Myocardial ischemia/reperfusion (I/R) injury is a major human health problem causing millions of deaths per year. Myocardial I/R involves severe cardiac myocyte dysfunction and myocyte death for which there is no cure. It has been challenging to dissect the role of specific mechanistic pathways in I/R owing to the multitude of cellular processes altered in I/R, including elevated reactive oxygen species (ROS), membrane instability, intracellular Ca2+ mishandling, mitochondrial uncoupling and others. Despite these challenges, myocyte generated ROS is widely considered a key initiating event leading to cellular damage in cardiac I/R. We provide exciting new evidence of a significant uncoupling of myocyte-generated ROS and damage in cardiac I/R. Thus, this proposal focuses on a new paradigm in testing the hypothesis that sarcolemma stability, independent of increased ROS production, is central to I/R injury. To interrogate I/R mechanisms we will implement sarcolemma stabilizers that in preliminary work significantly limit myocyte leak, Ca2+ mishandling, mitochondrial membrane depolarization and preserve myocyte viability despite I/R-mediated increased ROS. These results challenge the dogma of the mechanism of I/R damage by highlighting sarcolemma stabilization as central in the I/R injury pathway. Sarcolemma stabilization by cell surface interacting synthetic copolymers is proposed here as a tool for mechanistic dissection of the direct role of cardiac muscle membrane integrity in I/R. Copolymer-based membrane stabilizers are amphiphilic long-chain macromolecular copolymers that interact with and protect cellular membranes during stress. The overarching hypothesis of this proposal is that, independent of I/R-mediated ROS production, synthetic sarcolemma stabilizers function to significantly limit myocyte Ca2+ dysregulation and mitochondrial depolarization to increase heart pump performance in vivo. Stated differently, we will test the hypothesis that ROS alone is insufficient to cause I/R injury. This hypothesis, if correct, will change the field by providing direct evidence in establishing membrane integrity as central in I/R pathogenesis. The impact of this work derives from using synthetic sarcolemma stabilizers as a viable new therapeutic option that could be readily translated to clinical settings of I/R.
The Specific Aims are:
Aim 1. To test the hypothesis that during I/R, independent of myocyte ROS production, copolymer sarcolemma stabilizers will significantly limit membrane leak, intracellular Ca2+ mishandling and mitochondrial membrane depolarization to promote cell viability in rodent adult myocytes and human iPSC-derived cardiac myocytes in vitro.
Aim 2. To test the hypothesis that copolymer sarcolemma stabilization will promote myocyte viability and preserve myocardial function in a clinically relevant porcine model of myocardial I/R injury in vivo.

Public Health Relevance

The potential health significance and impact of this proposal are enormous owing to mechanistic insights and in the potential for therapeutic translation of chemical-based cardiac membrane stabilization to enhance the lives of cardiac patients

National Institute of Health (NIH)
National Heart, Lung, and Blood Institute (NHLBI)
Research Project (R01)
Project #
Application #
Study Section
Myocardial Ischemia and Metabolism Study Section (MIM)
Program Officer
Wong, Renee P
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
University of Minnesota Twin Cities
Schools of Medicine
United States
Zip Code
Kim, Mihee; Vala, Milan; Ertsgaard, Christopher T et al. (2018) Surface Plasmon Resonance Study of the Binding of PEO-PPO-PEO Triblock Copolymer and PEO Homopolymer to Supported Lipid Bilayers. Langmuir 34:6703-6712
Kim, Mihee; Haman, Karen J; Houang, Evelyne M et al. (2017) PEO-PPO Diblock Copolymers Protect Myoblasts from Hypo-Osmotic Stress In Vitro Dependent on Copolymer Size, Composition, and Architecture. Biomacromolecules 18:2090-2101
Houang, Evelyne M; Haman, Karen J; Kim, Mihee et al. (2017) Chemical End Group Modified Diblock Copolymers Elucidate Anchor and Chain Mechanism of Membrane Stabilization. Mol Pharm 14:2333-2339
Zhang, Wenjia; Haman, Karen J; Metzger, Joseph M et al. (2017) Quantifying Binding of Ethylene Oxide-Propylene Oxide Block Copolymers with Lipid Bilayers. Langmuir 33:12624-12634
Bartos, Jason A; Matsuura, Timothy R; Tsangaris, Adamantios et al. (2016) Intracoronary Poloxamer 188 Prevents Reperfusion Injury in a Porcine Model of ST-Segment Elevation Myocardial Infarction. JACC Basic Transl Sci 1:224-234
Duan, Dongsheng; Rafael-Fortney, Jill A; Blain, Alison et al. (2016) Standard Operating Procedures (SOPs) for Evaluating the Heart in Preclinical Studies of Duchenne Muscular Dystrophy. J Cardiovasc Transl Res 9:85-6
Bedada, Fikru B; Wheelwright, Matthew; Metzger, Joseph M (2016) Maturation status of sarcomere structure and function in human iPSC-derived cardiac myocytes. Biochim Biophys Acta 1863:1829-38
Bartos, Jason A; Matsuura, Timothy R; Sarraf, Mohammad et al. (2015) Bundled postconditioning therapies improve hemodynamics and neurologic recovery after 17 min of untreated cardiac arrest. Resuscitation 87:7-13
Houang, Evelyne M; Haman, Karen J; Filareto, Antonio et al. (2015) Membrane-stabilizing copolymers confer marked protection to dystrophic skeletal muscle in vivo. Mol Ther Methods Clin Dev 2:15042
Martindale, Joshua J; Metzger, Joseph M (2014) Uncoupling of increased cellular oxidative stress and myocardial ischemia reperfusion injury by directed sarcolemma stabilization. J Mol Cell Cardiol 67:26-37