Probing molecular crowding in compressed tissues with Brillouin light scattering

Area of Science:

• Biophysics
• Cell Biology
• Biomaterials

Background:

• Cell volume regulation is essential for tissue functions like growth and healing.
• Current methods for monitoring cellular stress lack the ability to track liquid flow's impact on volume.
• Understanding intracellular dynamics is key to comprehending cellular responses.

Purpose of the Study:

• To investigate cellular volume regulation and molecular crowding using Brillouin light scattering (BLS).
• To analyze the effects of osmotic perturbations and mechanical compression on cell compressibility.
• To develop a model explaining the relationship between intracellular fluid reduction and polymer interactions.

Main Methods:

• Utilized Brillouin light scattering (BLS) to probe picosecond timescale density fluctuations.
• Induced osmotic perturbations using Dextran (Dx) in multicellular spheroids (MCSs).
• Applied local compression to cells within MCSs to observe mechanical responses.

Main Results:

• Observed an increase in BLS frequency shift during osmotic compression, indicating altered compressibility.
• Developed a mixing law model to explain increased molecular crowding due to reduced intracellular fluid.
• Data suggests a nonlinear increase in compressibility linked to dense crowding and polymer interactions.

Conclusions:

• BLS is a valuable tool for studying cellular volume regulation and intracellular dynamics.
• Molecular crowding significantly impacts cell compressibility and hydrodynamic interactions.
• The findings provide new insights into the biophysical mechanisms governing cell volume homeostasis.