In 2015, after a flurry of stem cell developments were profiled in the media, I wrote this story to help answer one of the most popular questions that we receive about stem cell therapies for blindness and sight loss: will they work for you and for your eye disease?
On March 19, 2018, the results from an innovative stem cell clinical trial for people living with age-related macular degeneration (AMD) were published in the respected biomedical journal Nature Biotechnology. We wrote a story about this latest development for the FFB website, which you can read here. Now, we are getting lots of questions about what this development means for people who are living with blindness and for those who are affected with a variety of different blinding eye diseases.
In response to these questions, I’m updating this story, which I wrote after the first induced pluripotent stem cell (iPSC) clinical trial for AMD was initiated at the RIKEN Institute in Japan. What’s an iPSC? Keep reading to find out the answer and why it matters.
This story is designed to help you find an answer to the question: will a stem cell therapy work for me? To get an answer, we suggest that you pay attention to three key points when you read new stories about stem cell discoveries or clinical trials:
- 1. The kind of stem cell matters (embryonic stem cell, progenitor cell, etc.)
- 2. The kind of eye cell matters (“RPE” cell, photoreceptor cell, etc.).
- 3. The kind of clinical trial matters (Phase 1, Phase 2, randomized, etc.).
- 1. The Kind of Stem Cell Matters
There are many different kinds of stem cells, including embryonic stem cells, neural stem cells, blood stem cells, skin stem cells, eye stem cells, induced pluripotent stem cells (iPSCs)—the list goes on. Importantly, these different kinds of stem cells can do different things, so it matters if a new clinical trial involves embryonic stem cells or neural stem cells. It matters because embryonic stem cells have the ability to make all of the different cell types that are needed to make a human body. In contrast, neural stem cells can only make brain cells. Because these cells have different properties, there are different safety concerns involved. For example, some people are concerned about using embryonic stem cells (ESCs) for therapeutic purposes because they have the potential to produce the wrong cell type in the wrong place. One of the main differences between the AMD clinical trial at the RIKEN Institute in Japan and the AMD trial at Moorfields Eye Hospital in London, is that the RIKEN trial used iPSCs, which are derived from the patient’s own skin and therefore do not require any immunosuppressive drugs after transplantation. In contrast, the Moorfields trial used a patch of cells generated from embryonic stem cells. As a result, the patients who participated had to take drugs to stop their immune system from rejecting the foreign cells.
Earlier, we also wrote a story to explain JCyte’s retinal progenitor cell clinical trial for retinitis pigmentosa (RP) in more detail. In that story we described the difference between stem cells and retinal progenitor cells. This distinction matters because the trial is not planning to regenerate lost tissue, which is an assumption that people often have when they think about stem cells. Instead, the trial is injecting a single-celled suspension of retinal progenitor cells into the vitreous of the eye so that these cells can have a protective effect. Since we first posted this story, the team that is running this trial at JCyte successfully completed their Phase 1 trial, which was designed to test safety, and has moved forward to a Phase 2 trial, which is designed to test if this new approach works (for more on the different clinical trial “Phases” keep reading).
- 2. The Kind of Eye Cell Matters
Stem cells can make a number of different kinds of eye cells. For example, the latest headline story involves transplanting a kind of eye cell called retinal pigmented epithelial (RPE) cells to treat wet age-related macular degeneration (AMD). All of the ongoing clinical trials for vision loss involve RPE cells, or retinal progenitor cells (described in the section above). RPE cells are not the light-sensing cells in the eye; they are the support cells. The AMD stem cell trials are replacing the RPE cells in people with wet AMD who have recently experienced rapid vision loss, with the unique goal of replacing the damaged RPE cells and, as a result, restoring lost sight before the photoreceptors become too damaged. If this works, it would be a tremendous breakthrough and it could be life changing for people who might be diagnosed with AMD. This approach has the potential to save lost vision before it’s irreversible.
Unfortunately, transplanting RPE cells alone won’t be able to restore vision to people who are currently living with low vision or who are completely blind as a result of an inherited retinal disease (IRD), such as RP, that has damaged their photoreceptors cells, the eye’s light-sensitive cells.
For many people, the only way to restore vision with stem cells is to replace damaged photoreceptors.
There are two different kinds of photoreceptors: cones and rods. Cones are needed for high acuity central vision and rods are needed for low light and peripheral vision. Around the world, scientists are trying to use stem cells to make rods and cones. It is not easy!! Photoreceptors are more complicated cells than RPE cells. Fortunately, scientists around the world, including FFB-funded scientists, have been making amazing progress.
In summary, if you are blind or losing your vision because your disease is damaging your photoreceptors, then you should be on the lookout for research and clinical trial announcements about photoreceptors, not just stem cells (because often these stem cell headlines are referring to RPE cells and not photoreceptors).
- 3. The Kind of Clinical Trial Matters
There are many different kinds of clinical trials. In a clinical trial, participants receive some kind of intervention (such as drugs or transplanted stem cells). Clinical trials involve dividing the participants into groups so that the new intervention can be compared to an alternative, which may be an existing treatment or a placebo. The main goal of a clinical trial is to determine if the new intervention is safe and effective. The word intervention is used instead of the word treatment to help people remember that the drug and/or surgery that the participant is receiving is not an established treatment. A clinical trial is not a treatment; rather it is an experiment. It is not surprising, however, that many participants are very hopeful that a clinical trial might benefit them. This latest trial to treat wet-AMD is a Phase 1 clinical trial, which means that it evaluated the safety of this new approach and also measure if there was any benefit to the patient. An important thing to remember about clinical trials is that it should never cost you money to participate. You are participating in research and this should be communicated to you clearly.
Read the FFB’s Everything you need to know about clinical trials resource to learn more.
Will this new stem cell treatment work for you? Only time will tell. At the Foundation Fighting Blindness we have a lot of hope about the future of stem cell therapeutics to treat vision loss. This is why, thanks to FFB donors, we continue to fund promising stem cell research. And with every new announcement, our confidence in the future of stem cell-based treatments for vision loss grows stronger. But we also know that it will take time, effort, and teamwork to safely and appropriately translate science into new, accessible therapies.
What can you do while you wait? Enroll on the Foundation Fighting Blindness Patient Registry, which is a tool that is designed to connect people living with inherited retinal diseases (IRDs) to clinical trials. You should also plan to attend FFB’s educational sessions, Vision Quest, where you can ask scientists about what’s coming next. And you can help us raise awareness about the importance of vision research and the need for new sight-saving therapies. We know that research is a long-term investment, but it is changing the future.