Name: monitoring astrocyte reactivity and proliferation in vitro under ischemic-like conditions
Uploaded: 2017-10-21T13:00:00
Description: Watch this Scientific Journal Video about Monitoring Astrocyte Reactivity and Proliferation in Vitro Under Ischemic-Like Conditions at JoVE.com

The authors want to thank Paola L&#243;pez Pieraldi for the technical assistance. A.H.M. is grateful for the grants 8G12MD007600 and U54-NS083924 that supported this publication. We thank NIH-NIMHD-G12-MD007583 grant for the facility support. D.E.R.A. is grateful for the fellowship provided by NIHNIGMS-R25GM110513.We are grateful for the use of the Common Instrumentation Area and the aid of Dr. Priscila Sanabria for the use of the Optical Imaging Facility of the RCMI program by grant G12MD007583. In addition, we want to thank Jose Padilla for his outstanding role in filming and editing the visual protocol.

Postnatal rats (Sprague Dawley) 1-4 days old are used to isolate cortices. The method of euthanasia is decapitation, as approved by NIH guidelines.
1. Preparation of Instruments and Materials for Surgery
<ol>
	<li>Sterilize instruments in an autoclave (temperature: 121 &#186;C, pressure: 15 psi, time: 30 mins) using a steel box or an instant sealing sterilization pouch. See materials in Table of Materials.</li>
</ol>
2. Complete DMEM Preparation
<ol...

<ol>
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This protocol describes the isolation of astrocytes from rat cortices. In this method, it is critical to decrease contamination with other cellular types such as microglia, oligodendrocytes, and fibroblasts. To reduce the number of microglia, several steps can be taken: changing the media, orbital shaking, and chemical treatments. Once culture purity is confirmed by immunofluorescence using selective cellular markers or for the most prominent cell contaminants, experiments can be performed. For instance, antibody against...

Stroke is defined as &#34;an acute neurological dysfunction of vascular origin with either sudden or rapid development of symptoms and signs, corresponding to the involvement of focal areas in the brain&#34;1,2. There are two types of stroke: hemorrhagic and ischemic. When vascular dysfunction is caused either by an aneurysm or an arteriovenous malfunction, accompanied by weakening with posterior rupture of an artery,&#160;this is termed hemorrhagic stroke3 which, in most cases, leads to death. When a thrombus or an embolus obstructs blood flow, causing a temporary deprivation of oxygen and glucose to a brain region, it is called ischemic stroke4. Failure to nourish cells around the affected area or ischemic core leads to a homeostatic and metabolic imbalance, energetic dysfunction, neuronal death, and inflammation5, which can induce a life-long disability for patients6.
Ischemic stroke is a multifactorial injury involving several types of cells that react and exert their effects at different time points. Many interactions create a difficult environment to study the behavior of individual cells. So, how do we study the contribution of a specific cell type under such a complex environment? An accepted in vitro model of ischemia consists of exposing cells to oxygen and glucose deprivation (OGD), for a certain period, followed by the restoration of cells to a normoxic environment. This system simulates an ischemic stroke followed by blood reperfusion. In this method, cells or tissues are exposed to a glucose-free media in an environment purged of oxygen, using a specialized hypoxic chamber. The OGD incubation time can vary from a few minutes up to 24 h, depending on the hypothesis that wants to be tested. Studies have shown that depending on the times of OGD and normoxic environment, specific phenotypes of stroke (i.e., acute or subchronic) can be achieved. Primary isolated astrocytes, exposed to OGD with posterior restoration to normoxic conditions, is a well-studied cellular model to mimic stroke in vitro7. Using OGD is possible to reveal the independent molecular mechanisms of isolated cells under a stroke-like environment.
As our knowledge of astrocyte biology increases, it has become evident that they are crucial for maintaining synapses and sustaining neural repair, development, and plasticity8. Under normal conditions, astrocytes release and respond to cytokines, chemokines, growth factors and gliotransmitters, keeping metabolic balance and homeostasis within synapses5,9. In acute neuroinflammation, such as ischemic stroke, these cells can become reactive, show a long-term overexpression of Glial Fibrillary Acidic Protein (GFAP), and show hypertrophy in their morphology5,10,11,12. As the ischemic infarct develops, the homeostasis provided by astrocytes becomes affected, regarding normal glutamate uptake, energy metabolism, exchange of active molecules, and antioxidant activity13.
Reactivated astrocytes proliferate around the infarct tissue while leukocytes migrate towards the lesioned area14. Astrocytic proliferation can be measured using markers such as proliferating cell nuclear antigen (PCNA), Ki67, and bromodeoxyuridine (BrdU)15. This proliferative response is generated in a time-dependent manner and it helps forming the glial scar, an array of irreversibly reactive astrocytes along the parenchyma of the damaged site after an injury9. One of the initial functions of this scar is to limit the immune cell extravasation from this area. However, studies have shown that the scar becomes a physical impediment for axons to extend, as they release molecules inhibiting axonal growth, and create a physical barrier preventing axons from extending around the injured area16. Nevertheless, there is scientific evidence showing that after a spinal cord injury, completely preventing glial scar formation can impair the regeneration of axons17. Thus, the context in which the specific astrocytic response is measured, must be considered upon the framework of the injury studied.
The presented methodology can be applied to study the individualized function of astrocytes after oxygen glucose deprivation and it can be modified depending on the questions that the investigator wants to answer. For example, besides the morphological change and the markers expressed at different OGD times, the supernatants from astrocytes exposed to OGD can be further analyzed to identify soluble factors released by these cells, or used as a conditioned media to assess its effect in other brain cells. This approach enables studies on astrocyte reactivity that could lead to the elucidation of the factors that govern and modulate their response in an ischemic-stroke scenario.

<table border="0" cellpadding="0" cellspacing="0" width="933">
	<tbody>
		<tr height="34">
			<td height="34" style="height:34px;width:395px;">Instruments for Surgery - Step 1</td>
			<td style="width:167px;"></td>
			<td style="width:119px;"></td>
			<td style="width:253px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">Operating scissor 5.5&#8221;</td>
			<td>Roboz Company</td>
			<td style="width:119px;">RS-6812</td>
			<td style="width:253px;">Tools used to decapitate the rats.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:395px;">Curved forceps 7&#8221;&#160;</td>
			<td>Roboz Company</td>
			<td>RS-5271</td>
			<td style="width:253px;">Holds the skin of the rat while the skull is removed.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:395px;">Micro-dissecting scissors 4&#8221;&#160;</td>
			<td>Roboz Company</td>
			<td>RS-5882</td>
			<td style="width:253px;">Cuts both the skin and skull of the rat.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:395px;">Micro-dissecting forceps 4&#8221; angled, fine sharp&#160;</td>
			<td>Roboz Company</td>
			<td>RS-5095</td>
			<td style="width:253px;">Holds the skin of the rat while the skull is removed.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">Micro-dissecting forceps 4&#8221; slightly curved 0.8</td>
			<td>Roboz Company</td>
			<td>RS-5135</td>
			<td>Tool used to separate cortices.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">Micro-dissecting tweezers</td>
			<td>Roboz Company</td>
			<td>RS-4972</td>
			<td>Peels brain meninges.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:395px;">Dissection microscope</td>
			<td style="width:167px;">Olympus</td>
			<td style="width:119px;">SZX16</td>
			<td style="width:253px;">Important for removing the meninge from the cortices.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">DMEM Preparation - step 2</td>
			<td style="width:167px;"></td>
			<td style="width:119px;"></td>
			<td style="width:253px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">Dulbecco&#8217;s Modified Eagle&#8217;s Medium (DMEM)</td>
			<td>GibCo. Company</td>
			<td>11995-065</td>
			<td style="width:253px;">Supports the growth of cells.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">Sodium bicarbonate</td>
			<td>Sigma-Aldrich Company</td>
			<td>S7277</td>
			<td style="width:253px;">Supplement for the cell culture media.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">Fetal bovine serum (FBS)</td>
			<td>GibCo. Company</td>
			<td>10437-010</td>
			<td style="width:253px;">Serum-supplement for the cell culture.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">Penicillin-Streptomycin&#160;</td>
			<td>GibCo. Company</td>
			<td>15140-148</td>
			<td style="width:253px;">Inhibits the growth of bacterias in the cell culture.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Filter System 1L with 0.22um pore</td>
			<td>Corning</td>
			<td>431098</td>
			<td></td>
		</tr>
		<tr height="34">
			<td height="34" style="height:34px;">Astrocyte culture - step 3</td>
			<td></td>
			<td></td>
			<td style="width:253px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:395px;">Serological pipets 5mL</td>
			<td style="width:167px;">VWR</td>
			<td style="width:119px;">89130-896</td>
			<td style="width:253px;">To pipette DMEM to containers with cells.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:395px;">Serological pipets 10mL</td>
			<td style="width:167px;">VWR</td>
			<td style="width:119px;">89130-898</td>
			<td style="width:253px;">To pipette DMEM to containers with cells.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:395px;">Serological pipets 25mL</td>
			<td style="width:167px;">VWR</td>
			<td style="width:119px;">89130-900</td>
			<td style="width:253px;">To pipette DMEM to containers with cells.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:395px;">Centrifuge conical tube 15mL</td>
			<td style="width:167px;">Santa Cruz Biotechnology</td>
			<td style="width:119px;">sc-200250</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">Safe-lock tube 1.5mL</td>
			<td style="width:167px;">Eppendorf</td>
			<td style="width:119px;">022363204</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:395px;">Barrier Tips 200 uL</td>
			<td style="width:167px;">Santa Cruz Biotechnology</td>
			<td style="width:119px;">sc-201725</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:395px;">Barrier Tips 1 mL</td>
			<td style="width:167px;">Santa Cruz Biotechnology</td>
			<td>sc-201727</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">Biohazard Orange Bag 14 x 19&#34;</td>
			<td>VWR</td>
			<td>14220-048</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">60mm petri dishes</td>
			<td>Falcon</td>
			<td>351007</td>
			<td style="width:253px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">Sterile gauze pads</td>
			<td>Honeywell Safety</td>
			<td>89133-086</td>
			<td style="width:253px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">Stomacher 80 Biomaster</td>
			<td style="width:167px;">Sewar Lab System</td>
			<td style="width:119px;">030010019</td>
			<td style="width:253px;">Triturate the brain tissue.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:395px;">Stomacher 80 Blender Sterile Bags</td>
			<td style="width:167px;">Sewar Lab System</td>
			<td style="width:119px;">BA6040</td>
			<td style="width:253px;">Sterile bag for the stomacher cell homogenizer.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">Beaker 400mL</td>
			<td style="width:167px;">Pyrex</td>
			<td style="width:119px;">1000</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:395px;">Sterile cell dissociation sieve, mesh #60&#160;</td>
			<td>Sigma-Aldrich Company</td>
			<td>S1020</td>
			<td style="width:253px;">To obtain a uniform single cell suspension.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:395px;">Sterile cell dissociation sieve, mesh #100</td>
			<td>Sigma-Aldrich Company</td>
			<td>S3895</td>
			<td style="width:253px;">To obtain a uniform single cell suspension.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:395px;">Invert phase microscope</td>
			<td style="width:167px;">Nikon</td>
			<td style="width:119px;">Eclypse Ti-S</td>
			<td style="width:253px;">Verify cells for contamination or abnormal cell growth.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">75cm2 sterile flasks</td>
			<td>Falcon</td>
			<td>353136</td>
			<td style="width:253px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">Multi-well plate</td>
			<td>Falcon</td>
			<td>353046</td>
			<td style="width:253px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">Micro cover glasses (coverslips), 18mm, round</td>
			<td>VWR</td>
			<td>48380-046</td>
			<td style="width:253px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">Bright-Line hemacytometer</td>
			<td style="width:167px;">Sigma-Aldrich Company</td>
			<td style="width:119px;">Z359629</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">Pasteur pipettes</td>
			<td style="width:167px;">Fisher Scientific</td>
			<td style="width:119px;">13-678-20D</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">Ethyl alcohol&#160;</td>
			<td style="width:167px;">Sigma-Aldrich Company</td>
			<td style="width:119px;">E7023</td>
			<td></td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;">L-leucine methyl ester hydrochloride 98% (LME)</td>
			<td>Sigma-Aldrich Company</td>
			<td>L1002</td>
			<td style="width:253px;">Promotes the elimination of microglia cells in the primary cortical astrocyte cultutre.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Cytosine &#946;-D-arabinofuranoside (Ara-C)</td>
			<td>Sigma-Aldrich Company</td>
			<td>C1768</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Poly-D-Lysine Hydrobromide, mol wt 70,000-150,000</td>
			<td>Sigma-Aldrich Company</td>
			<td>P0899</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Trypsin/EDTA</td>
			<td>GibCo. Company</td>
			<td>15400-054</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Trypan Blue</td>
			<td>Sigma-Aldrich Company</td>
			<td>T8154</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Phosphate buffer saline (PBS) tablets</td>
			<td>Calbiochem</td>
			<td>524650</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">Sterile Water</td>
			<td style="width:167px;">Sigma-Aldrich Company</td>
			<td style="width:119px;">W3500</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">&#160;OGD Medium Preparation - step 5</td>
			<td style="width:167px;"></td>
			<td style="width:119px;"></td>
			<td style="width:253px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">Centrifuge conical tube 50 mL</td>
			<td style="width:167px;">VWR</td>
			<td style="width:119px;">89039-658</td>
			<td style="width:253px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Dulbecco&#8217;s modified Eagle&#8217;s medium-free glucose</td>
			<td>Sigma-Aldrich Company</td>
			<td>D5030</td>
			<td style="width:253px;">Supports the growth of cells.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">Sodium bicarbonate</td>
			<td>Sigma-Aldrich Company</td>
			<td>S7277</td>
			<td style="width:253px;">Supplement for the cell culture media.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">Penicillin-Streptomycin&#160;</td>
			<td>GibCo. Company</td>
			<td>15140-148</td>
			<td style="width:253px;">Inhibits the growth of bacterias in the cell culture.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">200mM&#160; L-glutamine&#160;</td>
			<td>GibCo. Company</td>
			<td>25030-081</td>
			<td style="width:253px;">Amino acid that supplements the growth of cells.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Phospahet buffer saline (PBS) tablets</td>
			<td>Calbiochem</td>
			<td>524650</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">Filter System 50mL with 0.22um pore</td>
			<td>Corning</td>
			<td>430320</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">Centrifuge conical tube 50 mL</td>
			<td style="width:167px;">VWR</td>
			<td style="width:119px;">89039-658</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Single Flow Meter&#160;</td>
			<td>Billups-Rothenberg</td>
			<td>SMF3001</td>
			<td style="width:253px;">Measure gas flow in oxygen purge.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">Hypoxia Incubator Chamber&#160;</td>
			<td>StemCell</td>
			<td>27310</td>
			<td style="width:253px;">Generates a hypoxic environment for the cell culture.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Traceable Dissolved Oxygen Meter</td>
			<td>VWR</td>
			<td>21800-022</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">95% N2/ 5% CO2 Gas Mixture</td>
			<td>Linde</td>
			<td></td>
			<td style="width:253px;">Purges the environment of oxygen.</td>
		</tr>
		<tr height="32">
			<td height="32" style="height:32px;width:395px;">primary astrocyte immunofluorescence - step 6</td>
			<td style="width:167px;"></td>
			<td style="width:119px;"></td>
			<td style="width:253px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Phosphate buffer saline (PBS) tablets</td>
			<td>Calbiochem</td>
			<td>524650</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">Formaline Solution Neutral Buffer 10%</td>
			<td style="width:167px;">Sigma-Aldrich</td>
			<td style="width:119px;">HT501128</td>
			<td style="width:253px;">Solution used to fix cells.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">Methanol&#160;</td>
			<td style="width:167px;">Fisher</td>
			<td style="width:119px;">A4544</td>
			<td style="width:253px;">Solution used to fix cells.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">Non-ionic surfactant (Triton X-100)</td>
			<td style="width:167px;">Sigma-Aldrich</td>
			<td style="width:119px;">T8787</td>
			<td style="width:253px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">Fetal bovine serum (FBS)</td>
			<td>GibCo. Company</td>
			<td>10437-010</td>
			<td style="width:253px;">Serum-supplement for the cell culture.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">Anti-NeuN</td>
			<td>Cell Signaling</td>
			<td>24307</td>
			<td style="width:253px;">Detects mature neurons, serves to validate the astrocytic culture.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Anti-PCNA</td>
			<td>Cell Signaling</td>
			<td>2586</td>
			<td style="width:253px;">Detects proliferating cells.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Propidium Iodide (PI)</td>
			<td>Sigma-Aldrich Company</td>
			<td>P4170</td>
			<td style="width:253px;">Apoptosis staining.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Anti-Olig1</td>
			<td>Abcam</td>
			<td>AB68105</td>
			<td style="width:253px;">Detects mature oligodendrocytes.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Anti-Iba1+</td>
			<td>Wako</td>
			<td>016-20001</td>
			<td style="width:253px;">Detects microglial cells.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:395px;">Anti-GFAP Conjugated with Cy3&#160;</td>
			<td>Sigma-Aldrich Company</td>
			<td>C9205</td>
			<td style="width:253px;">Detects reactive astrocytes in the treated cells.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:395px;">Alexa Fluor 488</td>
			<td style="width:167px;">Molecular Probe Life Technology</td>
			<td style="width:119px;">A1101</td>
			<td style="width:253px;">Anti-Mouse Secondary Antibody</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:395px;">Alexa Fluor 555</td>
			<td style="width:167px;">Molecular Probe Life Technology</td>
			<td style="width:119px;">A21428</td>
			<td style="width:253px;">Anti-Rabbit Secondary Antibody</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">4&#8217;,6&#8217;-diamidino-2-phenylindole (DAPI)</td>
			<td style="width:167px;">Sigma-Aldrich Company</td>
			<td style="width:119px;">D9542</td>
			<td style="width:253px;">Nuclear staining</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">Confocal microscope</td>
			<td style="width:167px;">Olympus</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

monitoring astrocyte reactivity and proliferation in vitro under ischemic-like conditions

Ischemic stroke is a complex brain injury caused by a thrombus or embolus obstructing blood flow to parts of the brain. This leads to deprivation of oxygen and glucose, which causes energy failure and neuronal death. After an ischemic stroke insult, astrocytes become reactive and proliferate around the injury site as it develops. Under this scenario, it is difficult to study the specific contribution of astrocytes to the brain region exposed to ischemia. Therefore, this article introduces a methodology to study primary astrocyte reactivity and proliferation under an in vitro model of an ischemia-like environment, called oxygen glucose deprivation (OGD). Astrocytes were isolated from 1-4 day-old neonatal rats and the number of non-specific astrocytic cells was assessed using astrocyte selective marker Glial Fibrillary Acidic Protein (GFAP) and nuclear staining. The period in which astrocytes are subjected to the OGD condition can be customized, as well as the percentage of oxygen they are exposed to. This flexibility allows scientists to characterize the duration of the ischemic-like condition in different groups of cells in vitro. This article discusses the timeframes of OGD that induce astrocyte reactivity, hypertrophic morphology, and proliferation as measured by immunofluorescence using Proliferating Cell Nuclear Antigen (PCNA). Besides proliferation, astrocytes undergo energy and oxidative stress, and respond to OGD by releasing soluble factors into the cell medium. This medium can be collected and used to analyze the effects of molecules released by astrocytes in primary neuronal cultures without cell-to-cell interaction. In summary, this primary cell culture model can be efficiently used to understand the role of isolated astrocytes upon injury.

One of the main concerns of primary astrocytic culture is the presence of other cells such as neurons, oligodendrocytes, fibroblasts, and microglia. In Figure 1, isolated cells from rat cortices had media changes every 3 days and were either untreated or treated with added LME for 1 h. 24 h later, cells were immunostained for GFAP and counterstained with DAPI. Untreated cells showed an average of 39% non-GFAP positive cells, while LME-treated cells showed 8%....

Watch this Scientific Journal Video about Monitoring Astrocyte Reactivity and Proliferation in Vitro Under Ischemic-Like Conditions at JoVE.com

Monitoring Astrocyte Reactivity and Proliferation in Vitro Under Ischemic-Like Conditions

Ischemic stroke is a complex event in which the specific contribution of astrocytes to the affected brain region exposed to oxygen glucose deprivation (OGD) is difficult to study. This article introduces a methodology to obtain isolated astrocytes and study their reactivity and proliferation under OGD conditions.

Monitoring Astrocyte Reactivity and Proliferation in Vitro Under Ischemic-Like Conditions

Ischemic stroke is a complex brain injury caused by a thrombus or embolus obstructing blood flow to parts of the brain. This leads to deprivation of ...

The following protocol is intended to show the isolation of a primary astrocytes from brains of pup rats to perform oxygen glucose deprivation or OGD. Exposure of purified astrocytes, to oxygen glucose deprived environment is a module that allows us to test the reaction to some of the conditions found in ischemic strokes. Methodical changes, after exposure to oxygen glucose deprivation can be observed and measured using selective astrocyte markers such as GFAP.In summary, these isolated cells exposed to ischemic-like conditions can be used to test new part ways activated in hypoxic conditions and other drugs that protect against ischemic stroke. In this part of the protocol astrocytes will be isolated from pup rat cortices. The purpose of this procedure is to obtain a primary astrocytic cell culture to perform oxygen glucose deprivation experiments.The materials for this procedure are the following, Autoclave all materials before using them in this procedure. And expose hood to at least 20 minutes of UV lights before starting the protocol. To begin this procedure, pipet three to five milliliters of complete DME media in each plate.It will be divided as following, one for each mouse brain, two for all of the cortices, and three will be for all of the cortices without the meninges. Decapitate a pup after disinfecting with 70%ethanol. Make an incision starting from the back of the head towards the nose.Remove skull with curved forcep and gently scrape out the cerebellum exposing the cortices. Remove the exposed brains with a pair of tweezers and place the brain in the first petri dish with media. Repeat these steps for all of the other pups.Separate the cerebral hemispheres by gently dividing along the midline fissure with the sharp end of the micro dissecting forceps. Peel the cortices by removing the white matter and hippocampus using the tweezers with a pinching movement, leaving them behind. Transfer the peel cortices to the petri dish labeled number two.Repeat the procedure for all the brains combining all the dissected cortices in the petri dish. Gently shake the dish to equally distribute the media between all the cortices. Use the dissection microscope to identify the meninges lining the peeled cortices.Meninges are a very thin transparent layer that can be identified by searching for the small red capillaries surrounding the tissue. Carefully inspect and remove the meninges lining the cortices and gently peel them off from the individual cortical lobes using fine tweezers on both sides of each cortex. Place the clean cortices into a new petri dish labeled number three.For tissue dissociation using the stomach or blender method, pour the clean, peeled cortices and the media from the petri dish into a sterile blender bag. And add enough media to bring the total volume of the bag to five milliliters. Place the bag into the stomacher 80 leaving approximately two centimeters of the bag visible above the closed door.The cell dissociation in this instrument is done after 2.5 minutes at high speed. Alternatively, tissue dissociation can be made by closing the sterile bag and gently pounding the tissue with a beaker in the hood until tissue particles have become a fine suspension. Make sure to use a cloth in between bag and beaker to avoid friction and breaking the bag.Pour the cell suspension into the center of sleeve with a mesh number 60. Pour the filtered cells into the middle of a mesh number 100 allowing it to filter by gravity. Pour the filtered cell suspension into a conical 15 milliliter tube.Center fuge the cell suspension at 200 times G in a center fuge preferably with a swing bucket router for five minutes. Remove the supernatant and discard in a beaker. Add complete fresh media to the cell palette.Using a serological pipet resuspend and dissociate the palette of cells in a maximum of five milliliter of medium. Add the desired amount of cell suspension on a flask and complete with media. Add the resuspended palette into the flask with medium.Distribute cells evenly throughout the flask and place them in an incubator at 37 degrees Celsius with 5%carbon dioxide. Remember to change the media every three days. The following methodology is intended to deprive cells of oxygen and glucose in a controlled environment.The purpose of this model is to study the response of astrocytes in an ischemic-like stroke condition. The materials used for this procedure are, Purge the glucose-free medium by inserting a serological pipet connected to the gas system. Bubble the solution with the gas mixture for 10 minutes at a flow of 10 to 15 litters per minute.After the 10 minutes are done, adjust the pH of the OGD medium to 7.4. Filter the purged glucose-free medium using the 50 milliliter tube filter system. It is important to always make fresh OGD medium for every experiment.This will ensure that the medium is purged of oxygen. Remove astrocyte media and wash with cellular PBS two times to remove glucose from the cells. Add the OGD medium to the wells.Place the multi well dish with the lid open inside the hypoxia chamber. Connect the gas mixture to the entrance valve and leave the exit valve open. Flush the chamber with the gas mixture at 10 to 15 litter per minute, for five to seven minutes.Stop the gas flow and first close the clamp on the exit valve. Then, close the clamp on the gas entrance valve tubing. Place the hypoxic chamber into the cell culture incubator at 37 degrees Celsius for the desired time in OGD.After incubation time is over, aspirate the OGD media and carefully add complete DMEM to the cells for the normoxic condition. Return the cells to the culture incubator for zero 24 and 48 hours of normoxic conditions. This protocol describes the isolation of astrocytes from neonatal rat cortices.After validating the purity of the primary cultures OGD experiments were performed. In this ischemic-like model, glucose and oxygen deprivation induced a more phological change that was monitored by the immunofluorescence using astrocytic markers such as GFAP or proliferation markers such as PCNA. One of the advantages of this model is that is allows us to study a specific cell type response.Although the limitation in this technique is the lack of cell to cell interaction due to the isolation of astrocytes. One of the possible ways to overcome this limitation, is to expose astrocytes to condition media from other cells types or a co-culture. In summary, the oxygen glucose deprivation method in an isolated cell system, allows us to directly test the effects of different neural protective or neurotoxic molecules.Also, it is a valid tool to study astrocyte biology. Finally, this model sets a strong basis to study developmental drugs in experimental conditions using in vivo models.

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Determining Cell-surface Expression and Endocytic Rate of Proteins in Primary Astrocyte Cultures Using Biotinylation

Cell-surface proteins mediate a wide array of functions. In many cases, their activity is regulated by endocytic processes that modulate their levels at ...

A Novel In Vitro Live-imaging Assay of Astrocyte-mediated Phagocytosis Using pH Indicator-conjugated Synaptosomes

A Novel In Vitro Live-imaging Assay of Astrocyte-mediated Phagocytosis Using pH Indicator-conjugated Synaptosomes

Astrocytes are the major cell type in the brain and directly contact synapses and blood vessels. Although microglial cells have been considered the major ...

Diffuse Reflectance Spectroscopy: Getting the Capillary Refill Test Under One's Thumb

The capillary refill test was introduced in 1947 to help estimate circulatory status in critically ill patients. Guidelines commonly state that refill ...

Levator Auris Longus Preparation for Examination of Mammalian Neuromuscular Transmission Under Voltage Clamp Conditions

Levator Auris Longus Preparation for Examination of Mammalian Neuromuscular Transmission Under Voltage Clamp Conditions

This protocol describes a technique to record synaptic transmission from the neuromuscular junction under current-clamp and voltage-clamp conditions. An ...

Real-time In Vitro Monitoring of Odorant Receptor Activation by an Odorant in the Vapor Phase

Olfactory perception begins with the interaction of odorants with odorant receptors (OR) expressed by olfactory sensory neurons (OSN). Odor recognition ...

Visualizing Astrocyte Morphology Using Lucifer Yellow Iontophoresis

Astrocytes are essential components of neural circuits. They tile the entire central nervous system (CNS) and are involved in a variety of functions, ...