Enhancing cardiac reprogramming via synthetic RNA oligonucleotides

Area of Science:

• Cardiovascular Research
• Regenerative Medicine
• Molecular Biology

Background:

• Cardiac injury leads to scar formation, hindering heart function.
• Reprogramming scar fibroblasts into cardiomyocytes offers a therapeutic strategy for heart repair.
• Current reprogramming methods have low efficiency and face challenges with inflammatory side effects from RNA-sensing receptor ligands.

Purpose of the Study:

• To investigate if synthetic, nuclease-resistant RNA analogs of natural ligands can enhance fibroblast reprogramming into cardiomyocytes.
• To determine if these analogs avoid the adverse inflammatory events associated with natural ligands.
• To identify the specific RNA-sensing receptors involved in the enhanced reprogramming process.

Main Methods:

• Utilized a synthetic stabilized RNA oligonucleotide, ICR2, designed as an analog of natural RNA-sensing receptor ligands.
• Assessed the expression of cardiomyocyte-specific messenger RNAs (mRNAs) in reprogrammed fibroblasts.
• Evaluated the maturation of newly formed cardiomyocytes, including sarcomere development.
• Performed knockdown assays to identify the roles of RNA-sensing receptors (Rig-I and TLR3).
• Determined the impact of ICR2 on the required dose and number of reprogramming factors.

Main Results:

• The synthetic RNA ICR2 significantly increased the expression of cardiomyocyte-specific mRNAs.
• ICR2 promoted the development of cardiomyocytes with mature sarcomeres.
• Knockdown experiments confirmed that Rig-I and TLR3 mediate the effects of ICR2.
• ICR2 reduced the necessary dose and number of reprogramming factors for efficient cardiac reprogramming.
• ICR2 did not induce inflammatory insults, unlike natural ligands.

Conclusions:

• Synthetic RNA oligonucleotides, exemplified by ICR2, are effective in enhancing cardiac reprogramming efficiency.
• ICR2 represents a promising therapeutic agent for improving heart repair after injury by boosting cardiomyocyte generation.
• This strategy overcomes the inflammatory limitations of previous methods, paving the way for safer and more effective cardiac regenerative therapies.