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Microglia have recently been established as key regulators of brain development. However, their role in neuronal subtype specification remains largely unknown. Using three different co-culture setups, we show that microglia-secreted factors enhance dopaminergic differentiation of somatic and induced pluripotent stem cell-derived human neural stem cells (NSCs). The effect was consistent across different NSC and microglial cell lines and was independent of prior microglial activation, although restricted to microglia of embryonic origin. We provide evidence that the effect is mediated through reduced cell proliferation and decreased apoptosis and necrosis orchestrated in a sequential manner during the differentiation process. tumor necrosis factor alpha, interleukin-1β, and insulinlike growth factor 1 are identified as key mediators of the effect and shown to directly increase dopaminergic differentiation of human NSCs. These findings demonstrate a positive effect of microglia on dopaminergic neurogenesis and may provide new insights into inductive and protective factors that can stimulate in vitro derivation of dopaminergic neurons.

PARK2 (parkin) mutations cause early-onset Parkinson's disease (PD). Parkin is an ubiquitin E3 ligase that participates in several cellular functions, including mitochondrial homeostasis. However, the specific metabolomic changes caused by parkin depletion remain unknown. Here, we used isogenic human induced pluripotent stem cells (iPSCs) with and without PARK2 knockout (KO) to investigate the effect of parkin loss of function by comparative metabolomics supplemented with ultrastructural and functional analyses. PARK2 KO neurons displayed increased tricarboxylic acid (TCA) cycle activity, perturbed mitochondrial ultrastructure, ATP depletion, and dysregulation of glycolysis and carnitine metabolism. These perturbations were combined with increased oxidative stress and a decreased anti-oxidative response. Key findings for PARK2 KO cells were confirmed using patient-specific iPSC-derived neurons. Overall, our data describe a unique metabolomic profile associated with parkin dysfunction and show that combining metabolomics with an iPSC-derived dopaminergic neuronal model of PD is a valuable approach to obtain novel insight into the disease pathogenesis.

Stine Munk Hald,1,2 Christine Kring Sloth,1 Mikkel Agger,1 Maria Therese Schelde-Olesen,1 Miriam Højholt,1 Mette Hasle,1 Helle Bogetofte,1 Ida Olesrud,1 Stefanie Binzer,3 Charlotte Madsen,1 Willy Krone,4 Luis Alberto García Rodríguez,5 Rustam Al-Shahi Salman,6 Jesper Hallas,7 David Gaist1,2,8 1Department of Neurology, Odense University Hospital, Odense, Denmark; 2Department of Clinical Research, Neurology Research Unit, Faculty of Health Sciences, University of Southern Denmark, Odense, Denmark; 3Department of Neurology, Lillebaelt Hospital, Kolding, Denmark; 4Department of Radiology, Odense University Hospital, Odense, Denmark; 5Centro Español Investigación Farmacoepidemiológica (CEIFE), Madrid, Spain; 6Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, UK; 7Clinical Pharmacology and Pharmacy, Department of Public Health, University of Southern Denmark, Odense, Denmark; 8Odense Patient Data Explorative Network (OPEN), Odense University Hospital, Odense, DenmarkCorrespondence: David GaistDepartment of Neurology, Odense University Hospital, J.B. Winsløwsvej 4, 5000 Odense C, Odense, DenmarkTel +45 65412485Fax +45 65413389Email dgaist@health.sdu.dkPurpose: To establish the validity of intracerebral hemorrhage (ICH) diagnoses in the Danish Stroke Registry (DSR) and the Danish National Patient Registry (DNPR).Patients and Methods: Based on discharge summaries and brain imaging reports, we estimated the positive predictive value (PPV) of a first-ever diagnosis code for ICH (ICD-10, code I61) for all patients in the Region of Southern Denmark (1.2 million) during 2009– 2017 according to either DNPR or DSR. We estimated PPVs for any non-traumatic ICH (a-ICH) and spontaneous ICH (s-ICH) alone (ie, without underlying structural cause). We also calculated the sensitivity of these diagnoses in each of the registers. Finally, we classified the location of verified s-ICH.R

The protein parkin, encoded by the PARK2 gene, is vital for mitochondrial homeostasis, and although it has been implicated in Parkinson's disease (PD), the disease mechanisms remain unclear. We have applied mass spectrometry-based proteomics to investigate the effects of parkin dysfunction on the mitochondrial proteome in human isogenic induced pluripotent stem cell-derived neurons with and without PARK2 knockout (KO). The proteomic analysis quantified nearly 60% of all mitochondrial proteins, 119 of which were dysregulated in neurons with PARK2 KO. The protein changes indicated disturbances in oxidative stress defense, mitochondrial respiration and morphology, cell cycle control, and cell viability. Structural and functional analyses revealed an increase in mitochondrial area and the presence of elongated mitochondria as well as impaired glycolysis and lactate-supported respiration, leading to an impaired cell survival in PARK2 KO neurons. This adds valuable insight into the effect of parkin dysfunction in human neurons and provides knowledge of disease-related pathways that can potentially be targeted for therapeutic intervention.

© 2014 Nordic Association for the Publication of BCPT (former Nordic Pharmacological Society). Human neural stem cells (NSCs) from the developing embryo or the subventricular zone of the adult brain can potentially elicit brain repair after injury or disease, either via endogenous cell proliferation or by cell transplantation. Profound knowledge of the diverse signals affecting these cells is, however, needed to realize their therapeutic potential. Glutamate and group I metabotropic glutamate receptors (mGluRs) affect proliferation and survival of rodent NSCs both during embryonic and post-natal development. To investigate the role of group I mGluRs (mGluR1 and mGluR5) on human NSCs, we differentiated an immortalized, forebrain-derived stem cell line in the presence or absence of glutamate and with addition of either the group I mGluR agonist DHPG or the selective antagonists, MPEP (mGluR5) and LY367385 (mGluR1). Characterization of differentiated cells revealed that both mGluR1 and mGluR5 were present on the cells. Addition of glutamate to the growth medium significantly increased cell proliferation and reduced cell death, resulting in increased cell numbers. In the presence of glutamate, selective activation of group I mGluRs reduced gliogenesis, whereas selective inhibition of group I mGluRs reduced neurogenesis. Our results substantiate the importance of glutamate signalling in the regulation of human NSCs and may as such be applied to promote proliferation and neuronal differentiation.