Hot on the heels of last week’s European Court of Justice’s provisional announcement, in favor of California’s company Stem Cell International, that it may be possible to patent some pluripotent stem cells – those derived from unfertilized human eggs in this case – comes another remarkable announcement from the pluripotent stem cell community. A group of scientists led by Joseph Cibelli at Michigan State Univeristy reported, in the journal Science by studying cellular transcriptional regulatory networks, of having discovered a key factor directing differentiation of human adult dermal fibroblasts into undifferentiated iPSCs.
Up until now, one concern with identifying such iPSC reprogramming factors was that many of them might be expressed at relatively low levels undetectable to microarray-based analysis. The factor, a histone-remodeling chaperone named ASF1A, in tandem with the OCT4 gene, was identified as being responsible for cellular reprogramming, after the authors analyzed more than 5,000 oocyte genes. ASF1A is part of a group of candidate oocyte reprogramming factors (CORFs) that are believed to regulate cell fate, alongside ARID2, ASF1B, DPPA3, ING3, MSL3, H1FOO, and KDM6B. OCT4 had previously been described as one of the key transciption factors regulating pluripotency.
Genomic approaches to understand pluripotency have been the subject of ongoing research for a considerable amount of time. The assumption that pluripotency states of embryonic stem cells and induced pluripotent stem cells are in fact different was just recently confirmed (see last week’s blog entry), but up until now the exact genetic cues that are directly responsible for pluripotency had not been identified.
The Science paper is the culmination of multiple years of investigation and represents a significant milestone on the path to understanding the subcellular mechanisms regulating pluripotency.
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Traditionally, pluripotent stem cells have been considered the most promising candidates for cell therapy due to their ability to develop into any cell type. Among these, embryonic stem cells have been the poster child for the potential of such cells. Because of ethical concerns surrounding the use of embryonic stem cells, however, scientists have instead turned to using alternative methods of obtaining pluripotent stem cells – two of these, namely somatic cell nuclear transfer (SCNT) and induced pluripotent stem cells (iPSC), have grown to particular prominence.
Last week, The Scientist published an interesting article on pluripotent stem cell banks, which are a relatively recent initiative that has appeared in response to the increasing interest in the commercial application and scientific exchange of induced pluripotent stem cells. Started less than five years ago by The National Institutes of Health’s Center for Regenerative Medicine and the New York Stem Cell Foundation, iPSC stem cell banks are rapidly increasing in numbers. Last October, an opinion piece in Nature, titled “What is the point of large-scale collections of human induced pluripotent stem cells?” listed 8 large-scale iPSC banks under development, 4 of which are located in the USA, 3 in Europe and 1 in Japan. The article in the Scientist states there are over 250 cell lines currently deposited in the various banks, but the number is set to exponentially increase over the next few years alone. According to the article:
In most cases, the banks aren’t looking to iPSC lines as profit-generators, but as resources that will hopefully sustain themselves through user fees. [...] For now, banks are primarily focused on iPSCs to be used in basic research, disease modeling, and drug screening, rather than for drug development. But therapeutic-grade banks are likely to come next.
Last week, an interesting development in the field of pluripotent stem cells appeared after an article in Nature was published that compared the “pluripotency” of stem cells obtained by somatic cell nuclear transfer and iPSC methods. In somatic cell transfer, the nucleus of an egg cell is replaced with the nucleus of a somatic (adult) cell. Induced pluripotent stem cells are typically obtained by genetic reprogramming of adult cells.
The Nature paper, by a group of researchers from University of California San Diego School of Medicine, Oregon Health & Science Univeristy and the Salk Institute for Biological Studies, reported that pluripotent stem cells obtained by different mechanisms are indeed different. Specifically, the authors generated nuclear transfer ES cell lines and iPS cell lines from the same donor skin cells and compared them to embryonic stem (ES) cells. All cells showed signs of pluripotency, but there were differences in their genetic profiles.
The authors found that DNA methylation profiles of somatic nuclear transfer cells were closer to those of ES cells, while iPS cells displayed DNA methylation patterns typical of adult somatic cells. This prompted them to postulate that pluripotent stem cells obtained by nuclear somatic cell transfer may be more optimal for cell therapy applications.
What implications these finding will have remains to be seen. There are numerous questions regarding the use of somatic transfer nuclear cells in patient therapy that remain unanswered, which is as fundamental as the methods of obtaining them in sufficient numbers, even before questions about their use in transplant medicine can be tackled.
The potential of stem cell therapy delivering on its promise of becoming a viable alternative in the clinic is perhaps best evident when looking at Mesoblast, the Australian biotech company that has made headlines many times over the past three years. The company, which develops adult (mesenchymal) stem cell products for the treatment of diseases, including orthopedic, cardiac and vascular, just announced it had received $5.05m from the Australian government for the development of their pipeline of products based on mesenchymal stem cells, buoyed by their recent announcement that trials using their proprietary mesenchymal precursor cells (MPCs) showed promising signs of success in patients with end-stage heart failure.
On the other hand, Mesoblast’s stock price is at an all-time low. This interesting dichotomy is a perfect reflection of the stem cell therapy field, where investments are fluorishing while returns are low on the horizon.
This high-risk, high-reward culture is kept afloat by new discoveries coming from leading research labs at a regular pace.
One such notable discovery, if reactions from the scientific community are to be believed, has the potential to make a significant impact on therapies employing mesenchymal stem cells, if proven to be correct. A research-team led by Juan Melero-Martin, assistant professor at the Cardiac Surgery Research Center at Boston Children’s Hospital, recently published a study in the Proceedings of the National Academy of Sciences which introduces a new paradigm for stem cell therapy: mesenchymal stem cell transplants require endothelial colony-forming cells for optimal engraftment. When the authors implanted mesenchymal stem cells into immunodeficient mice in the presence of cord blood-derived ECFCs, they observed improved engraftment and reduced early apoptosis, more commonly observed with mesenchymal stem cells implanted alone. They discovered that engraftment was regulated via platelet-derived growth factor BB (PDGF-BB)/platelet-derived growth factor receptor (PDGFR)-β signaling.
Based on these results, they finally postulated that co-transplanting MSCs with ECFCs improves transplant efficiency.
For every questions that it answers, however, the study leaves another one unanswered. The potential impact on current therapies – such as, for instance, those that companies like Mesoblast are championing – remains to be seen, as does the regulatory climate surrounding transplantation of what are now two cells into one patient, as opposed to a single one.
Last Saturday afternoon, the exhibition hall at the Vancouver Convention Center resembled a student apartment post-party: cardboard boxes scattered everywhere, glasses lingering on tables and exhausted participants packing to leave. The sentiment among those leaving was dual: on one hand, exhaustion from the grueling schedule of the previous four days and on the other, a sense of accomplishment thanks to a meeting that was, by all accounts, well attended and very successful.
The 12th Annual ISSCR Meeting had just wrapped. Akron was there, among over 40 other exhibitors, and over 3000 scientists sharing our latest research and showcasing our products and services.
For Akron, the meeting was a roaring success: our booth was a constant source of scientific exchange as was our scientific poster, presented on the first day of the meeting, on novel cryopreservation solutions.
Increasingly evident is the research community’s interest on reprogramming of pluripotent stem cells and as well as the development of novel scaffolds for 3D cell culture.
The meeting opened with the Presidential Symposium, where a number of talks were given. Among those, Dr. Lorenz Studer, Professor at the Sloan Kettering Institute for Cancer Research, discussed about his lab’s pioneering work on novel strategies for the differentiation of pluripotent stem cells for the treatment of Parkinson’s disease. Dr. Studer’s lab pioneered techniques to obtain dopamine neurons from mouse embryonic stem cells in a multi-step differentiation protocol, starting from embryonic stem cells, and generating, in sequence, embryoid bodies, early ectodermal cells, proliferating CNS precursors, and, finally, neurons and glia.
The meeting focused heavily on fundamental stem cell research, although some room was also given to tracks dedicated to clinical applications and translational work. One such track, titled “Therapies in the Clinic” had a varied mix of talks: from a patient advocate discussing her experiences with stem cell therapy, to a discussion on stem cell clinics to scientific talks. Among those, Dr. Leigh Turner from the University of Minnesota touched on a controversial subject: the regulatory climate surrounding dubiously legal stem cell clinics in the USA. Dr. Turner pointed out the rapid proliferation of such clinics and how they manage to fluorish in a regulatory climate that allows for minimal regulation. He used the Cell Surgical Network (CSN) as a case study, a controversial organization that is believed to be involved in the untested administration of an increasing number of cell therapies. That the subject is hotly debated right now is evident from a recent article published in Nature that discusses on this very same issue and touches on important regulatory efforts surrounding the operations of such clinics. It is evident that while many researchers, as well as doctors, are willing to push the administration of such unapproved therapies to willing patients, it is important to consider that many of these patients are coerced into accepting such therapies because they simply know no better and the potential outcomes sound too good.
The session on Aging and Metabolism presented some fascinating research on the current state of the stem cell field in answering questions related to aging. During the session, Dr. Kirsty Spalding, Assistant Professor in the Department of Cell and Molecular Biology at the Karolinska Institute discussed her lab’s focus on cell turnover in human brain and fat tissue. In particular, Dr. Spalding has long been fascinated on adipocyte turnover in humans as a target for the treatment of metabolic disease. The function of adipocytes has direct effects on blood vessels, appetite, energy homeostasis, blood pressure and lipid metabolism. Her latest research spanned years of work, during which she studied lipid age by by measuring (14)C derived from above ground nuclear bomb tests in adipocyte lipids and found that during a ten-year lifespan of human adipocytes, triglycerides contained within them are renewed six times. Moreover, the number of fat cells between an obese person and a person with normal weight is the same: it is their size that changes as the person loses or gains weight.
The plenary session on bioengineering featured some heavyweights in the bioengineering, chemical engineering and biochemical engineering fields: Dr. Molly Stevens from Imperial College London discussed the development of novel self assembling nanomaterial scaffolds for the sensing of biomolecules based on modular peptide functionalized gold nanoparticles and quantum dots. Technology also plays an important part in Dr. Peter Zandstra’s research. His research uses predictive mathematical modelling, microfabrication as well as traditional bioreactors to answer questions relating to the control of pluripotent stem cell self-renewal, the generation of blood and cardiac cells from pluripotent stem cells and inter-cellular signalling networks to grow human blood stem cells.
The poster sessions highlighted the current state of the research community by showcasing work of over 1,500 different labs around the world. The development of novel 3D scaffolds was a big draw: almost 100 posters showcased novel technologies and materials to achieve optimal 3D cell differentiation on engineered 3D substrates. Among these, Dr. Giuseppe Maria de Peppo from the The New York Stem Cell Foundation Research Institute highlighted some recent work on skeletal reconstitution using iPS cells on 3D clots of fibrin and decellularized bone scaffolds, while microfluidic technology was implemented in a poster by Dr. Yong Chen of Kyoto University on a high-throughput microfluidic device in based on a biocompatible and thermo-responsive hydrogel to create an artificial 3D niche for the systematic investigation of cellular function and fate decisions.
The marriage of technology and basic research was a reflection of the industry’s expansion and the broadening towards multidisciplinarity of what has traditionally been a fundamental science-driven field and a sign that in order to achieve more complex solutions, more complex systems will be needed.
Akron was also busy handing out our super-popular t-shirts: we actually ran out of them at the meeting (sorry to those who missed them). Check out the t-shirt below and contact us to get your own – we will contact you when they are available again.
We are pleased to announce the launch of our brand new 2014-2015 catalog. The digital version features enhancement such as seamless navigation via beautiful page-scrolling, fully clickable product links that take you directly to our website, and a more intuitive product selection list.
Check it out by clicking on the image below – we are sure you are going to enjoy it:
MEET AKRON AT ISSCR
The 12th annual ISSCR Meeting takes place from June 18-21 in Vancouver, Canada – and Akron will be there. We will be at booth #419 - stop by to hear about our newest products and research, and check out our poster on novel DMSO-free cryopreservation formulations on display on Wednesday June 18th from 6:30 – 8:30pm (Poster # W-2120).
Want to talk in private? If you would like to schedule a private, one-on-one meeting, Akron will have a special meeting room set up and we’d love to have you there – contact us at firstname.lastname@example.org.
See you in Vancouver!
Optimal cell viability during patient transfusion is one of the main hurdles facing cell therapy.
Last week, Ian Copland and colleagues at Emory University published a fascinating paper in Stem Cell Reports about the biological availability of mesenchymal stem cells following cryopreservation with DMSO. The authors reported that MSCs thawed after being cryopreserved with DMSO showed a 60% reduction in cytoskeletal actin, a globulal protein critically responsible for cell mobility. The importance of the findings was once again emphasized when the authors concluded that cryopreserved MSCs are distinct, and appear weaker, than fresh, live MSCs in terms of their bioavailability following transfusion.
In another recent manuscript, published by Mohapatra and colleagues, transfusion was again used as an example where a low concentration of DMSO is preferred. The authors found that while a concentration of 10% DMSO gave the highest viability of hematopoietic stem cells post-thaw (93%), a concentration of 2% DMSO, with the addition of trehalose or sucrose, was the preferred strategy to adopt for therapy.
These are just two of the many examples illustrating the complexity of the subject. The topic of cryoprotectant toxicity is indeed a controversial one, and one that sits at the heart of development of cell therapies. Strategies to either reduce or completely eliminate toxicity have been extensively researched, yet an optimal approach is still a controversial subject.
While some papers, such as that by Ali Eroglu’s lab at Georgia Health Sciences University, published in PLoS One in 2011, which investigated the effect of toxicity of penetrating cryoprotectants, have attempted to shed some light on the biochemical effect of cryoprotectants on the cryosurvival of cells, in this case oocytes, other approaches have focused on developing novel methodologies and formulations by completely moving away from standard cryoprotectants such as DMSO. New approaches, such as magnetic cryopreservation, a system employing magnetic field-programmed freezers called “Cells Alive System”, have tried to develop completely DMSO-free cryopreservation strategies.
It is clear that developing a comprehensive and robust cryopreservation strategy for direct patient use is a multi-pronged approach that requires consideration of multiple aspects of the cell preparation cascade. From obtaining cells, through to cryopreservation, transport and thawing such cells for use, this problem requires a multidisciplinary approach.
Some are taking a mathematical approach to solving such problems. Bayesian statistics were used in a recent paper published in Quantitative Methods, which investigated the compounded effect of a number of factors, including cooling rate and temperature, composition of cryoprotectant and additives as well as loading procedure to develop an optimized procedure for cryopreservation of cells.
In 2010, Etienne Sokal and colleagues asked, in a paper about hepatocye cryopreservation, “Is it time to change the strategy?” – and the answer is still unclear.
Akron has long been concerned with redesigning traditional cryopreservation approaches. But as we design strategies to facilitate this difficult process, we are curious to hear from you.
What is your cryopreservation strategy, and is it working for you? Have you tried any new approaches or cryopreservation formulation? Are you curious about trying out a new technology but have too many questions?
We would love to hear from you. Join the conversation by posting a comment to this article. To reward your feedback, we will be gifting a free Akron t-shirt to every person that comments on this this topic, so don’t forget to leave your email address. A free t-shirt for sharing your experience? It’s a no brainer.
MEET AKRON ONE-ON-ONE AT ISSCR IN VANCOUVER
Check out our blog next week for another opportunity to receive a free Akron t-shirt and details about meeting us at ISSCR in Vancouver, where we will be from June 18-June 21. To set up an individual meeting, contact us .