BIOMOMENTUM力学试验机--游离钙的变化改变椎间盘的机械性能

由于我们近发现人椎间盘（IVD）中游离钙（Ca 2+）浓度升高会导致基质降解（Grant等人ECM 2016），因此我们假设Ca 2+升高也会损害IVD力学。这项研究的目的是确定游离Ca 2+对IVD力学性能的影响。

从25个月大的牛尾中分离出IVD，并与1mM或5mM Ca 2+孵育4周。没有钙补充的IVD被认为是对照。使用Mach-1机械测试仪（加拿大Biomomentum Inc.），对每个IVD进行压缩动态机械测试（DMA），以使用5％的应变幅度在0.01Hz至5Hz的频率范围内评估其体积杨氏模量（E *）。随后，为了评估隔室的刚度，将IVD沿脊髓分为两半，并使用自动球形压痕技术（R = 3.2mm，15度量/ cm 2，振幅= 0.5 ）评估每半的中央部分毫米）。生成刚度图。

与对照相比，在1mM或5mM Ca 2+中孵育4周后，E *明显降低。与低Ca 2+浓度（1mM）的对照相比，IVD隔室的刚度几乎保持不变，而在高
浓度（5mM）时达到显着（p <0.0001 ）。纤维环（AF）的刚度从0.30±0.02MPa降低到0.06±0.01MPa。然而，对于髓核（NP）和终板（EP），组织刚度分别从0.030±0.001MPa增加到0.060±0.002MPa，从1.45±0.15MPa增加到2.5±0.07MPa
。

CHANGES IN FREE CALCIUM ALTER THE MECHANICAL PROPERTIES OF THE INTERVERTEBRAL DISC
Since we recently discovered that increased free calcium (Ca2+) concentration in the human intervertebral disc (IVD) leads to matrix degradation (Grant et al. ECM 2016), we hypothesized that elevations in Ca2+ also impair IVD mechanics. The aim of this study was to determine the effect of free Ca2+ on the mechanical properties of the IVD.

IVDs were isolated from 25-month-old bovine tails and incubated for 4 weeks with either 1mM or 5mM Ca2+. IVDs without calcium supplementation were considered as control. Using the Mach-1 mechanical tester (Biomomentum Inc, Canada), each IVD was subjected to compressive dynamic mechanical testing (DMA) to assess its bulk Young's modulus (E*) for frequencies ranging from 0.01Hz to 5Hz using 5% strain amplitude. Subsequently, to assess the compartmental stiffness, the IVDs were divided in two halves along the spinal cord, and the central section of each half was assessed using an automated spherical indentation technique (R=3.2mm, 15 measures/cm2, amplitude=0.5mm). Stiffness maps were generated.

After a 4-week incubation period in 1mM or 5mM Ca2+, E* decreased significantly compared to the control. Stiffness of IVD's compartments remained almost unchanged when compared to the control for low Ca2+ concentration (1mM), while it reached significance (p<0.0001) at the high
concentration (5mM). The stiffness decreased in annulus fibrosus (AF) from 0.30±0.02MPa to 0.06±0.01MPa. However, for both nucleus pulposus (NP) and endplates (EP), tissues stiffness increased from 0.030±0.001MPa to 0.060±0.002MPa and from 1.45±0.15MPa to 2.5±0.07MPa,
respectively.
High Ca2+ concentration alters IVD's bulk and compartmental mechanical properties. These results are consistent with our previous findings suggesting that increasing the calcium levels resulted in increases in the mineralisation of EP, and decrease the diffusion of nutrient into the disc. Consequently, assessing mechanical properties of each IVD's compartment may provide a better understanding of its bulk mechanical behavior and its integrity during degeneration.

Adapted from: I. Hadjab, M.P. Grant, L.M. Epure, M. Garon, E. Quenneville, J. Anthoniou, F. Mwale and M.D. Buschmann. Changes in Free Calcium Alter the Mechanical Properties of the Intervertebral Disc. International Conference on the Mechanics of Biomaterials and Tissues, Hawaii, USA, 12Dec2017, Podium O.48. 

biomomentum多轴机械测试仪Mach-1
 Mach-1多轴机械测试仪是模块化集成压缩，拉伸，剪切，摩擦，扭转和3D压痕映射、电位分布等测试设备
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biomomentum多轴机械测试仪Mach-1材料力学性能简介：
biomomentum多轴机械测试仪Mach-1材料力学性能是指材料在不同环境(温度、介质、湿度)下，承受各种外加载荷(拉伸、压缩、弯曲、扭转、冲击、交变应力等)时所表现出的力学特征。
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1.1、从骨等硬组织材料到脑组织、眼角膜等极软的组织材料
1.2、从粗的椎间盘的样品到极细的单纤维丝
2、力学类型测试分析功能齐全：
2.1、模块化集成压缩、张力、剪切、摩擦、扭转、穿刺、摩擦和非平面压痕、3D厚度、3D表面轮廓等各种力学类型支持,微观结构表征及动态力学分析研究
2.2、多物理场耦合加载测试