Single-cell RNA-seq analysis reveals reduction of B cells in the bone marrow promote fracture healing

Recent studies have identified B cells inhibit bone formation in rheumatoid arthritis by suppressing osteoblast differentiation. However, it remains unknown how B cells participate in the healing of fractures. Here we find that B cells decrease significantly during fracture healing and returned to normal levels after that by single-cell profiling. Furthermore, we found that exosomes derived from B cells inhibited the differentiation of osteoblasts and osteoclasts in vitro. Additionally, injection of these exosomes in mice delayed fracture healing. Thus, maintaining low B cell levels in the bone marrow microenvironment promotes fracture healing. Overall design: scRNA profiles of fracture at different stage (control group, 30th day)