Crohn's disease is a long-term, painful condition that causes inflammation of the lining of the digestive system, according to the NHS. It affects 115,000 people in the UK and causes people to suffer from diarrhoea, abdominal pain, extreme tiredness, weight loss and other symptoms that significantly impact quality of life.

A new trial using stem cell transplants to grow new immune systems for people with untreatable Crohn's disease has begun.

The study is being coordinated by the University of Sheffield's Clinical Trials Unit and is led by Queen Mary University of London and Barts Health NHS Trust. It has received funding of GBP2m from the Medical Research Council (MRC) and National Institute for Health Research (NIHR) partnership.

The trial, called ASTIClite (Autologous Stem cell Transplantation In refractory Crohn's disease – Low Intensity Therapy Evaluation), will recruit patients from centres in Sheffield, Cambridge, Edinburgh, Liverpool, London, Nottingham and Oxford.

Current treatments include anti-inflammatory drugs, which have varying results, so surgery is often required to remove the affected part of the bowel. In extreme cases, after multiple operations, patients may require a final operation to divert the bowel to an opening in the stomach, called a stoma.

Lizzie Swaby, study manager for the ASTIClite trial from the School of Health and Related Research (ScHARR) at the University of Sheffield, said: "Investigators in the ASTIClite trial hope that by completely resetting the patient's immune system through a stem cell transplant, it might be possible to radically alter the course of the disease. Stem cell transplant alone may not provide a cure, but it may allow some patients to start responding to drugs which had not worked previously.

"Although there are multiple treatment options available for patients with Crohn's disease, in many cases these do not work, with patients either not responding, or suffering unpleasant side effects.

"Surgery can be an option, which may allow patients to return to their normal daily activities, but this is not always a suitable, and some patients may not wish to consider surgery."

Stem cell transplants have already been used to wipe out and replace patients' immune systems when it comes in treating multiple sclerosis (MS). The ASTIClite trial will now investigate whether a similar treatment can reduce gut inflammation and offer a potential treatment to Crohn's disease.

The trial will see patients undergo chemotherapy and hormone treatment to mobilise their stem cells, which will then be harvested from their blood. Additional chemotherapy will then be used to wipe out their faulty immune system. When the stem cells are re-introduced into the body, they will develop into new immune cells, giving the patient a fresh immune system.

According to the University of Sheffield, in theory, the new immune system should not then react adversely to the patient's own gut to cause inflammation, and it will also not act on drug compounds to remove them from their gut before they have had a chance to work.

The current clinical trial is a follow-up to the research team's 2015 ASTIC trial which investigated a similar stem cell therapy. In the original trial, the stem cell therapy did not cure the disease but the team found that many patients benefited from the treatment. They felt this justified a further clinical trial. Some side-effects from the doses of the drugs used were also observed, so the follow-up trial will use a lower dose to minimise risk of toxicity.

Director of the NIHR Evaluation, Trials and Studies programmes, Professor Tom Walley, commented: "Stem cell therapies are an important, active and growing area of research with great potential. There are early findings showing a role for stem cells in replacing damaged tissue. In Crohn's disease this approach could offer real benefits for the clinical care and long term health of patients."