I'll slow it down. I'm sorry. It's too much coffee this morning.
Embryonic stem cells are derived from four-day-old to five-day-old embryos. These embryos were created for the purposes of in vitro fertilization and would otherwise have been discarded. These embryonic stem cells have the capacity to generate all possible cell types in the body. Adult stem cells, on the other hand, are more specialized. They reside within tissues and they give rise to a limited spectrum of cell types that are present in that tissue. For example, hematopoietic stem cells only give rise to different types of blood cells. Adult stem cells are found in all of us, in all of our tissues. They are also present in cord blood, amniotic fluid, and possibly the placenta.
The debate around embryonic stem cells has been overtaken by scientific progress. The most significant advance in the stem cell field in the past decade has been the seminal discovery by Shinya Yamanaka, of Kyoto, Japan in 2006, of induced pluripotent stem cells, so-called iPSC. What Yamanaka showed was that you could take any cell in your body--a skin cell from the tip of my nose, for example--and by applying a very simple procedure, introducing four genes into it, reprogram that cell to make it closely resemble in a way that the cell is essentially indistinguishable from an embryonic stem cell. So you can derive an embryonic stem-cell-like cell from any adult cell type. This is a paradigm-shifting discovery, a very, very important advance.
While this has not completely obviated the need to work with embryonic stem cells--we still need to compare and contrast iPSC cells with embryonic stem cells, and research needs to be conducted with human embryonic stem cells--this discovery has really transformed the field.
Seven years ago most of us were thinking about stem cells being used to regenerate replacement cells for transplant purposes for diseased organs, to treat degenerative diseases, and so on. That work still goes on. For example, here at the Ottawa Hospital my colleague Duncan Stewart is undertaking a trial to treat patients with pulmonary hypertension--this is a fatal disease that affects primarily women in their thirties, and it's a lethal disease--where stem cells are derived from the blood, are temporarily modified to contain a gene that stimulates blood vessel growth, and those cells are reintroduced into the circulation.
Another colleague, Harry Atkins, at the Ottawa Hospital has been using bone marrow transplant protocol for the treatment of severe cases of multiple sclerosis. Essentially, what he's doing is curing the autoimmune disease in those patients. It's really quite a phenomenal advance.
In a recent clinical trials workshop held by the Stem Cell Network, we identified over 50 Canadian-based trials involving stem cell therapies, and these will be entering the clinic in the next three to four years. So the field is advancing tremendously fast, much faster than all of us had anticipated.
Advances are being made at a similar pace outside of Canada. As committee members, I'm sure you've read about Geron, a U.S. company that has just initiated a clinical trial whereby spinal cord patients are receiving cells that have been differentiated from human embryonic stem cells, so-called oligodendrocytes, that will be used to treat spinal cord injury. That's just been started and is the first clinical trial using embryonic stem cell-derived material anywhere in the world.
Returning to iPSC cells, Yamanaka's discovery has opened the doors to the rapid and efficient creation of disease-specific stem cells and patient-specific stem cells. This has opened up whole new lines of inquiry and has allowed researchers, for example, to screen these cells against drug libraries. A library of drugs can be thousands and thousands--perhaps even up to one million or so--of compounds that represent all possible classes of chemicals. They can also be a library of drugs that's already in the clinic so they can rapidly move into clinical trials.
I'll give you a couple of examples. My colleague Bill Stanford at the University of Toronto has derived induced pluripotent stem cells from patients with progeria. Progeria is a genetic disease where kids rapidly age. They die at around age 13, resembling 96-year-olds. They die of atherosclerosis; they die of heart attacks and strokes.
He has derived iPSC from those patients and isolated vascular smooth muscle cells--blood vessel cells--from those patients. The remade blood vessel cells start off healthy, but they rapidly age in petri dishes, recapitulating the disease. So he's going to use those cells to screen for drugs that will prevent that aging process. These drugs could be used for the progeria patients, but they could also be used more widely in patients suffering from atherosclerosis.
Another colleague, Lee Rubin at Harvard Medical School, has done a similar procedure with SMA patients. This is a disease where spinal motor neurons die, and kids at a very young age are affected. It's a horrible disease. He screened for drugs that would promote neuron survival. These neurons were differentiated from the iPS cells. He identified drugs, and at least in mice he can treat SMA at this point. So it's a very exciting way to personalize drug screening approaches to identify new drugs that can be used rapidly in the clinic.
Other cell types can also be screened in the same way. Another Stem Cell Network member, David Kaplan at SickKids Research Institute in Toronto, has isolated cancer stem cells from neuroblastoma tumours in kids and screened for drugs. He identified some drugs that killed the tumour-initiating cells, the cancer stem cells. Within two years this has found its way into a compassionate clinical trial at SickKids, and is now in a multi-site trial across Canada and the U.S. It's phenomenal progress. Using the same approach, they're now attacking three other tumour types that cause cancer. It is really quite phenomenal.
Using stem cells to generate replacement cells and identify drug targets are just a couple of ways in which stem cells are transforming medical research. Some groups are using stem cells to better understand the diseases of early development. Other groups are using them to generate large quantities of human cardiac and neural cells to use to test drugs for toxicity before they are ever given to a patient, making clinical trials safer. Many groups are working to derive liver cells for the same purpose.
In short, the field remains exciting and is progressing very rapidly. It's not without challenges. This work is very important. What we're talking about is making changes to clinical practice that are going to help people. It will save lives and alleviate suffering.
At this point I will ask my colleague Drew Lyall to continue.