We would like to thank members of the Tsirka lab for their advice and helpful comments. This work was supported by R01NS42168 to SET, 12PRE12060489 to RB, an NSF-3MT IGERT and a Turner Dissertation fellowship to LT, and NSF-3MT IGERT to JCN.

1. Dissection (Day 0)
<ol>
	<li>Induce anesthesia to p0-2 mouse pups with hypothermia. Wipe the heads of the pups with a Kimwipe soaked in 70% ethanol to disinfect the tissue.</li>
	<li>Remove the heads with a pair of scissors, using 4 pups per 10 cm culture plate. Place the heads in a petri dish containing ice-cold Hank's buffer.</li>
	<li>Anchor the heads using curved forceps through the eye sockets and carefully remove the skin covering the skull with straight microforceps.</li>
	<li>Remove the cranial bones with st...

<ol>
	<li>Ransohoff, R. M., Perry, V. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microglial+Physiology:+Unique+Stimuli,+Specialized+Responses.">Microglial Physiology: Unique Stimuli, Specialized Responses.</a> Ann. Rev. Immunol. 27, 119-145 (2009).</li><li>Ginhoux, F., Greter, M., Leboeuf, M., Nandi, S., See, P., Gokhan, S., Mehler, M., Conway, S., Ng, L., Stanley, E., Samokhavalov, I., Merad, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fate+mapping+analysis+reveals+that+adult+microglia+derive+from+primitive+macrophages.">Fate mapping analysis reveals that adult microglia derive from primitive macrophages.</a> Science. 330, (2010).</li><li>Kraft, A. D., Harry, G. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Features+of+microglia+and+neuroinflammation+relevant+to+environmental+exposure+and+neurotoxicity.">Features of microglia and neuroinflammation relevant to environmental exposure and neurotoxicity.</a> Int. J. Env. Res. Pub. Health. 8, 2980-3018 (2011).</li><li>Sierra, A., Encinas, J. M., Deudero, J., Chancey, J., Enikolopov, G., Overstreet-Wadiche, L., Tsirka, S., Maletic-Savatic, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microglia+shape+adult+hippocampal+neurogenesis+through+apoptosis-coupled+phagocytosis.">Microglia shape adult hippocampal neurogenesis through apoptosis-coupled phagocytosis.</a> Cell Stem Cell. 7, 483-495 (2010).</li><li>Emmetsberger, J., Tsirka, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microglial+inhibitory+factor+(MIF/TKP)+mitigates+secondary+damage+following+spinal+cord+injury.">Microglial inhibitory factor (MIF/TKP) mitigates secondary damage following spinal cord injury.</a> Neurobiol. Dis. 47, 295-309 (2012).</li><li>Gao, Z., Tsirka, S. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Animal+Models+of+MS+Reveal+Multiple+Roles+of+Microglia+in+Disease+Pathogenesis.">Animal Models of MS Reveal Multiple Roles of Microglia in Disease Pathogenesis.</a> Neurol Res. Int. , 383087 (2011).</li><li>Beggs, S., Trang, T., Salter, M. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=P2X4R++microglia+drive+neuropathic+pain.">P2X4R+ microglia drive neuropathic pain.</a> Nature Neurosci. 15, 1068-1073 (2012).</li><li>Olson, J. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Immune+response+by+microglia+in+the+spinal+cord.">Immune response by microglia in the spinal cord.</a> Ann. N.Y. Acad. Sci. 1198, 271-278 (2010).</li><li>Batchelor, P. E., Tan, S., Wills, T. E., Porritt, M. J., Howells, D. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+of+inflammation+in+the+brain+and+spinal+cord+following+mechanical+injury.">Comparison of inflammation in the brain and spinal cord following mechanical injury.</a> J. Neurotrauma. 25, 1217-1225 (2008).</li><li>Schell, J. B., Crane, C. A., Smith, M. F., Roberts, M. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Differential+ex+vivo+nitric+oxide+production+by+acutely+isolated+neonatal+and+adult+microglia.">Differential ex vivo nitric oxide production by acutely isolated neonatal and adult microglia.</a> J. Neuroimmunol. 189, 75-87 (2007).</li><li>Brannan, C. A., Roberts, M. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Resident+microglia+from+adult+mice+are+refractory+to+nitric+oxide-inducing+stimuli+due+to+impaired+NOS2+gene+expression.">Resident microglia from adult mice are refractory to nitric oxide-inducing stimuli due to impaired NOS2 gene expression.</a> Glia. 48, 120-131 (2004).</li><li>Tamashiro, T. T., Dalgard, C. L., Byrnes, K. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Primary+microglia+isolation+from+mixed+glial+cell+cultures+of+neonatal+rat+brain+tissue.">Primary microglia isolation from mixed glial cell cultures of neonatal rat brain tissue.</a> J. Vis. Exp. (66), e3814 (2012).</li><li>Yip, P. K., Kaan, T. K., Fenesan, D., Malcangio, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+isolation+and+culture+of+primary+microglia+from+adult+mouse+spinal+cord.">Rapid isolation and culture of primary microglia from adult mouse spinal cord.</a> J. Neurosci. Methods. 183, 223-237 (2009).</li><li>Ponomarev, E. D., Novikova, M., Maresz, K., Shriver, L. P., Dittel, B. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+of+a+culture+system+that+supports+adult+microglial+cell+proliferation+and+maintenance+in+the+resting+state.">Development of a culture system that supports adult microglial cell proliferation and maintenance in the resting state.</a> J. Immunol. Meth. 300, 32-46 (2005).</li><li>Ji, K., Akgul, G., Wollmuth, L. P., Tsirka, S. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microglia+actively+regulate+the+number+of+functional+synapses.">Microglia actively regulate the number of functional synapses.</a> PLoS One. 8, e56293 (2013).</li><li>Tremblay, M. -. &. #. 2. 0. 0. ;., Majewska, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+role+for+microglia+in+synaptic+plasticity.">A role for microglia in synaptic plasticity.</a> Comm. Integr. Biol. 4, 220-222 (2011).</li><li>DeWitt, D. A., Perry, G., Cohen, M., Doller, C., Silver, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Astrocytes+regulate+microglial+phagocytosis+of+senile+plaque+cores+of+Alzheimer's+disease.">Astrocytes regulate microglial phagocytosis of senile plaque cores of Alzheimer's disease.</a> Expt. Neurol. 149, 329-340 (1998).</li><li>Aloisi, F., Penna, G., Cerase, J., Men&#233;ndez Iglesias, B., Adorini, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=IL-12+production+by+central+nervous+system+microglia+is+inhibited+by+astrocytes.">IL-12 production by central nervous system microglia is inhibited by astrocytes.</a> J. Immunol. 159, 1604-1612 (1997).</li><li>Min, K. -. J., Yang, M. -. S., Kim, S. -. U., Jou, I., Joe, E. -. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Astrocytes+induce+hemeoxygenase-1+expression+in+microglia:+a+feasible+mechanism+for+preventing+excessive+brain+inflammation.">Astrocytes induce hemeoxygenase-1 expression in microglia: a feasible mechanism for preventing excessive brain inflammation.</a> J. Neurosci. 26, 1880-1887 (2006).</li><li>Sasmono, R., Oceandy, D., Pollard, J., Tong, W., Pavli, P., Wainwright, B., Ostrowski, M., Himes, S., Hume, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+macrophage+colony-stimulating+factor+receptor-green+fluorescent+protein+transgene+is+expressed+throughout+the+mononuclear+phagocyte+system+of+the+mouse.">A macrophage colony-stimulating factor receptor-green fluorescent protein transgene is expressed throughout the mononuclear phagocyte system of the mouse.</a> Blood. 101, 1155-1163 (2003).</li><li>Ekdahl, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microglial+activation+-+tuning+and+pruning+adult+neurogenesis.">Microglial activation - tuning and pruning adult neurogenesis.</a> Front Pharmacol. 3, 14 (2012).</li><li>Sierra, A., Gottfried-Blackmore, A., McEwen, B., Bulloch, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microglia+derived+from+aging+mice+exhibit+an+altered+inflammatory+profile.">Microglia derived from aging mice exhibit an altered inflammatory profile.</a> Glia. 55, 412-424 (2007).</li></ol>

Microglia modulate CNS normal functioning as well as inflammatory responses to various pathologies. Functional synaptic remodeling by microglia has been implicated in the maintenance of normal brain homeostasis 15. During the neurogenic cascade they participate in the clearance of neural progenitor cells from the dentate gyrus of the hippocampus 4, 16. Therefore, it is necessary to develop a culture system in which to study neonatal and adult microglia, which will cover the vast swath of deve...

Microglia are the resident immune cells of the CNS, most closely resembling peripheral macrophages in structure and function 1. It has recently been demonstrated that postnatal microglial cells derive from primitive myeloid progenitors and are generated before the eighth day of embryogenesis, upending the previous notion that postnatal hematopoietic progenitors are the source of microglia in the adult brain 2. They play key roles in several neurological diseases and can quickly respond to infection or injury by releasing pro-inflammatory or anti-inflammatory cytokines 3. Thus microglia encompass a standalone unit in the CNS that can be manipulated to affect disease progression. Developing robust and reproducible methods to isolate and culture neonatal or adult microglial cells is important to future studies.
Microglia are known to be critical players in a number of brain pathologies. More recently, roles are emerging for the cells in normal brain development and function as microglia phagocytose excess neural progenitor cells from the dentate gyrus of the hippocampus 1, 4. Microglia can also modulate several neurological conditions that affect the spinal cord, such as MS, neuropathic pain, and spinal cord injury 5-7. Spinal cord microglia react differently compared to brain microglia in response to activation signals 8, 9, probably due to differences in the local environment. Thus it is important to establish an appropriate in vitro system to culture and study spinal cord microglia. Neonatal microglia produce significantly more of the pro-inflammatory cytokine nitric oxide compared to adult cells after in vitro stimulation with IFN-&gamma; or TNF-a10,11 further highlighting the need to use adult cells to study microglia in the context of certain diseases.
The protocol we employ in the lab to culture neonatal microglia is a variation of recent methods which utilize shaking of mixed glial cultures in an effort to remove the microglia from the surface of the cell culture flask 12. We also describe a method to culture microglia from the adult mouse spinal cord based on a protocol first described by Yip, et al13. This method provides a quicker way to culture adult cells compared to other available protocols 14. The resulting preparation is 70% microglia; the remaining percentage is composed of astrocytes. Although the purity of our culture is lower compared to other published methods 13, this culture system is useful for exploring the microglial in culture response to various activating stimuli as well as for the study of diseases that mainly affect the spinal cord and in which a strong inflammatory response is a main feature.
All the protocols described have been approved by the Stony Brook University IACUC.

<table border="1">
		<tbody>
		 <tr>
			<td>Name of the reagent</td>
			<td>Company</td>
			<td>Catalogue number</td>
			<td>Comments (optional)</td>
		 </tr>
		 <tr>
			<td>EDTA, 5mM</td>
			<td>Invitrogen</td>
			<td>15567-028</td>
			<td></td>
		 </tr>
		 <tr>
			<td>Lidocaine, 60mM</td>
			<td>Sigma</td>
			<td>L-5647</td>
			<td></td>
		 </tr>
		 <tr>
			<td>Trypan Blue</td>
			<td>Sigma</td>
			<td>T8154</td>
			<td></td>
		 </tr>
		 <tr>
			<td>Trypsin/EDTA</td>
			<td>Cellgro</td>
			<td>25-052-CI</td>
			<td></td>
		 </tr>
		 <tr>
			<td>DMEM, 1X</td>
			<td>Cellgro</td>
			<td>10-017</td>
			<td></td>
		 </tr>
		 <tr>
			<td>Sodium Pyruvate</td>
			<td>Cellgro</td>
			<td>25-000-Cl</td>
			<td></td>
		 </tr>
		 <tr>
			<td>Gentamycin Sulfate</td>
			<td>Biowittaker</td>
			<td>17-518Z</td>
			<td></td>
		 </tr>
		 <tr>
			<td>35 x 10mm tissue culture dish</td>
			<td>Falcon</td>
			<td>353001</td>
			<td></td>
		 </tr>
		 <tr>
			<td>Poly-D-Lysine, 100 &mu;g/ml</td>
			<td></td>
			<td></td>
			<td>Dilute 1:20</td>
		 </tr>
		 <tr>
			<td>HBSS, 1X</td>
			<td>Cellgro</td>
			<td>20-023-CV</td>
			<td></td>
		 </tr>
		</tbody>
 </table>

culturing microglia from the neonatal and adult central nervous system

Microglia are the resident macrophage-like cells of the central nervous system (CNS) and, as such, have critically important roles in physiological and pathological processes such as CNS maturation in development, multiple sclerosis, and spinal cord injury. Microglia can be activated and recruited to action by neuronal injury or stimulation, such as axonal damage seen in MS or ischemic brain trauma resulting from stroke. These immunocompetent members of the CNS are also thought to have roles in synaptic plasticity under non-pathological conditions. We employ protocols for culturing microglia from the neonatal and adult tissues that are aimed to maximize the viable cell numbers while minimizing confounding variables, such as the presence of other CNS cell types and cell culture debris. We utilize large and easily discernable CNS components (e.g. cortex, spinal cord segments), which makes the entire process feasible and reproducible. The use of adult cells is a suitable alternative to the use of neonatal brain microglia, as many pathologies studied mainly affect the postnatal spinal cord. These culture systems are also useful for directly testing the effect of compounds that may either inhibit or promote microglial activation. Since microglial activation can shape the outcomes of disease in the adult CNS, there is a need for in vitro systems in which neonatal and adult microglia can be cultured and studied.

An example of resting and activated microglial cells is shown in Figure 1. The microglia were visualized 24 hr after plating (Figure 1a) and exhibit ramified (resting) morphology. Exposure to the priming reagent, bacterial lipopolysaccharide (LPS) results in changes in microglial morphology as the cells become activated (Figure 1b).
An example of counting the cells for plating is shown in Figure 2. Due to the presence of cell ...

Watch this Scientific Journal Video about Culturing Microglia from the Neonatal and Adult Central Nervous System at JoVE.com

Culturing Microglia from the Neonatal and Adult Central Nervous System

We outline methods for the efficient and quick isolation/culture of viable microglia from the neonatal cerebral cortex and adult spinal cord. The dissection and plating of cortical microglia can be accomplished within 90 minutes, with the subsequent microglial harvest taking place ~ 10 days following the initial dissection.

Microglia are the resident macrophage-like cells of the central nervous system (CNS) and, as such, have critically important roles in physiological and ...

culturing-microglia-from-the-neonatal-and-adult-central-nervous-system

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Immunology and Infection

27.4K Views.  Stony Brook University. We outline methods for the efficient and quick isolation/culture of viable microglia from the neonatal cerebral cortex and adult spinal cord. The dissection and plating of cortical microglia can be accomplished within 90 minutes, with the subsequent microglial harvest taking place ~ 10 days following the initial dissection.