Changes Of Transcriptomic Landscape In Human Heart Failure And The Characteristics Of MNDCMs In Mouse Heart

Aims:To date,accumulating evidences suggests an important role of non-coding RNAs(nc RNAs)in Heart failure(HF).So far,the most studied nc RNAs mainly include micro-RNAs(mi RNAs),long non-coding RNA(lnc RNAs)and circular RNAs(circ RNAs),and serve as novel biomarkers and possible therapeutic targets for HF.The mononuclear diploid cardiomyocytes(MNDCMs)in the heart after HF may be the main cell source of endogenous myocardial regeneration.Also,in most studies,MNDCMs are limited in number and associated with cardiac regenerative capacity,leading to speculation that MNDCMs may be a proliferative cardiomyocyte population in the adult mammalian heart,but this has not been validated.The purpose of this project is to explore the lnc RNA/circ RNA-mi RNA-m RNA regulatory networks in restrictive cardiomyopathy(RCM),ischemic heart disease(IHD)and valvular disease of the heart(VDH),screen out the mouse MNDCMs cell population,explore its biological characteristics,and find its specific markers to obtain purified MNDCMs cells to explore its role,application in myocardial regeneration and potential application in the treatment of HF.Methods:We performed RNA-seq analysis with myocardial mRNAs/lncRNAs/circRNAs/mi RNAs from non-failing hearts(donor heart tissue from heart transplantation)and 3 groups of HF patients diagnosed as RCM,IHD and VHD,respectively.HF-related gene regulatory networks and gene co-expression networks were constructed based on the interaction relationship and expression profiles of differentially expressed m RNAs/nc RNAs.Single-cell RNA-Sequencing(scRNA-seq)was performed on mixed cardiac samples from mouse embryonic day 17.5(E17.5),P2,and P8,yielding a total of 12 645 cardiac cells.We further identified specific cell types and cell-cell interactions in the mouse heart by Uniform Manifold Approximation and Projection(UMAP)and investigated the characteristics of different cardiomyocyte types.On this basis,the presence of target cells was detected by immunohistochemistry.Results:Transcriptome sequencing analysis of patients indicated that HF with different etiologies were regulated by complex lnc RNA/circ RNA-mi RNA-m RNA regulatory networks,which comprised the common pathways that were shared by all HF types as well as the distinct pathways that were enriched in specific HF types.Three major cardiac developmental paths were identified by sc RNA-seq of mouse:two developing to CM maturation with close CM-fibroblast communications;and the third maintaining MNDCM status with least CM-fibroblast communications,which highlighting the importance of microenvironment contribution to CM fate during maturation.A novel non-proliferative MNDCM subpopulation with minimal cell-cell communications was unveiled.The distinct properties of these cells were depicted by:(1)the lowest mitochondria metabolisms;(2)the highest glycolysis;and(3)high expression of both Myl4 and Tnni1.The Myl4~+/Tnni1~+non-proliferative MNDCMs persisting in both embryonic and adult mice were proved by immunohistochemical staining,and the frequency of non-proliferative MNDCMs increased during development.Conclusions:The HF biomarkers identified in our study had important clinical application value in HF-staging and HF-type diagnosis.A novel subpopulation of non-proliferative MNDCMs was revealed and the importance of the microenvironment to CM developmental processes during myocardial maturation was revealed.These findings improved our understanding of MNDCMs heterogeneity and cardiac development,which provide new clues for approaches to achieve effective cardiac regeneration and the reatment of HF.