Differentiation of Human Cardiac Atrial Appendage Stem Cells into Adult Cardiomyocytes: A Role for the Wnt Pathway?

Differentiation, Metabolism, and Cardioprotective Secretory Functions of Human Cardiac Stromal Cells from Ischemic and Endocarditis Patients

This study investigates the characteristics of cardiac mesenchymal stem cell-like cells (CMSCLCs) isolated from the right atrial appendage of human donors with ischemia and a young patient with endocarditis (NE-CMSCLCs). Typical CMSCLCs from ischemic heart patients were derived from coronary artery bypass grafting procedures and compared against bone marrow mesenchymal stromal cells (BM-MSCs). NE-CMSCLCs had a normal immunophenotype, but exhibited enhanced osteogenic differentiation potential, rapid proliferation, reduced senescence, reduced glycolysis, and lower reactive oxygen species generation after oxidative stress compared with typical ischemic CMSCLCs. These differences suggest a unique functional status of NE-CMSCLCs, influenced by the donor health condition. Despite large variances in their paracrine secretome, NE-CMSCLCs retained therapeutic potential, as indicated by their ability to protect hypoxia/reoxygenation-injured human cardiomyocytes, albeit less effectively than typical CMSCLCs. This research describes a unique cell phenotype and underscores the importance of donor health status in the therapeutic efficacy of autologous cardiac cell therapy.

A Foxf1-Wnt-Nr2f1 cascade promotes atrial cardiomyocyte differentiation in zebrafish

Nr2f transcription factors (TFs) are conserved regulators of vertebrate atrial cardiomyocyte (AC) differentiation. However, little is known about the mechanisms directing Nr2f expression in ACs. Here, we identified a conserved enhancer 3' to the nr2f1a locus, which we call 3'reg1-nr2f1a (3'reg1), that can promote Nr2f1a expression in ACs. Sequence analysis of the enhancer identified putative Lef/Tcf and Foxf TF binding sites. Mutation of the Lef/Tcf sites within the 3'reg1 reporter, knockdown of Tcf7l1a, and manipulation of canonical Wnt signaling support that Tcf7l1a is derepressed via Wnt signaling to activate the transgenic enhancer and promote AC differentiation. Similarly, mutation of the Foxf binding sites in the 3'reg1 reporter, coupled with gain- and loss-of-function analysis supported that Foxf1 promotes expression of the enhancer and AC differentiation. Functionally, we find that Wnt signaling acts downstream of Foxf1 to promote expression of the 3'reg1 reporter within ACs and, importantly, both Foxf1 and Wnt signaling require Nr2f1a to promote a surplus of differentiated ACs. CRISPR-mediated deletion of the endogenous 3'reg1 abrogates the ability of Foxf1 and Wnt signaling to produce surplus ACs in zebrafish embryos. Together, our data support that downstream members of a conserved regulatory network involving Wnt signaling and Foxf1 function on a nr2f1a enhancer to promote AC differentiation in the zebrafish heart.

Special Issue "The Role of Mesenchymal Stem Cells on Inflammatory and Fibrotic Diseases"

This Special Issue focused on the complex role played by MSCs in the onset and development of inflammatory diseases: MSCs can support or counteract inflammation and, in turn, the onset of disease [...].

Loss of aquaporin 5 contributes to the corneal epithelial pathogenesis via Wnt/β-catenin pathway

AQP5 plays a crucial role in maintaining corneal transparency and the barrier function of the cornea. Here, we found that in the corneas of Aqp5-/- mice at older than 6 months, loss of AQP5 significantly increased corneal neovascularization, inflammatory cell infiltration, and corneal haze. The results of immunofluorescence staining showed that upregulation of K1, K10, and K14, and downregulation of K12 and Pax6 were detected in Aqp5-/- cornea and primary corneal epithelial cells. Loss of AQP5 aggravated wound-induced corneal neovascularization, inflammation, and haze. mRNA sequencing, western blotting, and qRT-PCR showed that Wnt2 and Wnt6 were significantly decreased in Aqp5-/- corneas and primary corneal epithelial cells, accompanied by decreased aggregation in the cytoplasm and nucleus of β-catenin. IIIC3 significantly suppressed corneal neovascularization, inflammation, haze, and maintained corneal transparent epithelial in Aqp5-/- corneas. We also found that pre-stimulated Aqp5-/- primary corneal epithelial cells with IIIC3 caused the decreased expression of K1, K10, and K14, the increased expression of K12, Pax6, and increased aggregation in the cytoplasm and nucleus of β-catenin. These findings revealed that AQP5 may regulate corneal epithelial homeostasis and function through the Wnt/β-catenin signaling pathway. Together, we uncovered a possible role of AQP5 in determining corneal epithelial cell fate and providing a potential therapeutic target for corneal epithelial dysfunction.

Cardiac Mesenchymal Stem Cell-like Cells Derived from a Young Patient with Bicuspid Aortic Valve Disease Have a Prematurely Aged Phenotype

There is significant interest in the role of stem cells in cardiac regeneration, and yet little is known about how cardiac disease progression affects native cardiac stem cells in the human heart. In this brief report, cardiac mesenchymal stem cell-like cells (CMSCLC) from the right atria of a 21-year-old female patient with a bicuspid aortic valve and aortic stenosis (referred to as biscuspid aortic valve disease BAVD-CMSCLC), were compared with those of a 78-year-old female patient undergoing coronary artery bypass surgery (referred to as coronary artery disease CAD-CMSCLC). Cells were analyzed for expression of MSC markers, ability to form CFU-Fs, metabolic activity, cell cycle kinetics, expression of NANOG and p16, and telomere length. The cardiac-derived cells expressed MSC markers and were able to form CFU-Fs, with higher rate of formation in CAD-CMSCLCs. BAVD-CMSCLCs did not display normal MSC morphology, had a much lower cell doubling rate, and were less metabolically active than CAD-CMSCLCs. Cell cycle analysis revealed a population of BAVD-CMSCLC in G2/M phase, whereas the bulk of CAD-CMSCLC were in the G0/G1 phase. BAVD-CMSCLC had lower expression of NANOG and shorter telomere lengths, but higher expression of p16 compared with the CAD-CMSCLC. In conclusion, BAVD-CMSCLC have a prematurely aged phenotype compared with CAD-CMSCLC, despite originating from a younger patient.

Wnt Signaling in Heart Development and Regeneration

PURPOSE OF REVIEW

Cardiovascular diseases are the leading cause of death worldwide, largely due to the limited regenerative capacity of the adult human heart. In contrast, teleost zebrafish hearts possess natural regeneration capacity by proliferation of pre-existing cardiomyocytes after injury. Hearts of mice can regenerate if injured in a few days after birth, which coincides with the transient capacity for cardiomyocyte proliferation. This review tends to elaborate the roles and mechanisms of Wnt/β-catenin signaling in heart development and regeneration in mammals and non-mammalian vertebrates.

RECENT FINDINGS

Studies in zebrafish, mice, and human embryonic stem cells demonstrate the binary effect for Wnt/β-catenin signaling during heart development. Both Wnts and Wnt antagonists are induced in multiple cell types during cardiac development and injury repair. In this review, we summarize composites of the Wnt signaling pathway and their different action routes, followed by the discussion of their involvements in cardiac specification, proliferation, and patterning. We provide overviews about canonical and non-canonical Wnt activity during heart homeostasis, remodeling, and regeneration. Wnt/β-catenin signaling exhibits biphasic and antagonistic effects on cardiac specification and differentiation depending on the stage of embryogenesis. Inhibition of Wnt signaling is beneficial for cardiac wound healing and functional recovery after injury. Understanding of the roles and mechanisms of Wnt signaling pathway in injured animal hearts will contribute to the development of potential therapeutics for human diseased hearts.

Long noncoding RNA DLGAP1-AS2 facilitates Wnt1 transcription through physically interacting with Six3 and drives the malignancy of gastric cancer

The long noncoding RNA (lncRNA) DLGAP1-AS2 has recently been characterized as an oncogenic lncRNA in several cancers. However, its biological roles and clinical significance in gastric cancer (GC) remains barely understood. In this study, we performed a systematic analysis of DLGAP1-AS2 expression with data from the TCGA and GEO database as well as our clinic GC samples. In agreement with previous studies, our findings demonstrated that DLGAP1-AS2 was significantly up-regulated in GC and its high expression was associated with poor prognosis, suggesting that DLGAP1-AS2 might be a putative oncogenic lncRNA of GC. Loss of DLGAP1-AS2 restricted cell proliferation, migration, and invasion in GC cell lines. Mechanically, Wnt1 was identified as the downstream target of DLGAP1-AS2 by using bioinformatics analysis coupled with qPCR and Western blot assays. Furthermore, DLGAP1-AS2 was found to directly interact with the transcriptional repressor Six3, and this interaction hampered Six3 binding to the promoter regions of the Wnt1 gene, thereby leading to transcriptional activation of Wnt1. Consequently, GC cells lacking DLGAP1-AS2 showed a decreased Wnt1 expression and weakened Wnt/β-catenin signaling. Further, Six3 silencing could reverse the above effects, highlighting a pivotal role of Six3 in the DLGAP1-AS2-mediated activation of Wnt/β-catenin signaling. Either genetic (Wnt1 knockdown) or pharmacological (LF3) inhibition of Wnt/β-catenin signaling could effectively abolish the activation of Wnt/β-catenin signaling by Six3 depletion, thereby preventing GC cell malignant transformation. Taken together, our results suggest that DLGAP1-AS2 functions as an oncogenic factor by directly interacting with Six3 to relieve its suppression on Wnt1 expression, thereby driving the malignancy of GC. DLGAP1-AS2/Six3/Wnt1/β-catenin signaling axis might serve as a promising diagnostic and therapeutic target for GC.

Stem cell-based approaches in cardiac tissue engineering: controlling the microenvironment for autologous cells

Cardiovascular disease is one of the leading causes of mortality worldwide. Cardiac tissue engineering strategies focusing on biomaterial scaffolds incorporating cells and growth factors are emerging as highly promising for cardiac repair and regeneration. The use of stem cells within cardiac microengineered tissue constructs present an inherent ability to differentiate into cell types of the human heart. Stem cells derived from various tissues including bone marrow, dental pulp, adipose tissue and umbilical cord can be used for this purpose. Approaches ranging from stem cell injections, stem cell spheroids, cell encapsulation in a suitable hydrogel, use of prefabricated scaffold and bioprinting technology are at the forefront in the field of cardiac tissue engineering. The stem cell microenvironment plays a key role in the maintenance of stemness and/or differentiation into cardiac specific lineages. This review provides a detailed overview of the recent advances in microengineering of autologous stem cell-based tissue engineering platforms for the repair of damaged cardiac tissue. A particular emphasis is given to the roles played by the extracellular matrix (ECM) in regulating the physiological response of stem cells within cardiac tissue engineering platforms.