Department of Orthopaedic Surgery, Graduate School of Medicine, Nagoya University, Nagoya, Japan.
Division for Therapies against Intractable Diseases, Institute for Comprehensive Medical Science, Fujita Health University, Toyoake, Japan.
J Orthop Res. 2021 Jun;39(6):1297-1304. doi: 10.1002/jor.24625. Epub 2020 Feb 21.
Heterotopic ossification (HO) is a pathological condition in which ectopic bone forms within soft tissues such as skeletal muscle. Human platelet-derived growth factor receptor α positive (PDGFRα+) cells, which were proved to be the original cells of HO were incubated in osteogenic differentiation medium with Food and Drug Administration-approved compounds. Alkaline phosphatase activity was measured as a screening to inhibit osteogenic differentiation. For the compounds which inhibited osteogenic differentiation of PDGFRα+ cells, we examined dose dependency of its effect using alizarin red S staining and its cell toxicity using WST-8. In addition, regulation of bone morphogenetic proteins (BMP)-Smad signaling which is the major signal of osteogenic differentiation was investigated by Western blotting to elucidate the mechanism of osteogenesis inhibitory effect by the compound. In vivo experiment, complete transverse incision of Achilles tendons in mice was made and mice were fed the compound by mixing with drinking water after operation. Ten weeks after operation, we assessed and quantified HO by micro-computed tomography scan. Intriguingly, we discovered desloratadine inhibited osteogenic differentiation of PDGFRα+ cells using the drug repositioning method. Desloratadine inhibited osteogenic differentiation of the cells dose dependently without cell toxicity. Desloratadine suppressed phosphorylation of Smad1/5/8 induced by BMP2 in PDGFRα+ cells. In Achilles tenotomy mice model, desloratadine treatment significantly inhibited ectopic bone formation compared with control. In conclusion, we discovered desloratadine inhibited osteogenic differentiation using human PDGFRα+ cells and proved its efficacy using Achilles tenotomy ectopic bone formation model in vivo. Our study paved the way to inhibit HO in early clinical use because of its guaranteed safety.
异位骨化（HO）是一种病理状态，其中异位骨在骨骼肌等软组织中形成。人类血小板衍生生长因子受体α阳性（PDGFRα+）细胞被证明是 HO 的原始细胞，这些细胞在含有食品和药物管理局批准的化合物的成骨分化培养基中孵育。碱性磷酸酶活性被测量作为抑制成骨分化的筛选。对于抑制 PDGFRα+细胞成骨分化的化合物，我们使用茜素红 S 染色检查其作用的剂量依赖性，并使用 WST-8 检查其细胞毒性。此外，通过 Western blot 研究了骨形态发生蛋白（BMP）-Smad 信号转导的调节，这是成骨分化的主要信号，以阐明该化合物对成骨作用的抑制机制。在体内实验中，通过手术在小鼠的跟腱上做完全横切口，并在手术后将化合物与饮用水混合喂养。手术后 10 周，我们通过 micro-CT 扫描评估和定量 HO。有趣的是，我们通过药物再定位方法发现地氯雷他定抑制了 PDGFRα+细胞的成骨分化。地氯雷他定没有细胞毒性地抑制细胞的成骨分化。地氯雷他定抑制 BMP2 诱导的 PDGFRα+细胞中 Smad1/5/8 的磷酸化。在跟腱切断小鼠模型中，与对照组相比，地氯雷他定治疗显著抑制了异位骨形成。总之，我们发现地氯雷他定抑制了人 PDGFRα+细胞的成骨分化，并通过体内 Achilles 腱切断异位骨形成模型证明了其疗效。我们的研究为早期临床应用抑制 HO 铺平了道路，因为它具有保证的安全性。
