Nucleoside‐Modified mRNA Encoding Alpha‐Galactosidase A Ameliorates Fabry Disease Phenotypes in Human IPSC‐Derived Cardiomyocytes

The lysosomal storage disorder Fabry disease results from α‐galactosidase A deficiency, leading to excessive glycosphingolipid substrate accumulation, primarily globotriaosylceramide (Gb3). While the underlying molecular mechanisms remain elusive, multi‐systemic complications ultimately culminate in premature death, with heart failure being the leading cause of death. Current treatment options fail to treat Fabry disease adequately and only delay its progression. Preclinical studies on an alternative approach, systemic delivery of nucleoside‐modified GLA mRNA (modGLA), suggest improved effectiveness over existing therapies in reducing glycosphingolipid levels in the heart. It remains unclear whether modGLA can rescue Fabry cardiomyopathy phenotypes at the cellular level, which are not faithfully recapitulated in current animal models. To address this, we investigated characteristic phenotypes in two new models of Fabry cardiomyopathy utilizing human iPSC‐derived cardiomyocytes in transcriptomic and functional analyses. These human Fabry disease cardiomyocytes displayed broad transcriptional dysregulation, apoptosis, mitochondrial dysfunction, impaired reactive oxygen species handling, altered contractility, and enhanced calcium transient decay parameters. Mechanistically, phospholamban hyperphosphorylation may contribute to this calcium dysregulation. Consistently, modGLA therapy restored α‐galactosidase A activity, reduced glycosphingolipid deposition, and normalized molecular alterations, including phospholamban hyperphosphorylation and calcium decay parameters, supporting modGLA as a promising therapeutic strategy for Fabry disease.