McDonnell Emily E, Buckley Conor T
Trinity Centre for Biomedical Engineering, Trinity Biomedical Sciences Institute, Trinity College Dublin The University of Dublin Dublin Ireland.
Discipline of Mechanical, Manufacturing and Biomedical Engineering, School of Engineering, Trinity College Dublin The University of Dublin Dublin Ireland.
JOR Spine. 2021 Mar 2;4(2):e1141. doi: 10.1002/jsp2.1141. eCollection 2021 Jun.
Ex vivo disc organ culture systems have become a valuable tool for the development and pre-clinical testing of potential intervertebral disc (IVD) regeneration strategies. Bovine caudal discs have been widely selected due to their large availability and comparability to human IVDs in terms of size and biochemical composition. However, despite their extensive use, it remains to be elucidated whether their nutrient microenvironment is comparable to human degeneration.
This work aims to create the first experimentally validated in silico model which can be used to predict and characterize the metabolite concentrations within ex vivo culture systems.
MATERIALS & METHODS: Finite element models of cultured discs governed by previously established coupled reaction-diffusion equations were created using COMSOL Multiphysics. Experimental validation was performed by measuring oxygen, glucose and pH levels within discs cultured for 7 days, in a static compression bioreactor.
The in silico model was successfully validated through good agreement between the predicted and experimentally measured concentrations. For an ex vivo organ cultured in high glucose medium (4.5 g/L or 25 mM) and normoxia, a larger bovine caudal disc (Cd1-2 to Cd3-4) had a central concentration of ~2.6 %O, ~8 mM of glucose and a pH value of 6.7, while the smallest caudal discs investigated (Cd6-7 and Cd7-8), had a central concentration of ~6.5 %O, ~12 mM of glucose and a pH value of 6.9.
This work advances the knowledge of ex vivo disc culture microenvironments and highlights a critical need for optimization and standardization of culturing conditions.
Ultimately, for assessment of cell-based therapies and successful clinical translation based on nutritional demands, it is imperative that the critical metabolite values within organ cultures (minimum glucose, oxygen and pH values) are physiologically relevant and comparable to the stages of human degeneration.
椎间盘器官体外培养系统已成为开发和临床前测试潜在椎间盘（IVD）再生策略的重要工具。牛尾椎间盘因其易于获取且在大小和生化组成方面与人类IVD具有可比性，而被广泛选用。然而，尽管其被广泛应用，但它们的营养微环境是否与人类退变情况相当仍有待阐明。
本研究旨在创建首个经过实验验证的计算机模拟模型，该模型可用于预测和表征体外培养系统中的代谢物浓度。
使用COMSOL Multiphysics创建了由先前建立的耦合反应扩散方程控制的培养椎间盘有限元模型。通过在静态压缩生物反应器中测量培养7天的椎间盘内的氧气、葡萄糖和pH水平进行实验验证。
通过预测浓度与实验测量浓度之间的良好一致性，成功验证了计算机模拟模型。对于在高糖培养基（4.5 g/L或25 mM）和常氧条件下培养的体外器官，较大的牛尾椎间盘（Cd1-2至Cd3-4）的中心浓度约为2.6%O、约8 mM葡萄糖，pH值为6.7，而所研究的最小尾椎间盘（Cd6-7和Cd7-8）的中心浓度约为6.5%O、约12 mM葡萄糖，pH值为6.9。
本研究推进了对椎间盘体外培养微环境的认识，并突出了优化和标准化培养条件的迫切需求。
最终，为了基于营养需求评估基于细胞的疗法并成功实现临床转化，器官培养中的关键代谢物值（最低葡萄糖、氧气和pH值）在生理上具有相关性且与人类退变阶段相当至关重要。
