Osseointegration effect of biomimetic intrafibrillarly mineralized collagen applied simultaneously with titanium implant: A pilot in vivo study

Objectives To investigate the promoting effects of biomimetic intrafibrillarly mineralized collagen (IMC) bone scaffold material on the osseointegration of a titanium implant simultaneously grafted into a critical-sized bone defect as well as the underlying mechanisms involved. Materials and Methods A critical-sized bone defect was created in the rat femur, and a titanium (Ti) implant surrounded by IMC or extrafibrillarly mineralized collagen (EMC) bone scaffold material was placed in the defect. A blank group and a natural bone group were included as controls. Osseointegration was assessed by micro-computed tomographic, histological, and biochemical evaluations at 12 weeks postoperatively. Microarray technology was applied for transcriptional profile analysis at days 7 and 14 postoperatively. Results Significant bone regeneration and osseointegration were observed in the IMC and EMC groups according to mu-CT and histological analyses. The bone volume (BV)/total volume (TV) fraction, bone-to-implant contact percentage, and bone area percentage as well as ultimate shear strength and maximal pull-out force were all significantly higher in the IMC group than in the EMC group (all p < 0.05). Transcriptional analysis revealed overexpression of genes mainly associated with cell proliferation, immuno-inflammatory response, skeletogenesis, angiogenesis, neurogenesis, and skeletogenesis-related pathways during the early process of osseointegration in the IMC group. Conclusion Our data suggest that IMC placed simultaneously with a Ti implant may be a promising strategy in jawbone defect reconstruction. Several candidate genes that were found to be differentially expressed in the IMC group may be responsible for the superior osseointegration effects in this model.