# Impact of cardiomyocyte cell cycle activity on atrial structural and functional remodeling following myocardial infarction

> **NIH NIH R01** · INDIANA UNIVERSITY INDIANAPOLIS · 2022 · $641,207

## Abstract

Both experimental and clinical studies have demonstrated that chronic myocardial infarction is associated with
adverse remodeling of the left atrium, which in turn has an adverse impact on left atrial function. Left atrial
dilatation is a powerful and independent predictor of mortality after myocardial infarction, but the mechanisms
underlying the remodeling process are only poorly understood. Surprisingly, we have observed very high rates
of cardiomyocyte cell cycle activity in the left atrium of infarcted mice. However, the role that cardiomyocyte cell
cycle activity plays in mitigating or exacerbating structural and/or functional remodeling following myocardial
infarction is not known. To directly address this question, we have generated a transgenic mouse model wherein
infarct-induced left atrial cell cycle activity is silenced secondary to p16-Ink4a (p16) expression (p16 is a potent
inhibitor of the proliferative kinase Cdk4 and transgenic expression in adult animals has previously been shown
to be a potent cell cycle inhibitor). Here we propose to compare wild-type and p16 transgenic mice to determine
the impact of atrial cardiomyocyte cell cycle activation on left atrial structural and functional remodeling following
infarction. The experiments proposed in Aim 1 will determine the degree to which cardiomyocyte cell cycle activity
impacts structural atrial remodeling following myocardial infarction. Left atrial structural analyses will be
performed (a) at the tissue level to quantitate myocardial mass, cardiomyocyte number, fibrosis, immune cell
infiltration, autonomic innervation and capillary density, (b) at the cardiomyocyte level to quantitate the extent of
cell cycle progression and cellular hypertrophy as well as frequency of cardiomyocyte apoptosis, and (c) at the
molecular level to quantitate transcriptome changes. The experiments proposed in Aim 2 will determine the
degree to which cardiomyocyte cell cycle activity impacts atrial function following myocardial infarction. Atrial
functional analyses will be performed (a) at whole organism level to quantitate echocardiographic and
hemodynamic parameters, (b) at the intact heart level to quantitate calcium and voltage transient parameters in
the left atrium (via optical mapping) and of cell clusters within the intact heart (via two-photon laser scanning
microscopy), and (c) at the isolated cell level to quantitate fractional shortening and calcium handling kinetics.
Importantly, cross-referencing the cell and molecular data from Aim 1 with the imaging and functional data from
Aim 2 should enable us to better determine which cell cycle-mediated changes have a relevant impact on cardiac
function. Such information may suggest interventions aimed at reversing compromised left atrial function in
infarcted hearts.

## Key facts

- **NIH application ID:** 10442795
- **Project number:** 1R01HL158597-01A1
- **Recipient organization:** INDIANA UNIVERSITY INDIANAPOLIS
- **Principal Investigator:** LOREN J FIELD
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $641,207
- **Award type:** 1
- **Project period:** 2022-04-22 → 2026-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10442795

## Citation

> US National Institutes of Health, RePORTER application 10442795, Impact of cardiomyocyte cell cycle activity on atrial structural and functional remodeling following myocardial infarction (1R01HL158597-01A1). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10442795. Licensed CC0.

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