Khosla, Kirkland and colleagues tested their hunch by treating 20-month-old mice (the equivalent of 70-year-old humans) with two senolytic compounds previously identified by Kirkland's screens: quercetin and dasatinib. Quercetin is a plant-based natural product. Dasatinib is a drug used to treat leukaemia, though the doses used here were much smaller.
Mice received their senolytic cocktail once a month for four months. Those treated showed a 50% increase in their bone volume. Scans showed that not only had their bone mass increased - a finding that could be due to increased mineralization - but the structure of their bone revealed new deposition of bone tissue, increasing its strength. This ability to stimulate new bone growth is not seen with current osteoporosis drugs, says Khosla.