Bad news for science fiction writers, good news for patients. New studies are beginning to break the link between the two major concerns of using stem cells in regenerative medicine: cancer and inflammation.
Of Mice and Monkeys-Early studies showed mice would develop slow growing tumors when injected with large amounts of stem cells. But there were a few seeming keys to causing cancer: the mice had suppressed immune systems and cancer within the study was considered a positive outcome because the tumors demonstrated the cells were pluripotent, able to integrate into the animal’s body and grow. A new study recently reported in Cell Reports used monkeys with healthy immune systems and tumors only developed when the monkeys were given 20 times the amount of stem cells that caused tumors in mice.
The other concern about implanted stem cells is risk of inflammation at the injection sites. The new foreign stem cells were thought in early studies to set off alarms with the immune system causing inflammation and possible rejection of the new cells. The new study found that as long as the stem cells were differentiated toward the cells they were meant to become, and inserted into the same individual who donated the cells, they did not cause inflammation. Previous studies also showed differentiated cells did not cause inflammation but there was a catch, one study inserted the cells into the brain, hoping to regenerate cells lost in Parkinson’s disease and the other inserted the cells into the eye, and these areas tend to have weak immune responses that may have been behind the lack of inflammation. Yet another study inserted differentiated bone precursor stem cells next to bone, where there is a vigorous immune response. Within eight weeks new bone had formed, without major inflammation and a year later there were almost no tumors.
So why is this bad news for sci-fi writers? I post so much about regenerative medicine because some of my characters regenerate using stem cells and anyone who writes knows you have to have conflicts, heavy prices to pay, and often, tragedy, in order to have a story. If there are no negative side-effects to stem cell regeneration, where’s the story? Studies like the ones above remind me to focus on the social, historical and personal consequences of immortality. As much as we have come a long way in creating stem cells that may one day cure disease safely and fully, it is much harder to predict what we humans will do, with all our intricacies and contradictions, hopes and failures, wisdom and foolishness. Maybe that is where the best stories lie anyway.