SPINAL MUSCULAR ATROPHY ORGANOIDS REVEAL DEVELOPMENTAL DEFECTS RESCUED BY ANTISENSE OLIGONUCLEOTIDES TREATMENT

Spinal muscular atrophy (SMA) is a neuromuscular disease caused by mutations in the SMN1 gene. Recent therapies have significantly modified SMA natural course, but treatment efficacy remains variable and the reasons beyond this variability are still largely unexplored. Identifying pre-symptomatic SMA features is crucial to define the optimal therapeutic window and most efficient strategy in order to increase drug efficacy. Recent studies have shown that patients start to develop pathological signs in utero, suggesting that SMA retains an important, and still under investigated, developmental phenotype. In the present study, we generated SMA type 1 cerebral and spinal cord organoids (SCOs) to recapitulate human-specific early neurodevelopmental features. Single-cell transcriptomics revealed a pervasive transcriptional alteration in multiple cell populations, along with drastic changes in motor neuron gene expression. Morphological analyses detected early differentiation defects in SMA SCOs, unveiling a significant developmental component to the SMA pathology. Whole organoids electrophysiological acute recording revealed altered basal activity and pronounced hyperexcitability. Optimized peptide-conjugated antisense oligonucleotide tested in SMA SCOs successfully reverted both morphological and functional deficits. Of note, SMA cerebral organoids displayed similar functional deficits, revealing the widespread impact of the disease, beyond the spinal cord. Our findings provide proof of concept that SMA organoids can be used for effective drug testing, while demonstrating early-onset and pervasive features of SMA, which need to be considered in the therapeutic perspectives.