Comparison of Immune Cell Transfection by Different Vaccine Vectors After Intradermal Injection

Area of Science:

• Immunology
• Molecular Biology
• Vaccinology

Background:

• Immune cells, including antigen-presenting cells (APCs), are crucial targets for vaccine antigen and transgene protein expression.
• Understanding the efficacy of different molecular therapy vectors for modifying these cells is essential for advancing vaccine and gene therapy strategies.

Purpose of the Study:

• To compare the genetic modification efficiency of mRNA and DNA-based vectors in immune cells following intradermal injection in mice.
• To evaluate naked DNA, DNA-lipid nanoparticles (LNPs), adenovirus (Ad) vectors, and mRNA-LNPs for their ability to modify immune cells.

Main Methods:

• Cre reporter mice were intradermally injected with various vectors (naked DNA, DNA-LNP, Ad, mRNA-LNP) to assess Cre recombinase delivery.
• Luciferase activity was measured in vivo and ex vivo in the skin, draining lymph node, and liver.
• Immune cell populations (CD45+, CD3+, CD11b+, CD207+) modified by Cre were identified using flow cytometry.

Main Results:

• Adenovirus (Ad) and mRNA-LNP vectors demonstrated superior luciferase and GFP expression in both skin and lymph nodes compared to DNA-LNP and naked DNA.
• mRNA-LNPs and Ad vectors significantly modified CD45+, CD3+, CD11b+, and CD207+ immune cells, with Ad showing higher expression levels.
• Both mRNA-LNP and Ad vectors showed off-target modification in the liver, while DNA-based vectors showed minimal and statistically insignificant activity.

Conclusions:

• mRNA-LNP and Ad vectors are more potent for genetically modifying skin and lymph node immune cells after intradermal delivery than DNA-based vectors.
• The findings support the higher vaccine potency observed with mRNA-LNP and Ad vectors.
• Targeting specific immune cell subsets may enhance efficacy and reduce off-target modifications in tissues like the liver.