Name: cell sorting of neural stem and progenitor cells from the adult mouse subventricular zone and live-imaging of their cell cycle dynamics
Uploaded: 2015-09-14T18:00:00
Duration: 9 min 27 s
Description: Watch this Scientific Journal Video about Cell Sorting of Neural Stem and Progenitor Cells from the Adult Mouse Subventricular Zone and Live-imaging of their Cell Cycle Dynamics at JoVE.com

We are indebted to C Joubert, V Neuville, V Barroca, J Tilliet and all the staff of animal facilities; to J Baijer and N Dechamps for cell sorting; O. Etienne for technical assistance, and A. Gouret for her administrative assistance. Flow cytometry and cell sorting were carried out at the iRCM Flow Cytometry Shared Resource, established by equipment grants from DIM-Stem-P&#244;le, INSERM, Fondation ARC, and CEA. This work was supported by grants of Electricit&#233; de France (EDF). M.D. has a fellowship from La Ligue Contre le Cancer and L.M. from R&#233;gion Ile-de-France (DIM Bioth&#233;rapies). Marc-Andr&#233;&#160;Mouthon and Fran&#231;ois D. Boussin share co-senior authorship.&#160;

This protocol has been designed in compliance with the European Communities Council Directive of November 24, 1986 (86/609/EEC) and has been approved by our animal welfare institutional committee (CETEA-CEA DSV IdF).
1. Basic Setup Prior to Culture and Videomicroscopy
<ol>
	<li>Use glass bottom culture plates or &#181;-Plates for confocal video microscopy. For 1 - 5 x 103&#160;cells/well, use 96-well plates and 24-well plates for more than 5 x 103 cells/well.</li>
	<li>At least one day prior to commencing the experiment, prepare sterile Poly-D-lysine (PDL) coated plates for adherent monolayer cultures. Add enough PDL (10 &#181;g/ml in dH2O) to coat the bottom of each well and incubate O/N at 37 &#176;C. Remove the PDL solution and rinse three times with dH2O before allowing the plate to dry in the hood during at least 2 hr&#160;under a laminar flow. If not used immediately, store the coated plate at -20 &#176;C.</li>
	<li>Prepare culture medium by mixing NSC Basal Medium and NSC Proliferation Supplement at a 9:1 ratio (see Material table) along with 2&#160;&#181;g/ml heparin, 20 ng/ml purified human recombinant epidermal growth factor (EGF), and 10 ng/ml human recombinant fibroblast growth factor 2 (FGF-2). Warm up the culture medium to 37 &#176;C in a water bath before use.</li>
	<li>For the SVZ dissociation, prepare papain solution: 1 mg/ml papain (15 UI/ml) in Earl&#8217;s Balance Salt Solution (EBSS) containing 0.2 mg/ml L-cysteine, 0.2 mg/ml EDTA, and 0.01 mg/ml DNase I in PBS. Sterilize the solution by passing through a 0.2 &#181;m filter. Equilibrate the solution at 37 &#176;C before use.</li>
	<li>To stop the enzymatic reaction, prepare a protease inhibitor solution (Ovomucoid): DMEM:F12 medium containing 0.7 mg/ml trypsin inhibitor type II. Filter the solution using a 0.2 &#181;m filter.</li>
	<li>Prepare PBS 0.6% glucose solution to collect the brains and PBS 0.15% BSA solution for washing steps and for antibody staining.</li>
	<li>Prepare dissection tools: scissors, dissecting and tying forceps, scalpel. Soak them in 70% ethanol.</li>
</ol>
2. Harvesting of Adult Mouse Brains and SVZ Microdissections
<ol>
	<li>Sacrifice adult FUCCI mice23 (2 to 3-month-old and/or 12-month-old for aging studies) performing a cervical dislocation in accordance to the appropriate institutional guidelines.</li>
	<li>Spray the mouse using 70% ethanol and cut the head off using sharp scissors.</li>
	<li>Make an incision along the scalp to reveal the skull.</li>
	<li>Perform a longitudinal midline cut starting at the base of the skull towards the olfactory bulbs using a small pair of scissors. Make sure to avoid damaging the underlying brain with the scissor blades. Remove the upper open part of the skull with curved forceps to expose the brain.</li>
	<li>Collect the brain in a 15 mm petri dish containing 0.6% glucose in PBS.</li>
	<li>Dissect away the olfactory bulbs. Place the brain on its dorsal surface and make a coronal section through the optic chiasm using a scalpel.</li>
	<li>Under a dissecting microscope, position the rostral part of the brain section with the cut coronal surface facing upwards toward the experimenter.</li>
	<li>To dissect the SVZ, remove the septum with a fine curved forceps then insert one tip of a fine forceps into the striatum immediately adjacent to the ventricle and detach the SVZ from the surrounding tissue. For additional details, refer to Azari et al.24. Place the dissected SVZ into a petri dish containing 1 ml of PBS-0.6% glucose.</li>
</ol>
3. SVZ Tissue Dissociation
<ol>
	<li>Mince the dissected SVZ in the petri dish until no large pieces remain.</li>
	<li>Transfer the minced tissue along with the PBS-0.6% glucose to a 15 ml tube and centrifuge at 200 x g for 5 min.</li>
	<li>Discard the supernatant and add 1 ml of pre-warmed papain (1 mg/ml, prepared in step 1.4) supplemented with 0.01 mg/ml DNase I. Incubate for 10 min in a water bath at 37 &#176;C. Use 1 ml of papain per mouse.</li>
	<li>Centrifuge at 200 x g for 5 min and discard the supernatant.</li>
	<li>Add 1 ml of pre-warmed ovomucoid (0.7 mg/ml, prepared in step 1.5) to stop papain activity. Mechanically dissociate the minced tissue further into a single-cell suspension by gently pipetting up and down 20 times through a p1000 micropipette tip. Avoid air bubbles.</li>
	<li>Pass the cell suspension through a sterile 20 &#181;m filter in a new 15 ml tube. Make sure to wash the cell filter with PBS 0.15% BSA to avoid losing cells.</li>
	<li>Centrifuge at 200 x g for 10 min and discard the supernatant. Re-suspend the cells in 100 &#181;l&#160;of PBS containing 0.15% BSA.</li>
</ol>
4. Immunofluorescent Staining for Cell Sorting
For cell sorting using FUCCI-Red mice (Figure 2A), use the following antibodies: CD24 phycoerythrin-cyanine7 conjugate [PC7]&#160;; CD15/LeX fluorescein isothiocyanate [FITC] conjugated and Ax647 conjugated EGF ligand.
Note: LeX+EGFR+ cells and EGFR+ cells are not abundant in the adult SVZ: &#8776; 600 and 1500 cells/mouse respectively9. We recommend pooling SVZ cells from 2 to 3 mice to have enough material. Do not work with more than 12 mice on the same day so that the cell sorting duration doesn&#8217;t exceed 3 hr. Keep in mind that working with too many mice on the same day will lead to an increased cell sorting duration possibly resulting in increased cell death and/or cell differentiation.
<ol>
	<li>Perform the FACS staining in 100 &#181;l&#160;of PBS 0.15% BSA per mouse (or in 200 &#181;l for a group of 2 to 3 mice for optimal staining).</li>
	<li>Prepare the control tubes. Use compensation beads to prepare single color control&#160;tubes according to the manufacturer&#39;s protocol. Select a fraction of cells (1/10 of the cells extracted from one mouse is enough) and separate it in 4 tubes to prepare 1 negative control tube (unmarked cells) and 3 fluorescence minus one (FMO) control tubes. Resuspend the cells in 200 &#181;l of PBS 0.15% BSA per tube. 
	Hint: For LeX-FITC FMO control, label the cells with CD24-PC7 (1:50) and Ax647&#8208;conjugated EGF ligand (1:200); for CD24-PC7 FMO control, label the cells with CD15/LeX-FITC (1:50) and Ax647&#8208;conjugated EGF ligand (1:200) and for Ax647&#8208;conjugated EGF ligand FMO control, label the cells with CD15/LeX-FITC (1:50) and CD24-PC7 (1:50).</li>
	<li>For the tubes used for cell sorting, use the following antibodies at the indicated dilution in PBS 0.15% BSA: CD24-PC7 (1:50), CD15/LeX-FITC (1:50) and Ax647&#8208;conjugated EGF ligand (1:200).</li>
	<li>Incubate for 20 min at 4 &#176;C in the dark. Wash with 1 ml PBS 0.15% BSA and centrifuge at 200 x g for 10 min. Resuspend the cells in 200 &#181;l of PBS 0.15% BSA per brain. Keep the cell sorting tubes on ice and proceed immediately to the cell sorting.</li>
	<li>If using FUCCI-Green mice, separate LeX-positive and LeX-negative fractions using separation columns before cell sorting as the LeX-FITC antibody shares the same emission wavelength than the FUCCI-green fluorescence (Figure 3A,B).
	<ol>
		<li>First, label the cells with a mouse anti-human LeX-antibody (1:50) for 15 minutes at 4 &#176;C in the dark in 100 &#181;l&#160;of PBS 0.15% BSA.</li>
		<li>Wash the cells with 1 ml PBS 0.15% BSA and centrifuge at 200 x g for 10 min, then label the cells with anti-mouse IgM microbeads (1:10) for 15 minutes at 4 &#176;C in the dark.</li>
		<li>Wash the cells with 1 ml PBS 0.15% BSA and centrifuge at 200 x g for 10 min. Resuspend the cells in 500 &#181;l PBS 0.15% BSA and pour the cells through separation column in magnetic field as schematized in Figure 3 C. Wash the column with 1 ml PBS 0.15% BSA to obtain LeX negative fraction.</li>
		<li>To obtain LeX-positive fraction, remove the separation column from the magnetic field and elute the cells with 2 ml PBS 0.15% BSA.</li>
		<li>Proceed to CD24-PC7 and Ax647&#8208;conjugated EGF ligand staining as indicated in 4.2.</li>
	</ol>
	 </li>
</ol>
5. Cell Sorting
Note: Cells were sorted on a FACS sorter at 40 Psi with an 86 &#181;m noozle. Fluorescence was collected using the following filter set: 520/35nm (FITC), 575/26nm (PE), 670/20nm (Ax647) and 740LP (PC7). Compensation is necessary to prevent false-positive signals as an overlap is found between the emission spectrums of the FUCCI-red fluorescence and the PC7 dye.
<ol>
	<li>Immediately prior to cell sorting, add a vital dye to discriminate live from dead cells. We used HO (see material table) at a 2 &#181;g/ml final concentration. Run the negative control tube (unmarked cells) through the FACS sorter and select the cells using side scatter (SSC) and forward scatter (FSC) parameters (Figure 1A). 
	NOTE: Dead cells were excluded by gating only the HO-negative fraction (Figure 1A&#8217;) and then doublets were excluded by selecting the Pulse Width negative fraction (Figure 1A&#8217;&#8217;).</li>
	<li>Run the single color controls prepared in step 4.2 and adjust the photomultiplier tube (PMT) voltages if necessary (i.e. negative population too high and/or positive cells off scale). Perform color compensation in the compensation window of the software.</li>
	<li>Run FMO controls prepared in step 4.2 (LeX-FITC FMO control, CD24-PC7 FMO control and Ax647-conjugated EGF ligand FMO control) and draw the sorting gates (Figure 1). Sort the cells directly into 100 &#181;l of culture medium in 1.5 ml microtubes.</li>
</ol>
6. Preparation of Cells for Microscopy
<ol>
	<li>Plate the freshly sorted cells at a density of 1 - 3 x 103&#160;cells/well on Poly-D-Lysine- coated 96-well &#181;-Plate with 300 &#181;l of culture medium.</li>
	<li>Prior to video microscopy, incubate the culture plates at 37 &#176;C and 5% CO2 at least for 1 hr to allow cell adhesion.</li>
</ol>
7. Microscope Setup and Image Acquisition
<ol>
	<li>Perform live imaging using a Plan Apo VC 20x DIC objective (NA: 0.75) on a confocal laser scanning microscope system attached to an inverted thermostated chamber at 37 &#176;C under 5% of CO2 atmosphere.</li>
	<li>Position the 96-well &#181;-Plate inside the pre-warmed and equilibrated thermostated chamber and replace the lid by a thermostated cover.</li>
	<li>Open the NIS-Elements software and click in the menu bar on &#34;Acquire/Acquisition controls/ND acquisition&#8221; to select the options of the time-lapse (length, stage positions, confocal z-sections,&#8230;), &#34;Acquire/Acquisition controls/Ti Pad&#8221; to select the objectives and &#34;Acquire/Acquisition controls/A1plus Settings&#8221; to select the PMT level for each fluorescence in the menu bar. Select a folder to save the data files.</li>
	<li>Using the ND acquisition window, set the center of each well as a stage position and select the large image option to 7 x 7 mm&#178;. This will create a mosaic image around the center of each well. Set the overlap for the large mosaic image to 5%. Take pictures every 20 min for 24 hr. Select the Plan Apo VC 20x DIC objective (NA: 0.75) in the Ti Pad window.</li>
	<li>In the A1plus Settings window, acquire images using high speed resonant scanner at a 512 x 512 pixels format with a resolution of 1.26 &#181;m/pixel. Use brightfield to visualize cell shapes. In the case of FUCCI-Red mice, excite red fluorescence at 561 nm and collect using a 595/50 nm filter. In the case of FUCCI-Green mice, excite green fluorescence at 488 nm and collect using a 530/40 nm filter. Determine the optimal PMT level, offset and laser power for each wavelength. 
	NOTE: We recommend using the autofocus function for the brightfield channel to allow the software to autofocus at each stage position before each acquisition. Hint: A Plan Apo VC 20x DIC objective (NA: 0.75) was used for its excellent resolution without the need for oil. Other objectives may be used depending on the optical resolution desired.</li>
	<li>Select the &#39;Run now&#39; button on the ND acquisition window to begin acquisition. 
	Hint: Follow the computer work for 1 loop to be sure that everything in working properly.</li>
</ol>
8. Image Processing and Analysis
<ol>
	<li>Analyze the data directly on the NIS-Elements software by tracking the cells individually. Hint: To gain time, save each position in .avi format using NIS-Elements software and analyze the movies with ImageJ.</li>
	<li>In ImageJ software, track individual cells undergoing at least 2 divisions (i.e. one cell to a four-cell colony). Crop a small area around the cell and select &#39;Image/Duplicate&#39;.</li>
	<li>Select &#39;Image/Stacks/Make Montage&#39; in the menu bar to make a montage. Specify the frames to be included, the size of the images and save the montage as a .tif file for optimal resolution.</li>
	<li>To calculate the first S-G2/M phase length (Figure 2C,D), select a single red fluorescent cell (in G1) and then set t = 0 (S phase will begin once the red-fluorescence switches off). Count the number of frames until the cell divides to estimate the S-G2/M length. 
	NOTE: The calculated time depends on the time interval between each frame.</li>
	<li>To calculate the following G1 phase (Figure 2C,D), continue to track the cell that just divided. If the divided cell enters G1 phase, there will be an accumulation of cdt1 red-fluorescent protein. Calculate the number of frames until red-fluorescence switches off again for each cell. 
	Hint: At the beginning of G1 the red fluorescence might be weak so choose the onset of the G1 phase on the frame where the cell has divided to avoid approximations.</li>
</ol>

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L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neural+stem+cells+and+neurospheres+re+evaluating+the+relationship.">Neural stem cells and neurospheres re evaluating the relationship.</a> Nat Methods. 2, 333-336 (2005).</li><li>Pastrana, E., Silva Vargas, V., Doetsch, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Eyes+wide+open+a+critical+review+of+sphere+formation+as+an+assay+for+stem+cells.">Eyes wide open a critical review of sphere formation as an assay for stem cells.</a> Cell stem cell. 8, 486-498 (2011).</li><li>Spella, 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=Licensing+regulators+Geminin+and+Cdt1+identify+progenitor+cells+of+the+mouse+CNS+in+a+specific+phase+of+the+cell+cycle.">Licensing regulators Geminin and Cdt1 identify progenitor cells of the mouse CNS in a specific phase of the cell cycle.</a> Neuroscience. 147, 373-387 (2007).</li></ol>

The authors declare that they have no conflict of interest.

The cell sorting technique described herein allows reliable discrimination between quiescent NSCs, activated NSCs and their progeny enabling studies of their properties and dynamics in the adult brain9. Coupled with the FUCCI technology which permits the visualization of cell cycle progression in living cells23, we developed a rapid and efficient technique to follow the G1 and S-G2/M phases of the cell cycle from young adult and aged mouse brain cells.
The cell sorting technique used in this protocol was the first validated combination of markers allowing the purification of the five main neurogenic populations from the SVZ9. It was also the first validated technique enabling the distinction of quiescent and activated NSCs. It is noteworthy that this technique does not require the use of transgenic mice per se, which is necessary when adapted to transgenic mouse models such as FUCCI. Since then, Codega et al.10 have used a GFAP-GFP/CD133/EGFR triple labeling combination to distinguish quiescent NSCs from their activated counterpart but it cannot be adapted to FUCCI technology as it requires the use of GFAP-GFP transgenic mice. Mich et al.11 have developed a Glast/EGFR/CD24 triple labeling strategy that shares common results with the technique used in this study9. Indeed, a high correlation between LeX and Glast NSCs markers was already observed in Daynac et al. study9. However, the Glast antibody used in the Mich et al. technique is coupled to phycoerythrin and thus cannot be adapted with the use of FUCCI-Red mice.
There are several important technical points that require attention before sorting SVZ cells. First, the dissociation step is very important as the brain tissue has to be dissociated into single cells while preserving the structural integrity of the proteins used for the antibody labeling strategy. 0.05% trypsin-EDTA has been shown to be very effective in dissociating SVZ tissue27 but the LeX antigen was found to be highly sensitive as almost all LeX-FITC immunofluorescence was lost (data not shown). Thus, papain was used as it was more efficient and less destructive than other proteases on brain tissue. Moreover, neither LeX nor EGFR nor CD24 were affected by papain treatment. It should be noted that the antibody labeling was altered if the papain treatment exceeded 15 min. We obtained optimal results with a 10 min papain treatment associated with a mechanical dissociation (pipette up and down 20 times).
The poly-D-Lysine coating allows culture of adherent cells and the formation of colonies after several days in culture. It is now widely accepted that in vitro assays comes with their limitations28,29. We recommend determining only the first cell cycle for the cells undergoing at least one subsequent division to stay as close as possible to the in vivo cell phenotype.
It is noteworthy to mention that the Geminin (green fluorescence) and Cdt1 (red fluorescence) proteins used to design the FUCCI system23 were previously shown to be abundantly expressed by neural progenitors during early neurogenesis in mice30 and in adult brain tissues9,25. Although the mKO2-hCdt1(30/120) construct was mainly used in the present study to follow the G1 phase with red fluorescence, the use of both constructs [mKO2-hCdt1(30/120) and mAG-hGem(1/110)] could be envisioned to allow the visualization of the major phases of the cell cycle (G1 and S-G2/M) as well as the G1/S transition23. The main drawback of the dual-color imaging is the limited compatible sets of fluorescence that can still be used for the cell labeling. One solution is to use separation columns. For example, we have successfully depleted the CD24-positive fraction from cells using separation columns before cell sorting and live-imaging as we used a CD24-PE antibody that shared the same emission wavelength than the FUCCI-Red fluorescence25.
Few studies have investigated the cell cycle length of adult mouse SVZ populations. The total cell cycle length obtained with our technique is close to the one estimated in vitro by Costa et al.21, but we were able for the first time to distinguish the different cell cycle phases. In an in vivo study, Ponti et al.22 used the incorporation of thymidine analogs to determine the proliferation dynamics of the different SVZ cell populations. However, they could neither perform a continuous monitoring of the cell cycle nor track the cells at the single-cell level. This could be an issue as it was shown that a strong heterogeneity exists within a given SVZ cell population22,25. We describe here an alternative in vitro technique, easy to set up, that allows the live imaging of the cell cycle phases of different adult neurogenic populations at a single-cell level.
Understanding the regulation of the cell cycle of neural stem cells and progenitors remains a challenge for the development of new therapeutic approaches in the context of aging or brain pathologies. Our protocol can thus have a wide range of applications. In the context of aging, this technique could also prove useful to understand the effects of aging on NSCs differentiation. Indeed, it is possible to identify neural stem/progenitor cells entering differentiation as their red fluorescent intensity is distinctively higher26. Finally, it could also be of interest to exploit the continuous live imaging at a single-cell level to study the cell intrinsic and extrinsic processes responsible for the lineage progression of adult NSCs.

Quiescent neural stem cells (NSCs) are the source for adult neurogenesis1 and can convert into their proliferative &#8220;activated&#8221; form expressing the EGFR (aNSCs) 2. Once activated, they give rise to transit amplifying cells (TACs) 3 and then neuroblasts that migrate to the olfactory bulbs (OB) through a tube of astrocytes and finally differentiate into neurons4,5. NSCs and their progeny are organized in specialized &#8220;niches&#8221; architectures along the lateral ventricles, implicating a myriad of factors controlling their proliferation6. The isolation and purification of SVZ neurogenic cells is necessary to illuminate the complex molecular regulation of their proliferation but have remained a challenge for a long time due to the lack of specific markers and adapted techniques.
New approaches using flow cytometry have rendered possible the isolation of NSCs and their progeny from the adult SVZ2,7-11. Using the stem cell marker LeX12 along with neuroblast marker CD2413 and a fluorescence EGF to label EGFR on proliferating cells2, we recently developed a FACS strategy allowing the purification of five of the main SVZ neurogenic populations: quiescent and activated NSCs, TACs, immature as well as migrating neuroblasts9. Here, we describe in details this cell sorting technique and how a LeX/EGFR/CD24 triple staining allowed for the first time the isolation of both quiescent and activated NSCs.
Although neurogenesis persists during adulthood, the production of new neurons is drastically decreased in the aging brain14. Most studies agree on a progressive reduction in the number of proliferating progenitor cells in the SGZ and SVZ15-20. The consequences are not innocuous as the age-related decline in neurogenesis in the SVZ provokes a diminution of newborn neurons in the olfactory bulbs of the aged brain, ultimately leading to impairment in olfactory discrimination in aged mice18. Elucidating cell cycle kinetics of neural progenitors is a key step to understand the mechanisms underlying the evolution of adult neurogenesis during aging. Recent studies have investigated the cell cycle and lineage progression of adult neural stem cells in vitro21 and in vivo22 but none of them took advantage of cell sorting techniques and genetically encoded fluorescent cell-cycle probes to visualize the cell-cycle phases of isolated cells at a single-cell level.
Here we describe a protocol that takes advantage of the transgenic FUCCI mice in which cells are fluorescent during their cell cycle, allowing the distinction between G1 and S-G2/M phases23. This protocol shows how prospective isolation of NSCs and their progeny from adult FUCCI mice combined with time-lapse video microscopy allows the study of the cell cycle dynamics at a single-cell level.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>96-well uncoated glass bottom culture plates&#160;</td>
			<td>MatTek Corp.</td>
			<td>P96G-1.5-5-F</td>
			<td></td>
		</tr>
		<tr>
			<td>&#181;-Plates 96-well</td>
			<td>Ibidi</td>
			<td>89626</td>
			<td></td>
		</tr>
		<tr>
			<td>Poly-D-Lysine</td>
			<td>Millipore</td>
			<td>A003E</td>
			<td></td>
		</tr>
		<tr>
			<td>NeuroCult NSC Basal Medium</td>
			<td>STEMCELL Technologies</td>
			<td>5700</td>
			<td></td>
		</tr>
		<tr>
			<td>NeuroCult NSC Proliferation Supplement&#160;</td>
			<td>STEMCELL Technologies</td>
			<td>5701</td>
			<td></td>
		</tr>
		<tr>
			<td>Heparin</td>
			<td>STEMCELL Technologies</td>
			<td>7980</td>
			<td></td>
		</tr>
		<tr>
			<td>EGF</td>
			<td>Millipore</td>
			<td>GF144</td>
			<td></td>
		</tr>
		<tr>
			<td>FGF-2</td>
			<td>Millipore</td>
			<td>GF003</td>
			<td></td>
		</tr>
		<tr>
			<td>Papain</td>
			<td>Worthington</td>
			<td>LS003119</td>
			<td></td>
		</tr>
		<tr>
			<td>EBSS</td>
			<td>Invitrogen</td>
			<td>24010-043</td>
			<td></td>
		</tr>
		<tr>
			<td>L-cysteine</td>
			<td>Sigma</td>
			<td>C-7352</td>
			<td></td>
		</tr>
		<tr>
			<td>0.5M EDTA, pH 8.0</td>
			<td>Promega</td>
			<td>V4231</td>
			<td></td>
		</tr>
		<tr>
			<td>DNase I</td>
			<td>Sigma</td>
			<td>D5025-15KU</td>
			<td></td>
		</tr>
		<tr>
			<td>Trypsin inhibitor type II</td>
			<td>Sigma</td>
			<td>T9128</td>
			<td>Ovomucoid</td>
		</tr>
		<tr>
			<td>DMEM:F12 medium</td>
			<td>Life Technologies</td>
			<td>31330-038</td>
			<td></td>
		</tr>
		<tr>
			<td>20 &#181;m filter&#160;</td>
			<td>BD Medimachine Filcon</td>
			<td>340622</td>
			<td></td>
		</tr>
		<tr>
			<td>Eppendorf microtubes 3810X</td>
			<td>Sigma</td>
			<td>Z606340-1000EA</td>
			<td></td>
		</tr>
		<tr>
			<td>BSA</td>
			<td>Sigma</td>
			<td>A1595</td>
			<td>Bovine serum albumin solution</td>
		</tr>
		<tr>
			<td>CD24 phycoerythrin-cyanine7 conjugate [PC7]</td>
			<td>Life Technologies</td>
			<td>A14776</td>
			<td>Mouse IgM; clone MMA. 1:50</td>
		</tr>
		<tr>
			<td>CD15/LeX fluorescein isothiocyanate [FITC] - conjugated</td>
			<td>BD Biosciences</td>
			<td>332778</td>
			<td>Rat IgG2b; clone M1/69.&#160; 1:50</td>
		</tr>
		<tr>
			<td>Mouse anti-human LeX antibody</td>
			<td>BD Pharmingen</td>
			<td>559045</td>
			<td>Mouse IgM; clone MAM.&#160; 1:50</td>
		</tr>
		<tr>
			<td>Alexa647 - conjugated EGF ligand</td>
			<td>Life Technologies</td>
			<td>E35351</td>
			<td>1:200; Ax647-conjugated EGF ligand in the text</td>
		</tr>
		<tr>
			<td>CompBeads</td>
			<td>BD Biosciences</td>
			<td>644204</td>
			<td></td>
		</tr>
		<tr>
			<td>MACS LS separation columns&#160;</td>
			<td>Miltenyi Biotec</td>
			<td>130-042-401</td>
			<td>separation columns (in the manuscript)</td>
		</tr>
		<tr>
			<td>Anti-mouse IgM microbeads&#160;</td>
			<td>Miltenyi Biotec</td>
			<td>130-047-301</td>
			<td></td>
		</tr>
		<tr>
			<td>Hoechst 33258</td>
			<td>Sigma</td>
			<td>861405</td>
			<td>HO (in the manuscript)</td>
		</tr>
		<tr>
			<td>INFLUX cell sorter</td>
			<td>BD Biosciences</td>
			<td></td>
			<td>FACS sorter (in the text)</td>
		</tr>
		<tr>
			<td>Nikon A1R confocal laser scanning microscope system attached to an inverted ECLIPSE Ti</td>
			<td>Nikon Corp.</td>
			<td></td>
			<td>confocal laser scanning microscope (in the manuscript)</td>
		</tr>
		<tr>
			<td>NIS-Elements AR.4.13.01 64-bit software</td>
			<td>Nikon Corp.</td>
			<td></td>
			<td>NIS-Elements software (in the manuscript)</td>
		</tr>
		<tr>
			<td>Plan Apo VC 20x DIC objective (NA: 0.75)</td>
			<td>Nikon Corp.</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>ECLIPSE Ti thermostated chamber</td>
			<td>Nikon Corp.</td>
			<td></td>
			<td>thermostated chamber (in the manuscript)</td>
		</tr>
		<tr>
			<td>ImageJ</td>
			<td>RBS</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>FlowJo</td>
			<td>Tree Star, Ashland, OR</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>FUCCI mice</td>
			<td>RIKEN BioResource Center, JAPAN</td>
			<td></td>
			<td>Sakaue-Sawano et al. 2008</td>
		</tr>
	</tbody>
</table>

cell sorting of neural stem and progenitor cells from the adult mouse subventricular zone and live-imaging of their cell cycle dynamics

Neural stem cells (NSCs) in the subventricular zone of the lateral ventricles (SVZ) sustain olfactory neurogenesis throughout life in the mammalian brain. They successively generate transit amplifying cells (TACs) and neuroblasts that differentiate into neurons once they integrate the olfactory bulbs. Emerging fluorescent activated cell sorting (FACS) techniques have allowed the isolation of NSCs as well as their progeny and have started to shed light on gene regulatory networks in adult neurogenic niches. We report here a cell sorting technique that allows to follow and distinguish the cell cycle dynamics of the above-mentioned cell populations from the adult SVZ with a LeX/EGFR/CD24 triple staining. Isolated cells are then plated as adherent cells to explore in details their cell cycle progression by time-lapse video microscopy. To this end, we use transgenic Fluorescence Ubiquitination Cell Cycle Indicator (FUCCI) mice in which cells are red-fluorescent during G1 phase due to a G1 specific red-Cdt1 reporter. This method has recently revealed that proliferating NSCs progressively lengthen their G1 phase during aging, leading to neurogenesis impairment. This method is easily transposable to other systems and could be of great interest for the study of the cell cycle dynamics of brain cells in the context of brain pathologies.

The ability to reliably discriminate between the different cell populations of the adult mouse SVZ stem cell lineage is primordial to investigate their functional properties. To that purpose, we have developed a LeX/EGFR/CD24 triple-labeling strategy allowing the purification of specific cell populations from the adult SVZ: quiescent NSCs (LeXbright), activated NSCs (LeX+EGFR+), TACs (EGFR+), immature and migrating neuroblasts (CD24+EGFR+ and CD24+, respectively) 9 (Figure 1). Applied to FUCCI transgenic mice, the cell sorting technique allows the live imaging of the cell cycle phases of the different neurogenic populations at the single-cell level25. FUCCI-Red mice were used to follow the G1 phase with red fluorescence using time-lapse video microscopy (Figure 2A). FUCCI-Redneg cells represent the cells in S-G2/M phases of the cell cycle, FUCCI-Redpos cells are G1 cells and FUCCI-Redbright cells are cells exiting or out of the cell cycle (Figure 2B) 23,26. LeX+EGFR+ and EGFR+ cells from young adult (Figure 2C) and middle-aged mice (Figure 2D) were plated as adherent cells on poly-D-lysine coated culture plates. The first S-G2/M phase was identified on single cells once the red fluorescence switches off until the cell divides. As previously observed the S-G2/M phase length showed no difference between LeX+EGFR+ and EGFR+ cells, either in young or middle-aged mice. Then we calculated the next G1 phase length from the first division until the red fluorescence switches off. Interestingly, a G1 phase lengthening was found during aging in LeX+EGFR+ cells but not in EGFR+ cells25 (Figure 2C,D). In consequence, neurospheres obtained 5 days after plating are smaller in LeX+EGFR+ cells obtained from aged mice as shown in Figure 2E.
FUCCI-Green mice can also be used to visualize the S-G2/M phase with green fluorescence (Figure 3A,B) but cells have to be pre-sorted using separation columns as LeX-FITC antibody shared the same emission wavelength than the FUCCI-green fluorescence (Figure 3C). An example of FUCCI-green fluorescence for the first S-G2/M phase of young adult LeX+EGFR+ and EGFR+ cells is shown in Figure 3D.
<img alt="Figure 1" src="/files/ftp_upload/53247/53247fig1.jpg" /> 
Figure 1: Strategy of cell selection by FACS. (A) Cells were first selected according to their morphology using Side scatter (SSC) vs Forward scatter (FSC) parameters. For further details on morphology gate selection, refer to Daynac et al. 9 (A&#8217;) Dead cells were labeled using HO marker and excluded from the selection. (A&#8217;&#8217;) Doublets were excluded using pulse width parameter. In order to set up the sorting gates, Fluorescence minus one (FMO) controls for CD24-PC7 (LeX-FITC/FUCCI-Red/EGF-Ax647 labeling; B) and LeX-FITC (FUCCI-Red/EGF-Ax647/CD24-PC7 labeling; B&#8217;) were used. (C,C&#8217;) Then, sorting gates were determined in LeX-FITC/FUCCI-Red/EGF-Ax647/CD24-PC7 labeled tubes along with FMO controls. The mean percentages of total cells are represented within the gates. If selecting CD24+ cells (neuroblasts), be careful to exclude CD24bright expressing cells from the gate. Indeed, CD24bright correspond to ependymal cells2,9. C&#8217; represents the CD24 negative cells (black square in C). Only LeX+EGFR+ and EGFR+ (C&#8217;) sorting gates were used for this study.
<img alt="Figure 2" src="/files/ftp_upload/53247/53247fig2.jpg" /> 
Figure 2: Live analyses of cell cycle using FUCCI-Red mice. (A) Schematic representation of FUCCI-Red cell cycle where cells are red-fluorescent during G1 phase and colorless during S-G2/M phases23. (B) FACS representation of FUCCI-Red fluorescence on SVZ cells. (C,D) Video microscopy with LeX+EGFR+ and EGFR+ cells sorted from young (C) and middle-aged (D) FUCCI-Red mice allows the tracking of the G1 phase with red fluorescence whereas the S-G2/M phases can be deduced when the red fluorescence switches off. Successive images are shown with a time scale presented in D. (E) Representative images of colonies (neurospheres) obtained 5 days after plating. Scale bar: 10 &#181;m (C, D), 30&#181;m (E). <a href="https://www.jove.com/files/ftp_upload/53247/53247fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" src="/files/ftp_upload/53247/53247fig3.jpg" /> 
Figure 3: Strategy for live analyses of cell cycle using FUCCI-Green mice. (A) Schematic representation of FUCCI-Green cell cycle where cells are green during S-G2/M phase and colorless during G1 phase23. (B) FACS representation of FUCCI-Green fluorescence: FUCCI-Greenneg cells represent the cells in G1 phase of the cell cycle while FUCCI-Greenpos cells are cells in S-G2/M23. (C) In order to follow the green-fluorescent S-G2/M phases of LeX+EGFR+ and EGFR+ cells, SVZ cells had to be pre-sorted with separation columns. Cells were labeled with anti-mouse LeX antibody and LeX+ fraction was retained on the column using anti-mouse microbeads (see protocol 4.). Then, LeX+ and LeX- fractions were eluted and labeled with EGF-Ax647 and CD24-PC7 antibodies for FACS sorting. (D) Video microscopy of LeX+EGFR+ and EGFR+ cells sorted from young FUCCI-Green mice allows the tracking of the S-G2/M phases with green fluorescence. Successive images are shown with a time scale presented in D. Scale bar: 10 &#181;m (D).

Watch this Scientific Journal Video about Cell Sorting of Neural Stem and Progenitor Cells from the Adult Mouse Subventricular Zone and Live-imaging of their Cell Cycle Dynamics at JoVE.com

Cell Sorting of Neural Stem and Progenitor Cells from the Adult Mouse Subventricular Zone and Live-imaging of their Cell Cycle Dynamics

We report a Fluorescent Activated Cell Sorting (FACS)-based method to isolate neural stem cells (NSCs) and their progeny from the subventricular zone (SVZ) of the adult mouse brain. Applied to Fluorescence Ubiquitination Cell Cycle Indicator (FUCCI) transgenic mice, it allows the study of cell cycle progression by live imaging.

Neural stem cells (NSCs) in the subventricular zone of the lateral ventricles (SVZ) sustain olfactory neurogenesis throughout life in the mammalian brain. ...

cell-sorting-neural-stem-progenitor-cells-from-adult-mouse

Research

JoVE Journal

Neuroscience

The Subventricular Zone En-face: Wholemount Staining and Ependymal Flow

The walls of the lateral ventricles contain the largest germinal region in the adult mammalian brain. The subventricular zone (SVZ) in these walls is an extensively studied model system for understanding the behavior of neural stem cells and the regulation of adult neurogenesis. Traditionally, these studies have relied on classical sectioning techniques for histological analysis. Here we present an alternative approach, the wholemount technique, which provides a comprehensive, en-face view of this germinal region. Compared to sections, wholemounts preserve the complete cytoarchitecture and cellular relationships within the SVZ. This approach has recently revealed that the adult neural stem cells, or type B1 cells, are part of a mixed neuroepithelium with differentiated ependymal cells lining the lateral ventricles. In addition, this approach has been used to study the planar polarization of ependymal cells and the cerebrospinal fluid flow they generate in the ventricle. With recent evidence that adult neural stem cells are a heterogeneous population that is regionally specified, the wholemount approach will likely be an essential tool for understanding the organization and parcellation of this stem cell niche.

The lateral ventricle walls contain the largest germinal region in the adult mammalian brain. Traditionally, studies on neurogenesis in this region have relied on classical sectioning techniques for histological analysis. Here we present an alternative approach, the wholemount technique, which provides a comprehensive, en-face view of this germinal region.

The walls of the lateral ventricles contain the largest germinal region in the adult mammalian brain. The subventricular zone (SVZ) in these walls is an ...

Live-cell Imaging of Sensory Organ Precursor Cells in Intact Drosophila Pupae

Since the discovery of Green Fluorescent Protein (GFP), there has been a revolutionary change in the use of live-cell imaging as a tool for understanding fundamental biological mechanisms. Striking progress has been particularly evident in Drosophila, whose extensive toolkit of mutants and transgenic lines provides a convenient model to study evolutionarily-conserved developmental and cell biological mechanisms. We are interested in understanding the mechanisms that control cell fate specification in the adult peripheral nervous system (PNS) in Drosophila. Bristles that cover the head, thorax, abdomen, legs and wings of the adult fly are individual mechanosensory organs, and have been studied as a model system for understanding mechanisms of Notch-dependent cell fate decisions. Sensory organ precursor (SOP) cells of the microchaetes (or small bristles), are distributed throughout the epithelium of the pupal thorax, and are specified during the first 12 hours after the onset of pupariation. After specification, the SOP cells begin to divide, segregating the cell fate determinant Numb to one daughter cell during mitosis. Numb functions as a cell-autonomous inhibitor of the Notch signaling pathway.
Here, we show a method to follow protein dynamics in SOP cell and its progeny within the intact pupal thorax using a combination of tissue-specific Gal4 drivers and GFP-tagged fusion proteins 1,2.This technique has the advantage over fixed tissue or cultured explants because it allows us to follow the entire development of an organ from specification of the neural precursor to growth and terminal differentiation of the organ. We can therefore directly correlate changes in cell behavior to changes in terminal differentiation. Moreover, we can combine the live imaging technique with mosaic analysis with a repressible cell marker (MARCM) system to assess the dynamics of tagged proteins in mitotic SOPs under mutant or wildtype conditions. Using this technique, we and others have revealed novel insights into regulation of asymmetric cell division and the control of Notch signaling activation in SOP cells (examples include references 1-6,7 ,8).

Live-cell Imaging of Sensory Organ Precursor Cells in Intact Drosophila Pupae

In this video, we describe a method for live cell imaging of asymmetrically dividing sensory organ progenitor cells and epidermal cells in intact Drosophila pupae

Since the discovery of Green Fluorescent Protein (GFP), there has been a revolutionary change in the use of live-cell imaging as a tool for understanding ...

Isolation and Culture of Neural Crest Cells from Embryonic Murine Neural Tube

The embryonic neural crest (NC) is a multipotent progenitor population that originates at the dorsal aspect of the neural tube, undergoes an epithelial to mesenchymal transition (EMT) and migrates throughout the embryo, giving rise to diverse cell types 1-3. NC also has the unique ability to influence the differentiation and maturation of target organs4-6. When explanted in vitro, NC progenitors undergo self-renewal, migrate and differentiate into a variety of tissue types including neurons, glia, smooth muscle cells, cartilage and bone. 
NC multipotency was first described from explants of the avian neural tube7-9. In vitro isolation of NC cells facilitates the study of NC dynamics including proliferation, migration, and multipotency. Further work in the avian and rat systems demonstrated that explanted NC cells retain their NC potential when transplanted back into the embryo10-13. Because these inherent cellular properties are preserved in explanted NC progenitors, the neural tube explant assay provides an attractive option for studying the NC in vitro. 
To attain a better understanding of the mammalian NC, many methods have been employed to isolate NC populations. NC-derived progenitors can be cultured from post-migratory locations in both the embryo and adult to study the dynamics of post-migratory NC progenitors11,14-20, however isolation of NC progenitors as they emigrate from the neural tube provides optimal preservation of NC cell potential and migratory properties13,21,22. Some protocols employ fluorescence activated cell sorting (FACS) to isolate a NC population enriched for particular progenitors11,13,14,17. However, when starting with early stage embryos, cell numbers adequate for analyses are difficult to obtain with FACS, complicating the isolation of early NC populations from individual embryos. Here, we describe an approach that does not rely on FACS and results in an approximately 96% pure NC population based on a Wnt1-Cre activated lineage reporter23. 
The method presented here is adapted from protocols optimized for the culture of rat NC11,13. The advantages of this protocol compared to previous methods are that 1) the cells are not grown on a feeder layer, 2) FACS is not required to obtain a relatively pure NC population, 3) premigratory NC cells are isolated and 4) results are easily quantified. Furthermore, this protocol can be used for isolation of NC from any mutant mouse model, facilitating the study of NC characteristics with different genetic manipulations. The limitation of this approach is that the NC is removed from the context of the embryo, which is known to influence the survival, migration and differentiation of the NC2,24-28.

Isolation of embryonic neural crest from the neural tube facilitates the use of in vitro methods for studying migration, self-renewal, and multipotency of neural crest.

The embryonic neural crest (NC) is a multipotent progenitor population that originates at the dorsal aspect of the neural tube, undergoes an epithelial to ...

Assessing Cell Cycle Progression of Neural Stem and Progenitor Cells in the Mouse Developing Brain after Genotoxic Stress

Neurons of the cerebral cortex are generated during brain development from different types of neural stem and progenitor cells (NSPC), which form a pseudostratified epithelium lining the lateral ventricles of the embryonic brain. Genotoxic stresses, such as ionizing radiation, have highly deleterious effects on the developing brain related to the high sensitivity of NSPC. Elucidation of the cellular and molecular mechanisms involved depends on the characterization of the DNA damage response of these particular types of cells, which requires an accurate method to determine NSPC progression through the cell cycle in the damaged tissue. Here is shown a method based on successive intraperitoneal injections of EdU and BrdU in pregnant mice and further detection of these two thymidine analogues in coronal sections of the embryonic brain. EdU and BrdU are both incorporated in DNA of replicating cells during S phase and are detected by two different techniques (azide or a specific antibody, respectively), which facilitate their simultaneous detection. EdU and BrdU staining are then determined for each NSPC nucleus in function of its distance from the ventricular margin in a standard region of the dorsal telencephalon. Thus this dual labeling technique allows distinguishing cells that progressed through the cell cycle from those that have activated a cell cycle checkpoint leading to cell cycle arrest in response to DNA damage.
An example of experiment is presented, in which EdU was injected before irradiation and BrdU immediately after and analyzes performed within the 4 hr&#160;following irradiation. This protocol provides an accurate analysis of the acute DNA damage response of NSPC in function of the phase of the cell cycle at which they have been irradiated. This method is easily transposable to many other systems in order to determine the impact of a particular treatment on cell cycle progression in living tissues.

Administration of two analogs of thymidine, EdU and BrdU, in pregnant mice allows the analysis of cell cycle progression in neural and progenitor cells in the embryonic mouse brain. This method is useful to determine the effects of genotoxic stress, including ionizing radiation, during brain development.

Neurons of the cerebral cortex are generated during brain development from different types of neural stem and progenitor cells (NSPC), which form a ...

Feeder-free Derivation of Neural Crest Progenitor Cells from Human Pluripotent Stem Cells

Human pluripotent stem cells (hPSCs) have great potential for studying human embryonic development, for modeling human diseases in the dish and as a source of transplantable cells for regenerative applications after disease or accidents. Neural crest (NC) cells are the precursors for a large variety of adult somatic cells, such as cells from the peripheral nervous system and glia, melanocytes and mesenchymal cells. They are a valuable source of cells to study aspects of human embryonic development, including cell fate specification and migration. Further differentiation of NC progenitor cells into terminally differentiated cell types offers the possibility to model human diseases in vitro, investigate disease mechanisms and generate cells for regenerative medicine. This article presents the adaptation of a currently available in vitro differentiation protocol for the derivation of NC cells from hPSCs. This new protocol requires 18 days of differentiation, is feeder-free, easily scalable and highly reproducible among human embryonic stem cell (hESC) lines as well as human induced pluripotent stem cell (hiPSC) lines. Both old and new protocols yield NC cells of equal identity.

Neural crest (NC) cells derived from human pluripotent stem cells (hPSC) have great potential for modeling human development and disease and for cell replacement therapies. Here, a feeder-free adaptation of the currently widely used in vitro differentiation protocol for the derivation of NC cells from hPSCs is presented.

Human pluripotent stem cells (hPSCs) have great potential for studying human embryonic development, for modeling human diseases in the dish and as a ...

Derivation of Adult Human Fibroblasts and their Direct Conversion into Expandable Neural Progenitor Cells

Generation of&#160;induced pluripotent stem cell (iPSCs) from adult skin fibroblasts and subsequent differentiation into somatic cells provides fascinating prospects for the derivation of autologous transplants that circumvent histocompatibility barriers. However, progression through a pluripotent state and subsequent complete differentiation into desired lineages remains a roadblock for the clinical translation of iPSC technology because of the associated neoplastic potential and genomic instability. Recently, we and others showed that somatic cells cannot only be converted into iPSCs but also into different types of multipotent somatic stem cells by using defined factors, thereby circumventing progression through the pluripotent state. In particular, the direct conversion of human fibroblasts into induced neural progenitor cells (iNPCs) heralds the possibility of a novel autologous cell source for various applications such as cell replacement, disease modeling and drug screening. Here, we describe the isolation of adult human primary fibroblasts by skin biopsy and their efficient direct conversion into iNPCs by timely restricted expression of Oct4, Sox2, Klf4, as well as c-Myc. Sox2-positive neuroepithelial colonies appear after 17 days of induction and iNPC lines can be established efficiently by monoclonal isolation and expansion. Precise adjustment of viral multiplicity of infection and supplementation of leukemia inhibitory factor during the induction phase represent critical factors to achieve conversion efficiencies of up to 0.2%. Thus far, patient-specific iNPC lines could be expanded for more than 12 passages and uniformly display morphological and molecular features of neural stem/progenitor cells, such as the expression of Nestin and Sox2. The iNPC lines can be differentiated into neurons and astrocytes as judged by staining against TUJ1 and GFAP, respectively. In conclusion, we report a robust protocol for the derivation and direct conversion of human fibroblasts into stably expandable neural progenitor cells that might provide a cellular source for biomedical applications such as autologous neural cell replacement and disease modeling.

Generation of induced pluripotent stem cells provides fascinating prospects for the derivation of autologous transplants. However, progression through a pluripotent state and laborious re-differentiation still hinders clinical translation. Here we describe the derivation of adult human fibroblasts and their direct conversion into induced neural progenitor cells and the subsequent differentiation into neural lineages.

Generation of&#160;induced pluripotent stem cell (iPSCs) from adult skin fibroblasts and subsequent differentiation into somatic cells provides ...

Isolation and Culture of Adult Neural Stem Cells from the Mouse Subcallosal Zone

Adult neural stem cells (aNSCs) can be used for the regeneration of damaged brain tissue. NSCs have the potential for differentiation and proliferation into three types of cells: neurons, astrocytes, and oligodendrocytes. Identifying aNSC-derived regions and characterizing the aNSC properties are critical for the potential use of aNSCs and for the elucidation of their role in neural regeneration. The subcallosal zone (SCZ), located between white matter and the hippocampus, has recently been reported to contain aNSCs and continuously give rise to neuroblasts. A low percentage of aNSCs from the SCZ is differentiated into neurons; most cells are differentiated into glial cells, such as oligodendrocytes and astrocytes. These cells are suggested to have a therapeutic potential for traumatic cortical injury. This protocol describes in detail the process to generate SCZ-aNSCs from an adult mouse brain. A brain matrix with intervals of 1 mm is used to obtain the SCZ-containing coronal slices and to precisely dissect the SCZ from the whole brain. The SCZ sections are initially subjected to a neurosphere culture. A well-developed culture system allows for the verification of their characteristics and can increase research on NSCs. A neurosphere culture system provides a useful tool for determining proliferation and collecting the genuine NSCs. A monolayer culture is also an in vitro system to assay proliferation and differentiation. Significantly, this culture system provides a more homogenous environment for NSCs than the neurosphere culture system. Thus, using a discrete brain region, these culture systems will be helpful for expanding our knowledge about aNSCs and their applications for therapeutic uses.

Establishing culture systems for the expansion of adult neural stem cells (aNSCs) allows for the examination and application of aNSCs for therapy. The subcallosal zone (SCZ) has recently been recognized as a novel neuroblast-forming region in adult mice. Here, methods for the isolation, expansion, and differentiation of SCZ-aNSCs are described.

Adult neural stem cells (aNSCs) can be used for the regeneration of damaged brain tissue. NSCs have the potential for differentiation and proliferation ...

Organotypic Cultures of Adult Human Cortex as an Ex vivo Model for Human Stem Cell Transplantation and Validation

Neurodegenerative disorders are common and heterogeneous in terms of their symptoms and cellular affectation, making their study complicated due to the lack of proper animal models that fully mimic human diseases and the poor availability of post-mortem human brain tissue. Adult human nervous tissue culture offers the possibility to study different aspects of neurological disorders. Molecular, cellular, and biochemical mechanisms could be easily addressed in this system, as well as testing and validating drugs or different treatments, such as cell-based therapies. This method combines long-term organotypic cultures of the adult human cortex, obtained from epileptic patients undergoing resective surgery, and ex vivo intracortical transplantation of induced pluripotent stem cell-derived cortical progenitors. This method will allow the study of cell survival, neuronal differentiation, the formation of synaptic inputs and outputs, and the electrophysiological properties of human-derived cells after transplantation into intact adult human cortical tissue. This approach is an important step prior to the development of a 3D human disease modeling platform that will bring basic research closer to the clinical translation of stem cell-based therapies for patients with different neurological disorders and allow the development of new tools for reconstructing damaged neural circuits.

Organotypic Cultures of Adult Human Cortex as an Ex vivo Model for Human Stem Cell Transplantation and Validation

This protocol describes long-term organotypic cultures of adult human cortex combined with ex vivo intracortical transplantation of induced pluripotent stem cell-derived cortical progenitors, which present a novel methodology to further test stem cell-based therapies for human neurodegenerative disorders.

Neurodegenerative disorders are common and heterogeneous in terms of their symptoms and cellular affectation, making their study complicated due to the ...

Rat &quot;Brain Milking&quot; for Neural Stem and Oligodendrocyte Progenitor Cell Isolation

The "Brain Milking" Method for the Isolation of Neural Stem Cells and Oligodendrocyte Progenitor Cells from Live Rats

Tissue-specific neural stem cells (NSCs) remain active in the mammalian postnatal brain. They reside in specialized niches, where they generate new neurons and glia. One such niche is the subependymal zone (SEZ; also called the ventricular-subventricular zone), which is located across the lateral walls of the lateral ventricles, adjacent to the ependymal cell layer. Oligodendrocyte progenitor cells (OPCs) are abundantly distributed throughout the central nervous system, constituting a pool of proliferative progenitor cells that can generate oligodendrocytes.
Both NSCs and OPCs exhibit self-renewal potential and quiescence/activation cycles. Due to their location, the isolation and experimental investigation of these cells is performed postmortem. Here, we describe in detail &#34;brain milking&#34;, a method for the isolation of NSCs and OPCs, amongst other cells, from live animals. This is a two-step protocol designed for use in rodents and tested in rats. First, cells are &#34;released&#34; from the tissue via stereotaxic intracerebroventricular (i.c.v.) injection of a &#34;release cocktail&#34;. The main components are neuraminidase, which targets ependymal cells and induces ventricular wall denudation, an integrin-&#946;1-blocking antibody, and fibroblast growth factor-2. At a second &#34;collection&#34; step, liquid biopsies of cerebrospinal fluid are performed from the cisterna magna, in anesthetized rats without the need of an incision.
Results presented here show that isolated cells retain their endogenous profile and that NSCs of the SEZ preserve their quiescence. The denudation of the ependymal layer is restricted to the anatomical level of injection and the protocol (release and collection) is tolerated well&#160; by the animals. This novel approach paves the way for performing longitudinal studies of endogenous neurogenesis and gliogenesis in experimental animals.

Author Spotlight: Collecting Neural Stem and Progenitor Cells from Live Animals Using a Novel Brain Milking Protocol 

A method for the isolation of neural stem cells and oligodendrocyte progenitor cells from the brains of live rats is presented here in experimental detail. It allows multiple collections of these cells from the same animals without compromising their well-being.

Tissue-specific neural stem cells (NSCs) remain active in the mammalian postnatal brain. They reside in specialized niches, where they generate new ...

Efficient Nucleofection of NSCs Isolated from the Murine Subventricular Zone

Isolation, Expansion, and Nucleofection of Neural Stem Cells from Adult Murine Subventricular Zone

Isolation and expansion of neural stem cells (NSCs) from the subventricular zone (SVZ) of the adult mouse brain can be achieved in a medium supplemented with basic fibroblast growth factor (bFGF) and epidermal growth factor (EGF) as mitogens, producing clonal aggregates known as neurospheres. This in vitro system is a valuable tool for studying NSC potential. Transfection of siRNAs or genes carried in plasmids can be used to induce perturbations to gene expression and study NSC biology. However, the exogenous nucleic acid delivery to NSC cultures is challenging due to the low efficiency of central nervous system (CNS) cells transfection. Here, we present an improved nucleofection system that achieves high efficiency of gene delivery in expanded NSCs from adult murine SVZ. We demonstrate that this relatively simple method enhances gene perturbation in adult NSCs, surpassing traditional transfection protocols with survival rates exceeding 80%. Moreover, this method can also be applied in primary isolated NSCs, providing a crucial advancement in gene function studies through gene expression manipulation via knockdown or overexpression in neurosphere cultures.

Author Spotlight: Improved Nucleofection for High-Efficiency Gene Delivery in Murine Subventricular Zone-Derived Neural Stem Cell Cultures

Here, we describe a nucleofection system designed to enhance gene delivery efficiency in expanded neural stem cells (NSCs) isolated from the adult murine subventricular zone. The findings demonstrate that this method significantly improves gene perturbation in NSCs, surpassing the effectiveness of traditional transfection protocols and enhancing cell survival rate.

Isolation and expansion of neural stem cells (NSCs) from the subventricular zone (SVZ) of the adult mouse brain can be achieved in a medium supplemented ...