CAREER: Mechano-Metabolic Control of Electrical Remodeling of Human Induced Pluripotent Stem Cell Derived Engineered Heart Muscle

Washington University, Saint Louis MO

Investigators

Abstract

This Faculty Early Career Development (CAREER) award supports research to understand how to grow heart muscle from stem cells in the laboratory and use that muscle to predict how drugs will affect patients’ hearts. Induced pluripotent stem cells (iPSC) are cells from healthy adult patients that are “rewired” so that they can form any type of cell found in the body. Currently, heart muscle grown from iPSC in the laboratory is more similar to heart muscle in a fetus than an adult. This means that lab grown muscle does not accurately predict the way drugs will affect patients. This is a major obstacle to developing drugs to treat heart disease, the leading cause of death in the United States. Shortly after birth, babies’ hearts must pump with stronger force because their blood pressure increases. At the same time, their hearts’ energy source shifts from sugar to fat. Previous research suggests that individually mimicking these changes in mechanical resistance to pumping, or changing the energy source from sugar to fat, can enhance lab-grown heart muscle. This research project will support combining those changes, with the goal of producing muscle that more accurately predicts the way drugs will affect patients. In addition, planned collaborations between the scientists performing this work and local high school teachers will expose students who are underrepresented in the STEM pipeline to science and engineering. In the perinatal and postnatal stages of heart development, mechanical forces on the heart (preload and afterload) increase. Concurrently, ATP-sourcing switches from glucose to fatty acids. This research hypothesizes that mechanical loading and ATP-sourcing act in a synergistic manner to elicit electrical maturation of cardiomyocytes derived from iPSC by regulating Peroxisome Proliferator Activated Receptor (PPAR) signaling. To address this hypothesis, the PI will leverage a high-throughput, iPSC-derived micro-heart muscle array technology. Biophysical cues applied to the micro-tissues will be controlled using linear actuators to stretch tissue (preload) and magneto-rheoelastomeric substrates to control the rigidity of the substrate tissues work against (afterload). Overall changes in micro-tissue electrophysiology will be determined using voltage sensitive dye, genetic calcium indicator (GCaMP6f), high-speed microscopy and automated video analyses. Using a combination of ion channel specific blocking drugs, immunostaining and RNAseq, these overall changes in electrophysiology will be linked to changes in expression of specific ion channels. Finally, a series of studies with PPAR-pathway modifying drugs will be performed to specifically probe the role for the PPAR-pathway in electrical maturation of iPSC-cardiomyocytes. The overarching focus of the research is to obtain deep understanding of how mechanical cues synergize with soluble, chemical cues like the metabolic substrate, to affect cellular fate and function. This project will allow the PI to advance the knowledge base in mechanobiology and establish his long-term bioengineering career. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.