Acute brain slice elastic modulus decreases over time.

Area of Science:

• Neuroscience
• Biophysics
• Materials Science

Background:

• Acute brain slices are commonly used to study tissue mechanics.
• Current methods assume stable mechanical properties within 8 hours post-sacrifice due to minimal protein degradation.
• This assumption overlooks other factors like osmotic swelling that alter tissue properties.

Purpose of the Study:

• To investigate the mechanical property changes in acute brain slices over time.
• To identify factors influencing these changes and explore mitigation strategies.
• To improve the consistency and accuracy of brain mechanics measurements.

Main Methods:

• Utilized atomic force microscopy (AFM) for mechanical property assessment.
• Measured tissue hydration and volume changes.
• Tested acute brain slices in artificial cerebrospinal fluid (aCSF) at standard (300 mOsm/l) and increased (400 mOsm/l) osmolarity.
• Assessed the effect of chondroitinase ABC enzyme (CHABC) on mechanical properties.

Main Results:

• Acute brain slices exhibited rapid swelling, softening, and increased hydration within 2 hours in 300 mOsm/l aCSF.
• Chondroitinase ABC enzyme (CHABC) partially mitigated the reduction in elastic modulus.
• Increasing aCSF osmolarity to 400 mOsm/l did not prevent softening but accelerated equilibration for consistent measurements.

Conclusions:

• The assumption of stable mechanical properties in acute brain slices within 8 hours is flawed.
• Swelling and softening significantly impact brain tissue mechanics measurements.
• CHABC and optimized aCSF osmolarity are potential strategies to improve the reliability of brain slice mechanical testing.