Telomere recapping via gene therapy as a beneficial strategy for cardio-renal syndrome type 4

Cardio-renal syndrome type 4 (CRS4) is defined as heart failure driven by chronic kidney disease (CKD). Cardiovascular mortality is the leading cause of death in patients with advanced CKD with current medical treatments exhibiting limited efficacy. Short leukocyte telomere lengths in such patients are correlated with increased mortality, particularly cardiovascular mortality. Here, we examined telomere shortening in mouse and human cardiomyocyte models of CRS4 and its potential protective role by overexpression of telomerase reverse transcriptase.

We engineered an adeno-associated virus 9 (AAV9) gene therapy JV101, which overexpressed catalytically inactive and nuclear localized human telomerase reverse transcriptase (modhTERT) under cardiac troponin T promoter control. Both in vivo and in vitro models were utilized to conduct a comprehensive evaluation of the therapeutic effects of modhTERT on CRS4.

Overexpression of modhTERT recapped myocardial telomeres and reversed cardiac dysfunction, hypertrophy and fibrosis, and mitochondrial dysfunction in two CRS4 mouse models: 5/6 nephrectomy and Angiotensin II - high salt - uninephrectomy. The reversal of cardiac dysfunction by modhTERT was both long-term and persistent. In contrast, beta-blocker administration merely delayed the progression of heart failure in these models, without achieving functional reversal. Surprisingly, JV101 ameliorated kidney function as measured by blood urea nitrogen levels in CKD murine models. Experiments in human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) demonstrated that modhTERT bound to myocardial telomeric ends. Transcriptomic analysis of isolated mouse cardiomyocytes revealed that modhTERT reversed differentially repressed genes that were highly enriched in mitochondrial metabolism. Coculture of hiPSC-CMs with serum from hemodialysis patients or indoxyl sulfate toxin induced myocardial contractile dysfunction. Overexpression of modhTERT also blocked further telomere shortening and reversed contractile dysfunction in hiPSC-CMs.

Our results provide proof-of-concept evidence for treating CRS4 by telomere recapping gene therapy.