Meeting report: using stem cells for biological and therapeutics discovery in mental illness, April 2012

Advancing cell-based cancer immunotherapy through stem cell engineering

Advances in cell-based therapy, particularly CAR-T cell therapy, have transformed the treatment of hematological malignancies. Although an important step forward for the field, autologous CAR-T therapies are hindered by high costs, manufacturing challenges, and limited efficacy against solid tumors. With ongoing progress in gene editing and culture techniques, engineered stem cells and their application in cell therapy are poised to address some of these challenges. Here, we review stem cell-based immunotherapy approaches, stem cell sources, gene engineering and manufacturing strategies, therapeutic platforms, and clinical trials, as well as challenges and future directions for the field.

Recent Advances in the Genetics of Schizophrenia

The last decade brought tremendous progress in the field of schizophrenia genetics. As a result of extensive collaborations and multiple technological advances, we now recognize many types of genetic variants that increase the risk. These include large copy number variants, rare coding inherited and de novο variants, and over 100 loci harboring common risk variants. While the type and contribution to the risk vary among genetic variants, there is concordance in the functions of genes they implicate, such as those whose RNA binds the fragile X-related protein FMRP and members of the activity-regulated cytoskeletal complex involved in learning and memory. Gene expression studies add important information on the biology of the disease and recapitulate the same functional gene groups. Studies of alternative phenotypes help us widen our understanding of the genetic architecture of mental function and dysfunction, how diseases overlap not only with each other but also with non-disease phenotypes. The challenge is to apply this new knowledge to prevention and treatment and help patients. The data generated so far and emerging technologies, including new methods in cell engineering, offer significant promise that in the next decade we will unlock the translational potential of these significant discoveries.

Concise Review: Progress and Challenges in Using Human Stem Cells for Biological and Therapeutics Discovery: Neuropsychiatric Disorders

In facing the daunting challenge of using human embryonic and induced pluripotent stem cells to study complex neural circuit disorders such as schizophrenia, mood and anxiety disorders, and autism spectrum disorders, a 2012 National Institute of Mental Health workshop produced a set of recommendations to advance basic research and engage industry in cell-based studies of neuropsychiatric disorders. This review describes progress in meeting these recommendations, including the development of novel tools, strides in recapitulating relevant cell and tissue types, insights into the genetic basis of these disorders that permit integration of risk-associated gene regulatory networks with cell/circuit phenotypes, and promising findings of patient-control differences using cell-based assays. However, numerous challenges are still being addressed, requiring further technological development, approaches to resolve disease heterogeneity, and collaborative structures for investigators of different disciplines. Additionally, since data obtained so far is on small sample sizes, replication in larger sample sets is needed. A number of individual success stories point to a path forward in developing assays to translate discovery science to therapeutics development.

A Dishful of a Troubled Mind: Induced Pluripotent Stem Cells in Psychiatric Research

Neuronal differentiation of induced pluripotent stem cells and direct reprogramming represent powerful methods for modeling the development of neurons in vitro. Moreover, this approach is also a means for comparing various cellular phenotypes between cell lines originating from healthy and diseased individuals or isogenic cell lines engineered to differ at only one or a few genomic loci. Despite methodological constraints and initial skepticism regarding this approach, the field is expanding at a fast pace. The improvements include the development of new differentiation protocols resulting in selected neuronal populations (e.g., dopaminergic, GABAergic, hippocampal, and cortical), the widespread use of genome editing methods, and single-cell techniques. A major challenge awaiting in vitro disease modeling is the integration of clinical data in the models, by selection of well characterized clinical populations. Ideally, these models will also demonstrate how different diagnostic categories share overlapping molecular disease mechanisms, but also have unique characteristics. In this review we evaluate studies with regard to the described developments, to demonstrate how differentiation of induced pluripotent stem cells and direct reprogramming can contribute to psychiatry.

Creating Patient-Specific Neural Cells for the In Vitro Study of Brain Disorders

As a group, we met to discuss the current challenges for creating meaningful patient-specific in vitro models to study brain disorders. Although the convergence of findings between laboratories and patient cohorts provided us confidence and optimism that hiPSC-based platforms will inform future drug discovery efforts, a number of critical technical challenges remain. This opinion piece outlines our collective views on the current state of hiPSC-based disease modeling and discusses what we see to be the critical objectives that must be addressed collectively as a field.

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A key limitation of the field is difficulty in accurately defining cell state

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Next step will be building complexity by achieving network and circuit structures

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Epigenetic factors and somatic mosaicism in iPS cells may contribute to disease

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A critical advance will be improving scalability and reproducibility of assays

Importance of being Nernst: Synaptic activity and functional relevance in stem cell-derived neurons

Functional synaptogenesis and network emergence are signature endpoints of neurogenesis. These behaviors provide higher-order confirmation that biochemical and cellular processes necessary for neurotransmitter release, post-synaptic detection and network propagation of neuronal activity have been properly expressed and coordinated among cells. The development of synaptic neurotransmission can therefore be considered a defining property of neurons. Although dissociated primary neuron cultures readily form functioning synapses and network behaviors in vitro, continuously cultured neurogenic cell lines have historically failed to meet these criteria. Therefore, in vitro-derived neuron models that develop synaptic transmission are critically needed for a wide array of studies, including molecular neuroscience, developmental neurogenesis, disease research and neurotoxicology. Over the last decade, neurons derived from various stem cell lines have shown varying ability to develop into functionally mature neurons. In this review, we will discuss the neurogenic potential of various stem cells populations, addressing strengths and weaknesses of each, with particular attention to the emergence of functional behaviors. We will propose methods to functionally characterize new stem cell-derived neuron (SCN) platforms to improve their reliability as physiological relevant models. Finally, we will review how synaptically active SCNs can be applied to accelerate research in a variety of areas. Ultimately, emphasizing the critical importance of synaptic activity and network responses as a marker of neuronal maturation is anticipated to result in in vitro findings that better translate to efficacious clinical treatments.

Concise review: making and using clinically compliant pluripotent stem cell lines

The field of pluripotent stem cells (PSCs) is in a state of dynamic flux driven by significant advances in the derivation of specific phenotypes from embryonic stem cells, breakthroughs in somatic cell nuclear transfer, and dramatic improvements in generating induced PSCs using zero footprint methods. Spurred by these technological advances, companies have begun to plan clinical studies using human PSC derivatives manufactured in current Good Manufacturing Practice-compliant conditions. In the present review, we discuss the challenges in making these biological products, starting from tissue sourcing to the processes involved in manufacture, storage, and distribution. Additional challenges exist to meeting the regulatory requirements and keeping costs affordable. A model is described that has been proposed by the U.S. National Institutes of Health for reducing the costs and permitting flexibility and innovation by individual investigators. This model, combined with small adjustments in the regulatory processes tailored to address the unique properties of PSCs, has the potential of significantly accelerating the implementation of PSC-based cell therapy.

Human pluripotent stem cell culture: considerations for maintenance, expansion, and therapeutics

Human pluripotent stem cells (hPSCs) provide powerful resources for application in regenerative medicine and pharmaceutical development. In the past decade, various methods have been developed for large-scale hPSC culture that rely on combined use of multiple growth components, including media containing various growth factors, extracellular matrices, 3D environmental cues, and modes of multicellular association. In this Protocol Review, we dissect these growth components by comparing cell culture methods and identifying the benefits and pitfalls associated with each one. We further provide criteria, considerations, and suggestions to achieve optimal cell growth for hPSC expansion, differentiation, and use in future therapeutic applications.

Will brain cells derived from induced pluripotent stem cells or directly converted from somatic cells (iNs) be useful for schizophrenia research?

The reprogramming of nonneuronal somatic cells to induced pluripotent stem cells and their derivation to functional brain cells as well as the related methods for direct conversion of somatic cells to neurons have opened up the possibility of conducting research on cellular disease models from living schizophrenia patients. We review the published literature on schizophrenia that has used this rapidly developing technology, highlighting the need for specific aims and reproducibility. The key issues for consideration for future schizophrenia research in this field are discussed and potential investigations using this technology are put forward for critical assessment by the reader.