Improved Tools for Accessing Pain Following Fracture and Enabling Standardized Pain Phenotyping

摘要 骨折是全世界最常见的伤害之一，柳叶刀全球疾病负担报告 在2019.1例延迟愈合和骨不连中，1.78亿新骨折和4.45亿常见骨折是 基于纵向X线片中骨折线的持续性和疼痛/的定性临床诊断 承重不稳定。虽然无法获得对延迟/不联合的全球强劲估计，但最好的 目前的数据发现，8%-14%的骨折在受伤后2年内因愈合并发症而再次住院。 如果骨折发生在具有高共病负担的患者中，则延迟愈合率显著增加 随着年龄的增加，糖尿病或肥胖。3，4目前对这些骨折的标准护理是手术改变硬件 或者植入骨移植。目前还没有被批准用于加速骨折愈合的药物。 因此，临床上对能够刺激非外科手术中骨再生的生物制剂的需求尚未得到满足。 交付平台。Parent Grant的长期目标是开发和验证一种可注射、可生物降解的 用于局部和持续释放无痛神经生长因子(NGF)异构体的纳米线输送平台 在延迟愈合的临床情况下加速骨折愈合。为了支持家长助学金，我们有 发表NGF作用于软骨细胞以促进与软骨内相关的分子程序 骨化5和NGF可以被封装到生物材料平台中以进行受控和局部输送。 阿片类药物是治疗骨折后疼痛的标准护理。7-11本止痛补充剂的目标是 用机器学习验证一种测量诱发性和自发性疼痛的新技术 骨折。Parent Grant的一个创新和核心前提是治疗使用一种“无痛”的亚型 神经生长因子促进延迟修复模型小鼠骨折愈合。无痛性神经生长因子源于自然 野生型神经生长因子β序列(NGFR100W)发生点突变，使其能够与TrkA受体结合， 负责NGF的营养活性，而不是负责疼痛的p75受体。12我们的进展 在家长Grant的报告中，我们分享了新的数据，表明NGFR100W不会诱导疼痛敏感化 剂量是未骨折肢体后爪注射神经生长因子β的10倍。然而，标准的反身性回避 当转化为四肢骨折时，检测结果不能可靠地用于诱发疼痛。在这笔赠款中，我们颁发了第一个 使用一种新技术BlackBox，结合DeepLabCutTM机器学习来监控数据是如何 骨折后疼痛转移的可量化行为终点。然后我们利用这项技术来理解 通过评估(AIM 1)注射NGF治疗后引起的疼痛对骨折疼痛的扰动 2)延迟骨折愈合模型中自发性疼痛的变化，以及(3)神经生长因子受体的作用 在调节疼痛反应方面。我们通过在外部建立新的合作来实现这三个目标 我们目前的研究基地拥有疼痛研究方面的专业知识(NOSI目标B：艾伦·巴斯鲍姆实验室)。

ABSTRACT Fractures are one of the most common injuries worldwide with The Lancet Global Burden of Diseases reporting 178 million new fractures and 445 million prevalent fractures in 2019.1 Delayed healing and non-union are qualitative clinical diagnoses based on the persistence of a fracture line in longitudinal radiographs and pain/ instability with weight bearing. While robust global estimates of delayed/non-union are not available, the best current data finds that 8-14% of fractures were readmitted for healing complications within 2 years post-injury.2 Delayed healing rates increase significantly if the fracture occurs in patients with high co-morbidity burdens such as increased age, diabetes, or obesity.3,4 Current standard-of-care for these fractures is surgery to alter hardware or implant bone grafts. There are currently no pharmacological agents approved to accelerate fracture healing. As such, there exists an unmet clinical need for biologics that could stimulate bone regeneration in a non-surgical delivery platform. The long-term goal of the Parent Grant is to develop and validate an injectable, biodegradable nanowire delivery platform for local and sustained release of a “painless” nerve growth factor (NGF) isoform to accelerate fracture healing in clinical scenarios of delayed healing. In support of the Parent Grant, we have published that NGF acts on chondrocytes to promote molecular programs associated with endochondral ossification5 and that NGF can be encapsulated into biomaterial platforms for controlled and localized delivery6. Opioids are the standard of care for addressing post-fracture pain.7-11 The goal of this Pain Supplement is to validate a novel technology with machine learning for measuring induced and spontaneous pain following fractures. An innovative and central premise of the Parent Grant is the therapeutic use of a “painless” isoform of NGF to promote fracture healing in murine models of delayed repair. Painless NGF results from a naturally occurring point mutation in the wild type NGFβ sequence (NGFR100W) that enables binding to the TrkA receptor, responsible for the trophic activity of NGF, but not to the p75 receptor responsible for pain.12 In our progress report for the Parent Grant, we shared new data demonstrating that NGFR100W does not induce pain sensitization at a dose 10-fold higher than NGFβ in the hindpaw of an unfractured limb. However, standard reflexive avoidance assays were not reliable for induced pain when translated to a fractured limb. In this grant, we present the first data using a novel technology, the BlackBox, coupled with DeepLabCutTM machine learning to monitor how quantifiable behavioral endpoints of pain shift after bone fracture. We then utilize this technology to understand perturbations to fracture pain by evaluating (Aim 1) induced pain in response to the injected NGF therapy, (Aim 2) changes in spontaneous pain in models of delayed fracture healing, and (Aim 3) the role of the NGF receptors in modulating pain response. We accomplish these three Aims by establishing a new collaboration outside of our current research base that has expertise in pain research (NOSI Goal B: Allan Basbaum Laboratory).