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Harrison Kingsley, 28, suffered a serious stroke three months ago.
Mr Kingsley had suffered an ischemic stroke, where a blood clot cuts off the supply of blood and oxygen, to the brain.
Doctors at the RVI had hoped to remove the clot but discovered that could not be done.
Instead, Mr Kingsley became the first participant in the trial, to investigate whether an infusion of stem cells can aid recovery.
Why are stem cells being trialled in stroke treatment?
Stem cells are produced by bone marrow. Research has found that stem cells can repair damaged tissue in the brain and calm inflammation of brain tissue.
Stem cell infusions are seen as easy to administer. They are given to the patient intravenously, at the bedside.
This trial could also extend the window of time where stroke patients can be offered treatment.
At the moment, they need to arrive at hospital within hours of their stroke to be prescribed 'clot busting' medication.
Stroke research nurse, Michelle Fawcett, explained: "At the present time patients who have a blood clot on the brain can get active treatment if they come into the hospital within four and a half hours and we can give them a clot busting medication.
"After that there's a bit of a gap where really we could do with some more treatment for those patients that would probably aid their recovery and these sort of trials are looking at the potential of doing that."
Stem cell treatment could be offered up to 36 hours from the onset of a stroke, providing a much wider potential timeframe.
Consultant Dr Anand Dixit said: "It does reduce the inflammation and thereby limits the stroke size potentially and if it's proven to be an effective treatment, it's very easy to administer.
"It's just like a blood transfusion and that's where the potential lies."
In this trial, not every patient will receive the stem cell infusion - some will be given a placebo, or dummy, version.
Harrison Kingsley does not know which was administered to him, but said his recovery had been heartening.
"I was walking two weeks after the stroke which was amazing," he said.
"My left arm has taken a little while to come back but I've got movement in my left arm. Cognitively I'm back as well so everything's going really well."
Crucially, Mr Kingsley was able to leave hospital in time to attend the birth of his baby and is thankful for the opportunity to take part in the trial.
Over time, researchers hope the participation of patients like him will help determine the effectiveness of stem cell treatment for those who have suffered strokes.
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