Targeted therapies are the immediate future of cancer treatments: destroy only the cells that matter with few or no side-effects. Here, stem cells are used as the targeting mechanism: "Experiments in cell cultures and in mice showed the adult stem cells - a type known as mesenchymal stem cells - could home in on cancer cells and deliver a lethal protein that attacked only the cancer while sparing normal healthy tissue. ... We've developed cells which specifically target cancer through the body and deliver an anti-cancer protein to where it is needed in a seek-and-destroy approach ... [researchers] altered the cells to express or make the cancer-killing protein called TNF-related apoptosis-inducing ligand or TRAIL. ... This protein has the ability to cause the death only of cancer cells. By combining these two approaches, we have a cell which has the ability to go around the body and find and destroy tumors. ... An attractive property of these cells is that they are 'immunoprivileged,' meaning the body will not reject them as foreign invaders. That means they can be made in batches instead of having to make custom stem cell treatments for each patient ... the team hopes human trials could begin in two or three years."