# Optimized murine HFpEF models for translational preclinical studies

## TL;DR

Researchers improved mouse models of heart failure with preserved ejection fraction to work better across different mouse strains and sexes.

## Contribution

Modified 2-hit and 4-hit models to ensure HFpEF induction in multiple C57BL/6 substrains and both sexes.

## Key findings

- HFpEF was successfully induced in C57BL/6J mice with a 13-week 2-hit protocol.
- The 4-hit model produced a stable HFpEF phenotype in both C57BL/6 substrains and sexes.
- Modifications enhance reproducibility and prevent aldosterone escape in HFpEF models.

## Abstract

The most clinically representative murine models of heart failure with preserved ejection fraction (HFpEF) include a ‘2-hit’ model combining nitrosative stress with metabolic perturbation and a ‘3-hit’ model that also includes ageing. Both models have important limitations with regard to substrain and sex.

The 2-hit model protocol was modified to reproduce HFpEF in both C57BL/6N and 6J mice by increasing L-NAME doses (0.5 g/L to 1.75 g/L) and protocol lengths (7 weeks to 13 weeks). For the 3-hit model, in addition to deoxycorticosterone pivalate (DOCP), we added 1% NaCl drinking water to enhance and prolong the effect of DOCP (‘4-hit’). To maintain the phenotype, a second bolus of DOCP was administered after 8 weeks.

HFpEF was successfully induced in C57BL/6J mice when exposed to a 13-week 2-hit L-NAME protocol with gradually increasing dosage from 1.0 to 1.75 g/L. For the 4-hit mice, a clear HFpEF phenotype was observed in C57BL/6N and 6J mice in both male and females, and maintained for up to 12 weeks.

These modifications ensure the 2-hit model is induced in J substrain of C57BL/6 mice. The 4-hit model prevents aldosterone escape and enhances reproducibility across sexes and substrains.

Graphical AbstractSchematic overviews of the modified 2-hit and 4-hit murine models of heart failure with preserved ejection fraction (HFpEF). Modifications to commonly used murine models of HFpEF improve phenotype reproducibility across C57BL/6J and C57BL/6N substrains.For image description, please refer to the figure legend and surrounding text.

Schematic overviews of the modified 2-hit and 4-hit murine models of heart failure with preserved ejection fraction (HFpEF). Modifications to commonly used murine models of HFpEF improve phenotype reproducibility across C57BL/6J and C57BL/6N substrains.