08 Feb Part 2: Stem Cells to be Safe, Too
Last week we celebrated the announcement of improved vision in the first two patients receiving stem cells transplantation. Truly exciting and encouraging news, but also due to the fact that the methods used seem safe, too.
New medical discoveries, treatments, drugs, devices, etc. must all be shown (proven) to be both safe and effective for the patients. Last week, the “results” of these two patients hint that RPE stem cell transplantation may be effective, that is, stems cells have the hope of improving vision.
Stem cells, and their implementation, pose several risks and potential technical challenges.
In summary, human stem cells were cultivated to become RPE (retinal pigment epithelium) cells. These are the very cells defective in retinal diseases such as macular degeneration and Stargardt’s Disease.
RPE cells (retinal pigment epithelium) usually “live” in a layer just beneath the retina. The stem cell derived RPE cells were then injected underneath the retina.
Non-functioning diseased cells are replaced by healthy cells derived from stem cells.
Unrestricted Growth of Cells
Unrestricted growth of cells, by definition, is a tumor. Fortunately, there were no signs of abnormal proliferation either in the eye or elsewhere in the body. This has been reported to be a problem in animal studies. Why might this be a problem?
Stem cells have two attributes that make them so attractive. Not only do they have the potential to transform into almost any type of cell in the body, but they have the potential to multiply indefinitely.
These attributes might allow scientists to create the right type of cells and make them in large quantities.
Are Stem Cells Immune?
Another potential problem may be whether or not these “foreign” cells are immunologically tolerated by their new hosts. In theory, the new cells could be attacked by the immune system of each host (i.e. the patient receiving the cells). In anticipation of possible “rejection,” each patient was given low dose medicines to suppress, temporarily, any immune response.
The retina may be immunologically protected by the blood-brain-barrier.
Other factors may also contribute to a shorter than expected life span of the cells, but at 4 months the cells seem to be thriving and functioning.
Technical Challenges to Transplanting the Cells
The actual process of implantation could cause a retinal detachment. The cells were actually injected underneath the retina. In doing so a small hole was created, allowing the potiential for a retinal detachment to occur.
One of the largest challenges, from a retinal standpoint, is how to safely transplant the cells without causing further harm to the eye.
Neither patient sustained any complications from the procedure.
What Does This Mean? The news of stem cells improving vision for these patients is very promising. The news of doing so in a safe manner is a “home run.”
Just as important as the science is the technology…and the ability to implement the science.