Three-Dimensional Stem Cell-derived Spinal Cord Model for Investigating Therapeutic Mechanisms of Risdiplam-like Compounds in Spinal Muscular Atrophy
Andrea D'Angelo1, Francesca Beatrice1, Jessica Ongaro2, Paola Rinchetti1, Irene Faravelli1, Matteo Miotto3, Simona Lodato3, Monica Nizzardo2, Giacomo Comi1, Linda Ottoboni1, Stefania Corti1
1University of Milan, 2Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, 3Humanitas University
Objective:
To investigate the therapeutic mechanisms of a Risdiplam-like compound in a three-dimensional stem cell-derived spinal cord model for Spinal Muscular Atrophy (SMA) and assess its efficacy in reversing the disease's pathological hallmarks.
Background:
SMA is a severe neurological disorder resulting from early degeneration of lower motor neurons due to mutations in the SMN1 gene. Reliable human models are crucial for understanding and treating this condition.
Design/Methods:
We developed and phenotypically characterized human spinal cord organoids from induced pluripotent stem cells (iPSCs) of SMA type 1 subjects (n=3) and healthy controls (n=2). The organoids were treated with a Risdiplam-like compound targeted at restoring SMN protein levels. The treatment was administered bi-daily across the first 80 days of organoid development, mimicking the initial trimester post-conception. Analysis methods included bulk transcriptomics, single-cell RNAseq, multielectrode array analysis, and immunophenotypic characterization.
Results:
SMA samples in the organoid model displayed marked cellular and molecular developmental alterations in multiple cell populations, notably beyond motor neurons. The Risdiplam-like compound modified at least 15% of disease-affected genes and showcased excellent long-term in vitro tolerance. Furthermore, it restored the balance between full-length SMN2 and Δ7, and importantly, reversed pathological indicators in the SMA organoids.
Conclusions:
The SMA organoids present a reliable model for studying drug kinetics and therapeutic outcomes, emphasizing the early and pervasive developmental nature of SMA. The study spotlights the potential of Risdiplam-like therapies for comprehensive SMA treatment and highlights the need for a profound understanding of drug mechanisms. Our findings notably contribute to the optimization of Risdiplam therapy, offering avenues for complementary treatment strategies for SMA patients.