Remuscularization with triiodothyronine and β₁-blocker therapy reverses post-ischemic left ventricular dysfunction...

Area of Science:

• Cardiovascular Biology
• Regenerative Medicine
• Pharmacology

Background:

• Myocardial infarction (MI) leads to heart damage, necessitating strategies to restore cardiac tissue.
• Regenerating the heart muscle using existing cardiomyocytes is a promising therapeutic approach.
• Existing therapies for heart failure often manage symptoms rather than repair the underlying damage.

Purpose of the Study:

• To investigate the potential of combining two clinically approved drugs, metoprolol and triiodothyronine (T3), to induce cardiomyocyte proliferation and repair heart muscle.
• To elucidate the molecular mechanisms by which metoprolol and T3 synergistically enhance cardiac regeneration.

Main Methods:

• Adult murine cardiomyocytes were treated with metoprolol and T3.
• The study assessed cardiomyocyte proliferation, ERK1/2 phosphorylation, and gene expression, including dual-specificity phosphatase-5 (DUSP5).
• Therapeutic efficacy was evaluated in mouse models of myocardial infarction, assessing cardiac function, remodeling, and long-term outcomes.

Main Results:

• Metoprolol combined with T3, but neither drug alone, significantly increased cardiomyocyte proliferation.
• The drug combination enhanced T3-induced ERK1/2 phosphorylation by inhibiting DUSP5 expression.
• In a myocardial infarction model, metoprolol plus T3 therapy remuscularized the heart, improved contractile function, and reversed left ventricular dilatation with enduring effects.

Conclusions:

• The combination of metoprolol and T3 is a potent strategy for inducing cardiomyocyte proliferation and cardiac regeneration.
• This therapeutic approach effectively repairs heart muscle, restores function, and reverses adverse remodeling after myocardial infarction in mice.
• Metoprolol plus T3 therapy holds significant potential for treating ischemic heart failure in humans.