Signals Blog

As a basic researcher in stem cell biology, one of my biggest fears is moving too quickly with cell therapies that involve primitive, still largely mysterious, cell populations. At the World Stem Cells & Regenerative Medicine Congress meeting this week, I felt much better about the direction that regenerative medicine is headed.

It has been a while (2005 to be exact) since I last attended a conference primarily focused on the clinical applications of stem cells (the International Society for Cell Therapy) rather than on understanding the basic science that drives them. I remember leaving that conference thinking, “too fast…  way too fast,” especially when it came to the grandiose ideas that came from company heads about popping vials of stem cells into people’s hearts, spines, eyes, etc. While much of this over-hyping still exists, many sessions at this conference were focused on safety and standards, which I suspect may have been the result of some painful lessons learned in the early days of cell therapy.

The thing that brought a particular smile to my heart was the rigor with which the UK Stem Cell Bank approaches their cell banking. Its director, Glyn Stacey, stressed the importance of obtaining high quality cells in a litany of major concerns with major implications.  He complained of the field throwing words around with reckless abandon (e.g.: clinical grade, pluripotency, translation) without doing an appropriate amount of work to put the cell lines in context or to provide measurable evidence.

A key component of the UK Stem Cell Bank’s strategy is to create a pre-master set of vials (as close to the original cell line as possible), followed by a master set, and finally a distribution set which allows large scale distribution of equal cell line products. From a quality control perspective, pluripotent cell lines have their own specific set of additional challenges that introduce variability – spontaneous differentiation and genetic alteration being among them – and Dr. Stacey outlined strategies to track these changes and assess the underlying risk (functional and molecular analysis at each stage). He emphasized the role of cell banks as risk reducers, where lines purchased meet particular standards, in their case, the grade prescribed by the European Union Tissue and Cells Directive.

One of the most powerful graphs that came from Dr. Stacey’s talk described the huge variability that existed between frozen vials of cells to be banked.  Some cell lines take days, others weeks, others months before they can get to a master cell line state and even eventually to distribution level. This is perhaps the simplest, and certainly the first, stage of variability and already, it is difficult to imagine consistent banks of representative cell lines without extensive quality control – as Dr. Stacey put it, “It’s another case of rubbish in, rubbish out.”

These issues permeated through the crowd, forcing people to consider whether or not their group/company would pass such standards – had they cut corners, made too many assumptions? It certainly makes one wonder how many of the lines involved in various stages of clinical trials are defined, traceable, and safe before groups start working with them.

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David Kent

David Kent

Principal Investigator at University of Cambridge
Dr. David Kent is a Principal Investigator at the University of Cambridge in the Cambridge Stem Cell Institute ( His laboratory's research focuses on fate choice in single blood stem cells and how changes in their regulation lead to cancers. David is currently the Stem Cell Institute’s Public Engagement Champion and has a long history of public engagement and outreach including the creation of The Black Hole in 2009. He has been writing for Signals since 2010.