Polyplexes Are Endocytosed by and Trafficked within Filopodia

Area of Science:

• Biomedical Engineering
• Cell Biology
• Nanotechnology

Background:

• Nonviral gene therapies require understanding synthetic delivery systems' physical and biological properties.
• Cellular uptake and intracellular trafficking mechanisms of delivery vehicles are poorly understood.
• Polymer-based nanoparticle complexes (polyplexes) are key nonviral gene delivery systems.

Purpose of the Study:

• To investigate the cellular internalization and trafficking mechanisms of polyplexes.
• To elucidate the role of filopodia in polyplex cellular uptake.
• To quantify the kinetics and speed of polyplex intracellular transport.

Main Methods:

• Detailed observation of polyplex-cell interactions at the cellular level using confocal microscopy.
• Utilizing HeLa cells to study filopodial uptake and trafficking of polyplexes.
• Measurement of polyplex trafficking kinetics and speed.

Main Results:

• Filopodia directly mediate polyplex endocytosis, internalizing particles into vesicles within the projection.
• Polyplex-loaded vesicles are transported along actin to the cell body.
• Polyplex-loaded vesicles were observed trafficking between cells via filopodial bridges.
• Evidence suggests filopodia act as a direct route for polyplex internalization and transport.

Conclusions:

• Filopodia play a crucial role in the direct cellular uptake of polyplexes.
• Filopodia facilitate endocytic vesicle trafficking of polyplexes within and between cells.
• These findings offer fundamental insights for advancing nonviral gene editing, nucleic acid therapies, and biomedical materials.