Spinal cord extracts of amyotrophic lateral sclerosis spread TDP-43 pathology in cerebral organoids

Abstract

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder caused by progressive loss of motor neurons and there is currently no effective therapy. Cytoplasmic mislocalization and aggregation of TAR DNA-binding protein 43 kDa (TDP-43) within the CNS is a pathological hallmark in sporadic ALS and prion-like propagation of pathogenic TDP-43 is thought to be implicated in disease progression. However, cell-to-cell transmission of pathogenic TDP-43 in the human CNS has not been confirmed experimentally. Here we used induced pluripotent stem cells (iPSCs)-derived cerebral organoids as recipient CNS tissue model that are anatomically relevant human brain. We injected postmortem spinal cord protein extracts individually from three non-ALS or five sporadic ALS patients containing pathogenic TDP-43 into the cerebral organoids to validate the templated propagation and spreading of TDP-43 pathology in human CNS tissue. We first demonstrated that the administration of spinal cord extracts from an ALS patient induced the formation of TDP-43 pathology that progressively spread in a time-dependent manner in cerebral organoids, suggesting that pathogenic TDP-43 from ALS functioned as seeds and propagated cell-to-cell to form de novo TDP-43 pathology. We also reported that the administration of ALS patient-derived protein extracts caused astrocyte proliferation to form astrogliosis in cerebral organoids, reproducing the pathological feature seen in ALS. Moreover, we showed pathogenic TDP-43 induced cellular apoptosis and that TDP-43 pathology correlated with genomic damage due to DNA double-strand breaks. Thus, our results provide evidence that patient-derived pathogenic TDP-43 can mimic the prion-like propagation of TDP-43 pathology in human CNS tissue. Our findings indicate that our assays with human cerebral organoids that replicate ALS pathophysiology have a promising strategy for creating readouts that could be used in future drug discovery efforts against ALS.

Decellularized Brain Extracellular Matrix Hydrogel Aids the Formation of Human Spinal-Cord Organoids Recapitulating the Complex Three-Dimensional Organization

“…The use of organoids in vitro for physiological modeling and disease representation has achieved breakthroughs in several fields. These include early neural system development, trunk formation, visual pathway projections, nociceptive sensory circuits, signal transmission from brain to spinal cord, human nociceptive perception and opioid-induced tolerance, neuromuscular junctions, leukoencephalopathy with brain stem and spinal cord involvement and lactate elevation (LBSL), neural tube defects (NTDs), amyotrophic lateral sclerosis (ALS), acute flaccid myelitis (AFM), and glaucoma. − In summary, spinal cord organoids induced by DBECMH and small molecules offer an innovative, mass-amplifiable, and individually specific in vitro spinal cord model. This lays the groundwork for using organoids to construct in vitro models of spinal cord diseases, significantly advancing the field of medical research and therapeutics.…”

Somatic Mosaicism in Amyotrophic Lateral Sclerosis and Frontotemporal Dementia Reveals Widespread Degeneration from Focal Mutations

“…The focality of these mutations in the nervous system also suggests a mechanism by which degeneration may spread from a site containing mutant cells to eventually cause loss of neurons in regions that do not carry the mutation. This process is thought to involve the TDP-43 proteinopathy as supported by recent studies in cell and animal models [12][13][14][15][16][17][18] . Identification of predicted pathogenic somatic mutations in the primary motor cortex and in spinal cord from individuals with ALS suggests potential onset of disease in either UMNs or LMNs but eventual involvement of both.…”

“…ALS typically begins focally and spreads regionally as the disease progresses 5,6 , although whether degeneration begins in UMNs, LMNs, or both simultaneously, has remained controversial 7,8 , with some studies suggesting that focality can manifest independently in UMNs and LMNs 5,9 . TDP-43 pathology also follows stereotypical patterns in ALS and FTD brains [9][10][11] , thought to reflect focal onset and intercellular transmission of TDP-43 inclusions in a prion-like manner, as shown in cell and animal models [12][13][14][15][16][17][18] .…”

History of ALS and the competing theories on pathogenesis: IFCN handbook chapter

“…Cortical pathology increased excitatory inputs to the spinal cord to which local circuitry compensated with an upregulation of inhibition, indicating how TDP-43 mediated pathology spreads corticofugally in ALS ( Reale et al, 2023 ). Pathogenic TDP-43 may spread in a prion-like propagation ( Tamaki et al, 2023 ), but this is controversial and others suggest that ALS corticofugal propagation is likely not mediated by prion-like mechanisms, but relies on cortical hyperexcitability ( Scekic-Zahirovic et al, 2021 ).…”