Nucleoside-modified GLA mRNA rescues fabry cardiomyopathy phenotypes in human iPSC-derived cardiomyocytes

Abstract Background Numerous GLA gene variants result in α-galactosidase A enzyme (α-gal A) dysfunction. Being involved in glycosphingolipid (GSL) catabolism, α-gal A deficiency causes lysosomal accumulation of GSLs, primarily globotriaosylceramide (Gb3). This substrate deposition manifests as the progressive and multisystemic lysosomal storage disorder known as Fabry disease. While symptomatic heterogeneity is high, cardiovascular involvement stands as the leading cause of death in Fabry disease. However, the underlying mechanisms remain poorly understood, and available treatment options inadequately target the heavily affected cardiomyocytes (CMs). While this discrepancy underscores the need for additional therapeutic options, unfortunately, animal models fail to replicate the cardiac disease manifestation. Consequently, complementary models are needed to study disease mechanisms and evaluate novel treatment options. Purpose Prior preclinical studies investigating nucleoside-modified GLA mRNA (modGLA) as a candidate treatment, suggested an enhanced potential over existing therapies in reducing GSL levels in the heart 1. However, to this date modGLA’s potential to rescue cellular Fabry cardiomyopathy phenotypes secondary to substrate accumulation remains elusive. To elucidate this and to gain pathomechanistic insights, we established two new in vitro Fabry cardiomyopathy models. Methods ModGLA was produced by in vitro transcription and purified by reversed-phase HPLC. We generated both GLA-knockout (GLA-KO) and patient-derived hiPSCs (F01). Following differentiation into cardiomyocytes (hiPSC-CMs), alongside isogenic controls, we subjected these cells to transcriptomic and functional analyses, and investigated the therapeutic potential of modGLA in ameliorating pathological alterations. Results Fabry hiPSC-CMs exhibited the Fabry disease-specific phenotype of α-gal A enzyme deficiency and extensive Gb3 accumulation. Transcriptome analysis followed by gene set enrichment analysis and functional validation indicated mitochondrial dysfunction, elevated apoptosis, compromised autophagy, impaired ROS neutralising capacity, altered cAMP signalling, arrhythmias, and enhanced calcium handling. Strikingly, Western blotting implicated hyperphosphorylated phospholamban (PLN) as a mechanism for enhanced calcium cycling via disinhibition of the cardiac sarcoplasmic calcium ATPase. Congruently, comparative transcriptome analysis between both disease models particularly mirrored cAMP and calcium signalling to be a Fabry-distinctive signature. Importantly, modGLA treatment restored α-gal A enzyme activity, diminished GSL deposits and ameliorated the pathological alterations observed. Conclusion Fabry hiPSC-CMs represent a potent platform for drug development and the investigation of disease mechanisms. The effective normalization of cellular Fabry disease phenotypes by modGLA therapy further substantiates its potential as a future treatment modality.