TDO2-augmented fibroblasts secrete EVs enriched in immunomodulatory Y-derived small RNA.
Publication Year:
2023
PubMed ID:
38938522
Funding Grants:
Public Summary:
Scientists studied how certain heart-supporting cells can help heal the heart after a heart attack. They found that boosting a protein called TDO2 in skin cells makes the substances these cells release able to protect the heart.
These released substances, packed inside tiny bubbles called extracellular vesicles (EVs), carry a small RNA molecule named NT4. NT4 helps reduce inflammation and stress in heart tissue by calming immune cells called macrophages.
When NT4 was removed, the healing effect was weaker, but giving NT4 by itself helped protect the heart after injury. This research shows that increasing TDO2 in cells improves the healing power of their secreted particles by enriching them with NT4, which lowers harmful inflammation and cell stress in the heart.
Scientific Abstract:
Mounting evidence implicates extracellular vesicles (EVs) factors as mediators of cell therapy. Cardiosphere-derived cells are cardiac-derived cells with tissue reparative capacity. Activation of a downstream target of wnt/beta-catenin signalling, tryptophan 2,3 dioxygenase (TDO2) renders therapeutically inert skin fibroblasts cardioprotective. Here, we investigate the mechanism by which concentrated conditioned media from TDO2-augmented fibroblasts (TDO2-CCM) exert cardioprotective effects. TDO2-CCM is cardioprotective in a mouse model of MI compared to CCM from regular fibroblasts (HDF-CCM). Transcriptomic analysis of cardiac tissue at 24 h demonstrates broad suppression of inflammatory and cell stress markers in animals given TDO2-CCM compared to HDF-CCM or vehicle. Sequencing analysis of TDO2-EV RNA demonstrated abundance of a small Y-derived small RNA dubbed 'NT4'. Purification of TDO2-EVs by size-exclusion chromatography and RNAse protection assays demonstrated that NT4 is encapsulated inside EVs. Consistently with TDO2-CCM, macrophages exposed to NT4 showed suppression of the inflammatory and cell stress mediators, particularly p21/cdkn1a. NT4-depleted TDO2-CCM resulted in diminished immunomodulatory capacity. Finally, administration of NT4 alone was cardioprotective in an acute model of myocardial infarction. Taken together, these findings elucidate the mechanism by which TDO2 augmentation mediates potency in secreted EVs through enrichment of NT4 which suppresses upstream cell stress mediators including p21/cdkn1a.