Transcriptional and morphogenetic signatures of congenital heart disease pathways

Alessandro Bertero, PhD, Associate Professor in the Department of Molecular Biotechnology and Health Sciences at the University of Turin

Abstract: Approximately half of the patients with congenital heart disease (CHD) carry potentially damaging genetic variants. Yet in most cases, a definitive association for a given mutation to disease is lacking, as is an understanding of the cell type(s) affected and the underlying mechanism. These aspects greatly limit the usefulness of genetic testing as well as the development of targeted therapies. There is, therefore, a critical need to functionally annotate the role of a growing list of candidate CHD genes. Developing and validating rapid, scalable, and predictive models of CHD is equally key. We are pursuing these goals using human pluripotent stem cell (hiPSC)-derived cardiac progenitors and their derivatives. First, we have developed a new, phenotype-agnostic pooled screening approach called OPTiKD-seq (optimized inducible knockdown deconvoluted by sequencing). This method uses single-cell RNA-sequencing (scRNA-seq) to deconvolute the global effects of barcoded loss-of-function perturbations in hPSC-derived cells. Secondly, we are studying novel self-organizing hiPSC-derived cardiac organoids (cardioids) that form endothelial cells-lined chambered models of the first or second heart field. By comparing transcriptional and morphogenic signatures induced by CHD perturbations, we aim to advance genetic testing and provide the basis for the rational development and testing of personalized CHD therapies. 

Understanding Cardiac Malformations Through Targeted Cardiac Outflow Tract Mechanical Perturbation

Stephanie Lindsey, PhD,  Assistant Professor in the Mechanical and Aerospace Engineering Department at the University of California San Diego

Abstract: Hemodynamics plays a vital role in early cardiac morphogenesis. Disruption of established flow patterns during critical windows of development produces a range of defects that drastically alter function of the mature heart. Malformations of the outflow tract account for over 50% of clinically relevant congenital heart defects, yet the origin of such defects remains uncertain. A major limitation in determining causality of clinically relevant cardiac abnormalities is the difficulty of studying the effects of aberrant hemodynamics alone. Here, we use a combined experimental-computational approach to study the effects of altered flow dynamics on pre-programmed great vessel morphogenesis. Through the use of targeted nonlinear optics, we nucleate and control the growth of microbubbles within outflow vessels without disturbing surrounding tissues.  These targeted ablation experiments are coupled with subject-specific multiscale computational fluid dynamic models in order to track force propagation. Pressure, flow and wall shear maps obtained from these models serve as a basis for examining flow-mediated growth and adaptation in the heart and surrounding vessels. Results support a role for early great vessel hemodynamics in cardiac outflow tract rotation with wall shear stress presenting as a critical value to maintain. 

Models to Understand Vascular Adaptation in Single Ventricle Heart Disease

Abhay Ramachandra, PhD, Postdoctoral Associate in Biomedical Engineering (Jay Humphrey Lab) at Yale University

Abstract: Rewiring the circulation in single ventricle palliation surgeries subject the greater thoracic vessels to an altered hemodynamic environment. Not much is known about the ensuing longitudinal vascular remodeling, including adaptation versus maladaptation. Animal models provide the advantage of isolating the effects of individual insults, probing and gaining insights into these (mal)adaptations at multiple biological scales. I will present results of vascular remodeling in response to two insults to the circulatory systems in murine models – hypoxic injury and a Glenn surgery – both relevant to single ventricle heart disease. I will elaborate on the evolution of tissue mechanics from these perturbations and some associated changes in microstructure and cell signaling.  Finally, I will discuss how a multimodal data collection pipeline can inform computational models of vascular adaptation across biological scales and eventually lead to an integrative approach to guide vascular adaptations in single ventricle surgeries.