Stem cells and eyes – what role will they play in eyecare?
The longstanding goals of any health professional, whether it be physicians or optometrists, are to cure disease, promote patient health, and prevent sickness whenever possible. In the last few decades, significant strides have been made toward developing treatments for countless diseases, yet there are still debilitating disorders that remain incurable.
Tasked to confront these diseases in an innovative fashion and to produce new therapies and cures, regenerative medicine combines the fields of life science, engineering, and medicine to generate functioning human cells, tissues, and organs. As an important division of regenerative medicine, stem cell therapies utilize stem cells to replace missing or non-functioning tissues lost secondary to disease. They also offer an infinite source of renewable replacement cells and tissues for patient therapies.
In relation to the field of optometry, and in order to understand why stem cell science is important for the advent of new ocular disease therapies, it is necessary to briefly mention ocular physiology. After development in utero, the human retina has little to no capability of regenerating cells, unlike certain fish or newt species.
Secondary to retinal cell loss, functional vision is lost; this is often not associated with life-threatening conditions, but vision loss greatly impacts a patient’s quality of life.
Stem cells are utilized therapeutically in two large ways – transplantation via injection or scaffold placement – with the ultimate goal of replacing functional retinal cells back into eyes that have had significant retinal cell and vision loss.
To best understand the process by which stem cells can theoretically be utilized for treatment, consider a patient who has been diagnosed with age-related macular degeneration (AMD).
AMD currently has no known cause or cure and is the leading cause of vision loss in the United States, affecting upwards of 10 million Americans. Throughout the disease process, the first cells that are lost are retinal pigment epithelial (RPE) cells which, over time, induces progressive loss of photoreceptors. The following method is a simplified and theoretical treatment process which uses stem cells to address AMD.
Here is an excellent resource with OCT images and presentation on various forms of AMD.
A healthy donor patients’ blood is drawn – no more than is taken for standard blood tests run by a family practice physician – and then sent to a manufacturing cell culture lab. There, the blood undergoes a separation process in order to collect the patients’ blood cells, and a reprogramming process begins. The reprogramming process, which several protocols have outlined to date, produces cells termed ‘human induced-pluripotent stem cells’ (hiPSCs) from the donor patients’ blood cells.
The hiPSCs are then cultured to produce functional RPE cells and are prepared for transplantation. At this point the hiPSC derived RPE cells are prepared for transplantation in two ways: suspended in a buffer liquid and transferred into a small syringe or cultured and grown into a small scaffold which would be rolled up and placed into a syringe prior to transplantation.
Shortly after the hiPSC derived RPE cells are ready, the patient is prepared for a minimally invasive, delicate eye surgery in which the cells are transferred from a syringe to the patients’ eye directly under the retina. The entire surgical procedure, when perfected, could take fewer than 15 minutes. The patient is monitored closely throughout the healing process, but ideally, functional vision will return 3-4 months after surgery.
Although stem cell-based therapies are not yet available to patients outside of clinical trials, it is important to consider the role optometrists and ophthalmologists will play looking forward. Optometrists will play a major clinical role in regard to patient education and management pre- and post-operatively, alongside retinal ophthalmologists who will perform the transplant surgeries. In relation to corporate partners, optometrists and ophthalmologists will be involved with clinician education regarding available therapies and marketing of the products available after successful clinical trials are completed.
Stem cell therapies as a part of regenerative medicine offer an innovative and new route of treating incurable diseases. There is much left to finalize in regard to these therapies when it comes to stem cells and eyes, but the application has already made significant strides towards becoming a reality.
For more information regarding current clinical trials in the US visit clinicaltrials.gov and insert the following identifiers into the search box: NCT01691261, NCT03046407, NCT03011541, NCT02122159. For information regarding applications of stem cell therapies visit: https://stemcells.nih.gov/info/health.htm. For more information regarding a background of stem cells visit: https://stemcells.nih.gov/info/basics/1.htm.