Investigating the pathophysiology of amyotrophic lateral sclerosis (ALS) using motoneurons and astrocytes derived from induced pluripotent stem cells obtained from ALS patients

Abstract

Amyotrophic lateral sclerosis (ALS) is an adult onset, neurodegenerative disorder. Its pathophysiology is marked by initial changes in motoneuron (MN) function which subsequently lead to loss of motoneurons (MNs) both in the spinal cord and motor cortex. These functional changes include alterations in neuronal excitability i.e. neuronal activity, which modifies with disease progression. In this study, induced pluripotent stem cells (iPSCs) derived from ALS patients carrying C9orf72 mutations, iso-genic controls, and healthy controls were differentiated using two different protocols; the first produced neuron-enriched cultures (>90% neurons and less than 5% glial cells) and the second produced astrocyte enriched cultures (>90% astrocytes and less than 10% neurons). MNs were then cultured either alone, or on top of a monolayer of astrocytes. Results obtained using the whole-cell patch-clamp technique, demonstrate absence of excitability pathophysiology in C9orf72 patient iPSC-derived MNs in the absence of C9orf72 patient iPSC-derived astrocytes. This lack of functional pathophysiology in C9orf72 patient iPSC-derived MNs is not explained by their reduced maturity level. Using co-cultures of C9orf72 patient MNs and astrocytes I demonstrate that excitability changes in MNs involve astrocyte-MN interplay, which may be mediated via Na⁺/K⁺ ATPase located on MNs and could ultimately lead to neuronal loss in ALS. These findings highlight a non-cell autonomous disease mechanism involving Na⁺/K⁺ ATPase, also known as Na⁺/K⁺ pumps, which may contribute to changes in MN excitability and subsequent neurodegeneration in ALS. Finally, this enhanced patient iPSC-derived model of ALS implicates astrocyte-neuron communication as a potential target for drug development to help restore normal MN activity and function in ALS.

Date of Award	3 Dec 2019
Original language	English
Awarding Institution	University of St Andrews
Supervisor	Gareth Brian Miles (Supervisor)