Frontiers in Cellular Neuroscience (Jun 2023)

Moderate intrinsic phenotypic alterations in C9orf72 ALS/FTD iPSC-microglia despite the presence of C9orf72 pathological features

  • Ileana Lorenzini,
  • Eric Alsop,
  • Jennifer Levy,
  • Lauren M. Gittings,
  • Deepti Lall,
  • Benjamin E. Rabichow,
  • Stephen Moore,
  • Stephen Moore,
  • Ryan Pevey,
  • Ryan Pevey,
  • Lynette M. Bustos,
  • Lynette M. Bustos,
  • Camelia Burciu,
  • Divya Bhatia,
  • Mo Singer,
  • Justin Saul,
  • Amanda McQuade,
  • Amanda McQuade,
  • Amanda McQuade,
  • Makis Tzioras,
  • Makis Tzioras,
  • Thomas A. Mota,
  • Amber Logemann,
  • Jamie Rose,
  • Jamie Rose,
  • Sandra Almeida,
  • Fen-Biao Gao,
  • Michael Marks,
  • Christopher J. Donnelly,
  • Elizabeth Hutchins,
  • Shu-Ting Hung,
  • Justin Ichida,
  • Robert Bowser,
  • Tara Spires-Jones,
  • Tara Spires-Jones,
  • Mathew Blurton-Jones,
  • Mathew Blurton-Jones,
  • Mathew Blurton-Jones,
  • Tania F. Gendron,
  • Tania F. Gendron,
  • Robert H. Baloh,
  • Robert H. Baloh,
  • Kendall Van Keuren-Jensen,
  • Rita Sattler

DOI
https://doi.org/10.3389/fncel.2023.1179796
Journal volume & issue
Vol. 17

Abstract

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While motor and cortical neurons are affected in C9orf72 amyotrophic lateral sclerosis and frontotemporal dementia (ALS/FTD), it remains largely unknown if and how non-neuronal cells induce or exacerbate neuronal damage. We differentiated C9orf72 ALS/FTD patient-derived induced pluripotent stem cells into microglia (iPSC-MG) and examined their intrinsic phenotypes. Similar to iPSC motor neurons, C9orf72 ALS/FTD iPSC-MG mono-cultures form G4C2 repeat RNA foci, exhibit reduced C9orf72 protein levels, and generate dipeptide repeat proteins. Healthy control and C9orf72 ALS/FTD iPSC-MG equally express microglial specific genes and perform microglial functions, including inflammatory cytokine release and phagocytosis of extracellular cargos, such as synthetic amyloid beta peptides and healthy human brain synaptoneurosomes. RNA sequencing analysis revealed select transcriptional changes of genes associated with neuroinflammation or neurodegeneration in diseased microglia yet no significant differentially expressed microglial-enriched genes. Moderate molecular and functional differences were observed in C9orf72 iPSC-MG mono-cultures despite the presence of C9orf72 pathological features suggesting that a diseased microenvironment may be required to induce phenotypic changes in microglial cells and the associated neuronal dysfunction seen in C9orf72 ALS/FTD neurodegeneration.

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