Posted on Nov 05, 2018, 9 p.m.
Scientists from the University of Waterloo have been able to coax stem cells to grow into three dimensional retinas in a dish and show that the tissue responds to light, however putting those cells into the damaged eyes in a manner that will improve vision could present a much harder challenge.
The UofW faculty has about 100 researchers using stem cells to model disease, screen drugs, or develop therapies at the same university where in 2007 James Thomson gained international attention by announcing he was the first scientist to grow human embryonic stem cells outside of the body. Since then stem cell science has mostly shifted from hot flame to slow burn with biological achievements continuing to surface, but not being clear if or when transformative treatments may be served.
Induced pluripotent stem cells were developed easing concerns about destroying embryos to produce stem cells. Since then many scientists have guided blank slate embryonic stem cells to become specialized cells of the brain, heart, pancreas and other organs. Some of the cells may carry mutation that can cause disease, enabling better understandings of what goes wrong than can be provided in animal models; while others are used to test potential drugs for side effects; and some are prepared for potential replacements for patients with conditions in which cells are damaged or have died.
Blindness caused by disorders such as retinitis pigmentosa and macular degeneration are considered to be good candidates for stem cell therapies. Injecting treatment in to a blind eye carries low risks as eyes are encapsulated and wayward cells likely would not travel to other parts of the body. Should something go wrong an eye can be removed, and to see how transplanted cells are behaving doctors only have to dilate pupils to look without the need of MRI or PET scans.
Many of the human trials for stem cell therapies taking place currently are for vision disorders. One of the original embryonic stem cell lines developed at the UofW-Madison is being used in Asterias Biotherapeutic studies to create therapy for spinal cord injuries; initial clinical trials have found injection to be safe, with some improvement in motor function being observed.
UofW-Madison experimental treatment for graft vs host disease in bone marrow transplants became the first cell therapy developed there to be used in clinical trials by Cynata Therapeutics studies using blood cells derived from iPS.
Dr. David Gamm hopes to start clinical trials for vision loss in 2021, specifically retinal cells called photoreceptors that include rods to detect black and white images and cones that capture colour; in those with vision loss they may reignite site. Underneath these photoreceptors are the RPE which is another tier of cells which nourish the photoreceptors and remove their waste; photoreceptors may have main roles but RPE cells are key to supporting them.
Retinitis pigmentosa and macular degeneration attack photoreceptors and RPE cells, there are only a few treatments for these conditions including gene therapy which was approved in 2017 for treatment of retinitis pigmentosa.
Prosthetics are available for those with severe vision loss, such as sending signals from a camera imbedded in special glasses to chips implanted in the retina that allow the brain to perceive crude shapes, made by Second Sight. BrainPort bypasses the eye altogether translating digital information from cameras into stimulation patterns on user tongues which patients learn to interpret tongue signal as a form of vision. Gramm says these devices provide semblance of sight but do not restore RPE cells or photoreceptors through which cell therapy could produce more natural type of vision.
RPE cells derived from iPS have been transplanted into patients with macular degeneration in several trials, such as Advanced Cell Technology in 2012 which found no apparent complications and an increase in retinal pigmentation suggesting the cells transplanted survived.
The breakthrough of growing early stage retina cells from embryonic stem cells and iPS cells was announced and patented in 2009. In 2011 the team showed they could create 3D retina tissues including RPE cells and photoreceptors which were later shown to respond to light and assemble as they would in a developing fetus.
In 2016 Opsis Therapeutics was formed by Dr. David Gamm, which plans to transplant photoreceptors derived from iPS cells into retinitis pigmentosa patients, with a study of photoreceptors and RPE cells for macular degeneration to follow. Photoreceptors are grown under controlled conditions in a dish, they may be more adaptable to transplant than cells from a deceased donor as they are more used to harsh environments.
Gamm is troubled by rogue clinics and points out most of them often remove fat or blood from patients to inject saying they will help repair injury or illness charging significant fees and offer unproven stem cell therapies that the FDA has begun to crack down on. Best case scenario for many of these rogue clinics is that you lose a lot of money, worse is you are put in harm’s way.
The FDA is seeking court injunctions on clinics in Florida and California where some patients went blind after injections that were said to treat macular degeneration. The Federal Trade Commission has filed complaints against 2 other clinics in California for making overreaching claims for treatments costing up to $15,000.00.
When and if stem cell therapies are eventually approved the first ones will most likely only offer incremental improvements and gradually improve, just as any new technology.
Materials provided by:
Note: Content may be edited for style and length.