Science Interviews


Sun, 28th Oct 2007

Stem Cell Technologies

Professor Claudio Stern, University College London

Listen Now    Download as mp3 from the show Cloning, Chimeras and Stem Cells

Our show this week is all about Stem cells and cloning, which are topics that have received a lot of attention over the years and we’re going to try and dig deep and find out just how these methods work and why they’ve stirred up so much controversy.

To get us started, this week we sent Meera to UCL’s centre for Stem Cell Research, to find out the basics of stem cell technology.

Meera -   Stem cells…we’ve all probably read about them in the papers, but what exactly are they? And how are they benefiting scientific research? This week I went to the lab of developmental biology expert Professor Claudio Stern at University College London, to find out how his team create and use stem cells in their research.

But I had to start by asking just what a stem cell actually is…

Claudio -   Basically a Stem Cell is a cell that can self renew, which means it can grow for a very long time and retain its qualities. So, it stays the same as it grows through many many divisions. They’re found in many places in the adult, and in the embryo, where they divide and produce daughters that differentiate into different tissues of the body. In the adult for example, there is a need for parts of the body to renew constantly throughout life, for example in the skin, where we lose layers of the skin all the time, and so we have stem cells that are specialised in maintaining that so there’s a continuous production of cells that will replace the ones that are being lost.

Meera -   But you work with embryos don’t you in your lab?

Claudio -   Yes we do.

Meera -   How do you obtain the stem cells that you work with in your lab?

Human blastocystClaudio -   To obtain embryonic stem cells, which are cells that will not only divide for an unlimited period of time in the lab, but also are capable of giving rise to any cell type in the body, we just use very early embryos, in our case we use chick embryos, and so by taking these cells out of the embryo and placing them in a culture under appropriate conditions and in the right medium, some cells will survive to stage at which they will self-replicate for a very very long time and then you can maintain them forever pretty much in the lab.

Meera -   Is there a different process used in order to get human stem cells made?

Claudio -   In a sense the principle is the same. So, one possibility will be to have a human embryo, a very early embryo and then to take the cells from the embryo and place them in culture under similar conditions to what I described.

Meera -   But how could you get stem cells from an adult?

Claudio -   One way would be to try and get a biopsy, for example from tissue that contains stem cells, and then place that in culture. Another way, is to take the nucleus of a differentiated cell, which as I said the cell won’ divide, but if that is place in an environment which can re-programme it to become embryonic again, like an egg cell, then that nucleus will be reprogrammed and the genetic material of the adult individual will now become like an early embryonic stem cell that can then be allowed to divide in culture and then that will continue to divide and produce identical copies of itself.

Meera -   So that’s nuclear transfer that method?

Claudio -   Yes, that’s nuclear transfer.

Meera -   Is it actually quite hard for that to result in a growing cell after?

Claudio -   Technically it’s quite difficult to do, the cell is quite fragile and it’s very small. The nucleus is quite fragile itself and it’s quite an involved manipulation. It requires very good hands a very good microscopes and only a proportion of the cases will continue to establish a cell that will divide, so one has to do it many times to get a single cell that will establish itself.

Meera -   So Claudio, I mentioned earlier that you do most of your work with chick embryos, what are you hoping to find out with your research?

Claudio -   Well chick embryos have the advantage that they’re easy to get and they’re relatively inexpensive, we just get them out of the egg. One of the questions we’re trying to resolve really, is what makes a cell be a stem cell? What are the particular genes or gene combinations that establish a cells properties in terms if being able to divide and replicate itself for a very long time without differentiating. At the same time, conversely, what causes cells that are dividing to adopt particular fates? And we’re particularly interested in finding out what makes the nervous system and the brain? And what are the cues that cells use top become particular parts of the central nervous system. One of the most fundamental questions in biology is to explain how cells that are genetically identical can adopt different fates so that you end up with a body that’s made up of the right proportions of the right tissue types that can function together in a coherent way.

Being able to understand that, hopefully, will get us to a position where we manipulate the fates of those cells to generate, in culture, cells of particular types that might be useful for therapy or other clinical applications.

Meera -   So understanding how a cell chooses its fate could enable us to manipulate them into becoming the exact cell that we want. If that becomes possible, then it could transform treatments for conditions like diabetes, where a patients pancreas is unable to produce enough insulin to take up the glucose in their blood. Stem cells could be directed to make more insulin-producing cells, which could potentially be transplanted into a diabetic, enabling them to produce their own insulin and not use injections anymore.

It’s this therapeutic potential of stem cells; to provide treatments for numerous conditions that makes the work of teams like Claudio’s, so important for medical development.


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