Faculty of Veterinary Medicine, Urmia University Veterinary Research Forum 2008-8140 17 4 2026 04 01 Effects of polycaprolactone/hydroxyapatite nanocomposite scaffolds combined with platelet-rich fibrin for repair of rabbit calvarial bone defects 233 241 736401 10.30466/vrf.2025.2060149.4752 EN Sina Yal Beiranvand Department of Clinical Sciences, Faculty of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad, Iran Shiva Amanollahi Department of Clinical Sciences, School of Veterinary Medicine, Shiraz University, Shiraz, Iran 0000-0002-8656-3079 Hossein Nourani Department of Pathobiology, Faculty of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad, Iran Hossein Kazemi Mehrjerdi Department of Clinical Sciences, Faculty of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad, Iran 0000-0002-5593-6864 Journal Article 2025 05 09 Bone tissue engineering offers a potential alternative to conventional grafting by combining biocompatible scaffolds with biological stimulants. Polycaprolactone (PCL) is a biodegradable polyester with good mechanical strength and biocompatibility. Hydroxyapatite (HA) is a calcium phosphate mineral that is a major component of bone and has excellent bioactivity and biocompatibility. This research investigated the histopathological effects of PCL-HA nanocomposite scaffolds along with their combination with platelet-rich fibrin (PRF), on the regeneration of bone in rabbit calvarial bone defects. Four circular full-thickness bone defects of 5.00 mm in diameter were created on the calvarial bone of 15 male New Zealand white rabbits. Three defects were filled with PRF, PCL-HA, and PCL-HA/PRF, and one defect was served as a control with no filler. Histopathological evaluations were conducted at 4-, 8-, and 12-weeks post-implantation. Data were evaluated using the Kruskal-Wallis and Mann-Whitney U tests. Significant differences were observed between the treatment and control groups regarding bone regeneration throughout all 12^th weeks studied. In the 4^th weeks, no significant differences in bone regeneration were noted among the treatment groups. In the 8^th weeks, most new bone formation was observed in the PCL-HA/PRF group. Both the PCL-HA and PCL-HA/PRF groups significantly improved bone regeneration compared to the control and PRF groups, with the PCL-HA/PRF group demonstrating the greatest bone formation, and vascularization and the lowest inflammation by the 12^th week. Thus, PCL-HA/PRF could be considered as a suitable alternative to bone grafts and could be increasingly utilized in orthopedic surgery and bone tissue engineering. https://vrf.iranjournals.ir/article_736401_5f3562555cc2b996faad2cf3ad617e1c.pdf