U. SHEFFIELD (UK) — Engineers have developed a new technique to graft a biodegradable disc loaded with stem cells onto damaged eyes.
The team at the University of Sheffield describes the method, which involves producing membranes to assist with grafting, in the journal Acta Biomaterialia. The goal is to treat damage to the cornea, the transparent layer on the front of the eye, which is one of the major causes of blindness in the world.
Using a combination of techniques known as microstereolithography and electrospinning, the researchers made a disc of biodegradable material that can be fixed over the cornea. The disc is loaded with stem cells that multiply, allowing the body to heal the eye naturally.
“The disc has an outer ring containing pockets into which stem cells taken from the patient’s healthy eye can be placed,” explains Ílida Ortega Asencio. “The material across the center of the disc is thinner than the ring, so it will biodegrade more quickly allowing the stem cells to proliferate across the surface of the eye to repair the cornea.”
A key feature of the disc is that it contains niches or pockets to house and protect the stem cells, mirroring niches found around the rim of a healthy cornea.
Standard treatments for corneal blindness are corneal transplants or grafting stem cells onto the eye using donor human amniotic membrane as a temporary carrier to deliver these cells to the eye. For some patients, the treatment can fail after a few years as the repaired eyes do not retain these stem cells, which are required to carry out on-going repair of the cornea.
Without this constant repair, thick white scar tissue forms across the cornea causing partial or complete sight loss. The researchers designed the small pockets built into the membrane to help cells group together and act as a useful reservoir of daughter cells so that a healthy population of stem cells can be retained in the eye.
“One advantage of our design is that we have made the disc from materials already in use as biodegradable sutures in the eye, so we know they won’t cause a problem in the body,” says Sheila MacNeil.
Treating corneal blindness is a particularly pressing problem in the developing world, where there are high instances of chemical or accidental damage to the eye but complex treatments such as transplants or amniotic membrane grafts are not available to a large part of the population.
The technique has relevance in more developed countries such as the UK and US as well, according to Frederick Claeyssens.
“The current treatments for corneal blindness use donor tissue to deliver the cultured cells, which means that you need a tissue bank. But not everyone has access to banked tissues and it is impossible to completely eliminate all risks of disease transmission with living human tissue,” Claeyssens says. “By using a synthetic material, it will eliminate some of the risk to patients and be readily available for all surgeons.
“We also believe that the overall treatment using these discs will not only be better than current treatments, it will be cheaper as well.”
Wellcome Trust and the Engineering and Physical Sciences Research Council supported the work.
Source: University of Sheffield