Abstract
BackgroundCellular dedifferentiation is a regenerative prerequisite that warrants cell cycle reentry and appropriate mitotic division during de novo formation of cardiomyocytes. In the light of our previous finding that expression of injury-responsive element, Wilms Tumor factor 1 (WT1), in pericardial adipose stromal cells (ADSC) conferred a compelling reparative activity with concomitant IL-6 upregulation, we then aim to unravel the mechanistic network that governs the process of regenerative dedifferentiation after ADSC-based therapy.Methods and resultsWT1-expressing ADSC (eGFP:WT1) were irreversibly labeled in transgenic mice (WT1-iCre/Gt(ROSA)26Sor-eGFP) primed with myocardial infarction. EGFP:WT1 cells were enzymatically isolated from the pericardial adipose tissue and cytometrically purified (ADSCgfp+). Bulk RNA-seq revealed upregulation of cardiac-related genes and trophic factors in ADSCgfp+ subset, of which IL-6 was most abundant as compared to non-WT1 ADSC (ADSCgfp−). Injection of ADSCgfp+ subset into the infarcted hearts yielded striking structural repair and functional improvement in comparison to ADSCgfp− subset. Notably, ADSCgfp+ injection triggered significant quantity of dedifferentiated cardiomyocytes recognized as round-sharp, marginalization of sarcomeric proteins, expression of molecular signature of non-myogenic genes (Vimentin, RunX1), and proliferative markers (Ki-67, Aurora B and pH3). In the cultured neonatal cardiomyocytes, spontaneous dedifferentiation was accelerated by adding tissue extracts from the ADSC-treated hearts, which was neutralized by IL-6 antibody. Genetical lack of IL-6 in ADSC dampened cardiac dedifferentiation and reparative activity.ConclusionsTaken collectively, our results revealed a previous unappreciated effect of IL-6 on cardiac dedifferentiation and regeneration. The finding, therefore, fulfills the promise of stem cell therapy and may represent an innovative strategy in the treatment of ischemic heart disease.
Highlights
Cellular dedifferentiation is a regenerative prerequisite that warrants cell cycle reentry and appropriate mitotic division during de novo formation of cardiomyocytes
EGFP:Wilms Tumor factor 1 (WT1) positive cells were readily detectable in both the epicardial layer and epicardial tissue 2 weeks after infarction (Fig. 1B, 32.2% vs. 24.2%, respectively), while eGFP expression was almost absent in both the epicardial and the pericardial cells in sham animals, To obtain the pericardial origin of eGFP:WT1 cells, we enzymatically dissected the mass of pericardial adipose tissue and, after primary cultivation, eGFP negative population (ADSCgfp−) and eGFP-positive adipose stromal cells (ADSC) (ADSCgfp+) was separated by FACS sorting (Fig. 1C), leading significant enrichment of ADSCgfp+ cells with a purity up to 98.91% (Fig. 1D)
We demonstrated that injury-responsive gene, WT1, was linked to upregulation of IL-6, which in turn mediated the regenerative activity of ADSC via promoting cardiac dedifferentiation at the onset of cardiac ischemia
Summary
Cellular dedifferentiation is a regenerative prerequisite that warrants cell cycle reentry and appropriate mitotic division during de novo formation of cardiomyocytes. In the context of myocardial repair in lower vertebrates, such as zebrafish, or neonatal mice in which where cardiac proliferation is fully functional in response to acute injury [6, 8], formation of new cardiomyocytes is found to begin with the initial step of cardiac dedifferentiation followed by mitotic cell division, suggesting that cellular dedifferentiation is a pro-regenerative prerequisite for tissue renewal [9]. Unraveling the regulatory mechanism(s) that governs dedifferentiation progression is fundamentally imperative to understand how cell cycles in adult mammalian cardiomyocyte are regulated and to develop therapeutical strategies that stimulate turnover of cardiomyocytes and promote cardiac regeneration
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