A novel patterned magnetic micropillar array substrate for analysis of cellular mechanical responses

Area of Science:

• Cellular Mechanobiology
• Biophysics
• Materials Science

Background:

• Cellular focal adhesions (FAs) generate traction forces (1-100 nN) essential for cell functions.
• Measuring these forces involves observing substrate displacement, often using poly(dimethylsiloxane) (PDMS) micropillars.
• A tool to actively apply and measure forces at FAs is needed to understand cellular mechanotransduction.

Purpose of the Study:

• To develop a patterned magnetic micropillar array PDMS substrate for mechanical stimulation and traction force measurement at cellular focal adhesions.
• To investigate the dynamic changes in traction forces of aortic smooth muscle cells (SMCs) in response to mechanical stimuli.

Main Methods:

• Fabrication of PDMS micropillars (3 µm diameter, 9 µm length, 9 µm spacing) embedded with iron particles.
• Application of an external magnetic field (0.3 T) to bend micropillars (∼4 µm) and transfer forces to cellular FAs.
• Measurement of traction forces in cultured SMCs after local compressive stimuli.

Main Results:

• Two distinct mechanical responses observed in SMCs: decreased force with increased area, or increased force with decreased area.
• Traction forces fluctuated significantly during compression, with root mean square force increasing and returning to baseline post-stimulus.
• Cellular responses suggest active reorganization of the actin cytoskeleton and myosin interactions.

Conclusions:

• The developed magnetic micropillar array is a powerful tool for actively stimulating and measuring cellular traction forces.
• This technology facilitates the investigation of cellular mechanotransduction mechanisms.
• Understanding force dynamics is key to elucidating cytoskeleton and myosin involvement in cellular responses.