Impact of peripheral nerves on mesenchymal cell fate in extremity trauma

项目摘要 异位骨化(HO)的特征是驻留组织的骨软骨分化异常。 间充质祖细胞。近20%的肢体创伤、截肢和大表面积受累于HO 烧伤患者，临床上以疼痛为先兆。目前，尚无治疗方法可防止引发、逆转 或通过有效的非阿片类药物机制限制疼痛。在分析我们的 验证了创伤诱导的HO模型，我们观察到神经内长是创伤的早期反应。使用 独特的人类创伤性HO数据集的早期和晚期HO损害，我们已经证实了这一早期和不适应 神经内生先于HO。此外，我们发现外科手术去神经可以有效地抑制早期阶段。 HO形成的。在后续研究中，我们发现了神经生长因子(NGF)作为主要刺激因子的作用 HO前神经的内生，出乎意料的是，血管周围细胞(周细胞和血管平滑肌) 细胞)似乎是这种神经营养因子的主要来源。阐明神经生长因子诱导神经生长的作用 关于HO，我们进行了补充研究，表明神经向内生长可能激活间充质 前体细胞转化生长因子β-1信号转导局部间充质细胞向软骨细胞异常分化 祖细胞是HO前体细胞。这些观察结果导致了我们的中心假设，即血管周围起源于 神经生长因子刺激表达trkA的感觉树突入HO部位，进而释放转化生长因子β1至 刺激间充质祖细胞向骨软骨分化。为此，提出了以下目标： 目的1：明确血管周围神经生长因子在控制HO部位感觉神经生长中的作用 开始和进展。使用已建立的动物模型，我们假设组织特异性缺失 周细胞(PDGFRb-CreERT2；Ngffl/fl)或血管平滑肌细胞(vSMCs；MYH11-CreerT2；Ngffl/f1)中的NGF将 破坏损伤部位周围神经的生长和HO的形成。 目的：检测转化生长因子β1信号转导通路在大鼠感觉神经-间充质前体细胞信号传导中的作用。 呵呵。利用已建立的动物模型，我们假设感觉神经正向调节间充质。 转化生长因子β-1依赖的祖细胞向骨软骨分化。 目的3：确定抗NGF中和抗体作为一种新的HO治疗方法的潜在作用 干预。我们假设Fasinumab(一种NGF中和抗体)代表一种双重止痛剂和 HO疾病进展的负调节因子，它钝化了病理性神经的生长。

Project Summary Heterotopic ossification (HO) is characterized by the aberrant osteochondral differentiation of tissue resident mesenchymal progenitor cells. HO afflicts nearly 20% of extremity trauma, amputation and large surface area burn patients and is clinically preceded by pain. Currently, no treatments exist to prevent initiation, reverse disease progression, or limit pain through efficacious, non-opioid mechanisms. In the course of analyzing our validated trauma-induced HO model, we observed nerve ingrowth as an early response to trauma. Using a unique human traumatic HO dataset of early and late HO lesions, we have confirmed this early and maladaptive nerve ingrowth precedes HO. Additionally, we discovered that surgical denervation potently inhibits early stages of HO formation. In follow up studies, we uncovered the role of nerve growth factor (NGF) as the primary stimulus of this pre-HO nerve ingrowth and, unexpectedly, that perivascular cells (pericytes and vascular smooth muscle cells) appear to be the primary source of this neurotrophin. To elucidate the role of NGF induced nerve ingrowth on HO, we performed complementary studies which suggest that nerve ingrowth may activate mesenchymal progenitor cell TGFβ1 signaling to drive aberrant chondrogenic differentiation among local mesenchymal progenitor HO precursor cells. These observations have led to our central hypothesis that perivascular derived NGF stimulates TrkA-expressing sensory dendrite ingrowth into the HO site, which in turn releases TGFβ1 to stimulate mesenchymal progenitor cell osteochondral differentiation. As such, the following aims are proposed: Aim 1: Define the role of perivascular NGF in controlling sensory nerve ingrowth at sites of HO initiation and progression. Using established animal models, we hypothesize that tissue-specific deletion of Ngf in pericytes (Pdgfrb-CreERT2;Ngffl/fl) or vascular smooth muscle cells (vSMCs; Myh11-CreERT2;Ngffl/fl) will abrogate peripheral nerve ingrowth and HO formation at sites of trauma. Aim 2: Test the role of TGFβ1 signaling in sensory nerve-mesenchymal progenitor cell cross talk in HO. Using established animal models, we hypothesize that sensory nerves positively regulate mesenchymal progenitor cell osteochondral differentiation through a TGFβ1 dependent process. Aim 3: Define a potential role for anti-NGF neutralizing antibodies as a novel HO therapeutic intervention. We hypothesize that Fasinumab (an NGF neutralizing antibody) represents a dual analgesic and negative regulator of HO disease progression, which blunts pathologic nerve ingrowth.