Khosrowshahi Dara, Lagae Liesbet, Bolander Johanna
Department of Physics and Astronomy, KU Leuven, Leuven, Belgium.
IMEC, Leuven, Belgium.
FASEB J. 2025 Aug 31;39(16):e70914. doi: 10.1096/fj.202501025RR.
Chronic pain affects approximately 20% of the population, significantly impacting daily life and increasing psychosocial burden for patients due to the limited effect of analgesics in providing reliable pain relief. This clinical impediment is largely due to a limited mechanistic understanding of human pain pathophysiology, caused by the limitation of models to study human pain mechanisms. Further, the lack of reliable models to study human pain-associated mechanisms hinders the screening and evaluation of pain-related drugs and therapies, leading to significant obstacles in the development of pain medications without inducing unwanted side effects. More complex and physiologically relevant in vitro models provide an opportunity to study human cells and tissues in a controlled environment while replicating key aspects of the native human environment. Further, these models are ethically advantageous by serving the 3R principle and enable the direct study of human cells and their physiological environments, facilitating the development of translational findings. In this review, we present the key molecular mechanisms of the pain sensory process, highlight the bidirectional crosstalk between nociceptors and non-neuronal cells at the peripheral and central nervous system levels, discuss the current in vivo models and their drawbacks, and explore strategies for human-relevant modeling by generating human nociceptors in vitro through various differentiation protocols of induced pluripotent stem cells (iPSCs). We also review the state-of-the-art of in vitro pain model systems, including their electrophysiological characterization, compartmentalization strategies, and the use of agonist and antagonist assays targeting specific ion channels and receptors to validate these models. Additionally, we examine pain coculture model strategies that more closely replicate in vivo peripheral and central microenvironments. Finally, we discuss the current limitations and future perspectives of enhancing the physiological relevance and predictability of in vitro pain models for the development of novel analgesics and deepening mechanistic understanding.
慢性疼痛影响着约20%的人口，由于镇痛药在提供可靠疼痛缓解方面效果有限，对日常生活产生了重大影响，并增加了患者的心理社会负担。这一临床障碍很大程度上是由于对人类疼痛病理生理学的机制理解有限，这是由研究人类疼痛机制的模型局限性所导致的。此外，缺乏用于研究人类疼痛相关机制的可靠模型阻碍了疼痛相关药物和疗法的筛选与评估，在开发无不良副作用的止痛药物方面造成了重大障碍。更复杂且生理相关性更强的体外模型提供了一个机会，可在可控环境中研究人类细胞和组织，同时复制天然人类环境的关键方面。此外，这些模型符合3R原则，在伦理上具有优势，能够直接研究人类细胞及其生理环境，促进转化研究结果的发展。在本综述中，我们阐述了疼痛感觉过程的关键分子机制，强调了伤害感受器与外周和中枢神经系统水平的非神经元细胞之间的双向串扰，讨论了当前的体内模型及其缺点，并探索通过诱导多能干细胞（iPSC）的各种分化方案在体外生成人类伤害感受器来进行与人类相关建模的策略。我们还综述了体外疼痛模型系统的最新进展，包括其电生理特征、分隔策略以及使用针对特定离子通道和受体的激动剂和拮抗剂测定来验证这些模型。此外，我们研究了更紧密复制体内外周和中枢微环境的疼痛共培养模型策略。最后，我们讨论了当前在增强体外疼痛模型的生理相关性和可预测性以开发新型镇痛药及深化机制理解方面的局限性和未来展望。
