Friedreich's ataxia (FRDA) is an inherited neurodegenerative disorder caused by a GAA repeat expansion within the FXN gene, leading to reduced frataxin levels. This deficiency results in mitochondrial dysregulation, oxidative stress, and progressive cell death. Currently, only one approved treatment exists for FRDA in the United States, Canada, and the European Union, which improves neurological outcomes but has not been fully evaluated for broader disease symptoms. Therefore, identifying new therapeutic targets remains essential. Sphingolipids are increasingly recognized for their roles in neurodegeneration with emerging evidence indicating their dysregulation in FRDA. Here, we investigate whether sphingolipid-metabolizing enzymes are similarly affected and assess the therapeutic potential of targeting them. Our findings demonstrate that these enzymes are dysregulated across multiple FRDA models. Importantly, their modulation in vitro and in vivo significantly reduces mitochondrial dysfunction, enhances frataxin expression, and improves key pathological features of the disease, highlighting sphingolipid metabolism as a promising therapeutic target for FRDA.

Alzheimer’s disease (AD) is a devastating neurodegenerative condition that affects memory and cognition, characterized by neuronal loss and currently lacking a cure. Mutations in PSEN1 (Presenilin 1) are among the most common causes of early-onset familial AD (fAD). While changes in neuronal excitability are believed to be early indicators of AD progression, the link between PSEN1 mutations and neuronal excitability remains to be fully elucidated. This study examined iPSC-derived neurons (iNs) from fAD patients with PSEN1 mutations S290C or A246E, alongside CRISPR-corrected isogenic cell lines, to investigate early changes in excitability. Electrophysiological profiling revealed reduced excitability in both PSEN1 mutant iNs compared to their isogenic controls. Neurons bearing S290C and A246E mutations exhibited divergent passive membrane properties compared to isogenic controls, suggesting distinct effects of PSEN1 mutations on neuronal excitability. Additionally, both PSEN1 backgrounds exhibited higher current density of voltage-gated potassium (Kv) channels relative to their isogenic iNs, while displaying comparable voltage-gated sodium (Nav) channel current density. This suggests that the Nav/Kv imbalance contributes to impaired neuronal firing in fAD iNs. Deciphering these early cellular and molecular changes in AD is crucial for understanding disease pathogenesis.

It is advantageous to culture the ex vivo retina and other tissues at the air-liquid interface to allow for more efficient gas exchange. However, gene delivery to these cultures can be challenging. Electroporation is a fast and robust method of gene delivery, but typically requires submergence in liquid buffer for electrical current flow. We have developed a submergence-free electroporation technique that incorporates an agarose hydrogel disk between the positive electrode and retina. Inner retinal neurons and Müller glia are transfected with increased propensity toward Müller glia transfection after extended time in culture. We also observed an increase in BrdU incorporation in Müller glia following electrical stimulation, and variation in detection of transfected cells from expression vectors with different promoters. This method advances our ability to use ex vivo retinal tissue for genetic studies and should be adaptable for other tissues cultured at an air-liquid interface. Subject areas: Genetic engineering, Methodology in biological sciences, Bioelectrical engineering