Honeycomb Scaffold-Guided Bone Reconstruction of Critical-Sized Defects in Rabbit Ulnar Shafts

Abstract

Reconstruction of critical-sized defects (CSDs) in bone shafts remains a major challenge in orthopedics. Honeycomb (HC) scaffolds are considered promising as their uniaxial channels bridge the amputation stumps of bones and promote the ingrowth of bone and blood vessels (BV) into the scaffolds. In this study, the ability of the HC scaffolds, composed of the bone mineral or carbonate apatite (CAp), was evaluated by reconstructing 10, 15, and 20 mm segmental defects in the rabbit ulnar shaft. Radiographic and μ-computed tomography evaluations showed that bony calluses were formed around the scaffolds at 4 weeks post-surgery in all defects, whereas no callus bridged in the ulna without scaffolds. At 12 weeks post-surgery, the scaffolds were connected to the host bone in 10 and 15 mm defects, while a slight gap remained between the scaffold and host bone in the 20 mm defect. New bone formation and scaffold resorption progressed over 12 weeks. Histological evaluations showed that mature bones (MB) and BV were already formed at the edges of the scaffolds at 4 weeks post-surgery in 10, 15, and 20 mm defects. In the central region of the scaffold, in the 10 mm defect, MB and BV were formed at 4 weeks post-surgery. In the 15 mm defect, although BV were formed, a few MB were formed. It is concluded that CAp HC scaffolds have good potential value for the reconstruction of CSDs.

Structurally optimized honeycomb scaffolds with outstanding ability for vertical bone augmentation

“…Honeycomb (HC) scaffolds have the potential of achieving the abovementioned requirements owing to the following reasons: (1) their resorption rate and mechanical strength can be controlled by adjusting strut thickness [36] ; (2) their uniaxial channels facilitate the ingrowth of bone and blood vessels (channels with 230–300 μm opening size are more effective than smaller and larger channels) [36] , [37] , [38] ; (3) micropores (<2 μm) within the struts of HC scaffolds promote bone formation [39] , [40] , [41] ; and (4) predictably sized micropores can be created within the struts by constructing the struts with spherical components based on sphere packing theory: packing 5 μm spheres creates micropores <1 μm, resulting in the enhancement of osteogenesis and angiogenesis [37] , [38] , [41] . Notably, HC scaffolds consisting of carbonate apatite, which is analogous to a bone mineral, show a higher osteoconductivity than those consisting of β-tricalcium phosphate and hydroxyapatite [42] , [43] .…”

No-Observed-Effect Level of Silver Phosphate in Carbonate Apatite Artificial Bone on Initial Bone Regeneration

“…After healing for 4 weeks, the animals were sacrificed, and the implanted femurs were subsequently fixed in a solution of 10% formalin neutral buffer solution to perform X-ray μ-CT imaging (SkyScan, Bruker) and histological evaluations ( n = 3 per group). In μ-CT analysis, the BV/TV and the volume percentage of the remaining materials in the bone defect were measured as previously indicated . In histological evaluations, the specimens were first decalcified with 0.5 mol·L –1 of ethylenediaminetetraacetic acid.…”

“…In μ-CT analysis, the BV/TV and the volume percentage of the remaining materials in the bone defect were measured as previously indicated. 41 In histological evaluations, the specimens were first decalcified with 0.5 mol•L −1 of ethylenediaminetetraacetic acid. After decalcification, the specimens were embedded in paraffin and sliced at 3 μm thickness.…”

Antibacterial Honeycomb Scaffolds for Achieving Infection Prevention and Bone Regeneration

“…Previously, we fabricated honeycomb (HC) materials with uniaxial macropores, that is, channels that penetrate the material. , The HC materials were constructed from interconnecting spheres composed of carbonate apatite (CAp) crystals, − analogous to bone minerals, and contained micropores and nanopores in the HC struts. , Thus, the CAp HC materials are multiscale porous structures. Owing to these characteristics, CAp HC materials are osteoconductive and osteoinductive .…”