Hard tissue sections stained with toluidine blue light microscopy observations at week 24 after surgery.

<p>(A, B): implanted with a rhBMP-2-loaded/CS AVB (group A) A: × 20 magnification; B: × 40 magnification; (C, D): implanted with a non-drug-loaded/CS AVB (group B) C: × 20 magnification; D: × 40 magnification; (E, F):implanted with a autologous iliac bone graft (group C) E: × 20 magnification; F: × 40 magnification; the yellow arrow indicate the implant HA/ZrO₂-based AVB; the red arrow indicate the HA that under degradation; the green arrow indicate new bone, which was more immature would be tinted deeper blue; and the blue arrow indicate autologous.</p

Activities of the beagle dogs during the pre-surgical period and at weeks 6, 12 and 24 after surgery.

<p>(* indicates significant difference between the two groups, p<0.05).</p

Animal experimental situation.

<p>(a) the prepared half-cylinders HA/ZrO₂ porous bioceramic AVB; (b) the beagle dog could stand independently when recover postoperative; (c) postoperative specimens shown: the implanted AVB had integrated with autogenous bone at week 24; (d) embedded AVB in the vertebrae defect in operation; (e) a 56-mm-long surgical steel plate was used to stabilize the implanted AVB; (f) wound closure at last.</p

Hard tissue sections stained with toluidine blue light microscopy observations at week 24 after surgery.

<p>(A, B): implanted with a rhBMP-2-loaded/CS AVB (group A) A: × 20 magnification; B: × 40 magnification; (C, D): implanted with a non-drug-loaded/CS AVB (group B) C: × 20 magnification; D: × 40 magnification; (E, F):implanted with a autologous iliac bone graft (group C) E: × 20 magnification; F: × 40 magnification; the yellow arrow indicate the implant HA/ZrO₂-based AVB; the red arrow indicate the HA that under degradation; the green arrow indicate new bone, which was more immature would be tinted deeper blue; and the blue arrow indicate autologous.</p

Evaluation of a Novel HA/ZrO₂-Based Porous Bioceramic Artificial Vertebral Body Combined with a rhBMP-2/Chitosan Slow-Release Hydrogel

<div><p>A new HA/ZrO₂-based porous bioceramic artificial vertebral body (AVB), carried a recombinant human bone morphogenetic protein-2 (rhBMP-2)/chitosan slow-release hydrogel was prepared to repair vertebral bone defect in beagles. An ionic cross-linking was used to prepare the chitosan hydrogel (CS gel) as the rhBMP-2 slow-release carrier. The vertebral body defects were implanted with the rhBMP-2-loaded AVB in group A, or a non-drug-loaded AVB in group B, or autologous iliac in group C. The encapsulation rate of rhBMP-2 in rhBMP-2-loaded CS gel was 91.88±1.53%, with a drug load of 39.84±2.34 ng/mg. At 6, 12, 24 weeks postoperatively, radiography showed that the bone calluses gradually increased with time in group A, where the artificial vertebral body had completely fused with host-bone at 24 weeks after surgery. In group C, an apparent bone remodeling was occurred in the early stages, and the graft-bone and host-bone had also fused completely at 24 weeks postoperatively. In group B, fusion occurred less than in groups A and C. At 24 weeks after surgery, micro-computed tomography (Micro-CT) revealed that the volume of newly-formed bone in group A was significantly more than in group B (p<0.05). At 24 weeks after surgery, ultra-compressive strengths of the operated segments were 14.03±1.66 MPa in group A, 8.62±1.24 MPa in group B, and 13.78±1.43 MPa in group C. Groups A and C were both significantly higher than group B (p < 0.05). At 24 weeks postoperatively, the hard tissue sections showed that the AVB of group A had tightly fused with host bone, and that pores of the AVB had been filled with abundant nearly mature bone, and that the new bone structured similarly to a trabecular framework, which was similar to that in group C. In contrast, implant fusion of the AVB in group B was not as apparent as group A. In conclusion, the novel HA/ZrO₂-based porous bioceramic AVB carried the rhBMP-2-loaded CS gel can promote the repair of bony defect, and induce bone tissue to grow into the pores, which may replace iliac bone grafts as commonly applied in clinical practice.</p></div

X-ray results of group C after surgery.

<p>C1: at week 6, C2: at week 12, C3: at week 24.</p

Test results of new bone volume detected by micro-computed tomography at week 24.

<p>Test results of new bone volume detected by micro-computed tomography at week 24.</p

Scanning electron microscopy images of lyophilized hydrogel.

<p><b>(A)</b> the lyophilized hydrogel observed as an three-dimensional mesh structure (× 100); <b>(B)</b> the round chitosan microspheres with smooth surface were evenly distributed on the film-like surface (× 350)</p

In vitro release curve of the chitosan hydrogel complex with rhBMP-2.

<p>In vitro release curve of the chitosan hydrogel complex with rhBMP-2.</p