The Stem Cells 2012 meeting ran on Feb 2nd- 3rd and, as the name implies, featured the latest updates on the stem cell research field. EpiGenie fan and UCSD Postdoc Jennifer Lowe was on hand to take in the event and pass on the highlights for those of us who couldn’t make it. Check out her coverage below:
Select Biosciences Stem Cells 2012
On my return from a recent conference in Taos, New Mexico, it was a warm welcome to be attending the Stem Cell 2012 meeting in sunny San Diego. There was a great vibe about the meeting, which was quite an intimate affair promoting open and collaborative discussions. As well as hearing about the latest research from highly respected and prestigious speakers such as Hans Keirstead of the University of California Irvine, who discussed his work on the use of stem cells to develop strategies to enhance regeneration following spinal cord injury, the meeting also featured Alan Trounson from the California Institute for Regenerative Medicine, speaking on the financial aspects of stem cell research, and Bernard Siegel explaining the legal and ethical issues that must be overcome within the field.
Companies in Translation with CIRM
Alan Trounson, California Institute for Regenerative Medicine
Dr. Trounson, the President of the California Institute for Regenerative Medicine (CIRM), opened the meeting with a subject universal to all research, funding. He discussed the establishment of CIRM, which has to date provided $3 billion in funding for stem cell research at California universities and research institutions, and described how he is currently driving basic research in stem cell biology and medicine and facilitating the translation of stem cell discoveries into clinical treatments for patients. His current translation projects include but are not limited to collaborations with Mount Sinai to reduce cardiac scar tissue following injury to improve function of the left ventricular wall, and Sangamo BioSciences using a zinc finger nuclease-based targeting approach of the gene encoding CCR5, the major co-receptor used by HIV to infect cells of the immune system.
The Mandate to Deliver Cures: Aligning the Science, Industry and Patient-advocacy Agendas
Bernard Siegal, Genetics Policy Institute
In addition to Timo Faltus, who provided us with an insight into European stem cell research law, attorney and founder of the non-profit Genetics Policy Institute Bernard Siegal shared his knowledge detailing current US stem cell research laws. Interestingly, Seigal discussed how through his institute he spends a lot of his efforts supporting the global cause of stem cell research by promoting sound, ethical research within a framework of supportive public policy. His institute does this through public education initiatives and interdisciplinary global meetings among experts, patients and activists alike. After all, we are all the patient. Seigal delivered an inspirational talk, in which his take home message to the scientists in the audience was to not be afraid of sharing our ethical research achievements and goals with the public to remove the unethical stigmas that have been created by such things as science-fiction movies, and instead promote the advancement of stem cell and regenerative medical research within our communities.
In addition to the financial, political and ethical issues of stem cell research, there were a number of exciting talks highlighting the latest research developments in stem cell-derived neural and cardiac cells.
Epigenetics of FMR1 Gene and Aberrant Neurodevelopment in iPSC Models of Fragile X Syndrome
Steven Sheridan, Mass General Hospital & Harvard Med School
As the only epigenetic-specific talk during the meeting, Dr. Sheridan did not disappoint with his talk detailing how his group have used patient-specific iPSC models to demonstrate aberrant neuronal differentiation that is directly correlated with epigenetic modifications of the Fragile X Mental Retardation (FMR1) gene.
Modifications of the X-chromosome linked FMR1 gene in Fragile X Syndrome (FXS) are the most prevalent of autism spectrum disorders, a group of neurodevelopmental diseases caused by multiple genetic and environmental factors. In addition to cognitive abnormalities ranging from mild learning impairment to severe mental retardation, behavioral symptoms of FXS patients may include hyperactivity, attention deficits, social difficulties, anxiety, and other autistic-like behaviors.
Dr. Sheridan described how inactivation of the FMR1 gene in FXS is caused by an expanded CGG trinucleotide repeat in its 5’-untranslated region (5’UTR). Upon increasing CGG-repeat length (>200) in the FMR1 gene beyond the normal range of 6-50, through molecular mechanisms not fully understood, CpG sites in the promoter and CGG-repeat regions of FMR1 become hypermethylated, resulting in epigenetic silencing of the gene and loss of expression of the Fragile X Mental Retardation protein (FMRP). In this manner, FXS can be considered to be an epigenetic disorder, as loss of the FMRP has been shown to be causative for the cognitive and behavioral impairments of FXS. However, despite the known relationship between FMR1 CGG-repeat expansion and FMR1 silencing, the epigenetic modifications, and the consequences of the loss of FMRP on human neurodevelopment and neuronal function remain poorly understood. To begin to address these limitations, Dr. Sheridan’s group recently generated iPSC lines from three clinically diagnosed FXS patients and characterized their differentiation into post-mitotic neurons.
Using bisulfite pyrosequencing to quantitatively compare the levels of methylation within 22 CpG sites of the promoter region of FMR1, his group showed that full mutation fibroblast lines had highly methylated promoter regions, with a mean of ~85% of the CpG sites methylated, consistent with the expected hypermethylation of this region in FXS. In contrast, a control fibroblast line had barely detectable levels (<5%) of CpG methylation in the same region. Furthermore, all three FXS patient fibroblast lines had CGG-repeat sizes in the full mutation range (>200) in the FMR1 5’UTR on the X chromosome. As the combination of an expanded 5’-UTR CGG-repeat along with the high degree of CpG site methylation of this region would be expected to result in the silencing of the expression of the FMR1 gene, Dr. Sheridan’s group then showed by quantitative RT-PCR analysis and Western blot analysis that FMR1 mRNA and FMRP expression levels, respectively, were undetectable in any of the FXS patient lines, whereas FMR1 and FMRP were highly expressed in the unaffected control line.
Most strikingly, following reprogramming of these FXS patient fibroblasts to iPSC lines, and subsequent differentiation along a neural lineage, he demonstrated FXS-associated morphological differences in iPSC-derived neurons, with FXS cells having fewer and shorter neurites than controls, similar to the neuronal morphology reported in FMR1 knock-out mouse models. Moreover, these morphological differences directly correlated with epigenetic modification of the FMR1 gene and a loss of FMRP expression. Overall, the panel of FXS pluripotent stem cells generated in this study will be useful for understanding the mechanisms underlying the disease and for discovery of potential therapeutic interventions.
Efficient Cardiac Differentiation of Human Induced Pluripotent Stem Cells
Paul Burridge, Stanford University School of Medicine
In his talk Dr. Paul Burridge discussed a topic that lies close to my heart as it involves my current area of research: the cardiac differentiation of human pluripotent stem cells. The production of cardiomyocytes from human iPSCs holds great promise for patient-specific cardiotoxicity drug testing, disease modeling, and cardiac regeneration; however, existing protocols for the differentiation of iPSCs to the cardiac lineage are inefficient and highly variable.
Dr. Burridge described a universal system for highly efficient cardiac differentiation of human iPSCs that eliminates inter-line variability. Strikingly, by systematically and rigorously optimizing >45 experimental variables, the lab developed a universal cardiac differentiation system that produced contracting human embryoid bodies (EBs) with an improved efficiency of ~95% in an accelerated nine days, from numerous human embryonic stem cell and iPSC lines. This cost-effective differentiation method employed forced aggregation of EBs in a chemically defined medium, along with staged exposure to physiological (5%) oxygen, and optimized concentrations of mesodermal morphogens BMP-4 and FGF2. The contracting EBs derived using these methods were composed of high percentages (64-89%) of cardiac troponin I+ cells that displayed ultrastructural properties of functional cardiomyocytes and uniform electrophysiological profiles responsive to cardioactive drugs.
In conclusion, the Stem Cell 2012 meeting was a great success and provided a very different but interesting format in comparison to many a research conference I have attended. In addition to the basic research, the meeting provided a broad insight into the realistic financial, political and ethical issues that currently surround the field of stem cell research, and as a post-doc new to the USA it was a humbling experience to hear the rapid advances that are being made in my chosen field both inside and outside of the lab.
**EpiGenie would like to thank Jennifer Lowe, Ph.D. who is a Postdoctoral Scholar in the Ju Chen lab at UCSD, for providing this conference coverage.