Ti6Al4V/Xenogeneic bone composite promotes osseointegration by recapitulating the osteogenic microenvironment

Abstract

Ti6Al4V implants are used to repair critical-sized bone defects, but their bioinert surfaces often cause insufficient early osteogenic stimulation, potentially leading to compromised long-term fixation. The osteogenic microenvironment is vital for osseointegration between the host bone and the implant and influences long-term clinical outcomes. Consequently, researchers have attempted to mimic the natural osteogenic microenvironment using microporous design, physical and chemical modification, and loading of bioactive factors. The present study proposes a strategy for fully recapitulating the natural osteogenic microenvironment within microporous Ti6Al4V implants. First, Ti6Al4V scaffolds were implanted into rat femoral condyle defects to establish osseointegration. The resulting construct was then demineralized and decellularized to produce an implantable Ti6Al4V/xenogeneic bone composite. Pull-out tests demonstrated that the bone tissue remained well-integrated with the scaffold after processing. Nucleic acid detection and galactose-α-1,3-galactose (α-Gal) analysis verified the elimination of immunogenicity in the composite. Immunofluorescence staining for bone morphogenetic protein-2 and transforming growth factor-β confirmed the preservation of key bioactive factors. In vitro cell experiments revealed favorable biocompatibility and osteoinductive activity. When implanted into rabbit femoral condyle defects, the composite significantly enhanced bone ingrowth into the microporous Ti6Al4V implant and strengthened osseointegration. Histological and quantitative analyses further showed that the composite shifted the osteogenic pattern from the osteoconduction-dominant mode characteristic of Ti6Al4V implants to an osteoinduction-dominant pattern of bone formation. In summary, we developed a novel Ti6Al4V/xenogeneic bone composite that fully recreated the natural osteogenic microenvironment. This composite effectively improved the osseointegration capacity of conventional scaffolds and demonstrated considerable potential for clinical application.