Predictive modeling of non-viral gene transfer

Area of Science:

• Biotechnology
• Molecular Biology
• Cell Biology

Background:

• Non-viral gene delivery methods like Lipofectamine and PEI often result in variable transgene expression.
• This variability is largely attributed to the low efficiency of plasmid DNA successfully entering and functioning within cells.

Purpose of the Study:

• To experimentally determine gene expression distributions mediated by Lipofectamine and PEI using single-cell time-lapse analysis.
• To develop and validate a mathematical model explaining the stochastic nature of non-viral gene delivery and expression.

Main Methods:

• Single-cell time-lapse microscopy was employed to analyze exogenous gene expression distributions.
• Co-transfection experiments with distinct plasmids (YFP and CFP) were conducted.
• A stochastic, two-step mathematical model of transfection was developed.

Main Results:

• Both Lipofectamine and PEI showed broad, Poisson-like expression distributions in synchronized cell lines.
• Co-transfection indicated simultaneous expression of multiple plasmids, suggesting delivery in correlated units (complexes).
• The mathematical model accurately predicted transfection efficiency, co-transfection ratios, and expression level distributions.

Conclusions:

• Gene delivery occurs via a stochastic, two-step process: low-probability nuclear entry of plasmid complexes, followed by plasmid release and activation.
• This model elucidates the origin of expression noise in non-viral gene delivery.
• The findings provide a framework for evaluating and enhancing non-viral vector performance.