Traumatic heterotopic ossification (tHO) commonly develops in wounded service members who sustain high-energy and blast-related traumatic amputations. Currently, no safe and effective preventive measures have been identified for this patient population. Bone morphogenetic protein (BMP) signaling blockade has previously been shown to reduce ectopic bone formation in genetic models of HO. In this study, we demonstrate the efficacy of small-molecule inhibition with LDN193189 (ALK2/ALK3 inhibition), LDN212854 (ALK2-biased inhibition), and BMP ligand trap ALK3-Fc at inhibiting early and late osteogenic differentiation of tissue-resident mesenchymal progenitor cells (MPCs) harvested from mice subjected to burn/tenotomy, a well-characterized trauma-induced model of HO. Using an established rat tHO model of blast-related extremity trauma and methicillin-resistant Staphylococcus aureus infection, a significant decrease in ectopic bone volume was observed by micro-computed tomography imaging following treatment with LDN193189, LDN212854, and ALK3-Fc. The efficacy of LDN193189 and LDN212854 in this model was associated with weight loss (17%–19%) within the first two postoperative weeks, and in the case of LDN193189, delayed wound healing and metastatic infection was observed, while ALK3-Fc was well tolerated. At day 14 following injury, RNA-Seq and quantitative reverse transcriptase–polymerase chain reaction analysis revealed that ALK3-Fc enhanced the expression of skeletal muscle structural genes and myogenic transcriptional factors while inhibiting the expression of inflammatory genes. Tissue-resident MPCs harvested from rats treated with ALK3-Fc exhibited reduced osteogenic differentiation, proliferation, and self-renewal capacity and diminished expression of genes associated with endochondral ossification and SMAD-dependent signaling pathways. Together, these results confirm the contribution of BMP signaling in osteogenic differentiation and ectopic bone formation and that a selective ligand-trap approach such as ALK3-Fc may be an effective and tolerable prophylactic strategy for tHO.

中文翻译：

---

BMP 配体陷阱 ALK3-Fc 减弱爆炸相关下肢创伤中的成骨和异位骨化


创伤性异位骨化（tHO）通常发生在承受高能量和爆炸相关创伤性截肢的受伤服役人员中。目前，尚未针对该患者群体确定安全有效的预防措施。骨形态发生蛋白 (BMP) 信号传导阻断先前已被证明可以减少 HO 遗传模型中的异位骨形成。在这项研究中，我们证明了 LDN193189（ALK2/ALK3 抑制）、LDN212854（ALK2 偏向抑制）和 BMP 配体捕获 ALK3-Fc 的小分子抑制在抑制组织驻留间充质祖细胞的早期和晚期成骨分化方面的功效从遭受烧伤/腱切断术的小鼠身上采集的细胞（MPC），这是一种充分表征的创伤诱导的 HO 模型。使用已建立的爆炸相关肢体创伤和耐甲氧西林金黄色葡萄球菌感染的大鼠 tHO 模型，在使用 LDN193189、LDN212854 和 ALK3-Fc 治疗后，通过微型计算机断层扫描成像观察到异位骨体积显着减少。 LDN193189 和 LDN212854 在此模型中的疗效与术后前两周内体重减轻 (17%–19%) 相关，在 LDN193189 的情况下，观察到伤口愈合延迟和转移性感染，而 ALK3-Fc 则表现良好容忍的。损伤后第 14 天，RNA-Seq 和定量逆转录酶 - 聚合酶链反应分析表明 ALK3-Fc 增强骨骼肌结构基因和肌源性转录因子的表达，同时抑制炎症基因的表达。 从接受 ALK3-Fc 处理的大鼠中收获的组织驻留 MPC 表现出成骨分化、增殖和自我更新能力降低，以及与软骨内骨化和 SMAD 依赖性信号通路相关的基因表达减少。总之，这些结果证实了 BMP 信号在成骨分化和异位骨形成中的贡献，并且选择性配体捕获方法（例如 ALK3-Fc）可能是 tHO 的有效且可耐受的预防策略。