A xenotransplantation model for reactivation of paternal UBE3A using human-specific antisense oligonucleotides

Abstract

Abstract For many neurodevelopmental disorders, genetic treatment discovery is complicated by non-homology between human and non-human model system genomes. Antisense oligonucleotides (ASOs) influence protein expression by sequence-specific binding of RNA, resulting in targeted degradation or alternative splicing, and thereby provide a promising avenue for clinical therapeutics. Angelman Syndrome (AS), caused by loss-of-function of maternal UBE3A , has emerged as a monogenic neurodevelopmental disorder for which ASO therapy might be particularly amenable due to genomic imprinting. In an AS mouse model, Ube3a reactivation of the paternal allele using ASOs has been previously shown to rescue disease-relevant phenotypes. However, the poor sequence homology between murine and human UBE3A-ATS requires a human model system for screening of ASOs with clinical therapeutic potential. Here we evaluate an ASO targeting UBE3A-ATS using human induced pluripotent stem cell (hiPSC)-derived AS neurons in vitro and in vivo . We assessed the effect of ASO-treatment on cultured AS patient hiPSC-derived neurons through protein and RNA expression analysis. To increase clinical translatability, we designed a platform to evaluate this ASO in vivo by xenotransplantation of hiPSC-derived AS neurons into the brains of neonatal mice, with intracerebroventricular administration of the UBE3A-ATS ASO three weeks later. One week after ASO treatment, we observed in vivo reinstatement of UBE3A expression in xenotransplanted human neurons. These results highlight the potential for a versatile platform to evaluate efficacy of human-specific ASOs, for which AS provides an instructive proof-of-concept for therapeutic reactivation of UBE3A.