Patient iPSC-derived astrocytes reveal impaired homeostasis and reactive-like features in propionic acidemia.

Propionic acidemia (PA) is a neurometabolic disorder caused by propionyl-CoA carboxylase deficiency with frequent neurological involvement, yet cell-type-specific mechanisms remain poorly defined. We established human induced pluripotent stem cell (iPSC)-derived astrocytes (iAs) from patients harboring PCCA or PCCB mutations and investigated functional and molecular alterations associated with PA. Both control- and patient-derived iPSCs yielded astrocyte-enriched cultures through a neural progenitor intermediate, with expression of astrocyte-associated markers. Patient iAs showed impaired mitochondrial respiration (lower basal and maximal oxygen consumption and ATP-linked respiration), together with reduced high-affinity uptake of glutamate and glycine neurotransmitters and evidence of disturbed Ca2+ homeostasis. They also migrated faster in wound-healing assays and displayed reactive-like features, including increased GFAP and connexin 43 (Cx43) protein levels and elevated AQP4 mRNA levels. Targeted miRNA profiling revealed upregulation of miR-124-3p, miR-9-5p, and miR-125b-5p, concomitant with downregulation of miR-146a-5p, miR-155-5p, and miR-145-5p. Consistent with these changes, reported target genes associated with innate immune signaling (IRAK1, TRAF6, TAB2), astrocyte remodeling (GFAP), and water/ion homeostasis (AQP4) were upregulated. Inflammatory and proliferative markers were likewise increased, including IL1B, TNF, and MKI67. Together, these convergent alterations suggest a phenotype characterized by impaired homeostatic functions and reactive-like features, which may heighten neural network vulnerability under metabolic stress. Collectively, our data support astrocyte dysfunction as a potential contributor to PA neuropathology and highlight patient-derived iAs as a useful model for future mechanistic studies and therapeutic exploration. © 2026 The Author(s). The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.