One of the most famous stem cell scientists in the world said on Monday that the promise of stem cell treatments has in some ways been overstated.
In an interview with the New York Times, Dr. Shinya Yamanaka, one of the recipients of the 2012 Nobel Prize in Medicine for his discovery of induced pluripotent stem cells (iPS cells), said, “we can help just a small portion of patients by stem cell therapy.”
He explained that there are only 10 target diseases that he believes will benefit directly from stem cell therapies including, “Parkinson’s, retinal and corneal diseases, heart and liver failure, diabetes, spinal cord injury, joint disorders and some blood disorders. But maybe that’s all. The number of human diseases is enormous.”
This is a big statement coming from a key opinion leader in the field of stem cell research, and it’s likely to spur a larger conversation on the future of stem cell treatments.
Yamanaka also touched on another major point in his interview – progress takes time.
In the ten years since his discovery of iPS cells, he and other scientists have learned the hard way that the development of stem cell treatments can be time consuming. While autologous iPS cell treatments (making stem cell lines from a patient and transplanting them back into that patient) have entered clinical trials to treat patients with macular degeneration, a disease that causes blindness, the trials have been put on hold until the safety of the stem cell lines being used are confirmed.
At the World Alliance Forum in November, Yamanaka revealed that generating a single patient iPS cell line can cost up to one million dollars which isn’t feasible for the 1000’s of patients who need them. He admitted that the fate of personalized stem cell medicine, which once seemed so promising, now seems unrealistic because it’s time consuming and costly.
But with any obstacle, there is always a path around it. Under Yamanaka’s guidance, Japan is generating donor iPS cell lines that can be used to treat a large portion of the Japanese population. Yamanaka said that 100 lines would cover 100 million people in Japan and that 200 lines would be enough to cover the US population. iPS cell banks are being generated around the world, meaning that one day the millions of people suffering from the target diseases Yamanaka mentioned could be treated or even cured. Would this not fulfill a promise that was made about the potential of stem cell treatments?
Which brings me to my point, I don’t believe the promise of stem cells has been overstated. I think that it has yet to be realized, and it will take more research and more time to get there. As a community, we need to be understanding, patient, and supportive.
In my opinion (as a scientist aside from my role at CIRM), I believe that Yamanaka’s interview failed to reveal his optimism about the future of stem cell treatments. What I took from Yamanaka’s comments is that stem cell treatments can help a small number of patients with specific diseases right now. That’s not to say that stem cell research won’t produce promising treatments for other diseases in the future.
Retinal diseases and blood disorders are easier to target with stem cell treatments because only one type of cell needs to be replaced. It makes sense to tackle those diseases first and make sure that these stem cell treatments are effective and safe in patients before we focus on more complicated diseases where multiple cell types or organs are involved.
Part of the reason why scientists are unsure whether stem cell treatments can treat complex diseases is because we still don’t know the details of what causes these diseases. After we know more about what’s going wrong, including all the cell types and molecules involved, research might reveal new ways that stem cells could be used to help treat those diseases. Or on the other hand, stem cells could be used to model those diseases to help discover new drug treatments.
I’ve heard Yamanaka talk many times and recently I heard him speak at the World Alliance Forum in November, where he said that the two biggest hurdles we are facing for stem cell treatments to be successful is time and cost. After we overcome these hurdles, his outlook was optimistic that stem cell treatments could improve people’s lives. But he stressed that these advances will take time.
He shared a similar sentiment at the very end of the NY Times interview by referencing his father’s story and the decades it took to cure hepatitis C,
“You know, my father had a small factory. He injured his leg in the factory when I was in junior high. He had a transfusion, and he got hepatitis C. He passed away in 1989. Twenty-five years later, just two years ago, scientists developed a very effective cure. We now have a tablet. Three months and the virus is gone — it’s amazing. But it took 25 years. iPS cells are only 10 years old. The research takes time. That’s what everybody needs to understand.”
Yamanaka says more time is needed for stem cell treatments to become effective cures, but CIRM has already witnessed success. In our December Board meeting, we heard from two patients who were cured of genetic blood diseases by stem cell treatments that CIRM funded. One of them was diagnosed with severe combined immunodeficiency (SCID) and the other had chronic granulomatous disease (CGD). Both had their blood stem cells genetically engineered to removed disease-causing mutations and then transplanted back into their body to create a healthy immune system and cure them of their disease.
Hearing how grateful these patients and their families were to receive life-saving stem cell treatments and how this research brings new hope to other patients suffering from the same diseases, in my mind, fulfills the promise of stem cell research and makes funding stem cell treatments worth it.
I believe we will hear more and more of these success stories in the next decade and CIRM will most certainly play an important role in this future. There are others in the field who share a similar optimism for the future of stem cell treatments. Hank Greely, the Director for Law and the Biosciences at Stanford University, said in an interview with the Sacramento Bee about the future of CIRM,
“The next few years should determine just how good California’s investment has been. It is encouraging to see CIRM supporting so many clinical trials; it will be much more exciting when – and I do expect ‘when’ and not ‘if’ – one of those trials leads to an approved treatment.”