Scientists have used stem cells to repair arthritis damage in mice.They tweaked the stem cells’ genes to pump up production of a bone-building protein called BMP-4. When mice with knee injuries got those stem cells, their knees healed better than other mice with the same injuries. The finding comes from doctors including Ryosuke Kuroda, MD, PhD, of Children’s Hospital of Pittsburgh and the University of Pittsburgh. The experiment, described in Arthritis & Rheumatism, only included mice, not people. Joint damage is a hallmark of arthritis, and scientists don’t have a way to make arthritis-damaged joints as good as new.Healing an...