisol (CORT) is slowly incorporated into the growing hair shaft of humans, nonhuman primates, and other mammals. We developed and ...

Efficient Production and Purification of Recombinant Murine Kindlin-3 from Insect Cells for Biophysical Studies

Kindlins are essential coactivators, with talin, of the cell surface receptors&#160;integrins and also participate in integrin outside-in signalling, and the control of gene transcription in the cell nucleus. The kindlins are ~75 kDa multidomain proteins and bind to an NPxY motif and upstream T/S cluster of the integrin &#946;-subunit cytoplasmic tail. The hematopoietically-important kindlin isoform, kindlin-3, is critical for platelet aggregation during thrombus formation, leukocyte rolling in response to infection and inflammation and osteoclast podocyte formation in bone resorption. Kindlin-3&#39;s role in these processes has resulted in extensive cellular and physiological studies. However, there is a need for an efficient method of acquiring high quality milligram quantities of the protein for further studies. We have developed a protocol, here described, for the efficient expression and purification of recombinant murine kindlin-3 by use of a baculovirus-driven expression system in Sf9 cells yielding sufficient amounts of high purity full-length protein to allow its biophysical characterization. The same approach could be taken in the study of the other mammalian kindlin isoforms.

Kindlins are fundamental to cell adhesion through integrins but studies of them have been hampered by the difficulty encountered in expressing them recombinantly in bacterial hosts. We describe here methods for their efficient production in baculovirus-infected insect cells.

Kindlins are essential coactivators, with talin, of the cell surface receptors&#160;integrins and also participate in integrin outside-in signalling, and ...

Visualization and Quantification of Mesenchymal Cell Adipogenic Differentiation Potential with a Lineage Specific Marker

Several dyes are currently available for use in detecting differentiation of mesenchymal cells into adipocytes. Dyes, such as Oil Red O, are cheap, easy to use and widely utilized by laboratories analyzing the adipogenic potential of mesenchymal cells. However, they are not specific to changes in gene transcription. We have developed a gene-specific differentiation assay to analyze when a mesenchymal cell has switched its fate to an adipogenic lineage. Immuno-labelling against fatty acid binding protein-4 (FABP4), a lineage-specific marker of adipogenic differentiation, enabled visualization and quantification of differentiated cells. The ability to quantify adipogenic differentiation potential of mesenchymal cells in a 96 well microplate format has promising implications for a number of applications. Hundreds of clinical trials involve the use of adult mesenchymal stromal cells and it is currently difficult to correlate therapeutic outcomes within and especially between such clinical trials. This simple high-throughput FABP4 assay provides a quantitative assay for assessing the differentiation potential of patient-derived cells and is a robust tool for comparing different isolation and expansion methods. This is particularly important given the increasing recognition of the heterogeneity of the cells being administered to patients in mesenchymal cell products. The assay also has potential utility in high throughput drug screening, particularly in obesity and pre-diabetes research.

Traditional methods of assessing adipogenic differentiation are cheap and easy to use, but are not specific to changes in gene expression. We have developed an assay to quantify mesenchymal cell differentiation into mature adipocytes using a lineage specific marker. This assay has diverse applications across basic research and clinical medicine.

Several dyes are currently available for use in detecting differentiation of mesenchymal cells into adipocytes. Dyes, such as Oil Red O, are cheap, easy ...

Tissue Collection and RNA Extraction from the Human Osteoarthritic Knee Joint

Osteoarthritis (OA) is a chronic and degenerative joint disease most often affecting the knee. As there is currently no cure, total knee arthroplasty (TKA) is a common surgical intervention. Experiments using primary human OA tissues obtained from TKA provide the capability to investigate disease mechanisms ex vivo. While OA was previously thought to impact mainly the cartilage, it is now known to impact multiple tissues in the joint. This protocol describes patient selection, sample processing, tissue homogenization, RNA extraction, and quality control (based on RNA purity, integrity, and yield) from each of seven unique tissues to support disease mechanism investigation in the knee joint. With informed consent, samples were obtained from patients undergoing TKA for OA. Tissues were dissected, washed, and stored within 4 h of surgery by flash freezing for RNA or formalin fixation for histology. Collected tissues included articular cartilage, subchondral bone, meniscus, infrapatellar fat pad, anterior cruciate ligament, synovium, and vastus medialis oblique muscle. RNA extraction protocols were tested for each tissue type. The most significant modification involved the method of disintegration used for low-cell, high-matrix, hard tissues (considered as cartilage, bone, and meniscus) versus relatively high-cell, low-matrix, soft tissues (considered as fat pad, ligament, synovium, and muscle). It was found that pulverization was appropriate for hard tissues, and homogenization was appropriate for soft tissues. A proclivity for some subjects to yield higher RNA integrity number (RIN) values than other subjects consistently across multiple tissues was observed, suggesting that underlying factors such as disease severity may impact RNA quality. The ability to isolate high-quality RNA from primary human OA tissues provides a physiologically relevant model for sophisticated gene expression experiments, including sequencing, that can lead to clinical insights that are more readily translated to patients.

Primary tissues obtained from patients following total knee arthroplasty provide an experimental model for osteoarthritis research with maximal clinical translatability. This protocol describes how to identify, process, and isolate RNA from seven unique knee tissues to support mechanistic investigation in human osteoarthritis.

Osteoarthritis (OA) is a chronic and degenerative joint disease most often affecting the knee. As there is currently no cure, total knee arthroplasty ...

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 ...

Enhanced Bacterial Extracellular Vesicles Isolation for Microbiota Multi-Omics

Isolation and Purification of Bacterial Extracellular Vesicles from Human Feces Using Density Gradient Centrifugation

Bacterial extracellular vesicles (BEVs) are nanovesicles derived from bacteria that play an active role in bacteria-bacteria and bacteria-host communication, transferring bioactive molecules such as proteins, lipids, and nucleic acids inherited from the parent bacteria. BEVs derived from the gut microbiota have effects within the gastrointestinal tract and can reach distant organs, resulting in significant implications for physiology and pathology. Theoretical investigations that explore the types, quantities, and roles of BEVs derived from human feces are crucial for understanding the secretion and function of BEVs from the gut microbiota. These investigations also necessitate an improvement in the current strategy for isolating and purifying BEVs.
This study optimized the isolation and purification process of BEVs by establishing two density gradient centrifugation (DGC) modes: Top-down and Bottom-up. The enriched distribution of BEVs was determined in fractions 6 to 8 (F6-F8). The effectiveness of the approach was evaluated based on particle morphology, size, concentration, and protein content. The particle and protein recovery rates were calculated, and the presence of specific markers was analyzed to compare the recovery and purity of the two DGC modes. The results indicated that the Top-down centrifugation mode had lower contamination levels and achieved a recovery rate and purity similar to that of the Bottom-up mode. A centrifugation time of 7 h was sufficient to achieve a fecal BEV concentration of 108/mg.
Apart from feces, this method could be applied to other body fluid types with proper modification according to the differences in components and viscosity. In conclusion, this detailed and reliable protocol would facilitate the standardized isolation and purification of BEVs and thus, lay a foundation for subsequent multi-omics analysis and functional experiments.

Author Spotlight: Accelerating Research on Bacterial Extracellular Vesicles Separation and Heterogeneity 

This study describes a method to isolate and purify bacterial extracellular vesicles (BEVs) enriched from human feces via density gradient centrifugation (DGC), identifies the physical characteristics of BEVs from morphology, particle size, and concentration, and discusses the potential applications of the DGC approach in clinical and scientific research.