Stem cell transplants could offer hope of a cure for blindness after a trial showed the procedure improved the sight of patients with severely poor vision in just 18 months.
A study of 16 people with limbal stem cell deficiency – which affects around 1,800 people in England – found transplanting stem cells from the corneas of deceased donors helped improved the patients’ vision.
Scientists found it also reduced pain in the patients and made activities like reading easier.
Although early days, the ‘promising’ research shows ‘potential for safe stem cell eye surgery’, the researchers claim.
The research was carried out by the University of Edinburgh and led by Professor Balijean Dhillon, chair of clinical ophthalmology.
‘The findings from this small study are very promising and show the potential for safe stem cell eye surgery as well as improvements in eye repair,’ Professor Dhillon said.
‘Our next steps are to better understand how stem cells could promote tissue repair for diseases that are extremely hard to treat and if, and how, they could help to restore vision.’
The scientists analysed 13 people with limbal stem cell deficiency (LSCD).
In healthy people, the cells that line the surface of the cornea – the eye’s outermost layer – continually regenerate.
These stem cells come from a bank in the limbus – the border of the cornea and the white part of the eye, which is known as the sclera.
LSCD sufferers cannot regenerate these stem cells, leading to pain, scarring and severely reduced vision, which can even include blindness.
The condition can be brought on by damage from heat or chemicals, or a condition known as aniridia – the absence of the iris.
In the study, stem cells were grown from cornea samples taken from the eyes of organ donors within 24 hours of their death.
Stem cells have the unique ability to develop into any specialised cell type in the body.
The cells were then cultured on an amniotic membrane – tissue taken from the placenta that promotes healing – before being transplanted onto eight of the patients’ eyes.
The remaining patients were just transplanted with an amniotic membrane and acted as the controls.
All of the patients had their immune systems suppressed to prevent them rejecting the transplant.
They also all received eye drops with growth-promoting chemicals.
After 18 months, five of the treated patients and four of the controls reported clearer vision, which was not statistically different.
The similar results – published in the journal Stem Cells Translational Medicine -between the two groups may be due to the beneficial eye drops all the participants received.
But only the treated group experienced ‘significant, sustained improvement’ in their ocular surface scores (OSS), the authors wrote.
OSS take into account vision, eye pain, feelings of ‘grittiness’, light sensitivity, and the ease a person can read, drive, use a computer and watch TV.
In terms of side effects, two of the treated patients and one of the controls experienced intraocular pressure – swelling within the eye.
The researchers believe this may have been due to the steroid injection the participants were given after the transplant ‘according to standard of care’.
Overall, there were no serious adverse events, they add.
Although the findings are ‘promising’, the researchers stress the study was only intended to prove safety and feasibility of the transplant. Therefore further trials are required, they added.
Patients who were previously unable to make out a hand waving in front of their face were said to be able to read two lines of an optician’s vision chart after their operation.
Transplant patients saw their vision improve – but so did the people not given the treatment. This may be due to a beneficial effect of the eye drops used.