Baht Gurpreet S, Nadesan Puviindran, Silkstone David, Alman Benjamin A
Department of Orthopaedic Surgery, Duke University, Durham, USA; Duke Molecular Physiology Institute, Duke University, Durham, USA.
Department of Orthopaedic Surgery, Duke University, Durham, USA.
Bone. 2017 May;98:31-36. doi: 10.1016/j.bone.2017.02.012. Epub 2017 Feb 22.
Patients with Neurofibromatosis type 1 display delayed fracture healing and the increased deposition of fibrous tissue at the fracture site. Severe cases can lead to non-union and even congenital pseudarthrosis. Neurofibromatosis type 1 is caused by a mutation in the NF1 gene and mice lacking the Nf1 gene show a fracture repair phenotype similar to that seen in patients. Tissue from the fracture site of patients with Neurofibromatosis type 1 and from mice deficient in the Nf1 gene both show elevated levels of β-catenin protein and activation of β-catenin mediated signaling. Constitutively elevated β-catenin leads to a delayed and fibrous fracture repair process, and (RS)-5-methyl-1-phenyl-1,3,4,6-tetrahydro-2,5-benzoxazocine (Nefopam, a centrally-acting, non-narcotic analgesic agent) inhibits β-catenin mediated signaling during skin wound repair. Here we investigate Nefopam's potential as a modulator of bone repair in mice deficient in Nf1. Mice were treated with Nefopam and investigated for bone fracture repair. Bone marrow stromal cells flushed from the long bones of unfractured mice were treated with Nefopam and investigated for osteogenic potential. Treatment with Nefopam was able to lower the β-catenin level and the Axin2 transcript level in the fracture calluses of Nf1 deficient mice. Cultures from the bone marrow of Nf1 mice had significantly lower osteoblastic colonies and mineralized nodules, which was increased when cells were cultured in the presence of Nefopam. Fracture calluses were harvested and analyzed 14days and 21days after injury. Nf1 calluses had less bone, less cartilage, and higher fibrous tissue content than control calluses. Treatment with Nefopam increased the bone and cartilage content and decreased the fibrous tissue content in Nf1 calluses. These findings present a potential treatment for patients with Neurofibromatosis 1 in the context of bone repair. Since Nefopam is already in use in patient care, it could be rapidly translated to the clinical setting.
1型神经纤维瘤病患者表现出骨折愈合延迟以及骨折部位纤维组织沉积增加。严重病例可导致骨不连甚至先天性假关节。1型神经纤维瘤病由NF1基因突变引起，缺乏Nf1基因的小鼠表现出与患者相似的骨折修复表型。1型神经纤维瘤病患者骨折部位的组织以及缺乏Nf1基因的小鼠组织均显示β-连环蛋白水平升高以及β-连环蛋白介导的信号激活。持续升高的β-连环蛋白会导致骨折修复过程延迟并形成纤维组织，而（RS）-5-甲基-1-苯基-1,3,4,6-四氢-2,5-苯并恶唑嗪（奈福泮，一种中枢作用的非麻醉性镇痛药）在皮肤伤口修复过程中可抑制β-连环蛋白介导的信号传导。在此，我们研究奈福泮作为Nf1基因缺陷小鼠骨修复调节剂的潜力。用奈福泮处理小鼠并研究其骨折修复情况。从未骨折小鼠的长骨中冲洗出的骨髓基质细胞用奈福泮处理并研究其成骨潜力。用奈福泮治疗能够降低Nf1基因缺陷小鼠骨折痂中的β-连环蛋白水平和Axin2转录水平。Nf1小鼠骨髓培养物中的成骨细胞集落和矿化结节明显较少，当细胞在奈福泮存在的情况下培养时，这些情况有所增加。在损伤后14天和21天收集并分析骨折痂。与对照骨折痂相比，Nf1骨折痂的骨组织、软骨组织较少，纤维组织含量较高。用奈福泮治疗可增加Nf1骨折痂中的骨组织和软骨组织含量，并降低纤维组织含量。这些发现为1型神经纤维瘤病患者的骨修复提供了一种潜在的治疗方法。由于奈福泮已用于患者护理，它可以迅速转化为临床应用。
