Zhang Sijia, Singh Sagar, Winkelstein Beth A
Department of Bioengineering, University of Pennsylvania, 210 S. 33rd Street, 240 Skirkanich Hall, Philadelphia, Pennsylvania, 19104-6321.
Department of Neurosurgery, University of Pennsylvania, Philadelphia, Pennsylvania, 19104.
J Orthop Res. 2018 Feb;36(2):770-777. doi: 10.1002/jor.23657. Epub 2017 Aug 11.
Injury to the spinal facet capsule, an innervated ligament with heterogeneous collagen organization, produces pain. Although mechanical facet joint trauma activates embedded afferents, it is unclear if, and how, the varied extracellular microstructure of its ligament affects sensory transduction for pain from mechanical inputs. To investigate the effects of macroscopic deformations on afferents in collagen matrices with different organizations, an in vitro neuron-collagen construct (NCC) model was used. NCCs with either randomly organized or parallel aligned collagen fibers were used to mimic the varied microstructure in the facet capsular ligament. Embryonic rat dorsal root ganglia (DRG) were encapsulated in the NCCs; axonal outgrowth was uniform and in all directions in random NCCs, but parallel in aligned NCCs. NCCs underwent uniaxial stretch (0.25 ± 0.06 strain) corresponding to sub-failure facet capsule strains that induce pain. Macroscopic NCC mechanics were measured and axonal expression of phosphorylated extracellular signal-regulated kinase (pERK) and the neurotransmitter substance P (SP) was assayed at 1 day to assess neuronal activation and nociception. Stretch significantly upregulated pERK expression in both random and aligned gels (p < 0.001), with the increase in pERK being significantly higher (p = 0.013) in aligned than in random NCCs. That increase likely relates to the higher peak force (p = 0.025) and stronger axon alignment (p < 0.001) with stretch direction in the aligned NCCs. In contrast, SP expression was greater in stretched NCCs (p < 0.001) regardless of collagen organization. These findings suggest that collagen organization differentially modulates pain-related neuronal signaling and support structural heterogeneity of ligament tissue as mediating sensory function. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:770-777, 2018.
脊柱小关节囊损伤会引发疼痛，小关节囊是一种具有异质性胶原组织的神经支配韧带。尽管机械性小关节创伤会激活其中的传入神经，但尚不清楚其韧带多样的细胞外微观结构是否以及如何影响机械性输入所致疼痛的感觉传导。为了研究宏观变形对不同组织结构胶原基质中传入神经的影响，采用了一种体外神经元 - 胶原构建体（NCC）模型。具有随机排列或平行排列胶原纤维的NCC被用来模拟小关节囊韧带中多样的微观结构。将胚胎大鼠背根神经节（DRG）包裹在NCC中；在随机NCC中轴突生长是均匀且向各个方向的，但在排列的NCC中是平行的。对NCC进行单轴拉伸（应变0.25±0.06），对应于引发疼痛的小关节囊亚失效应变。测量NCC的宏观力学性能，并在1天时检测磷酸化细胞外信号调节激酶（pERK）和神经递质P物质（SP）的轴突表达，以评估神经元激活和伤害感受。拉伸显著上调了随机排列和排列的凝胶中pERK的表达（p < 0.001），排列的NCC中pERK的增加显著高于随机NCC（p = 0.013）。这种增加可能与排列的NCC中更高的峰值力（p = 0.025）以及与拉伸方向更强的轴突排列（p < 0.001）有关。相比之下，无论胶原组织如何，拉伸的NCC中SP的表达都更高（p < 0.001）。这些发现表明，胶原组织以不同方式调节与疼痛相关的神经元信号传导，并支持韧带组织的结构异质性介导感觉功能。©2017骨科学研究协会。由威利期刊公司出版。《矫形外科学研究杂志》36:770 - 777，2018年。
