01942nas a2200277   4500000000100000000000100001008004100002260001500043653002700058653001400085653003700099653002100136653003800157100002100195700001900216700001800235700003000253700002000283700001600303700001800319245010000337856010400437490000700541520110200548022001401650       2025                            d  c2025-10-0210aiPSC-derived 3D models10aMicroglia10amicrophysiological systems (MPS)10aneural organoids10aNew Approach Methodologies (NAMs)1 aAlex Rittenhouse1 aCaroline Krall1 aJesse Plotkin1 aDowlette-Mary Alam El Din1 aBreanne Kincaid1 aJason Laird1 aLena Smirnova00aMicroglia-containing neural organoids as brain microphysiological systems for long-term culture  uhttps://www.frontiersin.org/journals/cellular-neuroscience/articles/10.3389/fncel.2025.1616470/full0 v193 aMicroglia, essential for brain development, homeostasis, and neuroinflammation, originate from the yolk sac during embryogenesis and migrate into the developing brain. Because of this developmental origin, many brain organoid models naturally lack microglia and require co-culture. To address this issue, we developed a microglia-integrated brain organoid model (immune-competent brain microphysiological system, μbMPS) by aggregating hiPSC-derived neural and microglia progenitors in U-bottom 96-well plates, allowing controlled and reproducible incorporation of microglia progenitors. We demonstrated that microglia integrated, matured, and survived long-term in the neural environment without the need for costly exogenous microglia-specific growth factors or cytokines. We maintained microglia-containing organoids for over 9 weeks, demonstrating functional activity, phagocytosis, and neuroinflammatory responses. The μbMPS also exhibited enhanced neuronal activity and maturity, providing a scalable, reproducible model for neurodevelopment, disease modeling, and neurotoxicology research.  a1662-5102