Graef JD, Wu H, Ng C, Sun C, Villegas V, Qadir D, Jesseman K, Warren ST, Jaenisch R, Cacace A, Wallace O
The European Journal of Neuroscience, 2020
Summary:
Fragile X is a neurodevelopmental disorder caused by a mutation in the FMR1 gene. Previous studies have shown recovery of function in iPSC-derived Fragile X Syndrome (FXS) neurons with the use of gene editing tools. However, the minimum level of restoration for functional recovery is unknown.
In this publication, the authors used Axion MEA platform to confirm the spontaneous, hyperexcitable FXS phenotype in multiple patient iPSC-derived neuronal lines. Genetic editing tools, including CRISPR gene editing, cell mixed models, and ASO-mediated knockdown, demonstrated that a partial recovery of of FMRP expression can correct the hyperexcitable phenotype.
The MEA platform recorded spontaneous neural activity including burst and firing rates. The FXS neuronal and control neuronal cultures demonstrated both tonic and burst network activity patterns, however the FXS neurons had an overall high spontaneous activity.
Evaluation of different gene editing functional recovery of FMRP-expression in FXS neurons showed a normalized return to control level neuronal activity after greater than 20% partial restoration. Reduction in FMRP-expression in control lines due to knock-down or knock-out genetic engineering resulted in an increase in neuronal hyperexcitable spontaneous activity in vitro.
This data helps to establish a threshold of levels for potential therapeutics aimed at either full reactivation of FMR1 in a subset of neurons or partial reactivation of FMR1 in a large population of neurons.
