It’s Saturday morning in Denver – and its cold. We went from 70 degree temperatures to 30 degrees in one day and there’s a light dusting of snow.
This morning started early with the Stem Cell Education Summit. The keynote speaker, Mario Capecchi, is the molecular geneticist best known for his work with knock out mice, for which he was the co-winner of the 2007 Nobel Prize. The title of the talk was “Stem Cell Therapy: Hype or Reality?” He started his talk with the answer to that titular question - ‘There’s alot of hype, a little reality, and a tremendous amount of potential.”
Diseases that may be treatable by stem cell therapies: Parkinson’s, Alzheimer’s, insulin dependent diabetes, spinal cord injuries, and heart disease. Dr. Cappechi pointed out that it’s not all future – that stem cell therapies that have been used for a long time with bone marrow transplants for leukemia patients.
He then went on to explain stem cells to the audience – they are unspecialized cell types in the human body that are capable of becoming a specialized cell type. Stem cells are capable of self renewal and differentiation. There are two major classes of stem cells – embyonic (extremely rapid growth and very versatile, pluripotent) and adult (slower growing, restricted and require a niche)
Embryonic mouse cells can be harvested, reintroduced, and functon to create mouse tissue. We’re not there yet with humans and that’s why these stem cell therapies are still outside of our reach.
Then there’s the idea of reprogramming somatic cells to function as a different type of cell. There are two techniques for this – the first is nuclear transfer (remove the current nucleus and put in a different one). That technique is very inefficient (low success rates) and the resulting organism is fragile. The second is the Yamanaka method (inducing a forced exprssion of certain genes in a fibroblast) to create induced pluriplotent stem cells.
Dr Capecchi then turned his attention to stem cell work in the small intestine. The intestinal epithelium is the most rapidly self-renewing tissue (turns over every 5 days) in adult mammals. The stem cells of the small intestine are made in the crypt (at the base of the villus). Interestingly, the small intestine almost never gets cancer, while the colon (which doesn’t regnerate like this) is a common cancer site. The gut has many different types of absorbing cells, as you move along the length of the intestine. So, it turns out there are a number of different stem cell populations in the small intestine – multiple populations making one tissue type – an added complexity that is critical to understand. Though this system had been studied for year, they didn’t have a marker. A marker is really important for geneicsts because that’s their way in.
When asked how close are we to the clinic with this research, Dr. Capecchi said that ”the safe answer is 20 years” and then went on to reiterate how complex this research is. He explainted that we’re going to hear a lot of claims in the coming years and, unfortunately, most of those successes won’t be real. Even worse, it will be difficult to know whether or not the claims are valid . He reminds us that there are cancer patients who get better, even wtihout therapy, so, in some cases, you won’t know whether the improvement with cancer patients is due to the stem cell therapy or some other factor. But he concluded by saying that there is tremendous potential here – that stem cell research will provide cellular solutions for cellular problems.