This work is supported by grants from the Swedish Research Council, the Swedish Brain Foundation, the Swedish Stroke Foundation, Region Sk&#229;ne, The Thorsten and Elsa Segerfalk Foundation, and the Swedish Government Initiative for Strategic Research Areas (StemTherapy).

This protocol follows the guidelines approved by the Regional Ethical Committee, Lund, Sweden (ethical permit number 2021-07006-01). Healthy neocortical tissue was obtained from patients undergoing elective surgery for temporal lobe epilepsy. Informed consent was obtained from all patients.
NOTE: All the tissues obtained were processed regardless of their size. However, tissues smaller than 1-1.5 mm3 in size will be technically challenging to handle and section with a vibratome....

<ol>
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B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+current+state+of+animal+models+in+research:+A+review.">The current state of animal models in research: A review.</a> International Journal of Surgery. 72, 9-13 (2019).</li><li>Akhtar, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+flaws+and+human+harms+of+animal+experimentation.">The flaws and human harms of animal experimentation.</a> Cambridge Quarterly Healthcare Ethics. 24 (4), 407-419 (2015).</li><li>Gonzalez-Ramos, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+stem+cell-derived+GABAergic+neurons+functionally+integrate+into+human+neuronal+networks.">Human stem cell-derived GABAergic neurons functionally integrate into human neuronal networks.</a> Scientific Reports. 11, 22050 (2021).</li><li>Noraberg, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Organotypic+hippocampal+slice+cultures+for+studies+of+brain+damage,+neuroprotection+and+neurorepair.">Organotypic hippocampal slice cultures for studies of brain damage, neuroprotection and neurorepair.</a> Current Drug Targets. 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The authors declare no conflicts of interest.

Obtaining hACtx slices of high enough quality is the most critical step in this protocol. Cortical tissue is obtained from epileptic patients undergoing resective surgery24. The quality of the resected tissue, as well as the exposure time of the tissue between resection and culture, is critical; the faster the tissue is transferred from the surgery room to the laboratory and cut, the more optimal the organotypic culture will be. Ideally, the tissue should be cut and transferred to...

Neurodegenerative disorders, such as Parkinson&#39;s disease, Alzheimer&#39;s disease, or ischemic stroke, are a group of diseases that share the common feature of neuronal malfunction or death. They are heterogeneous in terms of the brain area and neuronal population affected. Unfortunately, treatments for these diseases are scarce or of limited efficacy due to the lack of animal models that mimic what occurs in the human brain1,2. Stem cell therapy is one of the most promising strategies for brain regeneration3. The generation of neuronal progenitors from stem cells from different sources has been greatly developed in recent years4,5. Recent publications have shown that human induced pluripotent stem (iPS) cell-derived long-term self-renewing neuroepithelial-like stem (lt-NES) cells, following a cortical differentiation protocol and after intracortical transplantation in a rat model with ischemic stroke affecting the somatosensory cortex, generate mature cortical neurons. In addition, the graft-derived neurons received afferent and efferent synaptic connections from the host neurons, showing their integration into the rat neuronal network6,7. The graft-derived axons were myelinated and found in different areas of the rat brain, including the peri-infarct area, corpus callosum, and contralateral somatosensory cortex. Most importantly, iPS cell-derived transplantation reversed motor deficits in stroke animals7.
Even if animal models help to study transplant survival, neuronal integration, and the effect of the grafted cells on motor and cognitive functions, information about interaction between human cells (graft-host) is missing in this system8,9. For this reason, a combined method of long-term human brain organotypic culture with the ex vivo transplantation of human iPS cell-derived neuronal progenitors is described here. Human brain organotypic cultures obtained from neurosurgical resections are physiologically relevant 3D models of the brain that allow researchers to increase their understanding of the human central nervous system circuitry and the most accurate way of testing treatments for human brain disorders. However, not enough research has been done in this context, and in most cases, human hippocampal brain organotypic cultures have been used10,11. The cerebral cortex is affected by several neurodegenerative disorders, such as ischemic stroke12 or Alzheimer&#39;s disease13, so it is important to have a human cortical 3D system that allows us to expand our knowledge and to test and validate different therapeutic strategies. Several studies in the last few years have used cultures from adult human cortical (hACtx) tissue to model human brain diseases14,15,16,17,18,19; however, limited information is available in the context of stem cell therapy. Two studies have already demonstrated the feasibility of the system described here. In 2018, human embryonic stem cells programmed with different transcription factors and transplanted into hACtx tissue were shown to give rise to mature cortical neurons that could integrate into adult human cortical networks20. In 2020, the transplantation of lt-NES cells into the human organotypic system revealed their capacity to differentiate into mature, layer-specific cortical neurons with the electrophysiological properties of functional neurons. The grafted neurons established both afferent and efferent synaptic contacts with the human cortical neurons in the adult brain slices, as corroborated by rabies virus retrograde monosynaptic tracing, whole-cell patch-clamp recordings, and immuno-electron microscopy21.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Tissue Cutting and electrophysiology</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Adenosine 5&#39;-triphosphate magnesium salt</td>
			<td>Sigma</td>
			<td>A9187</td>
			<td></td>
		</tr>
		<tr>
			<td>Bath temperature controller&#160;</td>
			<td>Luigs &#38; Neumann</td>
			<td>TC0511354</td>
			<td></td>
		</tr>
		<tr>
			<td>Calcium Chloride dihydrate</td>
			<td>Merck</td>
			<td>102382</td>
			<td></td>
		</tr>
		<tr>
			<td>Carbogen gas</td>
			<td>Air Liquide</td>
			<td>NA</td>
			<td></td>
		</tr>
		<tr>
			<td>Cooler</td>
			<td>Julaba FL 300</td>
			<td>9661012.03</td>
			<td></td>
		</tr>
		<tr>
			<td>D-(+)Glucose</td>
			<td>Sigma-Aldrich</td>
			<td>G7021</td>
			<td></td>
		</tr>
		<tr>
			<td>Double Patch-Clamp amplifier</td>
			<td>HEKA electronic</td>
			<td>EPC10</td>
			<td></td>
		</tr>
		<tr>
			<td>Guanosine 5&#39;-Triphosphate disodium salt</td>
			<td>Millipore</td>
			<td>371701</td>
			<td></td>
		</tr>
		<tr>
			<td>HEPES</td>
			<td>AppliChem</td>
			<td>A1069</td>
			<td></td>
		</tr>
		<tr>
			<td>Magnesium Chloride hexahydrate</td>
			<td>Sigma-Aldrich</td>
			<td>M2670</td>
			<td></td>
		</tr>
		<tr>
			<td>Magnesium Sulfate heptahydrate</td>
			<td>Sigma-Aldrich</td>
			<td>230391</td>
			<td></td>
		</tr>
		<tr>
			<td>Patchmaster</td>
			<td>HEKA electronic</td>
			<td>Patchmaster 2x91</td>
			<td></td>
		</tr>
		<tr>
			<td>Pipette Puller</td>
			<td>Sutter</td>
			<td>P-2000</td>
			<td></td>
		</tr>
		<tr>
			<td>Plastic Petri dish</td>
			<td>Any suitable</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Potassium chloride</td>
			<td>Merck</td>
			<td>104936</td>
			<td></td>
		</tr>
		<tr>
			<td>Potassium D-gluconate</td>
			<td>ThermoFisher</td>
			<td>B25135</td>
			<td></td>
		</tr>
		<tr>
			<td>Rubber teat + glass pipette</td>
			<td>Any suitable</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium Bicarbonate</td>
			<td>Sigma-Aldrich</td>
			<td>S5761</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium Chloride</td>
			<td>Sigma-Aldrich</td>
			<td>S7653</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium dihydrogen phosphate monohydrate</td>
			<td>Merck</td>
			<td>106346</td>
			<td></td>
		</tr>
		<tr>
			<td>Sucrose</td>
			<td>Sigma-Aldrich</td>
			<td>S7903</td>
			<td></td>
		</tr>
		<tr>
			<td>Tissue adhesive: Acryl super glue</td>
			<td>Loctite</td>
			<td>2062278</td>
			<td></td>
		</tr>
		<tr>
			<td>Upright microscope</td>
			<td>Olympus</td>
			<td>BX51WI&#160;</td>
			<td></td>
		</tr>
		<tr>
			<td>Vibratome&#160;</td>
			<td>Leica</td>
			<td>VT1200 S</td>
			<td></td>
		</tr>
		<tr>
			<td>RINSING SOLUTION</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>D-(+)Glucose</td>
			<td>Sigma-Aldrich</td>
			<td>G7021</td>
			<td></td>
		</tr>
		<tr>
			<td>HBSS (without Ca, Mg, or PhenolRed)</td>
			<td>ThermoFisher Scientific</td>
			<td>14175095</td>
			<td></td>
		</tr>
		<tr>
			<td>HEPES</td>
			<td>AppliChem</td>
			<td>A1069</td>
			<td></td>
		</tr>
		<tr>
			<td>Penicillin-Streptomycin (10,000 U/mL)</td>
			<td>ThermoFisher Scientific</td>
			<td>15-140-122</td>
			<td></td>
		</tr>
		<tr>
			<td>MANTAINANCE AND CULTURE OF HUMAN NEOCORTICAL TISSUE</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>6-well plate</td>
			<td>ThermoFisher Scientific</td>
			<td>140675</td>
			<td></td>
		</tr>
		<tr>
			<td>Alvetex scaffold 6 well insert</td>
			<td>Reinnervate Ltd</td>
			<td>AVP004-96</td>
			<td></td>
		</tr>
		<tr>
			<td>B27 Supplement (50x)</td>
			<td>ThermoFisher Scientific</td>
			<td>17504001</td>
			<td></td>
		</tr>
		<tr>
			<td>BrainPhys without Phenol Red</td>
			<td>StemCell technologies</td>
			<td>#05791</td>
			<td>Referenced as neuronal medium in the text</td>
		</tr>
		<tr>
			<td>Filter units 250 mL or 500 mL</td>
			<td>Corning Sigma</td>
			<td>CLS431096/97</td>
			<td></td>
		</tr>
		<tr>
			<td>Forceps</td>
			<td>Any suitable</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Gentamicin (50 mg/mL)</td>
			<td>ThermoFisher Scientific</td>
			<td>15750037</td>
			<td></td>
		</tr>
		<tr>
			<td>Glutamax Supplement (100x)</td>
			<td>ThermoFisher Scientific</td>
			<td>35050061</td>
			<td>Referenced as L-glutamine in the text</td>
		</tr>
		<tr>
			<td>Rubber teat + Glass pipette</td>
			<td>Any suitable</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>GENERATION OF lt-NES cells</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>2-Mercaptoethanol 50 mM</td>
			<td>ThermoFisher Scientific</td>
			<td>31350010</td>
			<td></td>
		</tr>
		<tr>
			<td>Animal Free Recombinant EGF</td>
			<td>Peprotech</td>
			<td>AF-100-15</td>
			<td></td>
		</tr>
		<tr>
			<td>B27 Suplemment (50x)</td>
			<td>Thermo Fisher Scientific</td>
			<td>17504001</td>
			<td></td>
		</tr>
		<tr>
			<td>bFGF</td>
			<td>Peprotech</td>
			<td>AF-100-18B</td>
			<td></td>
		</tr>
		<tr>
			<td>Bovine Albumin Fraction V (7.5% solution)</td>
			<td>ThermoFisher Scientific</td>
			<td>15260037</td>
			<td></td>
		</tr>
		<tr>
			<td>Cyclopamine, V. calcifornicum</td>
			<td>Calbiochem</td>
			<td># 239803</td>
			<td></td>
		</tr>
		<tr>
			<td>D (+) Glucose solution (45%)</td>
			<td>Sigma</td>
			<td>G8769</td>
			<td></td>
		</tr>
		<tr>
			<td>Dimethyl sulfoxide (DMSO)</td>
			<td>Sigma Aldrich</td>
			<td>D2438-10mL</td>
			<td></td>
		</tr>
		<tr>
			<td>DMEM/F12</td>
			<td>ThermoFisher Scientific</td>
			<td>11320074</td>
			<td></td>
		</tr>
		<tr>
			<td>Dulbecco&#39;s Phosphate Buffer Saline (DPBS)</td>
			<td>Thermo Fisher Scientific</td>
			<td>14190-144</td>
			<td>Without calcium and magnesium</td>
		</tr>
		<tr>
			<td>Laminin Mouse Protein, Natural</td>
			<td>Thermo Fisher Scientific</td>
			<td>23017015</td>
			<td></td>
		</tr>
		<tr>
			<td>MEM Non-essential aminoacids solutions (100x)</td>
			<td>ThermoFisher Scientific</td>
			<td>11140050</td>
			<td></td>
		</tr>
		<tr>
			<td>N-2 Supplement (100 x)</td>
			<td>ThermoFisher Scientific</td>
			<td>17502001</td>
			<td></td>
		</tr>
		<tr>
			<td>Poly-L-Ornithine</td>
			<td>Merk</td>
			<td>P3655</td>
			<td></td>
		</tr>
		<tr>
			<td>Recombinant Human BMP-4 Protein</td>
			<td>R&#38;D Systems</td>
			<td>314-BP-010</td>
			<td></td>
		</tr>
		<tr>
			<td>Recombinant Human Wnt-3a Protein</td>
			<td>R&#38;D Systems</td>
			<td>5036-WN</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium Pyruvate (100 mM)</td>
			<td>ThermoFisher Scientific</td>
			<td>11360070</td>
			<td></td>
		</tr>
		<tr>
			<td>Soybean Trypsin Inhibitor, powder</td>
			<td>Thermo Fisher Scientific</td>
			<td>17075029</td>
			<td></td>
		</tr>
		<tr>
			<td>Sterile deionized water</td>
			<td>MilliQ</td>
			<td></td>
			<td>MilliQ filter system</td>
		</tr>
		<tr>
			<td>Trypsin EDTA (0.25%)</td>
			<td>Sigma</td>
			<td>T4049-500ML</td>
			<td></td>
		</tr>
		<tr>
			<td>EQUIPMENT FOR CELL CULTURE&#160;</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Adjustable volume pipettes 10, 100, 200, 1000 &#181;L</td>
			<td>Eppendorf</td>
			<td>Various</td>
			<td></td>
		</tr>
		<tr>
			<td>Basement membrane matrix ESC-qualified (Matrigel)</td>
			<td>Corning</td>
			<td>CLS354277-1EA</td>
			<td></td>
		</tr>
		<tr>
			<td>Centrifuge</td>
			<td>Hettich Centrifugen</td>
			<td>Rotina 420R</td>
			<td>5% CO2, 37 &#176;C</td>
		</tr>
		<tr>
			<td>Incubator</td>
			<td>ThermoForma Steri-Cult CO2</td>
			<td>HEPA Class100</td>
			<td></td>
		</tr>
		<tr>
			<td>Stem cell cutting tool 0.190-0.210 mm</td>
			<td>Vitrolife</td>
			<td>14601</td>
			<td></td>
		</tr>
		<tr>
			<td>Sterile tubes</td>
			<td>Sarstedt</td>
			<td>Various</td>
			<td></td>
		</tr>
		<tr>
			<td>Sterile Disposable Glass Pasteur Pipettes 150 mm</td>
			<td>VWR</td>
			<td>612-1701</td>
			<td></td>
		</tr>
		<tr>
			<td>Sterile pipette tips 0.1-1000 &#160;&#181;L</td>
			<td>Biotix VWR</td>
			<td>Various</td>
			<td></td>
		</tr>
		<tr>
			<td>Sterile Serological Pipettes 5, 10, 25, 50 mL</td>
			<td>Costar</td>
			<td>Various</td>
			<td></td>
		</tr>
		<tr>
			<td>T25 flasks Nunc</td>
			<td>ThermoFisher Scientific</td>
			<td>156367</td>
			<td></td>
		</tr>
		<tr>
			<td>IMMUNOHISTOCHEMISTRY</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>488-conjugated AffinityPure Donkey anti-mouse IgG</td>
			<td>Jackson ImmunoReserach</td>
			<td>715-545-151</td>
			<td></td>
		</tr>
		<tr>
			<td>488-conjugated AffinityPure Donkey anti-rabbit IgG</td>
			<td>Jackson ImmunoReserach</td>
			<td>711-545-152</td>
			<td></td>
		</tr>
		<tr>
			<td>488-conjugated AffinityPure Donkey anti-chicken IgG</td>
			<td>Jackson ImmunoReserach</td>
			<td>703-545-155</td>
			<td></td>
		</tr>
		<tr>
			<td>Alexa fluor 647-conjugated Streptavidin</td>
			<td>Jackson ImmunoReserach</td>
			<td>016-600-084</td>
			<td></td>
		</tr>
		<tr>
			<td>Bovine Serum Albumin</td>
			<td>Jackson ImmunoReserach</td>
			<td>001-000-162</td>
			<td></td>
		</tr>
		<tr>
			<td>Chicken anti-GFP</td>
			<td>Merk Millipore</td>
			<td>AB16901</td>
			<td></td>
		</tr>
		<tr>
			<td>Chicken anti-MAP2&#160;</td>
			<td>Abcam</td>
			<td>ab5392</td>
			<td></td>
		</tr>
		<tr>
			<td>Cy3-conjugated AffinityPure Donkey anti-chicken IgG</td>
			<td>Jackson ImmunoReserach</td>
			<td>703-165-155</td>
			<td></td>
		</tr>
		<tr>
			<td>Cy3-conjugated AffinityPure Donkey anti-goat IgG</td>
			<td>Jackson ImmunoReserach</td>
			<td>705-165-147</td>
			<td></td>
		</tr>
		<tr>
			<td>Cy3-conjugated AffinityPure Donkey anti-mouse IgG</td>
			<td>Jackson ImmunoReserach</td>
			<td>715-165-151</td>
			<td></td>
		</tr>
		<tr>
			<td>Diazabicyclooctane (DABCO)</td>
			<td>Sigma Aldrich</td>
			<td>D27802</td>
			<td>Mounting media</td>
		</tr>
		<tr>
			<td>Goat anti-AIF1 (C-terminal)&#160;</td>
			<td>Biorad</td>
			<td>AHP2024</td>
			<td></td>
		</tr>
		<tr>
			<td>Hoechst 33342</td>
			<td>Molecular Probes</td>
			<td></td>
			<td>Nuclear staining</td>
		</tr>
		<tr>
			<td>Mouse anti-MBP&#160;</td>
			<td>BioLegend</td>
			<td>808402</td>
			<td></td>
		</tr>
		<tr>
			<td>Mouse anti-SC123&#160;</td>
			<td>Stem Cells Inc</td>
			<td>AB-123-U-050</td>
			<td></td>
		</tr>
		<tr>
			<td>Normal Donkey Serum</td>
			<td>Merk Millipore</td>
			<td>S30-100</td>
			<td></td>
		</tr>
		<tr>
			<td>Paint brush</td>
			<td>Any suitable</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Paraformaldehyde (PFA)</td>
			<td>Sigma Aldrich</td>
			<td>150127</td>
			<td></td>
		</tr>
		<tr>
			<td>Potassium Phospate Buffer Saline, KPBS (1x)</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>&#160;&#160;&#160;&#160; Distilled water</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>&#160;&#160;&#160;&#160; Potassium dihydrogen Phospate (KH2PO4)</td>
			<td>Merk Millipore</td>
			<td>104873</td>
			<td></td>
		</tr>
		<tr>
			<td>&#160;&#160;&#160;&#160; Potassium phospate dibasic (K2HPO4)</td>
			<td>Sigma Aldrich</td>
			<td>P3786</td>
			<td></td>
		</tr>
		<tr>
			<td>&#160;&#160;&#160;&#160; Sodium chloride (NaCl)</td>
			<td>Sigma Aldrich</td>
			<td>S3014</td>
			<td></td>
		</tr>
		<tr>
			<td>Rabbit anti-NeuN&#160;</td>
			<td>Abcam</td>
			<td>ab104225</td>
			<td></td>
		</tr>
		<tr>
			<td>Rabbit anti-Olig2&#160;</td>
			<td>Abcam</td>
			<td>ab109186</td>
			<td></td>
		</tr>
		<tr>
			<td>Rabbit anti-TMEM119&#160;</td>
			<td>Abcam</td>
			<td>ab185333</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium azide</td>
			<td>Sigma Aldrich</td>
			<td>S2002-5G</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium citrate</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>&#160;&#160;&#160;&#160;&#160;&#160; Distilled water</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>&#160;&#160;&#160;&#160;&#160;&#160; Tri-Sodium Citrate</td>
			<td>Sigma Aldrich</td>
			<td>S1804-500G</td>
			<td></td>
		</tr>
		<tr>
			<td>&#160;&#160;&#160;&#160;&#160;&#160; Tween-20</td>
			<td>Sigma Aldrich</td>
			<td>P1379</td>
			<td></td>
		</tr>
		<tr>
			<td>Triton X-100</td>
			<td>ThermoFisher Scientific</td>
			<td>327371000&#160;</td>
			<td></td>
		</tr>
		<tr>
			<td>EQUIPMENT FOR IMMUNOHISTOCHEMISTRY</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Confocal microscope</td>
			<td>Zeiss</td>
			<td>LSM 780</td>
			<td></td>
		</tr>
		<tr>
			<td>Microscope Slides 76 mm x 26 mm</td>
			<td>VWR</td>
			<td>630-1985</td>
			<td></td>
		</tr>
		<tr>
			<td>Microscope Coverslips 24 mm x 60 mm</td>
			<td>Marienfeld</td>
			<td>107242</td>
			<td></td>
		</tr>
		<tr>
			<td>Microscope Software</td>
			<td>Zeiss</td>
			<td>ZEN Black edition</td>
			<td></td>
		</tr>
		<tr>
			<td>Rubber teat + Glass pipette</td>
			<td>Any suitable</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

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.

Following the described protocol, hACtx tissue from a patient with temporal lobe epilepsy was collected and processed, as explained above. A few slices were fixed after 24 h in culture to study the starting point of the host tissue. The analysis of different neural cell populations such as neurons (expressing NeuN and Map2, Figure 1A), oligodendrocytes (Olig2 and MBP, Figure 1B), and astrocytes (human-specific GFAP, also named STEM123, Figur...

Watch this Scientific Journal Video about Organotypic Cultures of Adult Human Cortex as an Ex vivo Model for Human Stem Cell Transplantation and Validation at JoVE.com

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.

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 ...

Organotypic cultures of human adult cortex are so far the only system for testing stem cell therapies for damaged cortex that allows studying the interaction between human grafted and human host cells. A therapy tested in animal models usually fail when translated to the clinical settings due to the differences between rodent and human cells. Here, we can study grafted cells, survival, differentiation, and functionality in a human-to-human setting.This methodology will help us to understand how the neural circuitry operates in human brain, and also it'll stimulate the translation of this knowledge into the clinical settings to improve the functional recovery after brain damage. Demonstrating the procedure will be Raquel Martinez-Curiel, a PhD student, and Costanza Aretio-Medina, a masters student, both from my lab. To begin, place the culture inserts in a six-well plate using forceps in the cell culture lab under a ventilated hood.Add five milliliters of the human adult cortical medium on the bottom of the insert until it contacts the membrane. Avoid bubble formation and add two milliliters of the medium on top of the insert. Before transferring the tissue slices into the inserts, equilibrate them in the incubator at 37 degrees Celsius and 5%carbon dioxide for at least two hours.Collect the tissue from the patient in the operating room into a container of frozen, bubbled, and crushed cutting solution. Transfer the closed container on ice immediately to the cutting area of the lab. Inspect the tissue, and considering the cortical layer's orientation, locate the best surface to glue it to the vibratome's cutting stage.If needed, cut the uneven surface with the scalpel to place the tissue on the stage for optimal slice orientation. Then, glue the tissue to the stage with tissue adhesive. Place it in the slicing chamber and immediately fill it with cold, bubbled cutting solution.Continue the bubbling during the whole cutting procedure. Now cut coronal or sagittal slices depending on the tissue-to-blade orientation as described in the manuscript. Place the slices in the collection chamber with bubbling cutting solution at room temperature.Once all the tissue has been cut, transfer the slices into a sterile Petri dish with rinsing solution at room temperature to remove excess sucrose from the slices and transport them to the cell culture lab. Next, place the tissue slices individually on top of the wet and submerged inserts. After 24 hours, change the medium to remove any remaining sucrose or other residual substances from the cutting procedure.After two weeks, use human adult cortical medium without gentamycin. Remove the media from the cell culture flask. On day seven of differentiation, detach cortically-primed GFP-lt-NES cells by adding 500 microliters of trypsin and incubate for 5 to 10 minutes at room temperature.Next, add an equal volume of the trypsin inhibitor followed by five milliliters of DDM medium. Resuspend the cells, gently transfer the cell suspension into a 15-milliliter tube, and centrifuge for five minutes at 300 G.Meanwhile, transfer the plate containing the human tissue from the incubator to the hood, and remove two milliliters of media from the top of the insert. At the end of the centrifugation, remove the supernatant, resuspend the cells in a cold, pure, basement membrane matrix, and transfer the pension to a smaller tube.Collect the cell suspension into a cold glass capillary connected to a rubber teat for suction. Inject the cell suspension as tiny drops by stabbing the semi-dry tissue slice at various sites. Allow the gel to solidify at 37 degrees Celsius for 30 minutes.Then, transfer the plate from the incubator back to the hood and carefully add two milliliters of human adult cortical medium to the top of the insert to completely submerge the tissue. The acute human adult cortical tissue showed the presence of neurons, oligodendrocytes, and astrocytes displaying optimal preservation of the tissue. The tissue showed the expression of neuronal markers NeuN and Map2 after two weeks of cell culture.The whole cell patch clamp recording showed that neurons had sustained resting membrane potential and membrane input resistance, comparable to neurons from acute preparations. The cells were slightly less active than in fresh tissue, although most of the cells were able to fire at least one if not multiple action potentials. The acute cortical tissue showed the expression of microglial markers Iba1 and Tmem119.After two weeks in culture, the microglia became less ramified and acquired a more activated morphology than in acute tissue. Four weeks after ex vivo transplantation, the grafted GFP-lt-NES cells exhibited extended neurites with extensive and complex arborizations throughout the whole organotypic culture. Barely any grafted cells survived in poorly preserved tissue.Debris and unspecific labeling of antibodies on dead cells were broadly observed throughout the human slice. In the case of successful transplantation, the cells became functionally active and mature neurons showed repetitive and often spontaneous action potentials. Fast inward sodium, slow outward potassium currents, and a certain level of synaptic activity indicate functional integration of the graft with the host tissue four weeks post-grafting.The faster the human tissue is processed once it is out of the operation room, the higher the viability of the system and the success of the experimental procedure.

organotypic-cultures-adult-human-cortex-as-an-ex-vivo-model-for-human

Research

JoVE Journal

Neuroscience

2.2K visualizações.  Lund University. As culturas organotípicas do córtex adulto humano são até agora o único sistema para testar terapias com células-tronco para o córtex danificado que permite estudar a interação entre células hospedeiras humanas enxertadas e humanas. Uma terapia testada em modelos animais geralmente falha quando traduzida para os ambientes clínicos devido às diferenças entre células de roedores e humanos. Aqui, podemos estudar células enxertadas, sobrevivência, diferenciação e funcionalidade ...