I've pointed out work on systematically destroying and recreating an immune system, so as to remove life-threatening damage or errant behavior. Here, the New Scientist reports on a practical demonstration of the technique: "recruited 15 people aged 14 to 31 years who had recently been diagnosed with type 1 diabetes. Roughly 60% to 80% of these patients' insulin-producing cells had been destroyed [by their own immune system] by the time of their diagnosis, and all needed regular insulin shots. The researchers removed bone marrow stem cells from the patients, who were then given drugs such as cytotoxan to wipe out their immune cells. Without an immune system, the patients were vulnerable to infection and so they were given antibiotics and kept in an isolation ward. ... Two weeks later, the patients received infusions of their own stem cells into their bloodstream via the jugular vein, which re-established their immune systems. ... Of the 15 patients, 12 no longer needed insulin shots within a few days of undergoing the procedure." How beneficial could this sort of strategy be for an aged immune system, choked by a buildup of useless cells devoted to fighting non-threatening chronic infections?