The Role of Extracellular Matrix Dysregulation in Heterotopic Ossification

项目总结 异位骨化是异位骨在骨外组织中的病理性形成。 大约20%遭受某种肌肉骨骼损伤的患者会发生HO。这些伤害可能 创伤性质的或受控的组织损伤，作为常规矫形手术的一部分，如 关节置换手术或外科截肢手术。HO的风险对退伍军人的影响不成比例 与平民相比，尤其是由于经历创伤性冲击波、脑或脊柱创伤的风险更高 脐带受伤。事实上，在最近的冲突和伊拉克和阿富汗的军事爆炸伤中 导致了HO。HO的存在与慢性疼痛、慢性感染、溃疡、受损有关 伤口愈合，以及其他相关的健康并发症。这些由HO引起的并发症通常会阻止复发 损伤肢体的活动度和功能，并极大地限制假肢的使用，阻碍退伍军人 独立和重返工作岗位或融入平民生活。这些困难可能会导致阿片成瘾， 抑郁和自杀，这些都是退伍军人整体健康的主要问题。目前的治疗方案是 由于缺乏对驱动异位骨形成的分子机制的了解 软组织损伤后愈合。因此，拟议的工作试图阐明驱动 HO中的骨形成，以寻找预防和治疗的新的靶向治疗方法 异位成骨。细胞外基质(ECM)在许多生物调节中起着重要作用。 包括组织修复和维护的过程。虽然已知因损伤而导致的炎症增加 显著增加ECM合成，将异常ECM沉积与异位骨形成联系起来的机制 很大程度上仍未被勘探。我们已经在小鼠模型上进行了初步实验， 在患者体内形成组织学上类似于HO的异位骨。重要的是，软组织的变化 在这些导致HO的小鼠中观察到，尤其是ECM的异常和进行性积聚 胶原蛋白(COLS)和糖胺聚糖(GAG)等分子紧密地概括了观察到的变化 在病人身上。因此，我们假设I型胶原和硫酸软骨素(CS)的异常过度生产 GAGS创造了一种ECM环境，能够激活HO软组织中异常的成骨信号。这个 本研究的总体目标是阐明Col I和CS GAG在异位中的作用 骨形成，以确定潜在的治疗策略和诊断标志物使用 HO的小鼠模型。在目标1中，我们将确定COL的临界浓度和化学成分 I和CS在ECM中堵塞，能够建立有利于成骨的微环境生态位 分化并验证伴随而来的骨形成标志物的上调。在目标2中，我们将 建立抑制Col I和CS Gag蓄积作为抑制HO的潜在治疗策略。 在目标3中，我们将确定可以预测HO易感性的循环生物标记物，并验证我们的发现 从小鼠模型研究中确定的人类患者数据通过生物信息库分析来建立 临床相关性。这些研究的完成将在过度的环境影响管理之间建立直接联系 HO中骨形成的积累和激活，为开发新的治疗方法铺平了道路 可以通过靶向ECM产生机制来防止异位骨生长的策略。此外， 这项工作将为我们全面理解ECM生产在 创伤后的组织修复，这将为纤维化和伤口愈合的其他重要研究提供信息 提高退伍军人健康水平。

PROJECT SUMMARY Heterotopic ossification (HO) is the pathologic formation of ectopic bone in extra-skeletal tissues. Approximately 20% of patients who suffer some type of musculoskeletal injury develop HO. These injuries can be traumatic in nature or controlled tissue damage that occurs as a part of routine orthopaedic surgeries like joint replacement surgery or surgical amputations. The risk of HO disproportionately affects the Veteran population compared to civilians, especially due to higher risk of experiencing traumatic blast, brain, or spinal cord injury. Indeed, 64% of military blast injuries from the recent conflicts and Iraq and Afghanistan have resulted in HO. The presence of HO is associated with chronic pain, chronic infection, ulceration, impaired wound healing, and other related health complications. These complications from HO often preclude regaining mobility and function in the injured limb and substantially limit the use of prosthetics, impeding Veteran independence and return to duty or integration into civilian life. These difficulties can lead to opioid addiction, depression, and suicide, which are all major concerns to overall Veteran health. Current treatment options are limited due to the lack of understanding of the molecular mechanisms that drive ectopic bone formation during soft tissue healing following damage. Thus, the proposed work seeks to elucidate the mechanisms driving bone formation in HO in order to identify new, targeted therapeutic approaches for preventing and treating ectopic bone formation. The extracellular matrix (ECM) plays an essential role in regulating many biological processes including tissue repair and maintenance. While upregulated inflammation due to injury is known to significantly increase ECM synthesis, mechanisms linking aberrant ECM deposition to ectopic bone formation remain largely unexplored. We have carried out preliminary experiments in mouse models that consistently form ectopic bone that is histologically similar to HO in patients. Importantly, the soft tissue changes that are observed in these mice leading up to HO, particularly the aberrant and progressive accumulation of ECM molecules like collagens (COLs) and glycosaminoglycans (GAGs), closely recapitulate the changes observed in patients. Therefore, we hypothesize that abnormal overproduction of COL I and chondroitin sulfate (CS) GAGs creates an ECM environment capable of activating aberrant osteogenic signals in soft tissue in HO. The overall objective of this proposal is to elucidate the role of COL I and CS GAG accumulation in ectopic bone formation in order to identify potential therapeutic strategies and diagnostic markers using mouse models of HO. In Aim 1, we will determine the critical concentration and chemical composition of COL I and CS GAGs in the ECM that is able to establish a microenvironmental niche conducive for osteogenic differentiation and verify the concomitant upregulation of associated bone formation markers. In Aim 2, we will establish the inhibition of COL I and CS GAG accumulation as potential treatment strategies for inhibiting HO. In Aim 3, we will identify circulating biomarkers that may predict predisposition to HO and validate our findings from mouse model studies in deidentified human patient data through biorepository analyses to establish clinical relevance. The completion of these studies will establish direct links between excessive ECM accumulation and activation of bone formation in HO, paving the way for the development of new therapeutic strategies that can prevent ectopic bone growth by targeting mechanisms of ECM production. Furthermore, this work will provide critical, fundamental insights to our overall understanding of the role of ECM production in tissue repair following trauma, which will inform other important studies in fibrosis and wound healing to improve Veteran health.