Screening for modulators of autism spectrum disorder using induced human neurons

Autism Spectrum Disorder (ASD) is a heterogeneous neurodevelopmental disorder. There are no drugs to treat the core symptoms. De novo mutations often play an important role in ASD and multiple high-risk loci have been identified in the last decade. These mutations range from copy number variants to small insertion/deletion and single nucleotide variants. Large-scale exome sequencing has identified over 100 risk genes that are associated with ASD. Both etiological heterogeneity and unavailability of human neurons remain major hurdles in understanding the pathophysiology of ASD and testing of new drug candidates. Hence, the most achievable and relevant model to screen for potential drugs is human neurons from inducible pluripotent stem cells (iPSCs), including those from individuals with genetic mutations. In this study, we tested stem cells from individuals carrying mutations in ADNP, FOXP1 or SHANK3. They were scaled and reprogrammed to glutamatergic neurons and assessed for the effects of their specific mutations on neurite outgrowth. High Content Analysis allowed us to observe phenotypic differences between ASD neurons compared to controls, in terms of neuron number, neurite number and neurite length per neuron. Further, neurons were derived from both patient derived and genetically modified iPSCs with DDX3X mutation which were tested against 5088 drug like compounds. We assessed individual compound effects on the induced neurons to determine if they elicited changes that would indicate neurite growth (neuroprotection) or, alternatively, reduce outgrowth and hence appear neurotoxic. This report includes all methods, phenotypic outcomes, and results for the largest ASD small molecule screening effort done to date.