Biomomentum多轴机械测试仪Mach-1应用：使用压痕法绘制正常和骨关节炎小鼠的关节软骨生物力学特性

Mapping Articular Cartilage Biomechanical Properties of Normal and Osteoarthritic Mice Using Indentation (OARSI Poster)

Osteoarthritis Research Society International (OARSI), 2015 April 30, Seattle, WA, United States

Purpose: Due to their size (~1mm), mouse models pose significant challenges to map biomechanical properties over their articular surfaces. The purpose of this study was to determine if an automated indentation technique could be used to map the biomechanical properties of the articular surfaces in murine knees and to identify early alterations of the articular cartilage of a mouse strain (STR/ort) that spontaneously develops osteoarthritis (OA) on the medial side of their knees.

Materials and Methods: The biomechanical measurements were performed ex vivo, on the left femoral condyles and tibial plateaus of five healthy Balb/c males (age of 12-15 weeks) and five age- and sex-matched STR/ort mice, using a 3-axis mechanical tester (Mach-1 v500css, Biomomentum, Laval) equipped with a multiple-axis load cell. Indentation measurements (30-42/surfaces) were performed using a 0.35 mm diameter spherical indenter (30 m indentation in 1 second with 20 seconds relaxation). Following biomechanical testing, the articular surfaces were fixed in 4% paraformaldehyde for histological assessment. Data reported is the structural stiffness at an indentation depth of 10m. To compare the structural stiffness between healthy and OA-developing animals each articular surface were divided into 4 regions, exterior medial (I), inner medial (II), inner lateral (III) and exterior lateral (IV). Data is reported as the mean ± SE (n= 5) for each of these regions. Statistical analysis was performed by ANOVA.

Results: In healthy animals, mapping of the structural stiffness at an indentation depth of 10 ?m showed a spatial distribution similar to that of larger animals (Figure 1 & 2, insert). The structural stiffness of the lateral and inner half of the medial condyles (Figure 1) was similar in OA and healthy mice. The stiffness of the exterior lateral plateau was also not significantly different OA and healthy mice. In contrast, the stiffness of the exterior half of the medial condyle in OA mice (5.9±0.7 N/mm) was significantly lower than that of the healthy mice (10.2±1.1 N/mm, ANOVA, p<0.05). The structural stiffness of the exterior medial condyle and the inner half of the lateral plateaus in OA mice was inferior to that of healthy mice (ANOVA, p<0.05).

Conclusions: This study shows that this automated indentation technique can map the biomechanical properties of murine knee joints. The mapping of mechanical properties shows similar distribution patterns to those previously observed for larger species (human, sheep and rat). The identification of cartilage regions with lower structural stiffness, at sites known to develop OA in the STR/ort strain, suggests this method can be used to identify and characterize OA affected articular surfaces. Studies are ongoing to validate, by histology, the cartilage quality of the affected areas. These results show that indentation mapping could be used in mouse models to test the efficacy of drugs aiming to inhibit cartilage degradation or improving its healing in OA or following a joint injury.

使用压痕法绘制正常和骨关节炎小鼠的关节软骨生物力学特性（OARSI海报）

骨关节炎研究学会（OARSI）

目的：由于其尺寸（〜1mm），小鼠模型对在其关节表面上绘制生物力学特性提出了巨大的挑战。这项研究的目的是确定是否可以使用自动压痕技术来绘制鼠膝关节表面的生物力学特性，并确定自发发展成骨关节炎的小鼠品系（STR / ort）的关节软骨的早期改变（OA）位于膝盖内侧。

材料和方法： 使用三轴机械装置，对五名健康的Balb / c雄性（12-15周龄）和五只年龄和性别相匹配的STR / ort小鼠的左股骨dy和胫骨平台进行离体生物力学测量。测试仪（Mach-1 v500css，Biomomentum，Laval）配备了多轴称重传感器。使用直径为0.35 mm的球形压头（1秒内压入30 m，松弛20秒）进行压痕测量（30-42 /表面）。经过生物力学测试，将关节表面固定在4％多聚甲醛中以进行组织学评估。报告的数据是压痕深度为10m时的结构刚度。为了比较健康动物和OA发育动物的结构刚度，将每个关节表面分为4个区域，外部内侧（I），内部内侧（II），内侧（III）和外侧（IV）。数据报告为这些区域中每个区域的平均值±SE（n = 5）。通过ANOVA进行统计分析。

结果：在健康的动物中，压痕深度为10 µm时的结构刚度图显示出与较大动物相似的空间分布（图1和2，插图）。在OA和健康小鼠中，内侧les外侧和内侧一半的结构刚度（图1）相似。外侧高原的刚度也与OA小鼠和健康小鼠没有显着差异。相反，OA小鼠内侧con外侧一半的刚度（5.9±0.7 N / mm）显着低于健康小鼠（10.2±1.1 N / mm，ANOVA，p <0.05）。OA小鼠外media内侧和外侧平台内侧的结构刚度低于健康小鼠（ANOVA，p <0.05）。结论：这项研究表明，这种自动压痕技术可以绘制出鼠膝关节的生物力学特性图。力学性能的映射显示出与以前针对较大物种（人类，绵羊和大鼠）观察到的分布模式相似的分布模式。在已知在STR / ort应变中发展为OA的部位鉴定出具有较低结构刚度的软骨区域，表明该方法可用于鉴定和表征OA影响的关节表面。正在进行研究以通过组织学验证受影响区域的软骨质量。这些结果表明，压痕图谱可用于小鼠模型，以测试旨在抑制软骨降解或改善OA或关节损伤后软骨愈合的药物的功效。