BMP-7 Preserves Surface Integrity of Degradable-ceramic Cranioplasty in a Göttingen Minipig Model
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Published on: February 24, 2017
J Camilo Roldán1, Peter Schulz1, Tim Klünter1
1Division of Pediatric Facial Plastic Surgery and Craniofacial Anomalies, Catholic Children's Hospital Wilhelmstift, Hamburg, Germany; Teaching Hospital of the University of Lübeck, Lübeck, Germany; Department of Cranio-Maxillofacial Plastic Surgery, University of Regensburg, Regensburg, Germany; Friedrich-Baur-Research-Institute for Biomaterials, Bayreuth, Germany; Department of Cardiothoracic Surgery, University of Regensburg, Regensburg, Germany; Department of Orthodontics, University of Regensburg, Regensburg, Germany; and Department of Biomaterials, Cell Biology and Tissue Engineering, University of Erlangen, Erlangen, Germany.
Background:
The aim of the study was to evaluate the integrity of a craniotomy grafted site in a minipig model using different highly porous calcium phosphate ceramic scaffolds either loaded or nonloaded with bone morphogenetic protein-7 (BMP-7).
Methods:
Four craniotomies with a diameter of 15 mm (critical-size defect) were grafted with different highly porous (92-94 vol%) calcium phosphate ceramics [hydroxyapatite (HA), tricalcium phosphate (TCP), and biphasic calcium phosphate (BCP; a mixture of HA and TCP)] in 10 Göttingen minipigs: (a) group I (n = 5): HA versus BCP; (b) group II (n = 5): TCP versus BCP. One scaffold of each composition was supplied with 250 μg of BMP-7. In vivo computed tomography scan and fluorochrome bone labeling were performed. Specimens were evaluated 14 weeks after surgery by environmental scanning electron microscopy, fluorescence microscopy, and Giemsa staining histology.
Results:
BMP-7 significantly enhanced bone formation in TCP (P = 0.047). Slightly enhanced bone formation was observed in BCP (P = 0.059) but not in HA implants. BMP-7 enhanced ceramic degradation in TCP (P = 0.05) and BCP (P = 0.05) implants but not in HA implants. Surface integrity of grafted site was observed in all BMP-7-loaded implants after successful creeping substitution by the newly formed bone. In 9 of 10 HA implants without BMP-7, partial collapse of the implant site was observed. All TCP implants without BMP-7 collapsed. Fluorescent labeling showed bone formation at week 1 in BMP-7-stimulated implants.
Conclusions:
BMP-7 supports bone formation, ceramic degradation, implant integration, and surface integrity of the grafted site.
