Name: neuron-macrophage co-cultures to activate macrophages secreting molecular factors with neurite outgrowth activity
Uploaded: 2018-03-30T15:00:00
Description: Watch this Scientific Journal Video about Neuron-Macrophage Co-cultures to Activate Macrophages Secreting Molecular Factors with Neurite Outgrowth Activity at JoVE.com

This protocol is supported by a grant NRF-2015R1A2A1A01003410 from the Ministry of Science, ICT and Future Planning, Republic of Korea.

All experiments involving animals were approved by the institutional Animal Care and Use Committee of Ajou University School of Medicine.
1. Culture Preparation of Dissociated Adult DRG Neuron
<ol>
	<li>Before setting up the culture, pre-coat a 6-well plate with poly-D-lysine and laminin. Incubate a 6-well plate with 0.01% poly-D-lysine at 37&#176;C for 2 h or at 4&#176;C overnight. Then, wash the plate twice with distilled water.</li>
	<li>Incubate the plate with laminin solution at a conce...

<ol>
	<li>Donnelly, D. J., Popovich, P. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inflammation+and+its+role+in+neuroprotection,+axonal+regeneration+and+functional+recovery+after+spinal+cord+injury.">Inflammation and its role in neuroprotection, axonal regeneration and functional recovery after spinal cord injury.</a> Exp Neurol. 209 (2), 378-388 (2008).</li><li>Festoff, B. W., 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=Minocycline+neuroprotects,+reduces+microgliosis,+and+inhibits+caspase+protease+expression+early+after+spinal+cord+injury.">Minocycline neuroprotects, reduces microgliosis, and inhibits caspase protease expression early after spinal cord injury.</a> J Neurochem. 97 (5), 1314-1326 (2006).</li><li>Bowers, C. A., Kundu, B., Hawryluk, G. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Methylprednisolone+for+acute+spinal+cord+injury:+an+increasingly+philosophical+debate.">Methylprednisolone for acute spinal cord injury: an increasingly philosophical debate.</a> Neural Regen Res. 11 (6), 882-885 (2016).</li><li>Gensel, J. C., Kigerl, K. A., Mandrekar-Colucci, S. S., Gaudet, A. D., Popovich, P. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Achieving+CNS+axon+regeneration+by+manipulating+convergent+neuro-immune+signaling.">Achieving CNS axon regeneration by manipulating convergent neuro-immune signaling.</a> Cell Tissue Res. 349 (1), 201-213 (2012).</li><li>DiSabato, D. J., Quan, N., Godbout, J. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neuroinflammation:+the+devil+is+in+the+details.">Neuroinflammation: the devil is in the details.</a> J Neurochem. 139 Suppl 2, 136-153 (2016).</li><li>Jin, X., Yamashita, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microglia+in+central+nervous+system+repair+after+injury.">Microglia in central nervous system repair after injury.</a> J Biochem. 159 (5), 491-496 (2016).</li><li>Yin, Y., 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=Macrophage-derived+factors+stimulate+optic+nerve+regeneration.">Macrophage-derived factors stimulate optic nerve regeneration.</a> J Neurosci. 23 (6), 2284-2293 (2003).</li><li>Yin, Y., 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=Oncomodulin+is+a+macrophage-derived+signal+for+axon+regeneration+in+retinal+ganglion+cells.">Oncomodulin is a macrophage-derived signal for axon regeneration in retinal ganglion cells.</a> Nat Neurosci. 9 (6), 843-852 (2006).</li><li>Gensel, J. C., 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=Macrophages+promote+axon+regeneration+with+concurrent+neurotoxicity.">Macrophages promote axon regeneration with concurrent neurotoxicity.</a> J Neurosci. 29 (12), 3956-3968 (2009).</li><li>Barrette, 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=Requirement+of+myeloid+cells+for+axon+regeneration.">Requirement of myeloid cells for axon regeneration.</a> J Neurosci. 28 (38), 9363-9376 (2008).</li><li>Kwon, M. 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=Contribution+of+macrophages+to+enhanced+regenerative+capacity+of+dorsal+root+ganglia+sensory+neurons+by+conditioning+injury.">Contribution of macrophages to enhanced regenerative capacity of dorsal root ganglia sensory neurons by conditioning injury.</a> J Neurosci. 33 (38), 15095-15108 (2013).</li><li>Niemi, J. P., 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=A+critical+role+for+macrophages+near+axotomized+neuronal+cell+bodies+in+stimulating+nerve+regeneration.">A critical role for macrophages near axotomized neuronal cell bodies in stimulating nerve regeneration.</a> J Neurosci. 33 (41), 16236-16248 (2013).</li><li>Hannila, S. S., Filbin, M. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+role+of+cyclic+AMP+signaling+in+promoting+axonal+regeneration+after+spinal+cord+injury.">The role of cyclic AMP signaling in promoting axonal regeneration after spinal cord injury.</a> Exp Neurol. 209 (2), 321-332 (2008).</li><li>Kwon, M. 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=CCL2+Mediates+Neuron-Macrophage+Interactions+to+Drive+Proregenerative+Macrophage+Activation+Following+Preconditioning+Injury.">CCL2 Mediates Neuron-Macrophage Interactions to Drive Proregenerative Macrophage Activation Following Preconditioning Injury.</a> J Neurosci. 35 (48), 15934-15947 (2015).</li><li>Niemi, J. P., DeFrancesco-Lisowitz, A., Cregg, J. M., Howarth, M., Zigmond, R. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Overexpression+of+the+monocyte+chemokine+CCL2+in+dorsal+root+ganglion+neurons+causes+a+conditioning-like+increase+in+neurite+outgrowth+and+does+so+via+a+STAT3+dependent+mechanism.">Overexpression of the monocyte chemokine CCL2 in dorsal root ganglion neurons causes a conditioning-like increase in neurite outgrowth and does so via a STAT3 dependent mechanism.</a> Exp Neurol. 275 Pt 1, 25-37 (2016).</li><li>Cafferty, W. 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=Conditioning+injury-induced+spinal+axon+regeneration+fails+in+interleukin-6+knock-out+mice.">Conditioning injury-induced spinal axon regeneration fails in interleukin-6 knock-out mice.</a> J Neurosci. 24 (18), 4432-4443 (2004).</li><li>Cai, D., 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=Neuronal+cyclic+AMP+controls+the+developmental+loss+in+ability+of+axons+to+regenerate.">Neuronal cyclic AMP controls the developmental loss in ability of axons to regenerate.</a> J Neurosci. 21 (13), 4731-4739 (2001).</li><li>Neumann, S., Woolf, C. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Regeneration+of+dorsal+column+fibers+into+and+beyond+the+lesion+site+following+adult+spinal+cord+injury.">Regeneration of dorsal column fibers into and beyond the lesion site following adult spinal cord injury.</a> Neuron. 23 (1), 83-91 (1999).</li></ol>

There are several critical steps for the generation of this co-culture system. It is important to ensure that the mouse DRG neurons and peritoneal macrophages are prepared fresh and healthy. We have experienced diminished neurite outgrowth activity of the CM when the dissection of all the DRGs took more than 30 min. In addition, the contamination of blood components in peritoneal macrophages also led to a decrease of neurite outgrowth activity in the CM. In order to elicit robust neuron-macrophage interaction by db-cAMP,...

A variety of studies have sought to enhance CNS axon regeneration after the injuries of the spinal cord or brain. Inflammatory reactions, inevitably accompanying the injuries in the nervous system, are traditionally thought to participate in secondary pathological processes leading to the deleterious outcomes1,2. Indeed, methylprednisolone that can suppress inflammatory reactions is the only approved therapy for acute spinal cord injury3. However, more recent studies have provided evidence that macrophages, a representative inflammatory cell type, can participate in the regeneration or repair of injured nervous system4,5,6. For example, infiltrating macrophages following a lens injury produce pro-regenerative molecules to promote the regeneration of the retinal ganglion neurons7,8. In addition, transplanted DRG neurons increased axon growth up the region where macrophages were activated by zymosan9. Moreover, the macrophages at the lesion site can create a growth-permissive milieu for injured peripheral nerves10.
Our work also provided strong evidence that macrophages can contribute to the capacity of axon regeneration in adjacent neurons. We have shown that the activation of macrophages in the dorsal root ganglia (DRG) were essential in the enhanced regenerative capacity of DRG sensory neurons following a preconditioning peripheral nerve injury11. Similar research was independently reported from another laboratory12. We also showed that intraganglionic injection of dibutyryl cyclic AMP (db-cAMP), which is a well-known molecule to enhance the capacity of axon regeneration13, induced the activation of macrophages. The deactivation of macrophages abolished the effects of db-cAMP on neurite outgrowth activity. Subsequent works identified injury-induced expression of CCL2 in neurons as a signal to stimulate macrophages with a pro-regenerative phenotype14,15.
Based on the above experimental results, we have established an in vitro model resembling molecular events that occur in the DRGs following a preconditioning injury model11,14. In this model, db-cAMP is applied to the neuron-macrophage co-cultures eliciting intercellular signaling that leads to the activation of macrophages with a pro-regenerative phenotype. Here, we describe detailed protocols by which we can generate macrophages that secrete molecular factors promoting neurite outgrowth (Figure 1). This experimental model illustrates a concept that macrophages can be stimulated or induced to support axon regeneration following the injuries to nervous system. Our model will also be useful in studying mechanisms in intercellular signaling that leads to the activation of pro-regenerative macrophages.

<table>
	<tbody>
		<tr>
			<td>Cell culture insert transparent PET membrane 0.4&#956;m pore size</td>
			<td>Corning,Falcon</td>
			<td>353090</td>
			<td>Transparent PET membrane with 0.4-&#956;m pore size, for 6-well plate</td>
		</tr>
		<tr>
			<td>70-&#956;m nylon cell strainer</td>
			<td>Corning, Falcon</td>
			<td>352350</td>
			<td></td>
		</tr>
		<tr>
			<td>8-well culture slide</td>
			<td>Biocoat</td>
			<td>354632</td>
			<td>with a uniform application of Poly-D-Lysine</td>
		</tr>
		<tr>
			<td>Red blood cell lysis buffer</td>
			<td>Qiagen</td>
			<td>158904</td>
			<td></td>
		</tr>
		<tr>
			<td>Collagenase from Clostridium histolyticum</td>
			<td>Sigma-Aldrich</td>
			<td>C9407-100MG</td>
			<td></td>
		</tr>
		<tr>
			<td>Neurobasal medium</td>
			<td>Thermo Fisher Scientific, Gibco</td>
			<td>21103-049</td>
			<td>Containing 1% glutamax and 1% penicilin-streptomycin</td>
		</tr>
		<tr>
			<td>B-27 supplement, serum free</td>
			<td>Thermo Fisher Scientific, Gibco</td>
			<td>17504-044</td>
			<td>extracellular solution</td>
		</tr>
		<tr>
			<td>Glutamax</td>
			<td>Thermo Fisher Scientific, Gibco</td>
			<td>35050-061</td>
			<td></td>
		</tr>
		<tr>
			<td>Penicillin-streptomycin</td>
			<td>Thermo Fisher Scientific, Gibco</td>
			<td>15140-122</td>
			<td></td>
		</tr>
		<tr>
			<td>Poly-D-lysine Hydrobromide</td>
			<td>Sigma-Aldrich</td>
			<td>P6407-5MG</td>
			<td></td>
		</tr>
		<tr>
			<td>Laminin</td>
			<td>Thermo Fisher Scientific, Invitrogen</td>
			<td>23017-015</td>
			<td></td>
		</tr>
		<tr>
			<td>Adenosine 3&#39;, 5&#39;-cyclic monophosphate, N6,O2&#39;-dibutyryl-, sodium salt</td>
			<td>Merck Millipore Corporation, Calbiochem</td>
			<td>28745</td>
			<td></td>
		</tr>
		<tr>
			<td>10% Normal Goat Serum</td>
			<td>Thermo Fisher Scientific</td>
			<td>16210072</td>
			<td></td>
		</tr>
		<tr>
			<td>Triton-X-100</td>
			<td>Daejung Chemical and Metal Co</td>
			<td>8566-4405</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti &#946; III tubulin (Tuj-1)</td>
			<td>Promega Corporation</td>
			<td>G7121</td>
			<td>Mouse monoclonal antibody</td>
		</tr>
		<tr>
			<td>Goat anti-Mouse IgG (H+L) secondary antibody</td>
			<td>Thermo Fisher Scientific, Invitrogen</td>
			<td>A11005</td>
			<td></td>
		</tr>
		<tr>
			<td>Hemacytometer</td>
			<td>Marienfeld-Superior</td>
			<td>N/A</td>
			<td></td>
		</tr>
		<tr>
			<td>Cell culture CO2 incubator</td>
			<td>Panasonic</td>
			<td>N/A</td>
			<td></td>
		</tr>
		<tr>
			<td>Dissecting stereomicroscope</td>
			<td>Carl Zeiss</td>
			<td>Stemi DV4</td>
			<td></td>
		</tr>
		<tr>
			<td>Twist shaker</td>
			<td>FINEPCR</td>
			<td>Tw3t</td>
			<td></td>
		</tr>
		<tr>
			<td>Tabletop centrifuge</td>
			<td>Sorvall</td>
			<td>N/A</td>
			<td></td>
		</tr>
		<tr>
			<td>Confocal microscope</td>
			<td>Olympus America Inc</td>
			<td>IX71</td>
			<td></td>
		</tr>
		<tr>
			<td>FBS (Fetal Bovine Serum)</td>
			<td>VWR International, Hyclone</td>
			<td>SH30919.03</td>
			<td></td>
		</tr>
		<tr>
			<td>Friedman Pearson Rongeurs</td>
			<td>FST (Fine Science Tools)</td>
			<td>16021-14</td>
			<td>Stainless steel, 14cm, curved, single joint action</td>
		</tr>
		<tr>
			<td>Fine Scissors - Tungsten Carbide &#38; ToughCut</td>
			<td>FST (Fine Science Tools)</td>
			<td>14558-11</td>
			<td>sharp, serrated</td>
		</tr>
		<tr>
			<td>Dumont #7 Forceps</td>
			<td>FST (Fine Science Tools)</td>
			<td>11272-30</td>
			<td>Dumoxel, 0.07 x 0.04mm, curved</td>
		</tr>
		<tr>
			<td>Vannas Spring Scissors</td>
			<td>FST (Fine Science Tools)</td>
			<td>15000-00</td>
			<td>straight, 3mm cutting-edge, sharp</td>
		</tr>
		<tr>
			<td>Qualitron DW-41 Micro-Centrifuge</td>
			<td>Artisan Technology Group</td>
			<td>DW-41</td>
			<td>Input Voltage: 115VAC</td>
		</tr>
	</tbody>
</table>

neuron-macrophage co-cultures to activate macrophages secreting molecular factors with neurite outgrowth activity

There is strong evidence that macrophages can participate in the regeneration or repair of injured nervous system. Here, we describe a protocol in which macrophages are induced to produce conditioned medium (CM) that promotes neurite outgrowth. Adult dorsal root ganglion (DRG) neurons are acutely dissociated and plated. After the neurons are stably attached, peritoneal macrophages are co-cultured on a cell culture insert overlaid on the same well. Dibutyryl cyclic AMP (db-cAMP) is applied to the co-cultures for 24 h, after which the cell culture insert containing the macrophages is moved to another well to collect CM for 72 h. The CM from the co-cultures treated with db-cAMP, when applied to a separate adult DRG neuron culture, exhibits robust neurite outgrowth activity. The CM obtained from the db-cAMP-treated cultures consisting of single cell type alone, either DRG neuron or peritoneal macrophage, did not exhibit neurite outgrowth activity. This indicates that the interaction between neurons and macrophages is indispensable for the activation of macrophages secreting molecular factors with neurite outgrowth activity into CM. Thus, our co-culture paradigm will also be useful to study intercellular signaling in the neuron-macrophage interaction to stimulate the macrophages to be endowed with a pro-regenerative phenotype.

We describe a protocol that can generate macrophages capable of secreting molecular factors with neurite outgrowth activity. The macrophage CM obtained from the co-cultures treated with db-cAMP resulted in robust neurite outgrowth when applied to a separate DRG neuron culture (Figure 2A). In comparison, CM obtained from the PBS-treated co-cultures did not induce neurite outgrowth in our 15-h culture duration (Figure 2B). When db-...

Watch this Scientific Journal Video about Neuron-Macrophage Co-cultures to Activate Macrophages Secreting Molecular Factors with Neurite Outgrowth Activity at JoVE.com

Neuron-Macrophage Co-cultures to Activate Macrophages Secreting Molecular Factors with Neurite Outgrowth Activity

The current protocol presents experimental procedures to stimulate cultured macrophages to be endowed with capacity to release molecular factors that promote neurite outgrowth. Treatment of cAMP to the neuron-macrophage co-cultures induces the macrophages to produce conditioned medium that possesses strong neurite outgrowth activity.

There is strong evidence that macrophages can participate in the regeneration or repair of injured nervous system. Here, we describe a protocol in which ...

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