Human Stem Cell-derived Organoids Facilitates Research into ALS Pathogenesis, Therapy
Key findings
- Researchers at Massachusetts General Hospital used stem cells generated from patients with amyotrophic lateral sclerosis (ALS) to establish organoid cultures that contained neurons, muscle, astrocytes and microglia, and captured circuits involved in sensorimotor diseases
- Motor neurons and skeletal muscle in the organoids were connected via functional neuromuscular junctions (NMJs), the site of earliest pathology in ALS, and NMJs were confirmed to be significantly impaired in organoids derived from all three ALS cell lines
- Mutations in familial ALS genes gave rise to distinct NMJ phenotypes, and all had a structural deficit
- The ability to derive the NMJ synapse and cell types that affect motor neurons are important for modeling ALS and other motor and sensory diseases
Degeneration of the neuromuscular junction (NMJ), the core synapse in the neuromuscular nervous system, is the first pathological feature of amyotrophic lateral sclerosis. Modeling of the NMJ is crucial for understanding the pathophysiology of ALS and developing personalized treatments.
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Now, Brian Wainger, MD, PhD, an assistant professor in the Department of Neurology and the Department of Anesthesia, Critical Care and Pain Medicine at Massachusetts General Hospital, and a physician-scientist at the Sean M. Healey and AMG Center for ALS, and colleagues have generated the first cultured organoids that allow comparison of NMJs derived from ALS patients and those derived from controls. The team, which includes João D. Pereira, PhD, an instructor in the Department of Neurology and other members of the Wainger lab, reports their advance in Nature Communications. The project was supported by an NIH New Innovator award, the New York Stem Cell Foundation—Robertson Investigator award, as well as Target ALS.
Initial Experiments
The researchers first used five induced pluripotent stem cell (iPSC) cell lines: two from patients with familial ALS, one from a patient with sporadic ALS, and two from controls. All gave rise to organoid cultures that contained:
- Neuroectodermal derivatives—motor and sensory neurons and astrocytes
- Mesodermal derivatives—microglia, endothelial cells lining a lumen, and skeletal muscle
Muscle development and maturation occurred over six to ten weeks in culture. Motor neurons and skeletal muscle connected via physiologically active NMJs were substantially impaired in ALS cultures—the frequency of large muscle contractions was reduced by 73% compared with control cultures (P=0.035).
Gene Editing
The researchers then edited three familial ALS mutations into a control cell line, yielding three isogenic pairs of ALS and matched control lines. Key findings:
- The six isogenic lines yielded a consistent number of several different cell types
- Compared with the five original cell lines, the six isogenic lines showed marked reductions in both among-line and within-line variances in cell types, resulting in organoids more suitable for disease modeling studies
- Mutations in familial ALS genes gave rise to distinct NMJ phenotypes, and all had a structural deficit
Research and Clinical Implications
In vitro modeling of the human NMJ will help scientists construct hypotheses about the early pathogenesis of ALS and other motor diseases. In addition, it may facilitate the identification and validation of therapeutic targets and drug candidates.
Sensorimotor organoids should also be valuable for studying sensory diseases, including aggressive inherited conditions, such as hereditary sensory and autonomic neuropathies, and acquired ones such as painful diabetic neuropathy.
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