Zhou Zhiyu, Cui Shangbin, Du Jie, Richards R Geoff, Alini Mauro, Grad Sibylle, Li Zhen
The Seventh Affiliated Hospital of Sun Yat-sen University, Shenzhen, China.
AO Research Institute Davos, Davos, Switzerland.
J Orthop Translat. 2020 Oct 20;26:141-150. doi: 10.1016/j.jot.2020.08.003. eCollection 2021 Jan.
Acute trauma on intervertebral discs (IVDs) is thought to be one of the risk factors for IVD degeneration. The pathophysiology of IVD degeneration induced by single high impact mechanical injury is not very well understood. The aim of this study was using a post-traumatic IVD model in a whole organ culture system to analyze the biological and biomechanical consequences of the single high-impact loading event on the cultured IVDs.
Isolated healthy bovine IVDs were loaded with a physiological loading protocol in the control group or with injurious loading (compression at 50% of IVD height) in the one strike loading (OSL) group. After another 1 day (short term) or 8 days (long term) of whole organ culture within a bioreactor, the samples were collected to analyze the cell viability, histological morphology and gene expression. The conditioned medium was collected daily to analyze the release of glycosaminoglycan (GAG) and nitric oxide (NO).
The OSL IVD injury group showed signs of early degeneration including reduction of dynamic compressive stiffness, annulus fibrosus (AF) fissures and extracellular matrix degradation. Compared to the control group, the OSL model group showed more severe cell death (P < 0.01) and higher GAG release in the culture medium (P < 0.05). The MMP and ADAMTS families were up-regulated in both nucleus pulposus (NP) and AF tissues from the OSL model group (P < 0.05). The OSL injury model induced a traumatic degenerative cascade in the whole organ cultured IVD.
The present study shows a single hyperphysiological mechanical compression applied to healthy bovine IVDs caused significant drop of cell viability, altered the mRNA expression in the IVD, and increased ECM degradation. The OSL IVD model could provide new insights into the mechanism of mechanical injury induced early IVD degeneration.
This model has a high potential for investigation of the degeneration mechanism in post-traumatic IVD disease, identification of novel biomarkers and therapeutic targets, as well as screening of treatment therapies.
椎间盘急性创伤被认为是椎间盘退变的危险因素之一。单次高冲击力机械损伤诱导椎间盘退变的病理生理学机制尚不完全清楚。本研究的目的是在全器官培养系统中使用创伤后椎间盘模型，分析单次高冲击力加载事件对培养的椎间盘的生物学和生物力学影响。
在对照组中，对分离出的健康牛椎间盘采用生理加载方案进行加载，在单次冲击加载（OSL）组中采用损伤性加载（以椎间盘高度的50%进行压缩）。在生物反应器中进行1天（短期）或8天（长期）的全器官培养后，收集样本以分析细胞活力、组织形态学和基因表达。每天收集条件培养基以分析糖胺聚糖（GAG）和一氧化氮（NO）的释放。
OSL椎间盘损伤组表现出早期退变的迹象，包括动态压缩刚度降低、纤维环（AF）裂隙和细胞外基质降解。与对照组相比，OSL模型组表现出更严重的细胞死亡（P<0.01），且培养基中GAG释放量更高（P<0.05）。OSL模型组髓核（NP）和AF组织中基质金属蛋白酶（MMP）和含血小板解聚蛋白样金属蛋白酶（ADAMTS）家族均上调（P<0.05）。OSL损伤模型在全器官培养的椎间盘中诱导了创伤性退变级联反应。
本研究表明，对健康牛椎间盘施加单次超生理机械压缩会导致细胞活力显著下降，改变椎间盘中的mRNA表达，并增加细胞外基质降解。OSL椎间盘模型可为机械损伤诱导早期椎间盘退变的机制提供新的见解。
该模型在研究创伤后椎间盘疾病的退变机制、鉴定新的生物标志物和治疗靶点以及筛选治疗方法方面具有很高的潜力。
