Vertebral bone marrow clot breakthrough: a powerful osteogenic and antibacterial scaffold for spinal fusion surgery.

Achieving solid arthrodesis while minimizing postoperative infections remains a critical challenge in spinal fusion surgery. Clotted bone marrow aspirate (BMA) has emerged as promising tools to enhance bone fusion, yet their antimicrobial potential remains underexplored. This study investigates the biological and antimicrobial properties of vertebral body BMA (vBMA) clots as a multifunctional scaffold for spinal fusion. Human vBMA clots were characterized by growth factor and cytokine content via ELISA. Mesenchymal stromal cells (MSCs) were isolated and analyzed for morphology, viability, immunophenotype, and trilineage differentiation potential. The antibacterial activity of vBMA clots was assessed against Staphylococcus aureus and Escherichia coli strains by monitoring the bacterial concentration over time. Additionally, production of kinocidins (CXCL1, CCL5, CXCL7, CXCL8, CXCL12) was quantified. vBMA clots exhibited high levels of regenerative cytokines, especially PDGF-AB, and contained viable, multipotent MSCs expressing canonical surface markers. Antibacterial assays revealed potent, broad-spectrum bactericidal activity, with >99 % CFU reduction for both pathogens after 24 h of exposure to the clots, independently from the bacterial culture medium used. Notably, kinocidin production significantly increased upon bacterial exposure, particularly in response to E. coli, suggesting active immune engagement by clot-resident cells. vBMA clots possess a dual regenerative and antimicrobial function, offering a novel, one step and autologous strategy for enhancing spinal fusion outcomes while reducing infection risk. This bioactive scaffold may represent a paradigm shift in spinal surgery by unifying osteogenic support and localized antibacterial defense in a single therapeutic material.