RNAi-Based Gene Therapy Rescues Developmental and Epileptic Encephalopathy in a Genetic Mouse Model

Developmental and epileptic encephalopathy (DEE) associated with de novo variants in the gene encoding dynamin-1 (DNM1) is a severe debilitating disease with no pharmacological remedy. Like most genetic DEEs, the majority of DNM1 patients suffer from therapy-resistant seizures and comorbidities such as intellectual disability, developmental delay, and hypotonia. We tested RNAi gene therapy in the Dnm1 fitful mouse model of DEE using a Dnm1-targeted therapeutic microRNA delivered by a self-complementary adeno-associated virus vector. Untreated or control-injected fitful mice have growth delay, severe ataxia, and lethal tonic-clonic seizures by 3 weeks of age. These major impairments are mitigated following a single treatment in newborn mice, along with key underlying cellular features including gliosis, cell death, and aberrant neuronal metabolic activity typically associated with recurrent seizures. Our results underscore the potential for RNAi gene therapy to treat DNM1 disease and other genetic DEEs where treatment would require inhibition of the pathogenic gene product.

Adeno-associated virus serotype 9 mediated vascular endothelial growth factor gene overexpression in mdx mice

Duchenne muscular dystrophy (DMD) is a fatal neuromuscular disease caused by the absence of dystrophin. Vascular endothelial growth factor (VEGF) is a heparin-binding dimeric glycoprotein and principal angiogenic factor stimulating the migration, proliferation and expression of various genes in endothelial cells. Recently, VEGF was demonstrated to exhibit an antiapoptotic and direct myogenic effect, as well as to enhance muscle force restoration subsequent to traumatic injury. Therefore, the present study attempted to assess the muscle damage of VEGF overexpression in mdx mice. Adeno-associated virus serotype 9 (AAV9)-VEGF was administered intravenously to mdx mice. At 4 weeks after injection, VEGF was observed to be upregulated in the tibialis anterior muscle. In addition, the serum creatine kinase levels were significantly reduced and fatigue was slowed down, whereas the limb grip strength and weight of mice were markedly increased compared with the saline-treated mdx mice. Furthermore, significantly reduced inflammation and necrosis areas were observed in the muscle tissues of mice in the AAV9-VEGF group. These results suggested that AAV9-mediated VEGF gene overexpression was able to improve the muscle damage in mdx mice.