There is a fast growing interest in

There is a fast-growing interest in microglia, as they are increasingly implicated in neurodegenerative disease, neurodevelopmental disorders, and in neuropathic pain. Our iPSC microglia transcribe key ci-1033 involved in AD, PD, and MND. Several other disease-associated genes, including LRRK2, would be expected to be upregulated upon microglial stimulation (reviewed in Lee et al., 2017). Many of these genes are likely involved in phagocytosis and processing of misfolded proteins and of dying neurons (common features of these diseases), and in generating inappropriate chronic cytokine responses that exacerbate neuronal damage, creating a destructive cycle. Human iPSC microglia models enable study of these gene products at their correct gene dosage, in an authentic human in vitro system. Some of these functions and disease-relevant genes can be studied in the monoculture conditions detailed here, but others, involving crosstalk between microglia and neurons, such as paired receptor engagement, paracrine signaling, damage responses, synaptic surveillance, and pruning, will be better studied using the co-culture model we have described. The system is also amenable to scaling for the development of drug-screening assays to identify compounds that can improve microglial homeostatic clearance functions and dampen chronically activated microglia.
Experimental Procedures
Author Contributions
Acknowledgments Financial support: The Wellcome TrustWTISSF121302 and the Oxford Martin SchoolLC0910-004 (James Martin Stem Cell Facility Oxford, W.H., S.A.C.); the MRC Dementias Platform UK Stem Cell Network Capital Equipment MC_EX_MR/N50192X/1, Partnership MR/N013255/1 (W.H., S.A.C., N.A., R.W.-M.) and Momentum MC_PC_16034 (W.H., S.A.C., M.Z.C.) Awards; the Swiss National Foundation Early Postdoc Mobility, 148607, and ARUK Oxford pilot grant (W.H.); the Kennedy Institute of Rheumatology Trust (S.N.S.); Royal Society Dorothy Hodgkin Fellowship (S.E.N.); Medical Research Council, Heatley Merck Sharpe and Dohme studentship (J.B.); seventh Framework Program, RepairHD (C.S.). The work was supported by the Innovative Medicines Initiative Joint Undertaking under grant agreement number 115439, resources of which are composed of financial contribution from the European Union\'s Seventh Framework Program (FP7/2007e2013) and EFPIA companies\' in kind contribution. We thank the High-Throughput Genomics Group at the Wellcome Trust Center for Human Genetics, Oxford (Funded by Wellcome Trust grant reference 090532/Z/09/Z and MRC Hub grant G0900747 91070) for the generation of Illumina genotyping and transcriptome data. We would also like to thank the National Phenotypic Screening Center for instrument support. Samples and associated clinical data were supplied by the Oxford Parkinson\'s Disease Center (OPDC) study, funded by the Monument Trust Discovery Award from Parkinson\'s UK, a charity registered in England and Wales (2581970) and in Scotland (SC037554), with the support of the National Institute for Health Research (NIHR) Oxford Biomedical Research Center based at Oxford University Hospitals NHS Trust and University of Oxford, and the NIHR Comprehensive Local Research Network.
Introduction The mammalian CNS is composed mainly of three neural cell types, neurons, astrocytes, and oligodendrocytes, all of which are generated from common multipotent neural precursor cells (NPCs) (Namihira and Nakashima, 2013; Svendsen et al., 1998). With recent advances in stem cell culture techniques, NPCs derived from human pluripotent stem cells (hPSCs), and embryonic and induced pluripotent stem cells (hESCs and hiPSCs), have been shown to recapitulate neural development to some extent in vitro (Takahashi et al., 2007; Thomson et al., 1998; Yu et al., 2007) and to serve as a model for various neurological disorders (Israel et al., 2012; Marchetto et al., 2011; Park et al., 2008; Sanchez-Danes et al., 2012). However, although human NPCs (hNPCs) derived from hPSCs differentiate efficiently into neurons, an extremely low fraction of them generate astrocytes over a period of 4 weeks after the induction of differentiation (Hu et al., 2010). Recent studies have shown that hNPCs require prolonged culture (typically around 100–200 days) under sphere-forming conditions to efficiently differentiate into astrocytes (Edri et al., 2015; Kondo et al., 2013; Krencik et al., 2011; Williams et al., 2014), thus retarding human astrocyte functional research that is relevant to neurological diseases.