Adeno-Associated Virus-Mediated Gene Therapy in the Mashlool, Atp1a3^Mashl/+, Mouse Model of Alternating Hemiplegia of Childhood

Abstract

Alternating Hemiplegia of Childhood (AHC) is a devastating autosomal dominant disorder caused by ATP1A3 mutations, resulting in severe hemiplegia and dystonia spells, ataxia, debilitating disabilities, and premature death. Here, we determine the effects of delivering an extra copy of the normal gene in a mouse model carrying the most common mutation causing AHC in humans, the D801N mutation. We used an adeno-associated virus serotype 9 (AAV9) vector expressing the human ATP1A3 gene under the control of a human Synapsin promoter. We first demonstrated that intracerebroventricular (ICV) injection of this vector in wild-type mice on postnatal day 10 (P10) results in increases in ouabain-sensitive ATPase activity and in expression of reporter genes in targeted brain regions. We then tested this vector in mutant mice. Simultaneous intracisterna magna and bilateral ICV injections of this vector at P10 resulted, at P40, in reduction of inducible hemiplegia spells, improvement in balance beam test performance, and prolonged survival of treated mutant mice up to P70. Our study demonstrates, as a proof of concept, that gene therapy can induce favorable effects in a disease caused by a mutation of the gene of a protein that is, at the same time, an ATPase enzyme, a pump, and a signal transduction factor.

Genetically altered animal models forATP1A3-related disorders

“…This exogenous delivery of WT ATP1A3 to Mashl/+ mice resulted in a reduced occurrence of hemiplegic but not dystonic episodes induced by cold water swimming at P40, improvement in beam-walking performance at P40 and P70 (10 weeks) and prolonged survival compared with untreated Mashl/+ mice up to 10 weeks of age. Although other behavioural tests did not reveal differences in treated Mashl/+ mice ( Hunanyan et al, 2021 ), these results demonstrate that gene therapy can ameliorate some of the manifestations of AHC in the Mashlool model.…”

“…An adeno-associated virus serotype 9 (AAV9) vector expressing human ATP1A3 cDNA under the control of a human SYN1 (neurone-specific) promoter, which had been shown to increase brain NKA activity in WT mice, was injected into the CSF, via the cerebral ventricles and cisterna magna, of Mashl/+ mice on postnatal day (P)10 ( Hunanyan et al, 2021 ). This exogenous delivery of WT ATP1A3 to Mashl/+ mice resulted in a reduced occurrence of hemiplegic but not dystonic episodes induced by cold water swimming at P40, improvement in beam-walking performance at P40 and P70 (10 weeks) and prolonged survival compared with untreated Mashl/+ mice up to 10 weeks of age.…”

Methodology of a Natural History Study of a Rare Neurodevelopmental Disorder: Alternating Hemiplegia of Childhood as a Prototype Disease

“…This is of particular importance given the prospects of gene therapy for alternating hemiplegia of childhood based on current studies in its mouse model carrying the most frequent mutation causing alternating hemiplegia of childhood in humans, the D801N mutation. 42 Based on the methodology from this study, using the abovementioned univariable and multivariable analyses, we can be able to determine early-life clinical predictors for outcomes. We can note what factors (ie, age, sex, epilepsy, and baseline scores) affect the outcomes measures Nonparoxysmal Disability Index, Paroxysmal Disability Index, and Vineland-II.…”

“…This is of particular importance given the prospects of gene therapy for alternating hemiplegia of childhood based on current studies in its mouse model carrying the most frequent mutation causing alternating hemiplegia of childhood in humans, the D801N mutation. 42…”

US Food and Drug Administration Facilitated Pediatric Approval Programs: Application to Pediatric Neurological Disorders

“…Acquiring this knowledge is important as it relates to child's rights as well as to opportunities to develop novel and precision therapies that can have major and long-lasting impacts. [41][42][43][44] This knowledge also helps inform them on how to best develop novel therapies and how to best make referrals of patients for appropriate drug trials. Furthermore, this insight allows individuals to identify both the strengths and weaknesses of the current programs instated by the FDA.…”