Stromal-Cell-Derived Factor-1 Antibody Decreased Cancellous Osseointegration Strength in a Murine Tibial Implant Model

Background: Active recruitment of osteogenic cells by secreted signaling factors, such as stromal-cell-derived factor 1 (SDF-1), has recently been proposed as a novel strategy to enhance osseointegration. However, the intrinsic importance of the SDF-1/C-X-C chemokine receptor type 4 (CXCR4) axis in promoting osseointegration is unknown. To study the role of SDF-1/CXCR4 in osseointegration, we blocked the SDF-1/CXCR4 pathway in a murine tibial implant model through repeated administrations of an antibody against SDF-1. Methods: Using our previously described murine tibial implant model (N = 24), mice were randomized into an anti-SDF-1 group and a control group (N = 12/group). Intraperitoneal injections of CXCL12/SDF-1 monoclonal antibody (84 µg/mouse) or mouse IgG1 isotype were administered on days 2, 4, 7, 10, 13, 16, 19, 22, and 25 post-surgery. Mice were euthanized 4 weeks post-surgery. Peri-implant bone mass and architecture were determined through microcomputed tomography (µ-CT). Bone implant strength was detected through implant pull-out testing. Results: Inhibition of the SDF-1/CXCR4 pathway significantly reduced host bone–implant interface strength but did not significantly change the cancellous architecture surrounding the implant. Conclusion: SDF-1/CXCR4 is an important pathway to achieve maximum implant osseointegration. However, inhibition of the pathway did not completely eliminate osseointegration.