Event Review: How Do Stem Cells Grow?

How Do Stem Cells Grow? Organised by the Royal Society Royal Society, 6-9 Carlton House Terrace, London SW1Y 5AG Tuesday 2 July 2013

Can you grow an organ in the lab? Can you grow new cells to replace diseased ones? Embryonic stem (ES) cells have the potential to grow into any cell in the body, but how is the cell type determined? These are questions a Café Scientifique event at The Royal Society promised to explore.

This free event was part of The Royal Society's Summer Science Exhibition, an annual display of some of the UK's cutting-edge science and technology, and was led by Dr Kevin Chalut, a Royal Society research fellow from the University of Cambridge.

Dr Chalut began by asking the audience 'what is a stem cell and how can it be defined?' In reply, most scientists would recite the classic line that 'a stem cell comprises a self-renewing and dividing population whose function is to maintain healthy tissue'. However, Dr Chalut considers this definition unsatisfactory, and I now agree with him. We are defining stem cells by what they are doing, not what they are. He likened this to defining a hat as 'something you put on your head!'

Not having a decent definition for what stem cells are could cause considerable problems. Much work in the stem cell field is about reprogramming adult stem cells into an ES-like state. However, to quote Dr Chalut, 'we can't make them into a "thing" if we don't know what that "thing" is'.

The talk continued with an overview of how malfunctioning stem cells might actually lie at the root of some diseases. For example, in multiple sclerosis, stem cells should be able to replenish the cells that perish (oligodendrocytes) but something goes wrong and they are unable to do so. Conversely, in some cancers stem cells can divide in an unchecked and uncontrolled manner, resulting in tumour formation.

Dr Chalut then focused on his own lab's research. He believes that in order to understand stem cells and the diseases they cause, we need to understand the environment the stem cell is found in as much as the stem cell itself.

His team of researchers are trying to understand the physical interplay between stem cells and their environment. Stem cells respond to physical as well as biochemical cues and by providing the correct stimuli researchers hope to better control what stem cells differentiate into.

A question and answer session with the audience followed. Many of the questions were about potential clinical applications: 'has there been any practical medical success with stem cells?', 'how well do injected stem cells re-integrate into an organ?' and 'can we use our knowledge of stem cells to slow down the ageing process?'

Dr Chalut pointed out that he wasn't a clinician but still gave some intriguing answers. He discussed several recent medical accomplishments including the regeneration of organs, at least in part, using stem cells and the ability to make cells taken from human fetuses grow into functional kidneys in a mouse.

When asked 'how easy is it to re-program an adult stem cells into an ES cell-like state?' Dr Chalut discussed the outstanding research of Nobel laureates Professor Sir John Gurdon and Professor Shinya Yamanaka (see BioNews 676).

However, despite the advances that these two men in particular have made, Dr Chalut explained that further insight into the physical and biochemical cues controlling stem cells is still necessary. The process of re-programming adult cells needs to be more efficient, he said. If you try and reprogram one million adult stem cells only about 300 will revert into an ES-like state and these cells often don't stay there for very long. For instance, a neuron which has been reprogrammed into an ES cell-like cell will often wander back into a neuron-resembling cell type.

On a more personal level, when asked how he began researching stem cell development, Dr Chalut revealed that although he obtained a doctorate in accelerator physics he was drawn towards stem cell biology as he considers the problems in biology to be more important than those in physics!

Overall it was an engaging evening. I would definitely recommend joining scientists and other specialists to explore current issues in science over a drink at Café Scientifique.