* Early study shows stem cell infusion can cure superbug TB
* Researchers say more research needed to test treatment
* Some 450,000 people worldwide have drug-resistant TB (Updates with full title of journal)
By Kate Kelland
LONDON, Jan 9 (Reuters) - Patients with potentially fatal "superbug" forms of tuberculosis (TB) could in future be treated using stem cells taken from their own bone marrow, according to the results of an early-stage trial of the technique.
The finding, made by British and Swedish scientists, could pave the way for the development of a new treatment for the estimated 450,000 people worldwide who have multi drug-resistant (MDR) or extensively drug-resistant (XDR) TB.
In a study in The Lancet Respiratory Medicine journal on Thursday, researchers said more than half of 30 drug-resistant TB patients treated with a transfusion of their own bone marrow stem cells were cured of the disease after six months.
"The results ... show that the current challenges and difficulties of treating MDR-TB are not insurmountable, and they bring a unique opportunity with a fresh solution to treat hundreds of thousands of people who die unnecessarily," said TB expert Alimuddin Zumla at University College London, who co-led the study.
TB, which infects the lungs and can spread from one person to another through coughing and sneezing, is often falsely thought of as a disease of the past.
In recent years, drug-resistant strains of the disease have spread around the world, batting off standard antibiotic drug treatments.
The World Health Organisation (WHO) estimates that in Eastern Europe, Asia and South Africa 450,000 people have MDR-TB, and around half of these will fail to respond to existing treatments.
TB bacteria trigger an inflammatory response in immune cells and surrounding lung tissue that can cause immune dysfunction and tissue damage.
Bone-marrow stem cells are known to migrate to areas of lung injury and inflammation and repair damaged tissue. Since they also modify the body's immune response and could boost the clearance of TB bacteria, Zumla and his colleague, Markus Maeurer from Stockholm's Karolinska University Hospital, wanted to test them in patients with the disease.
In a phase 1 trial, 30 patients with either MDR or XDR TB aged between 21 and 65 who were receiving standard TB antibiotic treatment were also given an infusion of around 10 million of their own stem cells.
The cells were obtained from the patient's own bone marrow, then grown into large numbers in the laboratory before being re-transfused into the same patient, the researchers explained.
During six months of follow-up, the researchers found that the infusion treatment was generally safe and well tolerated, with no serious side effects recorded. The most common non-serious side effects were high cholesterol levels, nausea, low white blood cell counts and diarrhoea.
Although a phase 1 trial is primarily designed only to test a treatment's safety, the scientists said further analyses of the results showed that 16 patients treated with stem cells were deemed cured at 18 months compared with only five of 30 TB patients not treated with stem cells.
Maeurer stressed that further trials with more patients and longer follow-up were needed to better establish how safe and effective the stem cell treatment was.
But if future tests were successful, he said, it could become a viable extra new treatment for patients with MDR-TB who do not respond to conventional drug treatment or those with severe lung damage. (Reporting by Kate Kelland; Editing by Elizabeth Piper and Sonya Hepinstall)