Optimizing Lipid Nanoparticles for Efficient and Safe Drug Delivery: The Impact of Particle Size on Transfection Efficiency and Cytotoxicity

Emerging global health challenges—such as pandemics, cancer, and genetic
disorders—demand innovative therapeutic approaches for rapid and targeted
treatment. Lipid nanoparticles (LNPs) have become an important tool for the
delivery of nucleic acids and other therapeutic agents, playing a key role in the
development of mRNA-based vaccines. These nanoparticles offer protection
from degradation and enable targeted transport to cells, making them a
possible solution for gene therapy and other applications. [1]
However, despite their success, the optimization of LNP formulations remains
a challenge. Achieving the right balance between maximizing transfection
efficiency and minimizing cytotoxicity and immunogenicity is essential for their
safe and effective use. One of the most important factors influencing the
biological performance of LNPs is their particle size. [2] Particle size not only
affects the pharmacokinetics and biodistribution of LNPs in vivo, but also their
cellular uptake, intracellular trafficking, transfection efficiency, and cytotoxicity.
Smaller LNPs typically exhibit improved tissue penetration and faster cellular
uptake, while larger particles offer more efficient cargo encapsulation or
facilitate endosomal escape. However, a comprehensive understanding of how
particle size influences these parameters remains underexplored. [3]
This study investigates the impact of LNP size on cellular uptake, transfection
efficiency, and cytotoxicity using human liver (Hep-G2) and lung (A549) cell
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lines, representing two primary organs exposed to circulating nanoparticles. [4]
We compared three different LNP sizes to evaluate their effects on cell viability
and proliferation. The research integrates cell viability assays (CCK-8,
RealtimeGlo) and fluorescence microscopy to analyze cellular responses and
optimize LNP design for improved biocompatibility.
To gain a deeper understanding of LNP behavior during cellular uptake and
gene delivery, three types of LNPs will be used. A lipophilic dye will be
incorporated to stain the LNP membrane, enabling us to monitor interactions
between the LNPs and the cell membrane during the initial uptake process.
Additionally, a fluorescent dye encapsulated within the LNPs will allow tracking
of their internalization and endosomal escape. Another batch of LNPs will carry
mRNA encoding for green fluorescent protein (eGFP), which will enable the
evaluation of successful transfection through the expression of fluorescence in
the target cells. This combination of markers will provide a comprehensive
approach to studying LNP behavior at various stages of cellular uptake and
gene delivery.
The findings of this study will contribute to the development of safer and more
effective LNP-based drug delivery systems, ultimately advancing clinical
applications of these promising therapeutic agents.