Transcriptomic and proteomic profiling of bi-partite and tri-partite murine iPSC-derived neurospheroids under steady-state and inflammatory condition.

ABSTRACT

induced-pluripotent stem cell (iPSC)-derived neurospheroid (NSPH) models are an emerging in vitro toolkit to study the influence of inflammatory triggers on neurodegeneration and repair in a 3D neural environment. In contrast to their human counterpart, the absence of murine iPSC-derived NSPHs for profound characterisation and validation studies is a major experimental research gap, even though they offer the only possibility to truly compare or validate in vitro NSPH responses with in vivo brain responses. To contribute to these developments, we here describe the generation and characterisation of 5-week-old CX3CR1eGFP+/- CCR2RFP+/- murine (m)iPSC-derived bi-partite (neurons + astrocytes) and tri-partite (neurons + astrocytes + microglia) NSPH models that can be subjected to cellular activation following pro-inflammatory stimulation. First, cytokine analysis demonstrates that both bi-partite and tri-partite NSPHs can be triggered to release IL6 and CXCL10 following three days of stimulation with, respectively, TNFα + IL1ß + IFNγ and LPS + IFNγ. Additionally, immunocytochemical analysis for G3BP1 and PABPC1 revealed the development of stress granules in both bi-partite and tri-partite NSPHs after 3 days of stimulation. To further investigate the observed signs of inflammatory response and cellular stress, we performed an untargeted transcriptomic and proteomic analysis of bi- and tri-partite NSPHs under steady-state and inflammatory conditions. Here, using the combined differential gene and protein expression profiles between unstimulated and stimulated NSPHs, Ingenuity Pathway Analysis (IPA) confirms the activation of canonical pathways associated with inflammation and cellular stress in both bi-partite and tri-partite NSPHs. Moreover, our multi-omics analysis suggests a higher level of downstream inflammatory responses, impairment of homeostatic and developmental processes, as well as activation of cell death processes in stimulated tri-partite NSPHs compared to bi-partite NSPHs. Concluding, these results emphasise the advantages of including microglia in NSPH research to study inflammation-induced neurodegeneration in a 3D neural environment.