Comparing the Immune Response to PEEK as an Implant Material with and without P-15 Peptide as Bone Graft Material in a Rabbit Long Bone Model

• Published in: Bioengineering (Basel) Vol. 11; no. 9; p. 898
• Main Authors: Cheng, Boyle C, Swink, Isaac R, Cheng, Cooper T, Corcoran, Owen G, Wang, Vicki Z, McClain, 4th, Edward J, Vyas, Praveer S, Owen, Izzy, Xu, Chen, Altman, Daniel T, Yu, Alexander K
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 06.09.2024; MDPI
• Subjects: Allografts; Amino acids; Biomimetic materials; Bone density; bone graft; Bone grafts; Bone growth; Bone healing; Bone implants; bone regeneration; Bone remodeling; Bones; Computed tomography; Cytokines; Density; Femur; Grafting; Grafts; Immune response; Immune system; In vivo methods and tests; Inflammation; Interleukin 4; Interleukin 6; Interleukins; Long bone; Osteogenesis; P-15; PEEK; Peptides; Polyether ether ketones; Rabbits; Skin & tissue grafts; Substitute bone; Surgical implants; Surgical outcomes; Titanium; Transplants & implants; Tumor necrosis factor-α; United States > US; bone graft; P-15; immune response; inflammation; rabbits; bone regeneration; long bone; osteogenesis; PEEK
• ISSN: 2306-5354; 2306-5354
• DOI: 10.3390/bioengineering11090898

P-15 is a 15-amino-acid-long biomimetic peptide widely demonstrated to enhance osteogenesis in vivo. Despite the prevalence of polyether-ether-ketone (PEEK) in interbody device manufacturing, a growing body of evidence suggests it may produce an unfavorable immune response. The purpose of this preliminary study was to characterize the immune response and new bone growth surrounding PEEK implants with and without a P-15 peptide-based osteobiologic. A bilateral femoral defect model was conducted using New Zealand white rabbits. A total of 17 test subjects received one implant in each distal femur, either with or without bone graft material. Animals were allowed to survive to 4 or 8 weeks, at which time the femurs were collected and subjected to micro-computer tomography (microCT) or cytokine analysis. MicroCT analysis included the quantification of bone growth and density surrounding each implant. The cytokine analysis of periprosthetic tissue homogenates included the quantification of interleukins (ILs) and TNF-α expression via ELISA kits. Improvements in bone volume were observed in the P-15 cohort for the regions of interest, 500-136 and 136-0 µm from the implant surface, at 8 weeks post-op. Concentrations of IL-1β, IL-4, and IL-6 cytokines were significantly higher in the P-15 cohort compared to the PEEK cohort at the 4-week timepoint. Significant reductions in the concentrations of IL-4 and IL-6 cytokines from the 4- to 8-week cohort were observed in the P-15 cohort only. The P-15 peptide has the potential to modulate the immune response to implanted materials. We observed improvements in bone growth and a more active micro-environment in the P-15 cohort relative to the PEEK control. This may indicate an earlier transition from the inflammatory to remodeling phase of healing.