Last week, Thermo Fisher Scientific presented their third annual 24 Hours of Stem Cells, an innovative virtual conference covering many stem cell related topics, presented by Stem Cell Researchers. The conference materials will remain accessible through March 3, 2016, so you can still check out the presentation topics and speakers. Attendees are able to access a virtual conference hall with several options to explore, including an Exhibit Hall, Resource Center, Virtual Lab and Live and On Demand Presentations.
I attended several of the presentations and I have outlined a few of the talks below:
Biomaterials for Assembly of Stem Cell Derived Human Tissues by Bill Murphy Ph.D., Harvey D. Spangler Professor, Co-Director Stem Cell and Regenerative Medicine, Director EPA Human MAPs Center, University of Wisconsin
Dr. Murphy presented a very interesting keynote on his group’s work in developing Human Models for Analysis of Pathways (Human MAPs). These models will aid in drug discovery, toxicity screening and disease modeling and will provide an opportunity to use human cells and tissues early in the process rather than starting with rodent cells and tissues. Dr. Murphy begins his talk with a very interesting discussion about various synthetic material conditions and the impact they have on cells. One of the first steps that Dr. Murphy describes in the development of Human MAPS was the desire to remove Matrigel due to the large number of proteins present and replace it with synthetic material where the impact to cells could be more accurately predicted and controlled. They began by screening over 500 material conditions looking for “hits” or conditions that would induce assembly of endothelial cells into networks and maintain networks for 48 hours in culture. Dr. Murphy went on to describe one of their projects where they employed this strategy to use high throughput screening for vascular disrupting compounds (angiogenesis inhibitors). What they found was the synthetic material they had identified was more sensitive to identifying these compounds than Matrigel.
I was very interested in another project that his team is working on, which is screening for toxicity to the developing human brain. In this project a multi-disciplinary team worked to assemble brain mimics using synthetic materials and human pluripotent stem cells to produce stratified neural epithelial tissues with vascular networks embedded in them. The idea was to create a drug toxicity prediction model. In this model one could take a compound where toxicity was unknown, then expose the brain mimics to the compound and use a developed algorithm to predict whether the compound was toxic or not. They were able to form neural constructs with high sample uniformity.
Once ready to take the tissues through predictive screening, they began with 60 training compounds (34 know toxins/26 controls). They fed these testing compounds into a machine learning algorithm and were able to achieve 90% accuracy in predictive screening with the training compounds. Then they tested 10 blinded compounds (5 toxins/5 control) and were able to correctly predict 9/10. What they have developed is a system that is quite predictive and superior to previous models. They are planning improvements and are working with the Environmental Protection Agency (EPA) and the National Institutes of Health (NIH) to take the project further and develop an automated high throughput system. There have also been several other Human MAP projects launched including ones to look at cancer, the liver, the eye, the peripheral nervous system, and others.
Generation of Patient Specific iPSC Lines and Scalable Production of PSC-derived Cardiomyocytes, Emily Titus, Ph.D., Manager, Technology, Centre for Commercialization of Regenerative Medicine
Dr. Emily Titus began her presentation with an overview of the Centre for Commercialization of Regenerative medicine (CCRM) and their current work. She began her talk by discussing some of the technical challenges facing the application of pluripotent stem cells and how the Centre is working to provide solutions to these challenges. One step they have taken is to establish an iPSC facility that specializes in reprogramming using non-integrative iPSC generation from various cell sources. They offer contract reprogramming services which can be conducted in about four months and includes assisting with proper sampling techniques, continues to reprograming, expansion and banking followed by extensive characterization and lastly release of frozen vials of cells along with supporting clients as they thaw and culture cells in their own lab. They have also begun including projects, which include gene correction using CRISPR/Cas9.
In addition to their contract reprogramming work, they have also done extensive work to develop a scalable production system for the culture of iPSCs. Their goal was to develop and characterize an efficient, consistent and scalable aggregate-based hPSC manufacturing process in a stirred tank reactor system. They determined that it was important to move to agitated suspension and away from static culture for larger scale production. This was based primarily on the advantages that suspension reactor culture offers including more control of the culture through control of culture factors like dissolved oxygen, pH, temperature, metabolites and feeding. They found they could maximize cell density, culture homogeneity, process efficiency and cell yield. Part of their system includes the use of the AMBR Microbioreactor that allows them to run 25 x 15 ml samples simultaneously to test various culture conditions and a large number of culture parameters using only a small volume.
CCRM then developed a process for translation, scale up and production of PSC derived cardiomyocytes. Their goal was to couple PSC expansion with reproducible, scalable, efficient, cost effective method for cardiomyocyte production. This coupling provided a cost advantage with over 1 billion cardiomyocytes produced in one 12 day run (720 ml). They believe this system is translatable to multiple pluripotent lines and are developing a process to differentiate iPSCs in a similar process.
Essential 8™ Flex Medium Eliminating Daily Feeding in a Feeder-free, Xeno-free PSC Culture System, Matthew Dallas, Staff Scientist, Thermo Fisher Scientific
In this presentation Mr. Dallas begins with a brief history of the major development sin pluripotent stem cell culture and how media has evolved to meet changing industry needs. During 2005-2007 the first chemically defined media were launched, this included StemPro ESC SFM, mTeSR1, and others, but the challenge was that these still had bovine serum albumin and were thus not xeno-free. In 2011, xeno-free, chemically defined Essential 8 medium was launched, which removed all the animal components. However, even with the improvements in Essential 8, there were still challenges with the requirements of PSC culture, primarily the need for daily feeding. This need for daily feeding was driven by the heat sensitivity of a few key factors including FGF2, which dictated that cells must be fed daily to maintain pluripotency. As a result, scientists need to be in the lab 7 days a week. This often means that the same scientist won’t be culturing the cells daily as these tasks need to be delegated on days off. With more people involved in culturing, the risk of introducing variability increases. In addition, it makes scheduling a challenge since there needs to be someone in the lab daily, even on weekends and holidays. To address the challenges around daily feeding, Essential 8 Flex was launched earlier this year. It is a xeno-free and feeder-free pluripotent stem cell (PSC) medium that eliminates the need for weekend feeding.
The Essential 8 Flex formulation is based on the Essential 8 medium published by Guokai Chen et al. in James Thomson’s laboratory and later validated by Cellular Dynamics International. As such, it provides the same benefits of Gibco Essential 8 Medium, with increased flexibility. Mr. Dallas provided real insight into the development of Essential 8 Flex and described the steps taken to ensure that there was no impact on the health or pluripotency of PSC cultures versus Essential 8. They also conducted several studies to ensure that eliminating daily feeding would not create challenges to cell health or pluripotency. With these advancements in Essential 8 Flex it is possible to eliminate up to three feeds per week including the weekend, however Mr. Dallas recommends that no more than 3 days per week be eliminated and no more than 2 consecutive days of no feeding occurs to maintain optimal cell health.
I think the 24 hours of stem cells is a very interesting and easy to navigate virtual stem cell conference. I find that it is an innovative way to share information, is completely on demand, and requires no travel or coordination for time zones.
Definitely worth checking out and there’s still time to access the 3rd annual 24 Hours of Stem Cells event. Scientific presentations, content, resources, and more are all available on demand now through March 3, 2016.