This week saw the announcement of the first stem cell tissue transplant eye operation in Ireland. At the Royal Victoria Eye and Ear Hospital in Dublin, Ireland’s first patient underwent the procedure during an hour-long operation to help restore his deteriorating sight. This treatment uses a particular type of stem cell called a limbal stem cell to repair damage to the cornea (the clear, protective outer layer at the front of the eye) as a result of injury or disease. In a normal and healthy cornea, a resident supply of these stem cells can be found in a part of the eye called the limbus. These cells continually replenish the corneal cells and heal any damage. In cases where these stem cells themselves are damaged, the cornea can no longer be repaired and visual impairment or blindness can occur.
The stem cell therapy works by taking a tiny portion of the undamaged limbus (where the stem cells reside) and growing these cells in a laboratory to produce a sheet of cornea which was then transplanted back onto the patient’s eye. This process was initially developed by the National Institute for Cellular Biotechnology, Dublin City University and has since been established in the eye bank at the Irish Blood Transfusion Service (IBTS). By introducing these cultured limbal-cornea epithelial stem cells to the damaged eye, it is hoped the operation will lead to healthy stem cells growing in the cornea. Speaking just before his operation, the patient said “he hoped it would give him a better quality of life and lead to more independence. It will be up to six weeks before doctors can establish how successful the operation has been.” The surgery was led by ophthalmic surgeon William Power at the Royal Victoria Eye and Ear Hospital and it is hoped that around six such operations could be performed in Ireland this year.
This promising therapy is the culmination of over 20 years of excellent basic, preclinical and clinical research conducted by a team of internationally renowned scientists in the field of epithelial stem cell biology and includes researchers at the National Institute for Cellular Biotechnology, Dublin City University. This is an encouraging example of the potential application and therapeutic impact of stem cells in the front of the eye.
While this is an exciting step forward for vision loss resulting from damage to the cornea, repairing the retina (which is located at the back of the eye) using stem cells is not so simple and such a procedure can be extremely challenging and painstakingly complex. The eye is well protected from the body’s immune response but this barrier is often degraded in people with retinal diseases. Also, unlike the cornea, the retina does not contain a resident supply of stem cells and scientists must find another source of new retinal cells that may be able to replace the damaged or dying cells in the retina. Several studies have now reported that both embryonic stem cells and induced pluripotent stem (iPS) cells can be turned into different types of retinal cells in the lab. However, working with these cells is difficult and many factors need to be considered when developing these therapies, such as what stage of development the cells should be at prior to transplantation and how best to introduce these cells to the back of the eye.
Despite the retina being more complicated than other components of the eye, the retinal research community are committed to bringing a safe and successful stem cell technology that holds the potential to improve the lives of people who are affected by retinal degenerations. Central to this research is the development of the understanding of how different types of stem cells behave, and how best to harness their potential in the eye.
In March of this year ReNeuron, a stem-cell development company in the United Kingdom, reported that the first patient with retinitis pigmentosa (RP) had been treated with its stem cell therapy in a Phase I/II clinical trial (Clinicaltrial.gov identifier: NCT02464436) taking place at Massachusetts Eye and Ear Infirmary (MEEI). A second clinical trial for retinitis pigmentosa (Clinicaltrial.gov identifier: NCT02320812) is being conducted by Dr Henry Klassen of the University of Irvine, California under their start-up company Jcyte. Both therapies involve the injection of human retinal progenitor cells (hRPCs) into the patient’s eye. These are stem cells that have partially developed into photoreceptors, the cells in the retina that make vision possible. The most important measurements of these trials will be to test whether this approach is safe, and individuals will be followed up for 12 months post-treatment with safety monitoring. Vision measurements will also be taken and compared to the untreated eye as a preliminary way of seeing whether there is any efficacy with these approaches. From our point of view, this is a momentous step forward on the road to treatments for sight loss and gives hope for patients with disorders like late stage age-related macular degeneration (AMD) and inherited retinal degenerations, where the light-sensitive photoreceptor cells in the retina have already been lost.
What we observed this week in Ireland will serve to provide scientists and clinicians further insight into the development of safe and effective treatments to save or restore vision lost to retinal diseases using stem cells. We will be following these developments closely over the next few months and aim to keep you fully informed.
Fighting Blindness does not endorse any of the products, medications, treatments or information reported here, or on any of our communication platforms. Articles on Fighting Blindness websites and social media are intended for informational purposes only. We strongly advise that you discuss all medications, treatments, and/or products with your doctor.