The nano-biomechanical environment of the extracellular matrix is critical for cells to sense and respond to mechanical loading. However, to date, this important characteristic remains poorly understood in living tissue structures. This study reports the experimental measurement of the in vivo nano-elastic modulus of the tendon in a mouse tail model. The experiment was performed on the tail tendon of an 8-week-old C57BL/6 live mouse. Mechanical loading on tail tendons was regulated by changing both voltage and frequency of alternating current stimulation on the erector spinae. The nano-elastic modulus of the tail tendon was measured by atomic force microscope. The nano-elastic modulus showed significant variation (2.19–35.70 MPa) between different locations and up to 39% decrease under muscle contraction, suggesting a complicated biomechanical environment in which cells dwell. In addition, the nano-elastic modulus of the tail tendon measured in live mice was significantly lower than that measured in vitro, suggesting a disagreement of tissue mechanical properties in vivo and in vitro. This information is important for the designs of new extracellular biomaterial that can better mimic the biological environment, and improve clinical outcomes of musculoskeletal tissue degenerations and associated disorders.

细胞外基质的纳米生物力学环境对于细胞感知和响应机械负荷至关重要。然而，迄今为止，在活体组织结构中仍不清楚这一重要特征。这项研究报告了体内的实验测量小鼠尾巴模型中肌腱的纳米弹性模量。实验是对8周大的C57BL / 6活鼠的尾腱进行的。通过改变竖脊肌上交流电刺激的电压和频率，可以调节尾腱的机械负荷。通过原子力显微镜测量尾腱的纳米弹性模量。纳米弹性模量在不同位置之间表现出显着变化（2.19–35.70 MPa），在肌肉收缩下下降高达39％，这表明细胞在复杂的生物力学环境中驻留。此外，在活小鼠中测得的尾腱的纳米弹性模量明显低于在体外测得的值，这表明体内组织力学性能存在差异和体外。该信息对于设计新的细胞外生物材料非常重要，该材料可以更好地模仿生物环境，并改善肌肉骨骼组织变性和相关疾病的临床结果。