Human Induced Pluripotent Stem Cell-Derived TDP-43 Mutant Neurons Exhibit Consistent Functional Phenotypes Across Multiple Gene Edited Lines Despite Transcriptomic and Splicing Discrepancies

Smith AST, Chun C, Hesson J, Mathieu J, Valdmanis PN, Mack DL, Choi BO, Kim DH, and Bothwell M.

Frontiers in Cell and Developmental Biology, 2021.


Characterization of cell populations in ALS models essential for the development of novel therapies for neurodegenerative disorders

Understanding the underlying mechanisms of neurodegenerative conditions such as amyloid lateral sclerosis (ALS) could lead to the development of new therapeutic targets, but accurately modeling the disease is challenging due to clinical and genetic heterogeneity in ALS pathophysiology. Genetic engineering with CRISPR has the potential to isolate and test the impact of different mutations but the potential for transcriptomic and splicing discrepancies could introduce their own variability. Here the authors compare commercially available and in-house induced pluripotent stem cell (iPSC)-derived motor neurons bearing CRISPR-engineered, ALS-relevant TDP-43 mutations. Both lines exhibited consistent electrophysiological phenotypes despite transcriptomic and splicing discrepancies in vitro that correlated with patient derived lines—findings that highlight both the potential for modeling ALS as well as the importance of careful comparison of multiple cell lines when using models to study disease development and progression in humans.

To assess in vitro neural activity in the TDP-43 mutant motor neurons, the researchers used Axion’s Maestro multielectrode array (MEA) system and found that cells demonstrated significant differences in population-level function, with a decrease in bursting rate but an increase in burst duration and weighted mean firing rates. The authors suggest this pattern is similar to the hyperexcitability associated with ALS central and peripheral neurons in vivo. Taken with other findings in the study, this characterization of cell populations in ALS models may facilitate the identification of biomarkers and development of novel therapies for neurodegenerative disorders in the future.