Health A joint discovery Research into the effectiveness of stem cells in the treatment of osteoarthritis of the knee is proving promising words: Peter Stannett S tem cells are biological structures within the body that have the ability to develop into many different types of cell. They can also repair tissue by replacing damaged cells. Stem-cell therapy has long been thought of as a potential treatment for several conditions including osteoarthritis and can help treat people with damaged bone and cartilage. The first UK-based clinical trial to compare the effectiveness of stem cells with bone marrow and cartilage in those with knee osteoarthritis is now under way. The study which is taking place at the Robert Jones and Agnes Hunt Orthopaedic Hospital, in Oswestry, Shropshire is funded by the Medical Research Council, Arthritis Research UK and the Orthopaedic Institute. It is one of many research projects looking into treating osteoarthritis with stem-cell therapy. Researchers selected 100 people aged between 18 and 80, with early knee osteoarthritis, for the randomised, controlled trial. Participants were assigned to one of three groups: those receiving stem cells from bone marrow; those receiving stem cells from cartilage; and those receiving a combination of stem cells from bone marrow and cartilage. Once the study is complete, the patients will be followed up for 20 years. Best for the job The research aims to find out which type of cell would best repair damaged tissue. Initial analysis has been undertaken at the five-year stage, with very promising results suggesting that cartilage-cell implantations are the most favourable. Further findings are likely to be published as the study continues. In the trial, tissue is removed from either bone marrow or healthy cartilage in a non-load-bearing part of the knee. The cells are incubated so that they multiply, and these cells are inserted into the damaged knee joint three weeks later. After the second procedure, patients are enrolled on an intensive physiotherapy course. Several laboratory studies are running in parallel with this clinical study, to investigate the biological processes of repair and the predictors of success and failure, as well as to assess the characteristics and genetics of both cell types. The National Institute for Health and Care Excellence (NICE) has published draft guidance suggesting that the technique known as autologous chondrocyte implantation (ACI) should currently only be used for research purposes. The use of stem cells could reduce the need for knee replacement surgery in the future, and this trial will help identify which patients will get the most benefit. It is not yet known, however, whether stem cells will cure osteoarthritis or delay the need for surgery. n peter stannett is the information officer at arthritis Care