Imaging of cell/substrate contacts on polymers by total internal reflection fluorescence microscopy

Area of Science:

• Biomaterials Science
• Cell Biology
• Surface Chemistry

Background:

• Understanding cell-substrate interactions is crucial for biomaterial design.
• Polymer surface properties significantly impact cell behavior and adhesion.
• Total internal reflection fluorescence (TIRF) microscopy offers high-resolution imaging of cell-surface interfaces.

Purpose of the Study:

• To investigate the topographical differences of cell membranes on hydrophilic and hydrophobic polymer surfaces.
• To correlate cell-substrate separation distances with focal contact formation and cell adhesion strength.
• To determine the influence of polymer surface properties on bovine aortic endothelial cell (BAEC) attachment.

Main Methods:

• Utilized a simplified model of total internal reflection fluorescence (TIRF) emission.
• Employed spun cast films of poly(hydroxyethyl methacrylate) (polyHEMA) and poly(ethyl methacrylate) (polyEMA) as substrates.
• Examined BAEC attachment using TIRF microscopy, phase-contrast microscopy, and a parallel-plate flow chamber for adhesion strength testing.

Main Results:

• BAEC on polyHEMA showed no focal contacts and poor adhesion.
• BAEC on polyEMA exhibited well-spread morphology with focal contacts and enhanced adhesion.
• TIRF data revealed topographical maps of cell/substrate separation distances, correlating with observed cell behavior.

Conclusions:

• Hydrophobicity of polymer surfaces, exemplified by polyEMA, promotes focal contact formation and increases BAEC attachment strength.
• Surface properties of polyHEMA and polyEMA directly correlate with the presence of focal contacts and cell attachment strength.
• TIRF microscopy is effective in mapping cell-substrate topography and understanding adhesion mechanisms.