Doctors may one day be able to repair damaged bones and joints(関節)with a simple injection of stem cells(幹細胞). A team of researchers is currently experimenting with injectable immature stem cells that they say can be guided through the body with the use of a magnet. Using the patient’s own stem cells harvested from their bone marrow(骨髄), doctors would be able to treat people with arthritis and other injuries without invasive surgery or drugs. A similar technology, which combines a patient’s own stem cells with donor bone cells, has already been used to treat several patients with hip joint(股関節)problems.