The Osteogenetic Competence Comparison Of Three Biomaterials In Rat Cleft Palate Model

Background: The success of cleft palate repair operation depends on severalfactors, such as the anatomy and physiology character of palate. The using of animalmodel is beneficial to settle the clinical problems. This study aims to discuss therepairment of different biomaterials to cleft palate by establishing a stable rat cleftpalate model.Objective:1. To establish a stable rat cleft palate model by surgery.2. To compare the osteogenetic competence of collagen, hydroxyapatite andcollagen-hydroxyapatite (collagen bone)-recombinant human bone morphogenicproteins-2(rhBMP-2).Methods:1. The rat cleft palate model.25SD rats (4w) were recruited in this part (5rats/group). An artifical cleft palate starting from the junction of soft and hard palatewas made by surgery. It was4mm-long and0.7mm,0.9mm,1.1mm and1.3mm–width.The control group did not have defects. The critical size defect (CSD) which wasdetermined by gross structure and HE staining was used to evaluate the repairment at12w post-surgery.2.30SD rats (4w) were randomly divided into three groups. The rat cleft palatewas established the same way with part1. Collagen, hydroxyapatite and collagenbone/rhBMP-2were filled into the three groups respectively. The samples wereharvested at12w. The tetracycline hydrochloride was injected subcutaneously14daysand3days before the harvest.(1) The repairment of different groups was estimated bybone volume fraction as well as the number, width and separation of trabecular bonedetecting by Micro CT.(2) The width change of cleft palate and the difference ofosteogenesis rate were determined by tetracycline dual-fluorescence assay. Results:1. The rat cleft palate model and the critical size defect(1) Gross structure: There is no evident abnormality of these rats.(2) The width ofcleft suggested the rat model had similar phenotype with the human disease. After12w,two groups (1.1mm and1.3mm in width) showed no healing ability but the1.3mmgroup had higher lethality than other groups.(3) HE staining: Compare to the negativecontrol, the1.1mm group lost plenty of bone in the middle of palate plate. The cleft hadno soft tissues and even the nasal cavity was involved. Therefore the standard width forrat cleft palate model was1.1mm.2. The osteogenetic competence of three biomaterials(1) The cleft repairment: The collagen bone/rhBMP-2group had high bonevolume fraction than the other two groups (p<0.05). Furthermore, the width oftrabecular bone of collagen bone/rhBMP-2group was175%and350%higher than thecollagen and hydroxyapatite group(p<0.05). While the trabecular bone separationshowed the opposite outcome. The collagen bone/rhBMP-2group was only73%and27%of the other two groups(p<0.05).(2) The osteogenesis rate: the result wasconsistant with that of the cleft repairment. The collagen bone/rhBMP-2group showedbest effect among these three bilmaterials(p<0.05).Conclusions:1. The rat cleft palate model can be successfully established by surgery. The cleftwith4mm-long and1.1mm-width can be used as the standard defect.2. The collagen bone/rhBMP-2exhibits a greater osteo-inductive potential thanthe collagen and hydroxyapatite.