A red-hot anti-aging strategy quietly passed its first test earlier this year after 14 volunteers took drugs meant to kill off old, toxic cells in their bodies.
Patients took two pills that Kirkland and his colleagues believed could selectively get rid of aged cells: the leukemia drug dasatinib and a supplement called quercetin.
A bubble of commercial enthusiasm has been building around the idea that aging could be postponed, or its effects tempered, using drug treatments. A company called Unity Biotechnology of Brisbane, California, is developing two senolytic drugs, the first of which is in a phase 1 clinical trial for osteoarthritis—it’s being injected into people’s knees.
These drugs take aim at senescent cells, which have exhausted their ability to divide but remain capable of spewing out a potent mix of chemical signals. “It is thought that these cells and the substances they produce are involved in the process of aging,” says Nicolas Musi, who participated in the new study and directs the Sam and Ann Barshop Institute for Longevity and Aging Studies at the University of Texas at Austin. “The idea is that removing these cells may be beneficial to promote healthy aging and also to prevent diseases of aging.”
Not everything about senescent cells is bad. The cells, and their secretions, are believed to be important during the development of embryos, in the timing of labor, and in healing wounds and forming scar tissue. “You wouldn’t ever want to administer senolytics to a pregnant woman,” Campisi says. “It’s now becoming clear that you need these secretions for certain good things to happen. When the secretions become chronic as opposed to periodic or episodic, that’s when it starts to drive pathology.”