# Engineered Stem Cells for Cardiac Repair

> **NIH NIH R01** · UNIVERSITY OF WASHINGTON · 2022 · $809,808

## Abstract

ABSTRACT. Aim 1 of this project is built around years of collaborative work between Drs. Regnier and Murry
studying human stem cell derived cardiomyocytes as a potential cell replacement strategy for cardiac repair
following myocardial infarction (MI). We have shown that human stem cells can be differentiated into
cardiomyocytes (CMs), produced at a scale and purity that permit testing in rodent models and non-human
primates (NHP; Macaca nemestrina) and that these cells engraft and integrate with host tissue to improve left
ventricular performance. The premise for the proposed experiments is based on two fundamental discoveries:
1) 2-deoxy ATP (dATP) is a potent natural nucleotide stimulant of contractility when used by cardiac myosin, and
2) hiPSC-CMs that overexpress the rate-limiting enzyme for dATP synthesis, ribonucleotide reductase (RNR),
have increased contractility and also deliver dATP to the native myocardium heart via gap junctions. In our
current award we made excellent progress in testing the hypothesis that engineered hiPSC-CMs with elevated
RNR (hiPSC-CMRNR) improve outcomes in cell replacement therapy for MI (compared with control hiPSC-CMs).
For this proposal, we have generated new hiPSC-CM lines with gene-edited RNR and different transcriptional
promotors. These cells have greater RNR expression and produce multi-fold greater levels of cellular dATP.
Thus, we will test the dose dependence of elevated dATP for hiPSC-CMRNR engrafted into infarcted rat hearts.
The novel aspect of our approach is to go beyond replacement of lost tissue (with hiPSC-CMs) by using
engineered hiPSC-CMRNR to produce and deliver a small molecule therapeutic (dATP) that improves native heart
muscle contraction. This has the potential to substantially recover the post-MI depressed function of native
myocardium. Aim 2 will explore the mechanistic basis of how small increases in myocardial dATP result in
significant increases in contractile force and kinetics of activation and relaxation of muscle, and in the magnitude
of LV pressure development (LVDP) and kinetics of pressure development (+dP/dt) and decline (-dP/dt) of the
heart. Our recent reports and preliminary data strongly suggest at least three mechanisms are involved: 1)
disruption of the super-relaxed state (SRX) from the myosin backbone to a disordered relaxed state (DRX), 2)
movement of DRX myosin towards thin filaments via greater electrostatic interactions with actin, and 3) faster
crossbridge cycling. We have published multiple studies on the chemo-mechanics of faster crossbridge cycling
(3), so will focus primarily on mechanisms 1 and 2 here using multiple state of the art approaches. These include
low angle x-ray diffraction analysis of isolated myosin, cardiac muscle, and whole heart (Langendorff) levels,
stopped-flow ATPase, super-localization single molecule microscopy of thick filament zones, structure-based
computational models of myosin ± actin and multi-scale models of the heart. This ...

## Key facts

- **NIH application ID:** 10442970
- **Project number:** 2R01HL128368-05
- **Recipient organization:** UNIVERSITY OF WASHINGTON
- **Principal Investigator:** MICHAEL REGNIER
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $809,808
- **Award type:** 2
- **Project period:** 2018-02-01 → 2026-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10442970

## Citation

> US National Institutes of Health, RePORTER application 10442970, Engineered Stem Cells for Cardiac Repair (2R01HL128368-05). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10442970. Licensed CC0.

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