Bone cancer and its related chronic pain are huge clinical problems since the available drugs are often ineffective or cannot be used long term due to a broad range of side effects. The mechanisms, mediators and targets need to be identified to determine potential novel therapies. Here, we characterize a mouse bone cancer model induced by intratibial injection of K7M2 osteosarcoma cells using an integrative approach and investigate the role of capsaicin-sensitive peptidergic sensory nerves. The mechanical pain threshold was assessed by dynamic plantar aesthesiometry, limb loading by dynamic weight bearing, spontaneous pain-related behaviors via observation, knee diameter with a digital caliper, and structural changes by micro-CT and glia cell activation by immunohistochemistry in BALB/c mice of both sexes. Capsaicin-sensitive peptidergic sensory neurons were defunctionalized by systemic pretreatment with a high dose of the transient receptor potential vanilloid 1 (TRPV1) agonist resiniferatoxin (RTX). During the 14- and 28-day experiments, weight bearing on the affected limb and the paw mechanonociceptive thresholds significantly decreased, demonstrating secondary mechanical hyperalgesia. Signs of spontaneous pain and osteoplastic bone remodeling were detected both in male and female mice without any sex differences. Microglia activation was shown by the increased ionized calcium-binding adapter molecule 1 (Iba1) immunopositivity on day 14 and astrocyte activation by the enhanced glial fibrillary acidic protein (GFAP)-positive cell density on day 28 in the ipsilateral spinal dorsal horn. Interestingly, defunctionalization of the capsaicin-sensitive afferents representing approximately 2/3 of the nociceptive fibers did not alter any functional parameters. Here, we provide the first complex functional and morphological characterization of the K7M2 mouse osteosarcoma model. Bone-cancer-related chronic pain and hyperalgesia are likely to be mediated by central sensitization involving neuroinflammation via glial cell activation in the spinal dorsal horn, but not the capsaicin-sensitive sensory neuronal system.
骨癌及其相关的慢性疼痛是巨大的临床难题，因为现有药物往往疗效有限，或因其广泛的副作用而无法长期使用。为探索潜在的新型治疗方法，必须明确其机制、介质和作用靶点。本研究采用整合方法，通过胫骨内注射K7M2骨肉瘤细胞构建小鼠骨癌模型，并探讨辣椒素敏感性肽能感觉神经的作用。在雌雄BALB/c小鼠中，通过动态足底测痛仪评估机械痛阈值，动态负重测试评估肢体负荷，行为观察记录自发性疼痛相关行为，数字卡尺测量膝关节直径，微型计算机断层扫描分析结构变化，免疫组化检测胶质细胞活化。通过大剂量瞬时受体电位香草酸亚型1（TRPV1）激动剂树脂毒素（RTX）全身预处理，使辣椒素敏感性肽能感觉神经元功能失活。在14天和28天的实验周期中，患肢负重能力与足部机械伤害性阈值显著下降，表现为继发性机械痛觉过敏。雌雄小鼠均出现自发性疼痛迹象和成骨性骨重塑现象，且无性别差异。在同侧脊髓背角，小胶质细胞活化表现为第14天离子钙结合适配分子1（Iba1）免疫阳性增强，星形胶质细胞活化表现为第28天胶质纤维酸性蛋白（GFAP）阳性细胞密度增加。值得注意的是，约占伤害性感觉纤维三分之二的辣椒素敏感性传入神经功能失活后，所有功能参数均未发生改变。本研究首次对K7M2小鼠骨肉瘤模型进行了系统的功能与形态学表征。骨癌相关慢性疼痛和痛觉过敏可能由中枢敏化介导，该过程涉及脊髓背角胶质细胞活化引发的神经炎症，而非辣椒素敏感性感觉神经元系统。
肿瘤(癌症)患者之家