Compound soft regenerated skull material for repairing dog skull defects using bone morphogenetic protein as an inductor and nanohydroxyapatite as a scaffold

BACKGROUND：In previous studies of skull defects and regeneration, bone morphogenetic protein as an inductor and nanohydroxyapatite as a scaffold have been cocultured with osteoblasts. OBJECTIVE： To verify the characteristics of the new skull regenerated material after compound soft regenerated skull material implantation. DESIGN, TIME AND SETTING： The self-control and inter-group control animal experiment was performed at the Sun Yat-sen University, China from February to July 2007. MATERIALS： Twenty-four healthy adult dogs of both genders weighing 15–20 kg were used in this study. Nanohydroxyapatite as a scaffold was cocultured with osteoblasts. Using demineralized canine bone matrix as a carrier, recombinant human bone morphogenetic protein-2 was employed to prepare compound soft regenerated skull material. Self-designed compound soft regenerated skull material was implanted in models of skull defects. METHODS： Animals were randomly assigned into two groups, Group A （n = 16） and Group B （n = 8）. Bilateral 2.5-cm-diameter full-thickness parietal skull defects were made in all animals. In Group A, the right side was reconstructed with calcium alginate gel, osteoblasts, and nanometer bone meal composite; the left side was reconstructed with calcium alginate gel, osteoblasts, nanometer bone meal and recombinant human bone morphogenetic protein-2 composite. In Group B, the right side was kept as a simple skull defect, and the left side was reconstructed with calcium alginate gel, osteoblasts, nanometer bone meal and recombinant human bone morphogenetic protein-2 composite. MAIN OUTCOME MEASURES： Bone regeneration and histopathological changes at the site of the skull defect were observed with an optical microscope and a scanning electron microscope after surgery. The ability to form bone was measured by alizarin red S staining. In vitro cultured osteoblasts were observed for morphology. RESULTS： One month following surgery, newly formed bone trabeculae mostly covered the broken ends of the fractured bone and grew towards the defect regions. Two months after surgery, many disordered bone islands had formed. Three months after surgery, mature bone, medullary cavities and a large number of new bones were detected in the defect regions. Six months after surgery, the left defect was mostly repaired, with a high bone density compared with the right side in Groups A and B. The right defect was mostly repaired in Group A, but only a small fraction of the right defects was repaired in Group B. CONCLUSION： A composite of calcium alginate gel, osteoblasts, nanometer bone meal and recombinant human bone morphogenetic protein-2 can metabolize by itself, gradually ossify and form new bone.

Long-term in vivo monitoring of injury induced brain regeneration of the adult zebrafish by using spectral domain optical coherence tomography

Brain regenerative studies require precise visualization of the morphological structures. However, few imaging methods can effectively detect the adult zebrafish brain in real time with high resolution and good penetration depth. Long-term in vivo monitoring of brain injuries and brain regeneration on adult zebrafish is achieved in this study by using 1325 nm spectral-domain optical coherence tomography（SD-OCT）. The SD-OCT is able to noninvasively visualize the skull injury and brain lesion of adult zebrafish. Valuable phenomenon such as the fractured skull, swollen brain tissues, and part of the brain regeneration process can be conducted based on the SD-OCT images at different time points during a period of 43 days.