LPS-induced inflammation differentially affects endogenous Ca²⁺ activity in mouse and human iPSC-derived astrocytes

BACKGROUND: Mouse and human astrocytes exhibit substantial species-specific differences in both morphology and function. Their response to inflammatory stimuli, however, remains underexplored despite being crucial for understanding bidirectional astrocyte-neuron signaling dynamics and for translating preclinical findings to human-relevant applications. Induced pluripotent stem cell-based models thus offer a powerful platform to investigate these mechanisms in the context of the human neural connectome. METHODS: We apply two well-established in vitro protocols by exposing cultured astrocytes to lipopolysaccharide (LPS) for either 3 or 24 h to trigger an inflammatory response. We investigated how LPS-induced inflammation affects the endogenous Ca2+ activity in astrocytes derived from the mouse hippocampus (HC) and prefrontal cortex (PFC), as well as human induced pluripotent stem cell (hiPSC)-derived astrocytes. Both, morphological changes and Ca2+ activity were analyzed using the volume fraction (VF) approach and our previously developed multi-threshold event detection (MTED) combined with machine learning-driven non-negative matrix factorization (NMF). RESULTS: The comprehensive assessment of Ca2+ activity patterns and their relation to cell morphology revealed significant alterations in response to LPS treatment, and further between mouse and human hiPSC-derived astrocytes. While both mouse and human astrocytes show increased Ca2+ event frequency after short-term LPS exposure, after 24 h of LPS treatment Ca2+ activity is severely restricted in PFC astrocytes but substantially increased in human astrocytes. CONCLUSIONS: Our findings highlight the unique properties of human iPSC-derived astrocytes and provide detailed insights into how Ca2+ signaling becomes dysregulated under neuroinflammatory conditions. Understanding the species-specific responses is essential for advancing stem cell-based models of human astrocyte-neuron signaling circuits and for developing targeted therapeutic strategies to alleviate neuroinflammation and Ca2+-related dysregulation in neurological diseases.