This online, informational and interactive portal provides educational content and the ability to make connections and open new avenues of communication in our fast-moving field throughout the year.

GQD

Introducing CellNet -
A New Tool for Testing Engineered Cells

George Q. Daley, MD, PhD,
Director, Stem Cell Transplantation Program 
Boston Children's Hospital

Scientists around the world are engaged in culturing pluripotent stem cells and differentiating them for use in research and regenerative medicine. As reported in back-to-back papers in the August 14 issue of Cell, scientists at Boston Children’s Hospital, the Wyss Institute for Biologically Inspired Engineering at Harvard University and Boston University have created a computer algorithm called CellNet to ensure that cells engineered in the lab have the same favorable properties as cells in our own bodies.

ISSCR members can hear George Q. Daley, MD, PhD, the senior investigator of both articles, discuss the potential of this new resource on September 17 at 11:30 a.m. EDT

On-demand Plenary Talks from the ISSCR 12th Annual Meeting

We are now featuring select plenary sessions from the ISSCR 12th Annual Meeting on the ISSCR Connect Member's Channel. All ISSCR members and registrants of the meeting have complimentary access to this content. Simply log in by clicking the link above and use the same login and password you used to register for the meeting. The following speakers are currently being featured – click on each speaker to show the title and abstract of their presentation.

Presidential Symposium


Plenary III: Therapies in the Clinic



Newly added: August 8

 

Ernest McCulloch Memorial Lecture

Anne McLaren Memorial Lecture

Closing Keynote

Patient Advocate Address

Jennifer Molson, this year's patient advocate speaker, has kindly given us permission to release her talk to the public. Her talk, in which she describes her own experience undergoing a stem cell-based clinical trial for multiple sclerosis can be viewed below.

The Life of Breath: Stem Cells of the Lung

Cell turnover in the lung is normally very slow, relative to other organ systems such as the intestine and skin. However, if lung epithelial cells are damaged by toxic agents or viral infection, or placed under stress by partial pneumonectomy, the lung reveals an impressive capacity for regrowth and repair. By combining a variety of injury/repair models with in vivo cell lineage tracing experiments, new imaging methods, and 3D organoid culture, evidence has accrued that different regions of lung contain different populations of epithelial stem and progenitor cells. For example, in the larger airways lined by pseudostratified mucociliary epithelium the major stem cell population is the basal cell. By contrast, in the distal gas exchange alveolar region there are no basal cells and type 2 alveolar epithelial cells are largely responsible for long term maintenance and repair. This conclusion is complicated, however, by recent studies in a number of labs that show considerable plasticity in the phenotype of epithelial progenitor cells in response to different injuries. A major goal is to identify the cellular and molecular components of the niches in which lung stem cells reside and to identify the signaling pathways by which the components interact with each other. Research is also directed towards understanding how these niches are formed during development and how they change in response to injury, infection, inflammation and aging.

Modeling Duchenne Muscular Dystrophy with Embryonic Stem Cells

Key cell types including skeletal muscle have proven difficult to differentiate in vitro from pluripotent cells. Differentiation of mature contractile muscle fibers in vitro from mouse or human pluripotent cells has so far not been reported. During embryonic development, skeletal muscles arise from somites, which derive from the presomitic mesoderm (PSM). Based on our understanding of PSM development, we established conditions allowing efficient differentiation of monolayer cultures of mouse embryonic stem (ES) cells into PSM-like cells without introduction of exogenous genetic material or cell sorting. To optimize the differentiation of Embryonic Stem (ES) cells toward the muscle lineage, we used a series of reporter ES cell lines, expressing fluorescent proteins under the control of genes specific for key stages of myogenic development. These reporter lines were used to sequentially optimize the differentiation conditions in order to reach maximal differentiation for each population. Our optimized conditions were inferred based on the development of the PSM in vivo and from a microarray series of early developmental stages of this tissue. We next established simple conditions to recapitulate primary and secondary/foetal myogenesis in vitro from these PSM-like cells. Our strategy allowed for the production of contractile fibers from pluripotent cells in vitro with an efficiency comparing well with current cardiomyocytes differentiation protocols. The muscle fibers produced are striated and multinucleated and exhibit post-natal characteristics. They also provide a niche allowing the development of Pax7-positive satellite-like cells. We used these conditions to differentiate ES cells derived from dystrophin-deficient mdx mice. We show that these fibers exhibit a strikingly abnormal organization of the myofibrils accompanied by a dramatic increase in the number of branches. While such a branched phenotype has been reported in vivo in mdx animals or in Duchenne patients, it has been attributed to fusion defects consequent to the cycles of regeneration occurring in dystrophic muscles. Our results rather argue that the defect is intrinsic to the fibers thus challenging current views on the origin of the pathology of Duchenne Muscular Dystrophy. Thus our work opens the possibility to study pathological mutations in mouse models for muscular dystrophies in vitro.

Taking Stem Cell-based Therapies to the Clinic in Parkinson's Disease

Parkinson’s Disease (PD) is a common disorder that has, as part of its core pathology, the loss of the dopaminergic nigrostriatal neurons and the formation of alpha synuclein positive Lewy bodies. Whilst it is now recognised that PD has a much more complex pathology than this, most patients respond well to dopaminergic drug therapies in the early stages of disease but with time this efficacy wears off and side effects develop. Thus there is a need for a better, more biological, way to deliver dopamine to the parkinsonian brain which, whilst not curing the patient, should substantially improve their dopaminergic responsive symptoms and signs.

One approach has been to use dopamine producing cells grafted into the striatum, of which the most successful have been those derived from the developing human fetal ventral mesencephalon (hfVM). The use of this tissue was the subject of many successful open label trials in the late 1980s and 1990s, but at the turn of the century two “double blind placebo group” trials showed that this therapy was ineffective and produced side effects in the form of graft induced dyskinesias (GIDs). The outcome of these two trials essentially brought the field of cell based therapies in PD to a halt at a time when stem cell based approaches were still being actively pursued and developed.

In order to try and better reconcile this paradox, a re-evaluation of the data from all these hfVM trials was undertaken. This suggested that this therapy may work if targeted to a more specific population of patients with PD with greater standardization of the protocols for delivering and supporting the grafted tissue. This has led to a new EU funded trial of hfVM tissue in younger patients with earlier 8 0 # I S SCR2 0 1 4 INTERNATIONAL SOCIETY FOR STEM CELL RESEARCH PROGRAM AND ABSTRACTS stage PD (TRANSEURO). This trial is seen as creating a template for taking future dopaminergic cells derived from stem cell sources to clinic, as the ethical and logistical problems of using human fetal tissue precludes it from every becoming a main stream treatment for PD. As to which stem cells will act as the source of such neurons remains unresolved but it is likely to be human ES cell lines in the first instance.

In this talk I will confine my discussion to the history of neural grafting in PD and how stem cells could be trialled in patients with this disorder. In addition I will discuss some of the issues that will need to be resolved to ensure that these stem cell derivatives are true authentic nigral dopaminergic neurons.

My work in PD is supported by an NIHR award of a Biomedical Research Centre and Unit to Addenbrooke’s Hospital/University of Cambridge; Parkinson’s UK; Michael J Fox Foundation; Cure-PD; Rosetrees Trust; EU-FP7; and MRC.

U.S. Clinics Advertising and Administering Unproven Autologous "Stem Cell" Interventions: Ethical, Scientific and Legal Concerns

Clinics advertising autologous, adipose-derived, mesenchymal “stem cell” interventions are proliferating across the United States. These businesses market putative “stem cell therapies” for Amyotrophic Lateral Sclerosis, Parkinson’s disease, multiple sclerosis, muscular dystrophy, and many other diseases and medical conditions. Such clinics do not provide access to licensed medical products. Rather, doctors at such clinics typically claim that they are engaged in the “practice of medicine”. They deny that they are promoting and administering biological drugs that are supposed to go through regulatory review and receive approval from the FDA before entering the marketplace. In many cases, available evidence suggests that this “practice of medicine” rationale is incorrect. Rather, by advertising unproven and unlicensed biological drugs, clinics appear to violate regulatory standards, ethical norms, and guidelines for the responsible conduct of research.

Acknowledging the scientific and ethical case for evaluating adipose-derived, mesenchymal stem cells-based interventions in carefully designed, independently reviewed, and scrupulously conducted clinical trials, the spread of clinics engaging in “directto- consumer” marketing of autologous stem cell interventions raises serious ethical, scientific, and legal concerns. For example, such businesses use medical devices that are supposed to separate mesenchymal stem cells from fat tissue, isolate them, and prepare them for infusion or injection. Many “stem cell clinics” use medical devices that are not cleared or approved for use in the U.S. Other clinics use medical devices cleared for a particular intended use but not cleared or approved for adipose-derived stem cell processing. Use of unapproved, untested, or inadequately tested medical devices prompts troubling questions about safety and efficacy of advertised “stem cell” interventions. Enthusiastic marketing of stem cell “therapies” generates concern that prospective patients are not provided with comprehensive account of risks and benefits associated with undergoing unproven autologous stem cell interventions. Conflation of treatment with research, as when clinics advertise “stem cell treatments” available in “patientfunded clinical trials”, suggests that many clinics promote the therapeutic misconception. Administration of what appear to be nonhomologous, more-than-minimally-manipulated adiposederived stem cell products for ALS, multiple sclerosis, and other diseases suggests that clinics are charging for biological drugs that are supposed to be reviewed by IRBs and the FDA and, in general, made available free of charge until their safety and efficacy is established and they have entered the marketplace as licensed products. In addition, administration of purported stem cell interventions by physicians who appear to be operating outside their scope of competence prompts concerns about whether some clinics are failing to provide patients with a professional standard of medical care.

Clinics promoting ostensible “stem cell treatments” tap into broad cultural currents of hope and enthusiasm for the promise of stem cell therapies. It is understandable that some patients are drawn to such businesses by powerful rhetorical claims, dramatic testimonials, and convincing company websites. However, premature commercialization of putative “stem cell treatments” generates many ethical, legal, and scientific concerns.

Hematopoietic Stem Cells – an Evolving Paradigm

Hematopoietic stem cell research was launched with the recognition in the 1950’s that adult bone marrow contains cells able to repopulate a damaged hematopoietic system and regenerate multilineage blood cell production for sustained periods of time. This finding, coupled with an inability to use histological methods to recognize these cells, suggested that a retrospective, transplantation-based approach to detect their clonal progeny might be devised to enable their enumeration, isolation and characterization. The successful development and application of this principle has revolutionized the fields of hematopoiesis and leukemia and has led to discoveries of major relevance to other tissues. Interestingly, this same approach is now revealing new layers of biological and molecular heterogeneity in cells with extensive hematopoietic regenerative properties as they evolve during development and aging. The present era of cell state reversibility, together with increasing knowledge of the potentially profound effects external cues can have on primitive cells, is also adding exciting new challenges and opportunities to use these cells in the future for greater clinical benefit.

Sex, Stem Cells, Physiology and Policy

Understanding cell fate choice is a common goal in both developmental biology and stem cell research. Sex determination is a paradigm for understanding how such choices are made, where supporting cell precursors can become either granulosa cells typical of an ovary or Sertoli cells, which define and promote testis differentiation. These cells are essential to both nurture and direct differentiation of germ cells into oocytes and sperm, respectively. I will discuss our recent attempts to apply knowledge gained about how the supporting cell lineage develops and then makes a choice of fate to obtain Sertoli cells in vitro by both direct reprogramming of somatic cells and by directed differentiation from pluripotent cells in culture, which may allow efficient spermatogenesis in vitro. This will be a challenge, not only because it may be necessary to recapitulate aspects of the 3-D structure of the seminiferous tubule, but also because systemic factors that normally regulate the process will be missing. We have recently shown the importance of systemic factors acting on stem cells in the pituitary. The pituitary shows considerable plasticity, modulating hormone output according to demand, which can change significantly with “life-changing events”, such as puberty, pregnancy, lactation, castration, and other types of trauma. The output can be modulated by hypothalamic control of hormone secretion by differentiated cells in the pituitary, by replication of these cells, or through the activation and differentiation of multipotent pituitary stem cells into the appropriate endocrine cell type according to systemic influence from a target organ, such as the adrenals or gonads. Recent data on how changes in physiology and systemic signals act on pituitary stem cells will be presented. Cell fate choices during development depend on a combination of intrinsic factors and external influences. The same is true for a scientist’s career, and I was fortunate to have been influenced by Anne McLaren during a critical period of my scientific development. I am so grateful to Anne for encouraging me to study sex determination, and supporting my stem cell research, but also for introducing me to the value of engagement with issues of science policy. I will finish with a brief description of some of my involvement, and the importance of public dialogue, to help establish and maintain an appropriately regulated environment favourable for research on stem cells and embryos, which we largely have in the UK.

From Yeast Cells to Human Neurons – Modeling Complex Protein Folding Diseases

Many neurodegenerative diseases result from basic problems in protein folding and homeostasis. These disorders appear to have little in common besides their devastating effects on patients and their families. However, they share the occurrence of complexes of misfolded, aggregated proteins in affected neurons. In Parkinson’s disease (PD) the protein is alpha-synuclein (α-syn) and in Alzheimer’s disease (AD) Aβ and tau are involved. Exploiting the highly conserved nature of eukaryotic cell biology and protein homeostasis mechanisms, we have developed yeast models for the pathologies caused by these proteins. Yeast cells offer unmatched opportunities for systematic, high throughput combinatorial analyses of causative factors and the discovery of pathology modifiers. Remarkably, each of the models exhibits cellular toxicity by a different mechanism and each yields a discovery platform directly relevant to human disease.

Yeast cells overexpressing human α-syn or Aβ allow genetic and chemical screens, which would only be possible in yeast at such high throughput. Our α-syn screens yielded genes and compounds that rescued dopaminergic neurons in nematode, fruit fly and rat primary midbrain cultures as well as cortical human neurons differentiated from the iPS cells of patients with PD. Our Aβ screens revealed genes and compounds that specifically rescue neurons from Aβ, and other AD risk factors. Combining these discovery platforms with state-of-the art chemical genetics allowed the identification of compounds with high therapeutic potential as well as insight into their mechanisms of action.

CAR T Cell Therapy and the Promise of T Cell Engineering

T cell engineering is emerging as a powerful means to rapidly generate large supplies of tumor-targeted T cells for cancer immunotherapy. Over the past two decades, a new toolbox of synthetic receptors used to genetically enhance patient T lymphocytes has been created, the best known of which are chimeric antigen receptors (CARs). CARs are recombinant receptors for antigens that retarget and reprogram T cell function to enable sustained T cell persistence and function in the tumor microenvironment. Other receptors, such as chimeric costimulatory receptors (CCRs) and inhibitory CARs (iCARs) complement this new armamentarium. We previously reported that human T cells targeted to CD19 could eradicate established, systemic B cell malignancies in xenogeneic tumor models. Over the past two years, three groups, including our own, reported objective tumor responses when infusing autologous T cells genetically modified with CD19-targeted CARs into patients with chronic lymphocytic leukemia (CLL), indolent non-Hodgkin lymphomas (NHL) and, most dramatically, relapsed chemorefractory acute lymphoblastic leukemia (ALL). We recently reported the largest CAR study published to date, achieving a complete remission in 14 of 16 patients with refractory ALL. The CD19 model has emerged as the paradigm for CAR therapy and paves the way for extending this cell-based treatment to other cancers. CARs, CCRs and iCARs represent a new class of drugs that are the foundations for cell- based approaches to treat cancer and potentially other disorders. We recently initiated a program exploring the therapeutic potential of T cells derived from induced pluripotent stem cells, and demonstrated that human iPS cell-derived CAR-expressing T cells could eradicate tumors in mice. This approach holds promise for generating T cells with optimized features to broaden the usage of T cell therapies.