Three different human iPSC lines (KOLF2.1, from The Jackson Laboratory; BIONi010-C and BIONi037-A, from the European Bank for Induced Pluripotent Stem Cells) were used to generate microglia-like cells using a well-established protocol65. Briefly, 2.5 × 106 iPSCs were seeded into an AggreWellTM800 24-well plate (STEMCELL Technologies) to allow embryoid body (EBs) formation and were fed daily with mTeSR+ medium (STEMCELL Technologies) supplemented with 50 ng/ml BMP4 (Miltenyi Biotec), 50 ng/ml VEGF (Miltenyi Biotec), and 20 ng/ml SCF (R&D Systems). After 4 days, the EBs were differentiated in 6-well plates in X-VIVO15 medium (Lonza) supplemented with 100 ng/ml M-CSF (Miltenyi Biotec), 25 ng/ml IL-3 (Miltenyi Biotec), 2 mM Glutamax (Invitrogen Life Technologies), and 0.055 mM β-mercaptoethanol (Thermo Fisher Scientific), with weekly medium replenishment. Microglial precursors emerging in the cell culture supernatant after approximately 1 month were collected and seeded at a concentration 50,000/cm2 for further differentiation into microglia-like cells in Advanced DMEM/F12:Neurobasal medium (both Gibco) supplemented with 1x B27 supplement plus Vitamin A (Thermo Fisher Scientific), 2 mM GlutaMAX, 0.055 μM β-mercaptoethanol, 20 ng/ml M-CSF and 100 ng/ml IL-34 (PeproTech) for
