By Shane Huntington

Pioneering stem cell researcher Prof Martin Pera discusses where stem cell research has been and where its going, the therapeutic potential of stem cell technologies, and what we should and shouldnt expect from this fast-developing research field. With host Dr Shane Huntington.

SHANE HUNTINGTON Over the last couple of decades stem cells have been touted as the key to treating a wide range of diseases, with advantages that exceed surgical repair or even organ transplantation; but work on stem cells, especially those derived from human embryos, has drawn significant public scrutiny. In many countries embryonic stem cell research is tightly regulated, and researchers have been forced to explore other research options. Such restrictions are not present worldwide and, in some countries, regulation has yet to catch up with the science. This can make it especially challenging for patients trying to navigate through the world of therapeutic stem cell technologies, both in trial phase and on the consumer market. To explore these issues and the technology itself we are joined on Up Close by one of the pioneers of stem cell research: Professor Martin Pera, program leader of Stem Cells Australia, and professor of stem cell sciences at the University of Melbourne. Welcome to Up Close, Martin.

MARTIN PERA Thank you.

SHANE HUNTINGTON Could you start by giving us a bit of an overview of what a stem cell is and why these particular cells have generated so much interest over the last two decades?

MARTIN PERA Well, they're really two basic types of stem cells. One type of stem cell we cal pluripotent stem cells. And these can either be derived from very early stage embryos of they can now be created in the lab from adult cells, from patients, through a process we call reprogramming. And pluripotent stem cells are able to give rise to all the tissues of the body. The second class of stem cell is the tissue stem cell, sometimes called adult stem cells. These are stem cells that are minority populations in many adult tissues. They are, essentially, more limited in their potential; they usually only give rise to a few types. Both types of stem cells have two key properties. The first is that they are primitive cells that can give rise to more mature functional cell types like neurons or red blood cells. The second is that they can also divide to produce more stem cells. So stem cells provide a reservoir for tissue regeneration or repair. I think the excitement around pluripotential stem cells in particular has to do with the fact that they can be grown indefinitely in the laboratory and multiplied many times over to make more stem cells and that they can give rise to all the tissues of the body. So for the first time we've got an indefinitely renewable source of any healthy human tissue for use either in the laboratory or in transplantation medicine.

SHANE HUNTINGTON You've been working at the stem cells, essentially, from the beginning, when you and others first discovered that you could, potentially, coax these cells down particular differentiation pathways. Tell us a bit about what that was like back then because I can imagine there would have been an incredible sense of enthusiasm with regards to the possibilities of such cells.

MARTIN PERA Well, we were very excited. Of course, it was known since the 1980s that stem cells could be developed from the mouse embryo. Despite many attempts in the intervening years it proved difficult to derive these cells from other species. Then, in the mid-'90s, Jamie Thomson, in Wisconsin, showed that you could make pluripotent cells from the rhesus monkey embryo. And our laboratory, and a few others, set out to see if we could do this from human embryos. It was incredibly exciting when we first had some success, so that, indeed, we could make these cells and that they could turn in to human tissue-like nerves.

SHANE HUNTINGTON What does it mean in terms of the progress of, essentially, combating a range of diseases at that point in time? It seems as though you had something that looked like it was an answer but, decades later, we're still sort of a fair way off.

MARTIN PERA Well, at those early stages there was incredible promise and incredible potential. One of the most difficult things for us in the field was to convey that promise, and the excitement was not trying to claim that things were going to happen too quickly. To me, it's remarkable that only a little over a decade after human embryonic stem cells were discovered we're already seeing clinical trials of the first human embryonic stem cell derived products for conditions like macular degeneration, a very common cause of blindness. Now, that's remarkable because, as I say, it's only a little over a decade. Even in the drug industry - which is a well travelled paradigm for development of therapeutics - it's not unusual to have 10 to 15 years between the discovery and clinical trials. So I think this is quite remarkable. However, in many areas, we still have a long way to go for many applications.

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Stem Cell Therapy: The Hope and the Hype