Estimation of membrane permeability and intracellular diffusion coefficients

Area of Science:

• Biophysics
• Cell Biology
• Medical Imaging

Background:

• Accurate measurement of biophysical properties like membrane permeability and intracellular diffusion is crucial for understanding cell function.
• Leukocytes, as key immune cells, have complex transport dynamics that are challenging to quantify.
• Pulsed-gradient spin-echo (PGSE) NMR is a powerful technique for probing molecular diffusion.

Purpose of the Study:

• To develop and validate a combined PGSE NMR and numerical simulation approach for estimating membrane permeability and intracellular diffusion coefficients in leukocytes.
• To quantify these biophysical parameters for a specific leukocyte sample.

Main Methods:

• Utilized pulsed-gradient spin-echo measurements to obtain diffusion signal attenuation data for leukocytes across a range of q-space.
• Modeled leukocytes as 15 x 15 µm² squares in numerical simulations, varying membrane permeability and intracellular diffusion coefficients.
• Employed a minimization approach to match simulated signal attenuation with experimental data for parameter estimation.

Main Results:

• Successfully estimated membrane permeability and intracellular diffusion coefficients for leukocytes.
• Obtained a membrane permeability of 23 µm/s and an intracellular diffusion coefficient of 8.9 x 10⁻⁴ mm²/s for the tested cell sample (2.17 x 10⁸ cells/mL).

Conclusions:

• The proposed method effectively quantifies essential biophysical parameters of leukocytes.
• This technique offers a valuable tool for in-depth analysis of leukocyte transport properties and cell membrane dynamics.