Defective Host Immunity in a Mouse Hindlimb Ischemia Model Attenuates the Blood Flow Recovery Promoted by an mRNA/LNP...

Area of Science:

• Biotechnology
• Immunology
• Regenerative Medicine

Background:

• Messenger RNA (mRNA) therapeutics offer diverse clinical potential, including vaccines and regenerative therapies.
• Lipid nanoparticle (LNP) formulations of mRNA vaccines induce inflammation, causing side effects but enhancing efficacy.
• Understanding LNP-mediated biological responses is crucial for advancing mRNA therapeutics safely and effectively.

Purpose of the Study:

• To investigate the role of LNP formulations in immune responses and therapeutic effects.
• To determine if LNP-induced immune activation contributes to therapeutic benefits in a preclinical model.

Main Methods:

• Administered firefly luciferase (Fluc) mRNA/LNP formulation intramuscularly in mice.
• Assessed proinflammatory responses, including chemokine expression and leukocyte infiltration.
• Utilized a mouse hindlimb ischemia (HLI) model to evaluate blood flow recovery.
• Tested mRNA/LNP efficacy in severely immunocompromised NSG mice.

Main Results:

• The mRNA/LNP formulation enhanced proinflammatory responses, marked by increased chemokine expression and leukocyte infiltration.
• Intramuscular mRNA/LNP administration promoted blood flow recovery in the HLI model without pro-angiogenic genes.
• mRNA/LNP failed to induce blood flow recovery in immunocompromised NSG mice, indicating a dependence on immune activation.

Conclusions:

• The observed blood flow recovery in the HLI model was primarily driven by the immune response elicited by the mRNA/LNP formulation.
• LNP formulations themselves can act as immune activators, contributing to therapeutic outcomes.
• These findings suggest a novel mechanism for LNP-based therapies, leveraging immune activation for regenerative purposes.