Convective flow increases lipoplex delivery rate to in vitro cellular monolayers

Area of Science:

• Biotechnology
• Biophysics
• Gene Therapy

Background:

• Nonviral gene therapy utilizes liposome-DNA complexes (lipoplexes) for DNA delivery.
• Understanding lipoplex transport under fluid flow is crucial for optimizing gene therapy efficacy.
• Previous studies primarily focused on static, non-flow conditions.

Purpose of the Study:

• To evaluate the mass transport characteristics of lipoplexes under various fluid shear stresses.
• To investigate the impact of fluid convection on lipoplex delivery rates to cells.
• To explore the relationship between shear stress and lipoplex-cell binding.

Main Methods:

• Theoretical modeling of lipoplex transport via sedimentation and convection.
• Numerical solutions of derived transport equations.
• Experimental transfection assays using fluorescently labeled DNA in a parallel plate flow chamber.
• Flow cytometry to quantify lipoplex delivery under controlled fluid shear stress.

Main Results:

• Theoretical predictions indicated 12- to 19-fold faster lipoplex delivery with convection at physiological shear stresses (2.3-9.7 dyn/cm²).
• Experimental results showed a >9-fold increase in lipoplex delivery at 2.3 dyn/cm² compared to static conditions.
• A modest reduction in delivery (6-fold) was observed at higher shear stress, suggesting disruption of lipoplex-cell binding.

Conclusions:

• Fluid convection significantly enhances lipoplex delivery to cells, improving transfection efficiency.
• Hydrodynamic forces at high shear stress can negatively impact lipoplex delivery by disrupting binding.
• Optimizing fluid flow conditions is critical for effective nonviral gene therapy delivery.