Membrane aging during cell growth ascertained by Laurdan generalized polarization

Area of Science:

• Biophysics
• Cell Biology
• Membrane Biophysics

Background:

• Cell membrane physical state and composition are crucial for cell function.
• Fluorescent probes offer sensitive methods to study membrane properties.
• Laurdan's sensitivity to lipid phase transitions provides insights into membrane dynamics.

Purpose of the Study:

• To utilize the fluorescent probe Laurdan to detect modifications in cell membrane composition and physical state.
• To quantify changes in the lipid phase behavior of K562 cell membranes during growth and long-term culture.

Main Methods:

• Employing Laurdan as a fluorescent probe to assess lipid phase states in cell membranes.
• Utilizing the Generalized Polarization (GP) value for quantitative data analysis of Laurdan fluorescence spectra.
• Developing a procedure for labeling cell membranes with Laurdan and discussing influencing factors like cell metabolism and cholesterol.

Main Results:

• Observed a significant decrease in the liquid-crystalline phase of K562 cell membranes over 5 days of asynchronous growth.
• Detected a reduction in cell membrane fluidity in K562 cells maintained in culture for several months.
• Established Laurdan's limiting GP values for gel and liquid-crystalline lipid phases enabling quantitative phase determination.

Conclusions:

• Laurdan and GP value provide a reliable method for quantitative analysis of cell membrane physical state.
• K562 cell membranes exhibit altered lipid phase behavior and decreased fluidity during extended culture periods.
• The findings highlight the dynamic nature of cell membranes and their response to growth and culture conditions.