Aging is associated with reduced lean and bone mass, as well as alterations in gut microbiota composition. We previously demonstrated that gut microbiota composition differs between young adult and old mice, and that transplanting gut microbiota from old donors into young germ-free mice reduces lean mass, but not bone mass, compared with transplantation from young adult donors. In this study, we investigated whether the reduced lean and bone mass observed in old mice could be restored through gut microbiota transplantation from young adult donors. Old mice (18-month-old) were treated with antibiotics to deplete their gut microbiota and subsequently transplanted with gut microbiota from either young adult (5-month-old) or old (21-month-old) donors. Recipient mice colonized with gut microbiota from young adult donors showed distinct beta and alpha diversity compared with those colonized with gut microbiota from old donors, demonstrating successful transplantation. However, no differences in lean or bone mass were observed between old mice transplanted with gut microbiota from young adult donors and those receiving gut microbiota from old donors. In conclusion, our findings demonstrate that gut microbiota composition differs in mice transplanted with young adult compared with old gut microbiota but neither reduced lean mass nor reduced bone mass in old mice can be restored through gut microbiota transplantation from young adult donors.
Lawenius et al. (Wed,) studied this question.