Schizophrenia (SZ) is a debilitating psychiatric disorder. While 1.1% of the population suffers from SZ, the molecular mechanisms underlying the disease state remain unclear. Though its characteristic symptoms typically appear late in adolescence, SZ is believed to result from abnormal neurodevelopmental processes that begin years before the onset of symptoms. We previously reprogrammed fibroblasts from SZ patients into human induced pluripotent stem cells (hiPSCs) and subsequently differentiated these disorder-specific hiPSCs into neural progenitor cells (NPCs) and neurons. We and others have found that SZ hiPSC NPCs show evidence of aberrant migration 1, increased oxidative stress 1-3, perturbed responses to environmental stressors 4, while SZ hiPSC neurons exhibit decreased neurite number 5 reduced synaptic maturation 2,6-8 and reduced synaptic activity 6,8. Although hiPSC-derived neurons most resemble human fetal brain tissue9-11 and presumably best model disease predisposition, there has been good concordance between hiPSC studies and reports of aberrant migration 12,13, reduced neurite outgrowth 14,15, abnormal axon targeting 16 and impaired synaptic activity 17-21 in mouse models of SZ. We believe that hiPSC neural cells are best used to study the developmental effects that contribute to SZ risk.
Childhood Onset Schizophrenia
Childhood-onset SZ (COS) is a rare and particularly severe form of the disorder. Because COS patients present with symptoms much earlier than adult-onset cases of SZ, our hypothesis is that neural cells derived from patients with COS will share cellular phenotypes with those we have already reported for adult-onset SZ, but that the phenotypes may be accelerated and/or more severe. We believe that hiPSC studies of COS are an ideal platform from which to glean mechanistic insights into the early cellular and molecular factors responsible for disease initiation in SZ. We have four primary goals for project. First, we will generate hiPSC-based models of COS. Second, the cellular phenotypes of COS neural cells will be characterized across a panel of existing and validated assays. Third, mRNA and microRNA expression of COS neural cells will be integrated through causal network interference analysis in order to identify key microRNA regulators. Finally, we will begin mechanistic studies of candidate microRNAs altered in COS. We hope to use our novel hiPSC based platform to identify molecular insights into COS which may be generalizable across SZ.
Functional consequences of genetically modifying key SZ risk genes
CRISPR-Cas9 site-specific nuclease-mediated genome editing can be used to generate hiPSCs lines with knockout or mutant alleles. We are applying this method to generate isogenic hiPSC lines, be it correction of a precise mutation in SZ patient lines, or reproduction of a SZ mutation in control lines. This will allow us to test whether any SZ-associated allele is necessary or sufficient for the relevant SZ-associated neuronal phenotypes we have observed in vitro, such as aberrant synaptic morphology or reduced neuronal activity.
Improved methods to rapidly generate pure populations of neurons
Though the precise cell types affected in SZ remain unresolved, aberrant glutamate neurotransmitter signaling occurs in SZ. Critically, subtle differences in synaptic morphology and function, even in comparisons of our very same hiPSC lines, are best resolved in comparisons of defined subpopulations of neurons; for example, consider the findings of Brennand et al, 2011 and Yu et al, 2014, which compared heterogeneous forebrain neurons and glutamatergic hippocampal neurons, respectively. When the very same hiPSC lines, derived from the same patients, were compared by the same measures for spontaneous glutamatergic synaptic activity, we were only able to resolve differences when specifically comparing just the glutamatergic neurons within the heterogeneous neuronal populations. We have already adapted novel methods to generate glutamatergic neurons by a well-established NGN2-induction protocol, and are working to develop similar strategies by which we may be able to generate populations of GABAergic and dopaminergic as well.
- Hartley BJ, Tran N, Ladran I, Reggio K, Brennand KJ. 2015. Dopaminergic differentiation of schizophrenia hiPSCs. Molecular Psychiatry. [PubMed]
- Topol A, Tran N, Brennand KJ. 2014. A guide to generating and using hiPSC derived NPCs for the study of neurological diseases. JOVE.
- Roussos P, Mitchell AC, Voloudakis G, Fullard JF, Pothula VM, Tsang J, Stahl EA, Georgakopoulos A, Ruderfer DM, Charney A, Okada Y, Siminovitch KA, Worthington J, Padyukov L, Klareskog L, Gregersen PK, Plenge RM , Raychaudhuri S , Fromer M, Purcell SM, Brennand KJ, Robakis NK, Schadt EE, Akbarian S, Sklar P. 2014. A role for non-coding variation in schizophrenia. [PubMed] Cell Reports. Nov 20;9(4):1417-29.
- Hook V, Brennand KJ, Kim Y-S, Toneff T, Funkelstein L, Lee K, Ziegler M, Gage FH. 2013. Regulation of Catecholamine Neurotransmitters Secreted in Schizophrenia Modeled by Human Induced Pluripotent Stem Cell Neurons. [PubMed] Stem Cell Reports. DOI: 10.1016/j.stemcr.2014.08.001. [Epub ahead of print]
- Hashimoto-Torii K, Torii M, Ju M, Fujimoto M, Nakai A, Fatimy RE, Mezger V, Chao J, Brennand KJ, Gage FH and Rakic P. 2014. Heat Shock Factor 1 is an Intersection between Genetic and Prenatal Environmental risk factors for Neuropsychiatric Disorders. Neuron.
- Brennand KJ*, Silvas J, Kim, Y, Tran N, Simone A, Hashimoto-Torii K, Beaumont K, Kim H-J, Topol A, Ladran I, Abdelrahim M, Matikainen-Ankney B, Chao S-h, Mrksich M, Rakic P, Fang G, Zhang B, Yates J, Gage FH*. 2014. Phenotypic differences in hiPSC NPCs derived from patients with schizophrenia. [PubMed] Molecular Psychiatry. 1 April 2014; doi:10.1038/mp.2014.22. [Epub ahead of print]
- McConnell MJ, Lindberg MR, Brennand KJ, Piper J, Voet T, Cowing-Zitron C, Shumilina S, Lasken RS, Vermeesch J, Hall IM, and Gage FH. 2013. Mosaic Copy Number Variation in Human Neurons. [PubMed] Science.342(6158): 632-637. PMCID: 24179226.
- Brennand KJ, Simone A*, Jou J*, Gelboin-Burkhart C*, Tran N*, Sangar S, Li Y, Mu Y, Chen G, Yu D, McCarthy S, Sebat J, Gage FH. 2011. Modeling Schizophrenia Using hiPSC Neurons. [PubMed] Nature. 473(7346): 221-225. PMID: 21490598. Comment in Cell Stem Cell: Buxbaum JD, Sklar P. 2011. Human induced pluripotent stem cells: a new model for schizophrenia? [PubMed] Cell Stem Cell. 8(5):461-462.Comment in Nat Rev Neuro Neurosci.: Welberg L. 2011. Stem Cells: Zooming in on schizophrenia. [PubMed] 12(6):308-309.
Reviews and Chapters
- Schadt E, Buchanan S, Brennand KJ, Merchant KM. 2014. Evolving towards a human-cell based and multiscale approach to drug discovery for CNS disorders. [PubMed] Frontiers in Neuroscience. In press
- Brennand KJ. 2013. Inducing Cellular Aging: Enabling Neurodegeneration-in-a-Dish. [PubMed] Cell Stem Cell. 2013 Dec 5;13(6):635-6. doi: 10.1016/j.stem.2013.11.017.
- Brennand KJ*, Landek-Salgado MA, and Sawa A. 2013. Modeling heterogeneous patients with schizophrenia using cell-based models. [PubMed] Biological Psychiatry. 2013 Nov 15. pii: S0006-3223(13)01000-7. doi: 10.1016/j.biopsych.2013.10.025. [Epub ahead of print]
- Ladran IG, Tran NN, Topol A, Brennand KJ. 2013. Neural stem/progenitor cells in health and disease. [PubMed] WIRE Systems Biology and Medicine. Wiley Interdiscip Rev Syst Biol Med. 2013 Sep 20. doi: 10.1002/wsbm.1239. [Epub ahead of print]
Meet the Team
Psychiatry Research Fellow/PhD Student
Using Stem Cells to Model Disease – Cell Press Webinar, 2013
Approach modeling of Alzheimer’s disease, Schizophrenia and Neurodegenerative disorders using patient-derived iPSCs, and to learn how these approaches could be applicable to modeling complex diseases. Podcast.
The Black Family Stem Cell Institute: Pushing Against the Unknown
Induced Pluripotent Stem Cells
Stem Cell on the Mesa, 2009. Podcast
Presenting the Future. 2016.
The Friedman Brain Institute: Conquering Brain Disease
Uncovering schizophrenia through skin
Can skin cells help us to unravel the complexity of the schizophrenic brain? New research routes and the hope for better treatments. Podcast.
Gallery – Scientific Images
I am looking to hire a post-doctoral scientist with experience in molecular biology and stem cell biology who is willing to generate and target key schizophrenia genes using state-of-the-art CRISPR-based methods. The goal will be to compare synaptic morphology and neuronal function between precise isogenic lines. Email CV.