Frequency-induced morphology alterations in microconfined biological cells

Area of Science:

• Biophysics
• Cellular Mechanics
• Biomedical Engineering

Background:

• Low-intensity therapeutic ultrasound (LIPUS) is clinically proven for bone healing.
• The precise cellular mechanisms of LIPUS-induced osteoblast regeneration remain unclear.
• Understanding physical interactions is key to elucidating downstream biochemical pathways.

Purpose of the Study:

• To analyze cytomechanical changes in the cell membrane periphery due to LIPUS.
• To investigate the role of cell membrane perturbation as a primary physical principle.
• To explore frequency-dependent effects of LIPUS on single cells.

Main Methods:

• In situ single-cell analysis within microfluidic confinement.
• Application of low-intensity pulse ultrasound (LIPUS) with varying frequencies (1-3 MHz).
• Direct measurement of cell membrane area and cross-sectional area changes.

Main Results:

• LIPUS frequency alteration physically perturbs the cell membrane, inducing oscillations.
• Near resonance (approx. 1.7 MHz), cell membrane area expanded by 6.85% during exposure and contracted by 44.68% post-actuation.
• Frequency-dependent reversible changes in cell area were observed (e.g., 1.5 MHz expansion vs. 2 MHz contraction).

Conclusions:

• Altering LIPUS frequency (1-3 MHz) reversibly perturbs cell physical structure based on system resonance.
• These findings provide a foundation for understanding LIPUS mechanisms in therapeutic applications.
• The study highlights the significance of cytomechanical effects in LIPUS-mediated cell responses.