Modified hTERT treatment ameliorates pressure overload-induced heart failure

Background
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.

Methods
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.

Findings
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.

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

Funding
This research was supported by the National 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).