Delayed drug delivery improved bone repair in aged mice
In an experiment with six aged female mice per group, grafts that delayed ruxolitinib release produced more new bone after nine weeks.
9 weeks
Edited by Boris Djordjevic · AgingResearch.News
In a randomized experiment in aged female C57BL/6 mice, researchers implanted grafts into skull bone defects 3.5 millimeters wide. Six mice per group received grafts with ruxolitinib released immediately, with a coating that delayed its release, or without the drug. After nine weeks, delayed-release grafts produced more new bone and greater defect closure than either comparison. Bone formation with immediate delivery did not differ significantly from drug-free grafts.
In separate experiments, macrophages, immune cells taken from the bone marrow of 24-month-old female mice, were grown in the lab. Delayed drug delivery preserved early inflammatory gene activity before increasing activity of genes associated with repair. Immediate delivery suppressed the early inflammatory gene activity.
Why it matters
Bone repair needs an early inflammatory response, even though persistent inflammation can hinder it. This work addresses how to target age-related inflammation without disrupting that necessary first phase.
Caveats
The animal experiment tested local graft delivery in skull defects, not systemic dosing or healing in people. It included six aged female mice per group, and the preprint has not been peer-reviewed.
The paper
UConn Health
Research Square, May 22, 2026, Open access, Preprint, not peer-reviewed