# Modified hTERT treatment ameliorates pressure overload-induced heart failure

## TL;DR

A modified telomerase gene therapy improves heart function and prevents heart failure in animal models and human cells.

## Contribution

A novel gene therapy using modified hTERT is shown to protect against heart failure by reversing telomere damage and mitochondrial dysfunction.

## Key findings

- AAV9-modhTERTY707F, D868A reversed cardiac function decline and prevented fibrosis in TAC-induced HF mice.
- modhTERT alleviated contractile dysfunction and calcium handling in cardiomyocytes and reduced Ang II-induced hypertrophy.
- modhTERT blocked DDR and p53 activation, reduced inflammation and ROS, and restored mitochondrial function.

## Abstract

Heart failure (HF) is a currently incurable disorder that increases the risk for stroke and sudden cardiac death. Shortened telomeres have been linked to the development of cardiomyocyte abnormalities and dysfunction, and telomere reprotection has become a favourable strategy for designing novel heart failure therapies. This study aims to design a pan-HF gene therapy where modified human telomerase expression is driven by cardiac troponin promoter and to evaluate cardiac protection.

Telomere shortening was determined in cardiomyocytes from Macaca fascicularis (cynomolgus monkey) and patients with HF by quantitative fluorescence in situ hybridisation (Q-FISH) assays. We bioengineered a catalytic inactivation and nuclear retaining modified human TERT (telomerase reverse transcriptase) gene therapy (AAV9-modhTERTY707F, D868A). In transverse aortic constriction (TAC)-induced WT and myocardial p53 deficient (p53CKO) mice HF model, as well as Ang II-induced human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs), we evaluate cardiac protection of modhTERT via echocardiography, RNA-sequence, Western blotting, Proteome Profiler Mouse XL Cytokine Array panel, RT-qPCR, transmission electron microscopy, and immunofluorescence.

AAV9-modhTERTY707F, D868A reversed cardiac function decline and prevented onset of cardiac fibrosis in TAC-induced HF murine. At cellular level, modhTERT alleviated contractile dysfunction and aberrant calcium handling in cardiomyocytes isolated from TAC hearts and prevented Ang II-stimulated hiPSC-CMs hypertrophy. Overexpression of modhTERT blocked telomeric DNA damage response (DDR) and p53 ser15-phosphorylation. Myocardial chronic inflammation and reactive oxygen species (ROS) levels were reverted by modhTERT overexpression. Additionally, modhTERT rescued mitochondrial ultrastructure, increased mitochondrial DNA (mtDNA) copy, and restored ATP production through restoration of PGC-1 α and TFAM expression.

We provide evidence that telomere re-protection confers cardiac protection and may serve as a potential gene therapeutic option for treating heart failure.

This research was supported by the 10.13039/501100001809National Natural Science Foundation of China (82070248, 82300282, 82300476), the Program for Professor of Special Appointment (Eastern Scholar) at Shanghai Institutions of Higher Learning (0900000024), 2023 Shanghai Action Plan for Promoting Scientific and Technological Innovation and Industrial Development of Gene Therapy (23J11900600).