Canonical Wnt signaling directs the generation of functional human PSC-derived atrioventricular canal cardiomyocytes in bioprinted cardiac tissues

Dissecting cardiovascular disease-associated noncoding genetic variants using human iPSC models

Advancements in genomics have revealed hundreds of loci associated with cardiovascular diseases, highlighting the role genetic variants play in disease pathogenesis. Notably, most variants lie within noncoding genomic regions that modulate transcription factor binding, chromatin accessibility, and thereby the expression levels and cell type specificity of gene transcripts. Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) have emerged as a powerful tool to delineate the pathogenicity of such variants and elucidate the underlying transcriptional mechanisms. Our review discusses the basics of noncoding variant-mediated pathogenesis, the methodologies utilized, and how hiPSC-based heart models can be leveraged to dissect the mechanisms of noncoding variants.

Modeling the atrioventricular conduction axis using human pluripotent stem cell-derived cardiac assembloids

The atrioventricular (AV) conduction axis provides electrical continuity between the atrial and ventricular chambers. The "nodal" cardiomyocytes populating this region (AV canal in the embryo, AV node from fetal stages onward) propagate impulses slowly, ensuring sequential contraction of the chambers. Dysfunction of AV nodal tissue causes severe disturbances in rhythm and contraction, and human models that capture its salient features are limited. Here, we report an approach for the reproducible generation of AV canal cardiomyocytes (AVCMs) with in vivo-like gene expression and electrophysiological profiles. We created the so-called "assembloids" composed of atrial, AVCM, and ventricular spheroids, which effectively recapitulated unidirectional conduction and the "fast-slow-fast" activation pattern typical for the vertebrate heart. We utilized these systems to reveal intracellular calcium mishandling as the basis of LMNA-associated AV conduction block. In sum, our study introduces novel cell differentiation and tissue construction strategies to facilitate the study of complex disorders affecting heart rhythm.

Genetic Insights into Congenital Cardiac Septal Defects-A Narrative Review

Congenital heart diseases (CHDs) are a group of complex diseases characterized by structural and functional malformations during development in the human heart; they represent an important problem for public health worldwide. Within these malformations, septal defects such as ventricular (VSD) and atrial septal defects (ASD) are the most common forms of CHDs. Studies have reported that CHDs are the result of genetic and environmental factors. Here, we review and summarize the role of genetics involved in cardiogenesis and congenital cardiac septal defects. Moreover, treatment regarding these congenital cardiac septal defects is also addressed.

Differentiating the human heart: A focus on atrioventricular canal cardiomyocytes

Bioengineering of a functional human heart continues to face many challenges, including the production of distinct cardiac cell types. Now, in Cell Stem Cell, Ye et al.1 develop AVC-like cardiomyocytes through timing- and concentration-specific activation of canonical Wnt signaling.