Platelet-Rich Fibrin Induces New Bone Formation to Promote Extreme Lateral Interbody Fusion of Spine in Rabbits

Achieving rapid bone fusion is critical for preventing complications in Extreme Lateral Interbody Fusion (XLIF), yet harvesting sufficient autologous bone presents surgical limitations. Platelet-rich fibrin (PRF), an autologous biomaterial rich in osteogenic growth factors, offers potential as a bone graft enhancer. This study evaluated the efficacy of PRF combined with allogeneic bone in promoting interbody fusion using an XLIF-simulated rabbit model.

In vitro, bone marrow mesenchymal stem cells were cultured with PRF, allogeneic bone, or PRF/allogeneic bone composites. Assessments included biocompatibility (CCK-8, Calcein-AM/PI), cell adhesion (phalloidin/DAPI), and osteogenic differentiation (alkaline phosphatase activity/staining, Alizarin Red S). PRF, allogeneic bone, and their composite (PRF/allogeneic bone) were evaluated in a rabbit XLIF model. Autologous iliac crest bone served as a positive control, while empty cages provided negative controls. Endpoints included radiographic (micro-CT), mechanical (biomechanical testing), histological (H&E, methylene blue-acid fuchsin, TRAP), and biochemical (ELISA) evaluation at postoperative 2, 4, 8, and 12 weeks.

In vitro experiments demonstrated that PRF/allogeneic bone composites exhibited noncytotoxic properties and osteogenic-promoting effects when combined with titanium alloy cages. In vivo, fusion progressed temporally across all groups, with the PRF/allogeneic bone composite yielding 12-week fusion rates by manual palpation and micro-CT equivalent to autograft. Biomechanical strength and bone mineral density of PRF/allogeneic bone matched autograft, exceeding allogeneic bone. Histology demonstrated accelerated fusion kinetics: early angiogenesis (2 weeks), fibrocartilage formation (4 weeks), and complete trabecular bridging by 12 weeks. ELISA confirmed earlier BMP-2/VEGF peaks (2-4 weeks) versus allogeneic bone.

These results indicated that the combination of PRF and allogeneic bone successfully induced intervertebral bone formation in the rabbit XLIF model. PRF can serve as a physiological natural fusion material, inducing osteogenesis and achieving spinal fusion. Its osteopromotive effects, cost-effectiveness, and autologous origin support its potential as a superior graft alternative for XLIF procedures.