Delayed miR-199a Administration After Myocardial Infarction Precludes Pro-Regenerative Effects

Area of Science:

• Cardiovascular Research
• Gene Therapy
• Molecular Cardiology

Background:

• MicroRNA-199a (miR-199a) shows cardioreparative potential when delivered early after myocardial infarction (MI) using adeno-associated virus serotype 6 (AAV6).
• The efficacy and safety of delayed miR-199a administration post-MI remain unexplored.

Purpose of the Study:

• To investigate whether the therapeutic effects of miR-199a are maintained when administered 1 or 2 weeks after MI.
• To assess the impact of delayed AAV6-miR-199a delivery on cardiac function and survival in a pig model.

Main Methods:

• Pigs underwent induced myocardial infarction (MI).
• Adeno-associated virus serotype 6 carrying miR-199a (AAV6-miR-199a) or a control vector (AAV6) was administered 1 or 2 weeks post-MI.
• Cardiac function, scar mass, and survival rates were evaluated.

Main Results:

• No significant differences in scar mass or cardiac contractile performance were observed between AAV6-miR-199a and AAV6-control groups.
• A significant increase in mortality due to sudden death was noted in pigs treated with AAV6-miR-199a, occurring 40 to 52 days post-vector administration.
• Delayed administration of miR-199a via AAV6 did not confer therapeutic benefits and increased mortality.

Conclusions:

• Delayed administration of miR-199a using AAV6 is not therapeutically effective and is associated with increased mortality in a post-MI pig model.
• For clinical translation, early administration of miR-199a is mandatory.
• Alternative delivery modalities, avoiding permanent expression from viral vectors, should be explored for safe and effective miR-199a therapy post-MI.