German Science Weekly Highlight-18

Stem cell research has, as you probably know, been filled with ethical controversy. Until now, it’s involved destroying a human embryo – a small one, of course, just a few hundred cells. But in nine months, that embryo could be a healthy human baby. Not everybody is going to agree that a scientist should be allowed to do that, even if it helps us develop treatments for cancer, paralysis, and heart disease.

But now scientists are finding a way to skirt the ethical question – and keep going with their research in a way to which few would object. Instead of pulling the stem cell out of an embryo, they’re finding ways to take single stem cells from adults – a perfectly safe procedure – and then “reprogramming” them so they have all the flexibility that a stem cell has, if it came from an embryo.

Here’s how it works. Some stem cells, as you may know, are useful because they can produce any cell in the body. The right kind of stem cell – one which is “potent” enough – can become a blood cell, a bone cell, a nerve cell, or whatever it is you need to repair, or regrow, inside a patient’s body. Stem cells have different degrees of potency – that means, they have the potential to produce more or fewer different kinds of cells. The most potent kind of stem cell is called “totipotent” – they can grow into an entire organism, like a healthy, smiling baby. The second most potent is called “pluripotent” –they can become just about any kind of cell, but they can’t grow into a whole organism. Even less potent ones are called “multipotent”, “oligopotent”, and “unipotent” – they can only become one, or some kinds of cells.

Cells develop along a “programme” – that is, as you grow up, your cells become less and less potent. At least it seemed that way to scientists; they had always thought that as an adult, your skin cells, for example, can only produce new skin cells, and not, say, suddenly become liver cells. (Otherwise, you might just start growing a liver on your arm.) But just a few years ago, a group of scientists took the right nutrients and growth factors and managed to make neuron stem cells out of adult blood stem cells – which only stayed that way for a few days. Since then, scientists have been doing everything they can to figure out how this reprogramming works.

Now, at the Max Planck Institute for Molecular Biomedicine in Munster, Germany, scientists have isolated the part of the cell where the reprogramming takes place. It’s in the nucleus, where the genetic material is. Dr. Hans Schöler is going to tell us now how they found it, and how that brings us a step closer to reprogramming the way we do stem cell research.