Genetic Correction of Human Induced Pluripotent Stem Cells from Patients with Spinal Muscular Atrophy

Abstract

Spinal muscular atrophy (SMA) is among the most common genetic neurological diseases that cause infant mortality. Induced pluripotent stem cells (iPSCs) generated from skin fibroblasts from SMA patients and genetically corrected have been proposed to be useful for autologous cell therapy. We generated iPSCs from SMA patients (SMA-iPSCs) using nonviral, nonintegrating episomal vectors and used a targeted gene correction approach based on single-stranded oligonucleotides to convert the survival motor neuron 2 (SMN2) gene into an SMN1-like gene. Corrected iPSC lines contained no exogenous sequences. Motor neurons formed by differentiation of uncorrected SMA-iPSCs reproduced disease-specific features. These features were ameliorated in motor neurons derived from genetically corrected SMA-iPSCs. The different gene splicing profile in SMA-iPSC motor neurons was rescued after genetic correction. The transplantation of corrected motor neurons derived from SMA-iPSCs into an SMA mouse model extended the life span of the animals and improved the disease phenotype. These results suggest that generating genetically corrected SMA-iPSCs and differentiating them into motor neurons may provide a source of motor neurons for therapeutic transplantation for SMA.

Plastin 3 is upregulated in iPSC-derived motoneurons from asymptomatic SMN1-deleted individuals

“…Our data in iPSC-derived SMA I MN models confirmed previously published data showing marked reduction of SMN expression and gem counts [23,47]. SMN expression level in SMA III and asymptomatic showed mildly reduced levels in iPSC and smNPCs and no difference in MNs as compared to controls.…”

“…A cornerstone of SMA pathology in SMN1-deleted individuals is low SMN expression which was already demonstrated in iPSC-derived SMA I models [23,47].…”

How to make spinal motor neurons

“…More recently, work by Corti and colleagues demonstrated that MNs differentiated from genetically corrected SMA iPSCs could survive transplantation and correctly engraft in the spinal cord of a one-day-old mouse model of SMA (Corti et al, 2012). Furthermore, these cells could ameliorate disease phenotypes and extend the life span of SMN mutant mice, at least in part by providing neurotrophic support (Corti et al, 2012). It has also been shown that ESC-derived MNs, when transplanted into the tibial nerve of adult animals can form functional NMJs and ameliorate muscle atrophy caused by nerve transection (Yohn, et.…”

Stem Cell Therapy: In Treatment of Neurodegenerative Diseases

“…37 The correction of SMN gene, using singlestranded oligonucleotide, was shown to restore the SMN gene profile in neurons derived from SMA-iPSC, converting SMN2 in SMN1. 38 It is possible that for SMA, transient rescue of the developmental loss of SMN may be sufficient to confer efficacy, which may not be the case for other neurodegenerative diseases where long-term degeneration of the transplanted cells is a valid concern.…”