Meyer Luisa A, Johnson Michael G, Cullen Diane M, Vivanco Juan F, Blank Robert D, Ploeg Heidi-Lynn, Smith Everett L
Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA.
Department of Medicine, University of Wisconsin-Madison, Madison, WI 53706, USA; GRECC William S. Middleton Memorial Veterans Hospital, Madison, WI 53705, USA.
Bone. 2016 Apr;85:115-22. doi: 10.1016/j.bone.2016.02.001. Epub 2016 Feb 12.
Increased bone formation resulting from mechanical loading is well documented; however, the interactions of the mechanotransduction pathways are less well understood. Endothelin-1, a ubiquitous autocrine/paracrine signaling molecule promotes osteogenesis in metastatic disease. In the present study, it was hypothesized that exposure to big endothelin-1 (big ET1) and/or mechanical loading would promote osteogenesis in ex vivo trabecular bone cores. In a 2×2 factorial trial of daily mechanical loading (-2000με, 120cycles daily, "jump" waveform) and big ET1 (25ng/mL), 48 bovine sternal trabecular bone cores were maintained in bioreactor chambers for 23days. The bone cores' response to the treatment stimuli was assessed with percent change in core apparent elastic modulus (ΔEapp), static and dynamic histomorphometry, and prostaglandin E2 (PGE2) secretion. Two-way ANOVA with a post hoc Fisher's LSD test found no significant treatment effects on ΔEapp (p=0.25 and 0.51 for load and big ET1, respectively). The ΔEapp in the "no load + big ET1" (CE, 13±12.2%, p=0.56), "load + no big ET1" (LC, 17±3.9%, p=0.14) and "load + big ET1" (LE, 19±4.2%, p=0.13) treatment groups were not statistically different than the control group (CC, 3.3%±8.6%). Mineralizing surface (MS/BS), mineral apposition (MAR) and bone formation rates (BFR/BS) were significantly greater in LE than CC (p=0.037, 0.0040 and 0.019, respectively). While the histological bone formation markers in LC trended to be greater than CC (p=0.055, 0.11 and 0.074, respectively) there was no difference between CE and CC (p=0.61, 0.50 and 0.72, respectively). Cores in LE and LC had more than 50% greater MS/BS (p=0.037, p=0.055 respectively) and MAR (p=0.0040, p=0.11 respectively) than CC. The BFR/BS was more than two times greater in LE (p=0.019) and LC (p=0.074) than CC. The PGE2 levels were elevated at 8days post-osteotomy in all groups and the treatment groups remained elevated compared to the CC group on days 15, 19 and 23. The data suggest that combined exposure to big ET1 and mechanical loading results in increased osteogenesis as measured in biomechanical, histomorphometric and biochemical responses.
机械负荷导致骨形成增加已有充分文献记载；然而，机械转导途径之间的相互作用却鲜为人知。内皮素-1是一种普遍存在的自分泌/旁分泌信号分子，可促进转移性疾病中的骨生成。在本研究中，我们假设暴露于大内皮素-1（big ET1）和/或机械负荷会促进离体小梁骨芯的骨生成。在一项关于每日机械负荷（-2000με，每日120次循环，“跳跃”波形）和big ET1（25ng/mL）的2×2析因试验中，将48个牛胸骨小梁骨芯置于生物反应器腔室中23天。通过骨芯表观弹性模量（ΔEapp）的百分比变化、静态和动态组织形态计量学以及前列腺素E2（PGE2）分泌来评估骨芯对治疗刺激的反应。双向方差分析及事后费舍尔最小显著差异检验发现，治疗对ΔEapp无显著影响（负荷和big ET1的p值分别为0.25和0.51）。“无负荷 + big ET1”（CE，13±12.2%，p = 0.56）、“负荷 + 无big ET1”（LC，17±3.9%，p = 0.14）和“负荷 + big ET1”（LE，19±4.2%，p = 0.13）治疗组的ΔEapp与对照组（CC，3.3%±8.6%）相比无统计学差异。LE组的矿化表面（MS/BS）、矿化沉积率（MAR）和骨形成率（BFR/BS）显著高于CC组（分别为p = 0.037、0.0040和0.019）。虽然LC组的组织学骨形成标志物有高于CC组的趋势（分别为p = 0.055、0.11和0.074），但CE组和CC组之间无差异（分别为p = 0.61、0.50和0.72）。LE组和LC组的骨芯MS/BS（分别为p = 0.037、p = 0.055）和MAR（分别为p = 0.0040、p = 0.11）比CC组高50%以上。LE组（p = 0.019）和LC组（p = 0.074）的BFR/BS比CC组高出两倍多。所有组在截骨术后8天PGE2水平升高，且治疗组在第15、19和23天与CC组相比仍保持升高。数据表明，联合暴露于big ET1和机械负荷会导致骨生成增加，这在生物力学、组织形态计量学和生化反应中均有体现。
