This has the look of science we'll be hearing more of later: "The spleen might be a source of adult stem cells that could regenerate the insulin-producing islets of the pancreas. ... the same team now report that these potential adult stem cells produce a protein previously believed to be present only during the embryonic development of mammals. ... There may be a previously undiscovered pocket of primitive stem cells in the spleen that are important for healing several types of damage or injury." You might recall that researchers have also identified primitive or embryonic stem cells hiding in adult hair follicles. There may be more such cells to be found elsewhere as well - searching certainly seems to be a worthwhile activity.