KYOTO A team of Japanese doctors recently performed a landmark surgery involving the use of donated induced pluripotent stem, or iPS cells, to treat macular degeneration, an intractable eye disease.
The operation, which used cells gathered and prepared ahead of time, was performed at Kobe City Medical Center General Hospital as part of a joint project also involving researchers from Riken and Kyoto University's Center for iPS Cell Research and Application, or CiRA.
CiRA head Shinya Yamanaka, who won a Nobel Prize in 2012 for discovering iPS cells, said he has high hopes that the project will pave the way for cheaper, faster regenerative treatment.
How will using stored, donor-derived iPS cells lead to the proliferation of regenerative treatment? I think the spread of iPS cell-based regenerative treatment has started to become a real possibility. In 2014, researchers from Riken and other institutions created iPS cells from a patient's own body and transplanted them back into that patient. But this method is costly and time-consuming, creating an obstacle to its use as a widespread medical treatment. If you can create cells from donor iPS cells and store them, you can use them in multiple patients, cutting down on the cost and time required to culture cells.
The previous procedure was the first example of regenerative treatment using iPS cells, and it was tested on just one patient. This time, multiple patients are slated to receive transplants. Researchers will be able to analyze data collected from these patients to determine the safety and efficacy of the treatment in arresting the deterioration of the patients' eyesight.
What are the key issues that must be addressed before regenerative medicine can spread? First of all, we must ascertain whether it is safe [to use donor-derived cells], as there is the risk that the patient's immune system will reject a graft of cells or organs taken from someone else's body. The researchers this time screened iPS cells for immunity types that reduce the risk of rejection. If the immunity type of the iPS cells used in the transplant matches that of the patient to a certain degree, that will reduce the possibility of rejection. It is also important to monitor and make sure that the graft does become cancerous.
What other treatment-related research projects using iPS cells are on the horizon? Starting as early as the 2018 academic year, Kyoto University plans to treat patients with Parkinson's disease and an intractable disease that stops blood from clotting. Keio University aims to treat damaged spinal cords, while Osaka University is focusing on treatment for heart failure. There are also plans for cancer and kidney disease treatment. One thing to note is that the rejection risk differs depending on the organ or tissue being treated. There is also a higher risk for transplanted cells to become cancerous when a large number are transplanted. By contrast, transplants on eyes are less prone to rejection, and the number of transplanted cells is small. So you cannot talk about these upcoming projects as if they are similar [to the latest surgery].
Why is it important to build up a large stock of iPS cells for regenerative treatment? In order for treatments using iPS cells to be widely used, you need to secure a pool of iPS cells of many immunity types so that you can reduce the risk of rejection.
Kyoto University has been working to increase its stock of iPS cells for treatment. If only, say, 10 types of cells are needed, the university would be able to handle this on its own, but if we establish that something like 100 types will be needed in the future, then the burden of managing the stock will increase significantly.
In order to create high-quality iPS cells, we started working with Takara Bio in January to create a quality-control system. But we do not think that working with a business alone will necessarily reduce costs. We create iPS cells from people donating blood out of the goodness of their hearts. In that sense, I have reservations about working with a profit-driven company.
Interviewed by Nikkei staff writer Takuro Kusashio