Role of Cellular Retention and Intracellular State in Controlling Gene Delivery Efficiency of Multiple Nonviral Carriers

[Image: see text] Nonviral gene delivery has seen major progress in the last two decades owing to facile synthesis, low toxicity, and ease of modification of nanocarriers that take nucleic acids to cells and tissues. Gene delivery nanocomplexes need to reach the target locations in significant amounts by overcoming multiple barriers. While the importance of nanocomplex stability, cellular uptake, intracellular trafficking, and nuclear localization has been studied extensively, the role of cellular retention and recycling of these nanocomplexes is less understood in the context of gene delivery. In this study, we used different DNA carriers and made efforts to understand the role played by cellular retention in determining their gene delivery efficiency across multiple cell lines. In addition, we also analyzed whether state of complexation and localization of the nanocomplexes play a role in conjunction with cellular retention. We observed higher transfection efficiencies for nanocomplexes showing better retention, lower unpackaging, and low recycling. Our data also suggests that nanocomplexes made of peptides with terminal cysteine modification show enhanced retention and transfection efficiency compared to their counterparts with no terminal cysteine. Overall, the work highlights myriad of factors to be considered for improving gene delivery efficiency of nanocomplexes.