Search

Bone defects above critical size do not heal completely by itself and thus represent major clinical challenge to reconstructive surgery. Numerous bone substitutes have already been used to promote bone regeneration, however their use, particularly for critical-sized bone defects along with their long term in vivo safety and efficacy remains a concern. The present study was designed to obtain a complete healing of critical-size defect made in the proximal tibia of New Zealand White rabbit, using nano-hydroxyapatite/gelatin and chemically carboxymethylated chitin (n-HA/gel/CMC) scaffold construct. The bone-implant interfaces and defect site healing was evaluated for a period up to 25 weeks using radiography, micro-computed tomography, fluorescence labeling, and histology and compared with respective SHAM (empty contra lateral control). The viscoelastic porous scaffold construct allows easy surgical insertion and post-operatively facilitate oxygenation and angiogenesis. Radiography of defect treated with scaffold construct suggested expedited healing at defect edges and within the defect site, unlike confined healing at edges of the SHAM sites. The architecture indices analyzed by micro-computed tomography showed a significant increase in percentage of bone volume fraction, resulted in reconciled cortico-trabecular bone formation at n-HA/gel/CMC constructs treated site (15.2% to 52.7%) when compared with respective SHAM (10.2% to 31.8%). Histological examination and fluorescence labeling revealed that the uniformly interconnected porous surface of scaffold construct enhanced osteoblasts' activity and mineralization. These preclinical data suggest that, n-HA/gel/CMC construct exhibit stimulation of bone's innate regenerative capacity, thus underscoring their use in guided bone regeneration.

A novel three-dimensional (3D) scaffold has been developed from the unique combination of nanohydroxyapatite/gelatin/carboxymethyl chitin (n-HA/gel/CMC) for bone tissue engineering by using the solvent-casting method combined with vapor-phase crosslinking and freeze-drying. The surface morphology and physiochemical properties of the scaffold were investigated by dissolvability test, infrared absorption spectra (IR), X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM), mechanical testing, and soaking in simulated body fluid (SBF). An optimized (composition and processing parameters) ratio of n-HA:gel:CMC (1:2:1), exhibited ideal porous structure with regular interconnected pores (75-250 μm) and higher mechanical strength. Result suggested that the divalent (Ca(++)), carboxyl (COO(-)), amino (NH4(+)), and phosphate (PO4(3-)) groups created favorable ionic interactions which facilitated structural stability and integrity of the composite scaffold. The SBF soaking experiment confirmed the apatite nucleation ability, induced by CMC incorporation. Furthermore, hemocompatibility (hemolysis, platelet adhesion, and protein adsorption) and biocompatibility with MG63 osteoblast cells (MTT assay, cell morphology, and confocal studies from within the 3D scaffold) indicated that the structural and dimensional stability of composite scaffold provided an optimal mechanosensory environment for enhancement of cell adhesion, proliferation, and network formation. The n-HA/gel/CMC composite, therefore, may serve as a promising composite scaffold for guided bone regeneration., (Copyright © 2012 Wiley Periodicals, Inc.)