Does Sclerostin Depletion Stimulate Fracture Healing in a Mouse Model?
Does Sclerostin Depletion Stimulate Fracture Healing in a Mouse Model?
复制标题
DOI：
10.1007/s11999-015-4640-z
复制
发表时间：
2016-05-01
影响因子：
4.2
通讯作者：
Hamdy, Reggie C.
中科院分区：
文献类型：
--
作者：
Alzahrani, Mohammad M.;Rauch, Frank;Hamdy, Reggie C.
硬化蛋白是一种分泌型糖蛋白，抑制细胞内Wnt信号通路，当Wnt信号通路失活时，刺激骨形成。这已经在骨折研究中看到，其已经显示在sclerostin敲除和sclerostin抗体注射模型中具有加速骨折愈合的更大和更强的愈伤组织。然而，这两种机制的作用还没有在骨折愈合的背景下进行比较。（Scl-Ab注射）和完全硬化蛋白消耗抑制小鼠模型中的骨折愈合，如通过（1）骨折部位的形态测量骨小梁测量，方法将10周龄雄性sclerostin基因敲除小鼠（n = 20）和野生型小鼠（n = 40）插入胫骨髓内钉，然后进行胫骨中段截骨术。将小鼠分为三组：sclerostin敲除组（n = 20）、注射sclerostin抗体的野生型组（每周100 mg/kg的静脉内剂量）（n = 20）和注射盐水的野生型组（n = 20）。将每组的小鼠在手术后14、21、28和35天细分并安乐死，此时用microCT评估骨折的胫骨（以评估骨小梁形态测量：骨体积与总体积（BV/TV）、骨小梁厚度、骨小梁数量和骨折部位的结构模型指数）。还进行了三点弯曲形式的生物力学测试，以评估骨折部位的结构强度。根据我们的功效分析，我们的主要结果（BV/TV）中大于3.7%的差异将需要以80%的功效检测组之间的差异。结果与使用盐水的野生型组相比，使用sclerostin抗体的野生型组和sclerostin敲除组在骨折部位显示增加的小梁BV/TV，然而，除了在术后28天sclerostin敲除组显示出比野生型sclerostin抗体组更大的BV/TV之外，在具有可用数字的治疗组之间没有观察到差异（47.0 +/- 3.5 vs 40.1 +/- 2.1; p < 0.05）。在生物力学测试中，野生型sclerostin抗体在第14天和第28天分别显示与野生型盐水组相比增加的硬度（70.9 +/-6.4 vs 14.8 +/-8.1; p = 0.001），（106.8 +/-24.3 vs 74.9 +/-16.0; p = 0.004）。然而，在可用的数量下，在全骨结构强度方面，在具有sclerostin抗体的野生型和sclerostin敲除组之间没有检测到差异。结论Sclerostin抗体注射显示出有希望的结果，这与可用的数量没有差异，从sclerostin完全耗尽所获得的结果来看，特别是在愈合过程的早期阶段，因此在较早的时间完成了愈合过程。
Background Sclerostin is a secreted glycoprotein that inhibits the intracellular Wnt signaling pathway, which, when inactivated, stimulates bone formation. This has been seen in fracture studies, which have shown larger and stronger calluses with accelerated fracture healing in sclerostin knockout and sclerostin antibody injection models. However, the effects of these two mechanisms have not been compared in the context of fracture healing.Questions/purposes We sought to determine the degree to which sclerostin inhibition (Scl-Ab injection) and complete sclerostin depletion inhibit fracture healing in a mouse model as evaluated by (1) morphometric trabecular bone measures at the fracture site, and (2) fracture site structural strength.Methods Ten-week-old male sclerostin knockout (n = 20) and wild type (n = 40) mice underwent insertion of a tibial intramedullary pin after which a midshaft tibial osteotomy was performed. The mice were divided in three groups: sclerostin knockout (n = 20), wild type with sclerostin antibody injection (intravenous dose of 100 mg/kg weekly) (n = 20), and wild type with saline injection (n = 20). The mice for each group where subdivided and euthanized at 14, 21, 28, and 35 days after surgery, at which time the fractured tibias were assessed with microCT (to assess morphometric trabecular bone measures: bone volume to total volume (BV/TV), trabecular thickness, trabecular number, and structural model index at the fracture site. Biomechanical testing in the form of three-point bending also was done to assess fracture site structural strength. A difference greater than 3.7% in our primary outcome (BV/TV) would be required to detect a difference between groups with a power of 80%, as per our power analysis.Results The wild type with sclerostin antibody and the sclerostin knockout groups showed increased trabecular BV/TV at the fracture site compared with the wild type group with saline at all times, however no difference was seen between the treatment groups with the numbers available, except at 28 days postoperatively when the sclerostin knockout group showed greater BV/TV than the wild type sclerostin antibody group (47.0 +/- 3.5 vs 40.1 +/- 2.1; p < 0.05). On biomechanical testing the wild type sclerostin antibody showed increased stiffness at Days 14 and 28 compared with the wild type with saline group (70.9 +/- 6.4 vs 14.8 +/- 8.1; p = 0.001), (106.8 +/- 24.3 vs 74.9 +/- 16.0; p = 0.004); respectively. However, with the numbers available, no differences were detected between the wild type with sclerostin antibody and the sclerostin knockout groups in terms of whole-bone structural strength.Conclusions Sclerostin antibody injections showed promising results, which were not different with the numbers available, from results achieved with complete depletion of sclerostin, especially at earlier stages of the healing process, and therefore completed the healing process at an earlier time.