The Effect of Freezing Time on Muscle Fiber Mechanical Properties

Area of Science:

• Biophysics
• Muscle Physiology

Background:

• Preserving biological samples is crucial for research.
• Understanding the long-term effects of cryopreservation on muscle fiber mechanics is essential for standardized research protocols.

Purpose of the Study:

• To determine the optimal freezing time for preserving the mechanical properties of mouse muscle fibers.
• To establish a gold standard for muscle fiber preservation for future mechanical studies.

Main Methods:

• Passive mechanical testing of single soleus muscle fibers from mice.
• Cryopreservation of fibers at -20°C for 0, 3, 6, 9, and 12 months.
• Measurement of Young's modulus, dynamic and static stresses, and fitting data to a 3rd order viscoelastic Hill model.

Main Results:

• No significant difference in elastic modulus for fibers stored up to 6 months at -20°C.
• Significant degradation of mechanical properties and reduced resistance observed in fibers stored for 9 and 12 months.
• Demonstrated that muscle fibers retain mechanical integrity for up to 6 months of cryopreservation.

Conclusions:

• Cryopreservation at -20°C for up to 6 months is suitable for maintaining mouse muscle fiber mechanical properties.
• Longer storage periods (≥9 months) negatively impact fiber mechanics, compromising functional behavior.
• This study provides critical data for optimizing muscle fiber sample preservation techniques in research.