What is amazing is you can do this in the lab and transfer the cells back into the patient and get them to take, writes DICK AHLSTROM, Science Editor
IRELAND MAY soon be growing replacement eye tissues to order, in the process restoring sight lost due to accident or disease. Scientists here are using stem cells to grow corneal transplants, and these could become available as early as next year.
The project involved a collaborative effort by the Royal Victoria Eye and Ear Hospital, Dublin City University’s National Institute for Cellular Biotechnology and the Irish Blood Transfusion Service.
The idea was first conceived four years ago when William Power, consultant opthalmologist at the Royal Victoria, compared notes with Prof Martin Clynes at the DCU institute. Power knew that the US was using the technique and that the UK was developing it, and he wanted to use it for his own patients.
The institute in turn worked out methods of harvesting and then growing sheets of stem cells to produce replacement corneal tissues, the very outer layer of corneal cells called the epithelium.
These techniques, worked out by PhD research fellow Finbarr O’Sullivan and Prof Clynes, were then transferred across to the Irish Blood Transfusion Service. The service runs the national tissue bank that supplies ocular tissues for surgical use and is the only centre in Ireland that has the specialist clean-room laboratory facilities needed to meet the exacting standards applied under the EU’s Advanced Therapy Medicinal Products regulations.
And soon the service will begin providing a supply of corneal epithelial cells to surgeons such as Power.
“It has kind of gone full circle,” Power says. He raised the possibility of developing the techniques in Ireland and the DCU team agreed. “Very quickly Martin and Finbarr got the techniques down and working,” Power says.
The corneal epithelial layer can easily be burned by farming and industrial accidents and certain diseases can also damage this essential layer of cells leading to loss of vision.
The stem cells that grow into the corneal issues can be harvested from a patient’s own undamaged eye or provided by a donor. It takes only 10 to 14 days to grow the cells and deliver a sheet about three cells deep.
“What is amazing is you can do this in the lab and transfer the cells back into the patient and get them to take,” Power says. Once the service passes the regulatory hurdles Power would expect to treat up to 20 patients a year using the technique.
The institute has a clinical co-ordinator, Vincent Lynch, and is constantly looking to find ways research can be used to improve medical treatments, O’Sullivan says. When the idea was proposed the institute immediately took it on and began studying stem cells recovered from the limbus, the area where the white of the eye meets the cornea.
Challenges included finding them then getting them to grow in culture and to get them to form flat sheets, he says. “We collect the corneal epithelial stem cells from the limbus and grow them on to a carrier, amniotic membrane.”
Once the sheet is ready it can be transplanted on to the patient’s eye and sutured to hold it in place. The membrane is only a carrier and soon disappears, with the healthy epithelial cells remaining. “It looks quite promising,” O’Sullivan says.
Once the techniques for producing the cell sheets was established, the service had to become involved.
It was the only place where the highest standard of clean rooms was available to meet the demands for tissue-based treatments set by the EU, says Dr William Murphy, the service’s medical and research director, who is currently seconded to the HSE.
Many blood-transfusion services have, to varying degrees, got involved in providing ocular tissues for transplant, and the Irish service planned for this, installing two advanced clean rooms. “We built the new blood-transfusion building in 2000 and we anticipated this need,” he says.
It is now using the DCU methods and conducting tests on the resultant corneal cells, Murphy says. Once satisfied it can produce the tissues and meet standards it will then seek authorisation to supply from the Irish Medicines Board, which is responsible for policing EU regulations relating to medical products, he says.
Funding for the research effort came from the Royal Victoria and the Health Research Board. The service also contributed via a bequest given to it by Edith Ingram. “We decided to use it to fund our part of this collaboration with DCU,” Murphy says.
