Osteochondroprogenitor cells and neutrophils expressing p21 and senescence markers modulate fracture repair

In the present study we leverage the power of mass cytometry by time-of-flight (CyTOF) to define, at the single-cell level, mesenchymal bone and marrow senescent cells in mice during fracture. Three main CyTOF experiments were performed: 1) TIMECOURSE: Assessment of senescent cell burden in skeletal and immune cell populations during a 28-day timecourse of fracture healing. 2) P21-ATTAC: Identification of cell populations targeted through p21+ cell clearance in p21-ATTAC mice. 3) OCH-STEM: In-depth assessment of osteochondroprogenitor (OCH) cells through expanded panel, including skeletal stem cell (SSC) markers.