Objective

Employ an automated indentation technique, using a commercially available machine, to assess the effect of fibroblast growth factor 2 (FGF2) expression on structural stiffness over the surface of both murine femoral articular cartilage (AC) and temporomandibular joint (TMJ) mandibular condylar cartilage (MCC).

Design

Experiments were performed using 3-month-old female homozygote Fgf2KO mice with wild type (WT) littermates. After euthanization, isolated mandibles and hindlimbs were either processed for histology or subjected to automated indentation on a Biomomentum Mach-1 v500csst with a 3-axis motion controller in a phosphate buffered saline bath using a 0.3 mm spherical tip indenter. The effect of indentation depth on normal force was characterized, then structural stiffness was calculated and mapped at multiple positions on the AC and MCC.

Results

Automated indentation of the AC and TMJ MCC was successfully completed and was able to demonstrate both regional variation in structural stiffness and differences between WT and Fgf2KO mice. Structural stiffness values for Fgf2KO AC were significantly smaller than WT at both the medial/anterior (P < 0.05) and medial/posterior (P < 0.05) positions. Global Fgf2KO also lead to a decrease in MCC thickness of the TMJ compared with WT (P < 0.05) and increased structural stiffness values for Fgf2KO at both the posterior and anterior location (P < 0.05).

Conclusions

Automated indentation spatially resolved differences in structural stiffness between WT and Fgf2KO tissue, demonstrating FGF2 expression affects femoral AC and TMJ MCC. This quantitative method will provide a valuable approach for functional characterization of cartilage tissues in murine models relevant to knee joint and TMJ health and disease.

中文翻译：

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自动压痕显示 FgF2KO 小鼠股骨关节软骨和颞下颌关节下颌髁突软骨的结构刚度发生改变

客观的

采用自动压痕技术，使用市售机器，评估成纤维细胞生长因子 2 (FGF2) 表达对小鼠股骨关节软骨 (AC) 和颞下颌关节 (TMJ) 下颌髁软骨表面结构刚度的影响。中央委员会）。

设计

使用具有野生型 (WT) 同窝出生的 3 个月大的雌性纯合子 Fgf2KO 小鼠进行实验。安乐死后，分离的下颌骨和后肢要么进行组织学处理，要么在 Biomomentum Mach-1 v500csst 上使用 0.3 mm 球形尖端压头在磷酸盐缓冲盐水浴中使用 3 轴运动控制器进行自动压痕。表征压痕深度对法向力的影响，然后计算结构刚度并将其映射到 AC 和 MCC 上的多个位置。

结果

AC 和 TMJ MCC 的自动压痕已成功完成，并且能够证明结构刚度的区域变化以及 WT 和 Fgf2KO 小鼠之间的差异。Fgf2KO AC 的结构刚度值在内侧/前部 ( P < 0.05) 和内侧/后部 ( P < 0.05) 位置均显着小于 WT 。与 WT 相比，全局 Fgf2KO 还导致 TMJ 的 MCC 厚度减少（P < 0.05），并且 Fgf2KO 在后部和前部位置的结构刚度值增加（P < 0.05）。

结论

自动压痕空间分辨 WT 和 Fgf2KO 组织之间结构刚度的差异，表明 FGF2 表达影响股骨 AC 和 TMJ MCC。这种定量方法将为与膝关节和 TMJ 健康和疾病相关的小鼠模型中软骨组织的功能表征提供有价值的方法。