TDO2-augmented fibroblasts secrete EVs enriched in immunomodulatory Y-derived small RNA

Area of Science:

• Cardiovascular biology
• Cell therapy
• Extracellular vesicle biology

Background:

• Extracellular vesicles (EVs) are key mediators in cell therapy.
• Cardiosphere-derived cells exhibit cardiac repair potential.
• Activating tryptophan 2,3 dioxygenase (TDO2) in fibroblasts enhances their therapeutic properties.

Purpose of the Study:

• To elucidate the mechanism of cardioprotection mediated by TDO2-augmented fibroblast conditioned media (TDO2-CCM).
• To identify specific factors within TDO2-CCM responsible for its therapeutic effects.

Main Methods:

• Comparative analysis of TDO2-CCM and control fibroblast conditioned media (HDF-CCM) in a mouse myocardial infarction (MI) model.
• Transcriptomic analysis of cardiac tissue post-treatment.
• RNA sequencing of TDO2-EVs to identify encapsulated RNA species.
• In vitro studies exposing macrophages to purified RNA.
• Administration of purified RNA in an MI model.

Main Results:

• TDO2-CCM demonstrated significant cardioprotection in a mouse MI model compared to HDF-CCM.
• TDO2-CCM treatment broadly suppressed inflammatory and cell stress markers in cardiac tissue.
• A small RNA, NT4, was identified within TDO2-EVs and shown to suppress inflammatory and cell stress mediators in macrophages.
• NT4 administration alone was cardioprotective in an acute MI model.

Conclusions:

• TDO2 augmentation enhances the potency of fibroblast-derived EVs through enrichment of the small RNA NT4.
• NT4 acts as a key therapeutic cargo within EVs, suppressing cell stress mediators like p21/cdkn1a.
• NT4 represents a novel therapeutic target for myocardial infarction and potentially other inflammatory conditions.