这项工作得到了 NSF Grant （2152065） 和 NSF CAREER Award （1846857） 的支持。作者要感谢 Wachs 实验室的所有现任和前任成员为本协议做出贡献。 图 1 中的图表是在 Biorender 中制作的。

DRG 收获是按照内布拉斯加大学林肯分校的机构动物护理和使用委员会 （IACUC） 进行的。该研究使用 12 周龄 （~250 g） 的雌性 Sprague Dawley 大鼠。材料 表中列出了研究中使用的动物、试剂和设备的详细信息。
1. 多隔室器件制造和组装
<ol><li>多隔间设备的计算机辅助设计和 3D 打印 注意：MC 设备由三个隔室组成，用于分离 DRG 细胞体和神经突（<strong c...

用于研究 DRG 培养中神经元超敏反应的高级体外模型

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S., 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=Tunable+methacrylated+hyaluronic+acid-based+hydrogels+as+scaffolds+for+soft+tissue+engineering+applications.">Tunable methacrylated hyaluronic acid-based hydrogels as scaffolds for soft tissue engineering applications.</a> J Biomed Mater Res A. 108 (2), 279-291 (2020).</li><li>Zhu, W., Oxford, G. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Differential+gene+expression+of+neonatal+and+adult+DRG+neurons+correlates+with+the+differential+sensitization+of+TRPV1+responses+to+nerve+growth+factor.">Differential gene expression of neonatal and adult DRG neurons correlates with the differential sensitization of TRPV1 responses to nerve growth factor.</a> Neurosci Lett. 500 (3), 192-196 (2011).</li><li>Van De Wijdeven, R., 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=Structuring+a+multi-nodal+neural+network+in+vitro+within+a+novel+design+microfluidic+chip.">Structuring a multi-nodal neural network in vitro within a novel design microfluidic chip.</a> Biomed Microdevices. 20, 1-8 (2018).</li><li>Chan, J. R., 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=NGF+controls+axonal+receptivity+to+myelination+by+Schwann+cells+or+oligodendrocytes.">NGF controls axonal receptivity to myelination by Schwann cells or oligodendrocytes.</a> Neuron. 43 (2), 183-191 (2004).</li><li>Ng, B. K., Chen, L., Mandemakers, W., Cosgaya, J. M., Chan, J. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Anterograde+transport+and+secretion+of+brain-derived+neurotrophic+factor+along+sensory+axons+promote+Schwann+cell+myelination.">Anterograde transport and secretion of brain-derived neurotrophic factor along sensory axons promote Schwann cell myelination.</a> J Neurosci. 27 (28), 7597-7603 (2007).</li><li>Xiao, 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=BDNF+exerts+contrasting+effects+on+peripheral+myelination+of+NGF-dependent+and+BDNF-dependent+drg+neurons.">BDNF exerts contrasting effects on peripheral myelination of NGF-dependent and BDNF-dependent drg neurons.</a> J Neurosci. 29 (13), 4016-4022 (2009).</li><li>Seidlits, S. K., 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+effects+of+hyaluronic+acid+hydrogels+with+tunable+mechanical+properties+on+neural+progenitor+cell+differentiation.">The effects of hyaluronic acid hydrogels with tunable mechanical properties on neural progenitor cell differentiation.</a> Biomaterials. 31 (14), 3930-3940 (2010).</li><li>Tomal, W., Ortyl, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Water-soluble+photoinitiators+in+biomedical+applications.">Water-soluble photoinitiators in biomedical applications.</a> Polymers. 12 (5), 1073 (2020).</li><li>Leary, S., 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> Avma guidelines for the euthanasia of animals: 2013 edition. , (2013).</li><li>Sleigh, J. 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本研究的作者声明他们没有利益冲突。

该协议概述了一种收获成年 Sprague Dawley DRG 并在 3D 天然水凝胶中培养它们的方法。与这种方法相反，从小鼠和大鼠中收集 DRG 的其他方法包括分离脊柱。切除的脊柱减半，并切除脊髓以露出 DRG 23,24,25。脊髓损伤会限制血液供应，从而影响 DRG 和内部神经元26。这降低了 DRG 的活性，使手术方法更合适。此外，还...

慢性疼痛是全球残疾和失业的主要原因1。慢性疼痛影响着全球约 20% 的成年人，并造成了巨大的社会和经济负担2，在美国，每年的总成本估计在 560 至 6350 亿美元之间3。
慢性疼痛患者表现出的主要外周特征是神经刺激阈值降低，这导致神经系统对刺激更敏感 4,5。降低的刺激阈值会导致对先前非痛苦刺激的痛苦反应（痛觉异常）或对痛苦刺激的反应增强（痛觉过敏）6。目前的慢性疼痛治疗疗效有限，由于疼痛表现的机制差异，在动物模型中成功的治疗往往在人体试验中失败7。能够更准确地模拟外周敏化机制的体外模型有可能增加新疗法的翻译 8,9。此外，通过对培养系统中致敏神经的关键方面进行建模，研究人员可以更深入地了解驱动降低阈值的机制，并确定逆转阈值的新治疗靶点10。
理想的 体外 平台或微生理系统将结合远端神经突和背根神经节 （DRG） 细胞体的物理分离、三维 （3D） 细胞环境以及天然支持细胞的存在，以密切模拟 体内 条件。然而，Caparaso 等人最近的一篇论文 11 表明，当前的 DRG 培养平台缺乏这些关键特征中的一个或多个，这使得 它们在体内复制 条件方面不足。尽管这些平台易于设置，但它们并不模拟外周致敏的生物学基础，因此可能无法转化为 体内 疗效。为了解决这一限制，已经开发了一种生理学相关的 体外 模型，用于在具有三个隔离隔室的水凝胶基质中培养背根神经节 （DRG），以允许神经突和 DRG 细胞体的时间流体分离11。该模型提供了生理学和解剖学相关性，有可能在 体外研究神经元的外周敏化。
人们对在 3D 培养中使用 DRG 外植体的兴趣日益浓厚，是因为它们能够促进稳健的神经突生长，这是 DRG 活力的间接指标12。虽然原代新生儿或胚胎 DRG 外植体主要用于当前的体外培养平台13,14，但使用成年啮齿动物的外植体提供了更好的成熟神经元生理学模型，与新生儿或胚胎啮齿动物的外植体相比，它与人类 DRG 生理学非常相似15。外植体 DRG 是指主要通过维持天然非神经元支持细胞来保存天然 DRG 组织的细胞和分子组织。在此，该协议描述了在多室 （MC） 装置中从成年 Sprague Dawley 大鼠收获和培养 DRG 外植体的方法（图 1）。
在从颈椎、胸椎和腰椎培养 DRG 中已显示出有效性，神经突生长没有明显的差异。对于此应用，目标是诱使神经突生长到设备的外室中;因此，本文没有区分 DRG 水平。但是，如果特定实验需要，则可以定制 DRG 水平以满足实验者的需求。目前还有其他用于 DRGs16 3D 培养的区室化培养模型，但是，这些装置不包含保存的天然非神经元支持细胞，这可能会限制翻译。保留收获的 DRG 的天然结构很重要，因为它可以确保非神经元支持细胞的保留，这些支持细胞与 DRG 神经元的相互作用对于维持这些神经元的功能特性至关重要。几项研究将解离的 DRG 与非天然神经元细胞（如雪旺细胞）共培养，以促进神经元的髓鞘形成 17,18,19。

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>#5 forceps</td>
			<td>Fine Science Tools</td>
			<td>11252-00</td>
			<td>For trimming and cutting DRG</td>
		</tr>
		<tr>
			<td>10x DMEM</td>
			<td>MilliporeSigma</td>
			<td>D2429</td>
			<td></td>
		</tr>
		<tr>
			<td>1x PBS (autoclaved)</td>
			<td>Prepared in lab</td>
			<td></td>
			<td>7.3 - 7.5 pH</td>
		</tr>
		<tr>
			<td>24 well plates</td>
			<td>VWR</td>
			<td>82050-892</td>
			<td>To temporarily store harvested and cut DRGs</td>
		</tr>
		<tr>
			<td>3 mL Syringe sterile, single use</td>
			<td>BD</td>
			<td>309657</td>
			<td></td>
		</tr>
		<tr>
			<td>48 well plates</td>
			<td>Greiner Bio-One</td>
			<td>677180</td>
			<td></td>
		</tr>
		<tr>
			<td>60 mm Petri dish</td>
			<td>Fisher Scientific</td>
			<td>FB0875713A</td>
			<td>To hold media for trimming and cutting</td>
		</tr>
		<tr>
			<td>Aluminium foil</td>
			<td>Fisherbrand</td>
			<td>01-213-104</td>
			<td></td>
		</tr>
		<tr>
			<td>B27 Plus 50x</td>
			<td>ThermoFisher</td>
			<td>17504044</td>
			<td>For DRG media</td>
		</tr>
		<tr>
			<td>Collagen type I</td>
			<td>Ibidi</td>
			<td>50205</td>
			<td></td>
		</tr>
		<tr>
			<td>Curved cup Friedman Pearson Rongeur</td>
			<td>Fine Science Tools</td>
			<td>16221-14</td>
			<td>For dissection</td>
		</tr>
		<tr>
			<td>Dumont #3 forceps</td>
			<td>Fine Science Tools</td>
			<td>11293-00</td>
			<td>For dissection</td>
		</tr>
		<tr>
			<td>Fetal Bovine Serum (FBS)</td>
			<td>ThermoFisher</td>
			<td>16000044</td>
			<td>For DRG media</td>
		</tr>
		<tr>
			<td>Form cure</td>
			<td>Form Labs</td>
			<td></td>
			<td>curing agent</td>
		</tr>
		<tr>
			<td>Form wash</td>
			<td>Form Labs</td>
			<td></td>
			<td>To wash excess resins off MC</td>
		</tr>
		<tr>
			<td>Glass bead sterilizer</td>
			<td>Fisher Scientific</td>
			<td>NC9531961</td>
			<td></td>
		</tr>
		<tr>
			<td>Glass vials (8 mL)</td>
			<td>DWK Life Sciences (Wheaton)</td>
			<td>224724</td>
			<td></td>
		</tr>
		<tr>
			<td>GlutaMax</td>
			<td>ThermoFisher</td>
			<td>35050-061</td>
			<td>For DRG media</td>
		</tr>
		<tr>
			<td>HEPES (1M)</td>
			<td>Millipore Sigma</td>
			<td>H0887</td>
			<td></td>
		</tr>
		<tr>
			<td>High temp V2 resin</td>
			<td>FormLabs</td>
			<td>FLHTAM02</td>
			<td></td>
		</tr>
		<tr>
			<td>Hyaluronic Acid Sodium Salt</td>
			<td>MilliporeSigma</td>
			<td>53747</td>
			<td>Used to make MAHA</td>
		</tr>
		<tr>
			<td>Irgacure</td>
			<td>MilliporeSigma</td>
			<td>410896</td>
			<td></td>
		</tr>
		<tr>
			<td>Laminin</td>
			<td>R&#38;D Systems</td>
			<td>344600501</td>
			<td></td>
		</tr>
		<tr>
			<td>Large blunt-nose scissors</td>
			<td>Militex</td>
			<td>EG5-26</td>
			<td>For dissection</td>
		</tr>
		<tr>
			<td>Large forceps (serrated tips)</td>
			<td>Militex</td>
			<td>9538797</td>
			<td>For dissection</td>
		</tr>
		<tr>
			<td>Large sharp-nosed scissors</td>
			<td>Fine Science Tools</td>
			<td>14010-15</td>
			<td>For dissection</td>
		</tr>
		<tr>
			<td>Low Retention pipette tips</td>
			<td>Fisher Scientific</td>
			<td>02-707-017</td>
			<td>For pipetting collagen and MAHA</td>
		</tr>
		<tr>
			<td>Methacrylated hyaluronic acid (MAHA)</td>
			<td>Prepared in lab</td>
			<td>N/A</td>
			<td>85 - 115 % methacrylation</td>
		</tr>
		<tr>
			<td>Nerve Growth Factor (NGF)</td>
			<td>R&#38;D Systems</td>
			<td>556-NG-100</td>
			<td>For DRG media</td>
		</tr>
		<tr>
			<td>Neurobasal A Media</td>
			<td>ThermoFisher</td>
			<td>10888022</td>
			<td>For DRG media</td>
		</tr>
		<tr>
			<td>Parafilm</td>
			<td>Bemis</td>
			<td>PM996</td>
			<td></td>
		</tr>
		<tr>
			<td>Parafilm</td>
			<td>Bemis</td>
			<td>PM996</td>
			<td></td>
		</tr>
		<tr>
			<td>Penicillin/Streptomycin (PS)</td>
			<td>EMD Millipore</td>
			<td>516106</td>
			<td>For DRG media</td>
		</tr>
		<tr>
			<td>pH test strips</td>
			<td>VWR International</td>
			<td>BDH35309.606</td>
			<td></td>
		</tr>
		<tr>
			<td>Pipette tips (1000 &#181;L)</td>
			<td>USA Scientific</td>
			<td>1111-2021</td>
			<td></td>
		</tr>
		<tr>
			<td>Preform 3.23.1 software</td>
			<td>Formslab</td>
			<td></td>
			<td>To upload STL file</td>
		</tr>
		<tr>
			<td>Rat</td>
			<td>Charles River</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Resin 3D printer</td>
			<td>Form Labs</td>
			<td>Form 3L</td>
			<td>3D printing MC device</td>
		</tr>
		<tr>
			<td>Small sharp-nosed scissors</td>
			<td>Fine Science Tools</td>
			<td>14094-11</td>
			<td>For dissection</td>
		</tr>
		<tr>
			<td>Sodium bicarbonate</td>
			<td>MilliporeSigma</td>
			<td>S6014</td>
			<td></td>
		</tr>
		<tr>
			<td>Straight cup rongeur</td>
			<td>Fine Science Tools</td>
			<td>16004-16</td>
			<td>For dissection</td>
		</tr>
		<tr>
			<td>Straight edge spring scissors</td>
			<td>Fine Science Tools</td>
			<td>15024-10</td>
			<td>For dissection</td>
		</tr>
		<tr>
			<td>Surgical Scaplel blade (No. 10)</td>
			<td>Fisher Scientific</td>
			<td>22-079-690</td>
			<td></td>
		</tr>
		<tr>
			<td>Syring filters, PES (0.22 &#181;m)</td>
			<td>Celltreat</td>
			<td>229747</td>
			<td></td>
		</tr>
		<tr>
			<td>Tiny spring scissors</td>
			<td>World Precision Instruments</td>
			<td>14003</td>
			<td>For trimming and cutting DRG</td>
		</tr>
		<tr>
			<td>UV lamp</td>
			<td>Analytik Jena US</td>
			<td></td>
			<td>To photocrosslink hydrogel (15 - 18 mW/cm2)</td>
		</tr>
	</tbody>
</table>

harvesting, embedding, and culturing dorsal root ganglia in multi-compartment devices to study peripheral neuronal features

疼痛最常见的周围神经元特征是刺激阈值降低或背根神经节 （DRG） 终末神经超敏反应。这种超敏反应的一个拟议原因与外周组织中的免疫细胞和神经元之间的相互作用有关。 体外 模型为理解这些机制如何导致伤害感受器超敏反应提供了基础知识。然而， 体外 模型面临着将疗效转化为人类的挑战。为了应对这一挑战，已经开发了一种生理学和解剖学相关的 体外 模型，用于在 48 孔板的三个孤立隔室中培养完整的背根神经节 （DRG）。初级 DRG 是在人道安乐死后从成年 Sprague Dawley 大鼠身上收获的。修剪多余的神经根，并将 DRG 切成合适的大小进行培养。然后，DRG 在天然水凝胶中生长，从而在所有隔室中实现稳健生长。这种多室系统提供了从神经突、生理相关细胞类型和机械特性中分离 DRG 细胞体的解剖学相关分离，以研究神经细胞和免疫细胞之间的相互作用。因此，该培养平台为研究治疗隔离策略提供了有价值的工具，最终导致一种改进的预测疼痛的筛查方法。

Chronic pain is the leading cause of disability and loss of work globally1. Chronic pain affects about 20% of adults globally and imposes a significant societal and economic burden2, with total costs estimated between $560 and $635 billion every year in the United States3.
The main peripheral feature exhibited by chronic pain patients is a lowered stimulation threshold of nerves, which leads to the nervous system being more responsive to stimuli4,5. The lowered stimulation threshold can result in a painful response to a previously non-painful stimulus (allodynia) or a heightened response to a painful stimulus (hyperalgesia)6. Current chronic pain treatments have limited efficacy, and treatments that succeed in animal models often fail in human trials due to mechanistic differences in pain manifestation7. In vitro models that can more accurately mimic peripheral sensitization mechanisms have the potential to increase the translation of new therapeutics8,9. Further, by modeling key aspects of sensitized nerves in a culture system, researchers could develop a deeper understanding of the mechanisms that drive lowered thresholds and identify novel therapeutic targets that reverse them10.
The ideal in vitro platforms or microphysiological systems would incorporate the physical separation of distal neurites and dorsal root ganglia (DRG) cell body, a three-dimensional (3D) cellular environment, and the presence of native support cells to closely mimic in vivo conditions. However, a recent paper by Caparaso et al.11 shows that current DRG culture platforms lack one or more of these key features, making them insufficient in replicating in vivo conditions. Even though these platforms are easy to set up, they do not mimic the biological basis of peripheral sensitization and thus may not translate to in vivo efficacy. To address this limitation, a physiologically relevant in vitro model has been developed for the culture of dorsal root ganglia (DRG) within a hydrogel matrix with three isolated compartments to allow temporal fluidic isolation of neurites and DRG cell bodies11. This model offers both physiological and anatomical relevance, which has the potential to study peripheral sensitization of neurons in vitro.
The growing interest in the use of DRG explants in a 3D culture is due to their ability to facilitate robust neurite growth, which serves as an indirect indicator of DRG viability12. While primary neonatal or embryonic DRG explants are predominantly used in current in vitro culture platforms13,14, using explants from adult rodents provides a better model of mature neuronal physiology, which closely mimics human DRG physiology compared to explants from neonatal or embryonic rodents15. Explant DRGs refer to the preservation of the cellular and molecular tissue of native DRG tissue, primarily by maintaining native non-neuronal support cells.Herein, this protocol describes the methodology to harvest and culture DRG explants from adult Sprague Dawley rats in a multi-compartment (MC) device (Figure 1).
Efficacy has been shown in culturing DRGs from the cervical, thoracic, and lumbar spine with no observable differences in neurite growth. For this application, the objective was to elicit neurite growth into the outer compartments of the device; therefore, this article did not discriminate among DRG levels. However, if needed for a specific experiment, the DRG level can be tailored to meet experimenters&#39; needs. There are currently other compartmentalized culture models for the 3D culture of DRGs16, however, these devices do not contain preserved native non-neuronal support cells, which can limit translation. Preserving the native structure of harvested DRGs is important because it ensures the retention of non-neuronal support cells, whose interactions with DRG neurons are essential for maintaining the functional properties of these neurons. Several studies co-cultured dissociated DRGs with non-native neuronal cells such as Schwann cells to promote myelination of neurons17,18,19.

作者聚焦：提高慢性疼痛治疗效果的体外和体内模型

在多室装置中收获、包埋和培养背根神经节以研究外周神经元特征

Our research seeks to understand some of the underlying mechanisms that contribute to chronic musculoskeletal pain, so we can develop novel targeted treatments. Thus, we have developed in vitro and in vivo models of chronic low back pain and neuronal sensitization. Current therapeutics that work in vivo in animal models often fail clinical trials due to mechanistic differences between animal models and human subject chronic pain phenotype.Individual test by that model, nociceptor hypersensitivity present in chronic pain have the potential to identify more promising treatments for chronic pain in humans. Our protocol clearly demonstrates how to isolate primary dorsal root ganglia, and culture them in a multi compartment device. By keeping intact primary dorsal root ganglia, we maintain native support cells and culture them in a multi compartment device, allowing anatomically relevant isolation between neuronal somas and peripheral neurites.This tool will help to culture primary dorsal root ganglia in a more physiologically and anatomically relevant way, thereby increasing translational efficacy of findings. Specifically, we are excited to use this system to identify novel treatment for nociceptor hypersensitivity present in chronic pain.

本方案描述了一种在多隔室 （MC） 装置中从成年 Sprague Dawley 大鼠收获和培养 DRG 的技术。如图 1 所示， 从成年大鼠身上收获的 DRG 被修剪并切成 ~0.5 mm。然后将修剪和切割的 DRG 嵌入 MC 装置胞体区域的水凝胶中（图 2）并在神经突定量前培养 27 天。将 DRG 在普通凝胶中培养作为对照。用于本实验的水凝胶制剂浓度为 4.5/1.25 mg/mL 胶原蛋白：MA...

该协议提供了一种在多隔室 （MC） 装置中从成年 Sprague Dawley 大鼠收获和培养外植背根神经节 （DRG） 的技术。

The most common peripheral neuronal feature of pain is a lowered stimulation threshold or hypersensitivity of terminal nerves from the dorsal root ganglia ...

harvesting-embedding-culturing-dorsal-root-ganglia-multi-compartment

Research

JoVE Journal

Bioengineering

Harvesting, Embedding, and Culturing Dorsal Root Ganglia in Multi-compartment Devices to Study Peripheral Neuronal Features

314 Views.  University of Nebraska-Lincoln. Our research seeks to understand some of the underlying mechanisms that contribute to chronic musculoskeletal pain, so we can develop novel targeted treatments. Thus, we have developed in vitro and in vivo models of chronic low back pain and neuronal sensitization. Current therapeutics that work in vivo in animal models often fail clinical trials due to mechanistic differences between animal models and human subject chronic pain phenotype.Individual test by that model, nociceptor hyper...