A new early-stage clinical trial at the Massachusetts Eye and Ear Hospital and research center in Boston is using stem cells from an individual’s healthy eye to repair their damaged cornea.
There are different causes that can damage the cornea, which include infections, congenital diseases and traumatic injuries. The study includes 13 participants with corneal damage.
The eye is fertile ground for stem cell therapies. It is surgically accessible and it’s easy to monitor how well treatments are working. The study led by researcher Ula Jurkunas is one of several taking place worldwide that use stem cells to repair damaged corneas. Other researchers are trying to generate cells in the retina to treat other common causes of blindness such as age-related macular degeneration and glaucoma.
In a healthy eye, the cornea is surrounded by the limbus, a structure that contains corneal epithelial stem cells, which give rise to an epithelial layer that protects and supports the cornea. Injury and infection can deplete those cells, taking away an otherwise healthy cornea’s capacity to heal and causing it to turn opaque, blocking vision.
Damaged corneas can be replaced, but without stem cells to replenish the epithelium, the transplant will deteriorate in a similar way over time.
The study way of solving this problem starts by taking a small sample of stem cells from a patient’s healthy eye and culturing the cells. They grow on a sample of amniotic membrane, and once a big enough sheet of stem cells has been created they can be transplanted into the damaged eye. In some people whose stem cells have been depleted but who have an otherwise undamaged cornea, that patch is enough to restore sight.
The researchers have been developing the method of cultivating and expanding stem cells since 2006 and to avoid potential contamination, they grow the stem cells in a sterile laboratory where they need to wear protective suits and nurture the cells without using antibiotics or hormones in order to meet US FDA guidelines.
A commercially available corneal epithelial stem cell product, Holoclar, uses cells from mice as a feeder layer to support stem cell proliferation. It was developed in Italy by scientists at the University of Modena and Reggio Emilia in Modena. Jurkunas and Ritz, by contrast, have opted not to use mouse cells, a decision based in part on the belief that regulators would worry that animal cells could transmit animal diseases to humans.
Jurkunas says the use of feeder cells complicates the process of getting FDA approval for a therapy, and her version that does without them might have an easier time. But it will take further clinical trials, and probably the interest of an industry partner, before Jurkunas and Ritz’s technology is submitted for approval.
Stem cell therapies, as a new technology for eyesight will be expensive and limited, and will continue to get better over the years.
Neil Savage (2021, Sep 29). Reversing blindness with stem cells. Nature. Vol 597. Retrieved from: https://media.nature.com/original/magazine-assets/d41586-021-02629-w/d41586-021-02629-w.pdf