Biodegradation and bioabsorption innovation of the functionally graded bovine bone–originated apatite with blood permeability

Abstract

Bioabsorbable and functionally graded apatite (fg-HAp) ceramics were designed using bovine bone by the calcination and partial dissolution-precipitation methods. The fg-HAp ceramics that were developed had gradual distributions of the degree of crystallinity and the grain size of single-phase hydroxyapatite from the surface layer of the pore wall to the bulk structure region. Calcination at 1073 K gave a specific surface area of 30 m2 x g-1 and porosities of 60-80%. The pore structure of the fg-HAp was classified into two regions: a macro-pore region (100-600 microm) originating from spongy bone and a micro-pore region (10-160 nm) related to body fluid permeation and blood permeability. By implantation in subcutaneous tissue of rat, it was confirmed that body fluid permeated the bulk region of the fg-HAp ceramics through the micro-pores. The volumetric populations occupied by body fluid were 60% at 4 weeks and 68% at 8 weeks in the ceramics explants, indicating drastic bioabsorption, although the body fluid was found to be immunopositive for an albumin as the main serum protein in blood. On the fg-HAp ceramics developed here, the bioabsorption rate could be controlled by careful selection of the calcination temperature. These ceramics can be applied as new biomimetic ceramics exhibiting surface and bulk degradations and cellular absorption by giant cells.

The Effect of Partial Dissolution-Precipitation Treatment on Calcium Phosphate Ceramics in the Release of BMP-2 and Osteoinduction

“…Preparation and physicochemical characterization of calcium phosphate ceramics fg-HAp ceramics were fabricated in the same method as described previously 8,9) . Briefly, bovine spongy and cortical bones were cut into cubic samples, which were boiled and calcined at 800-1100℃for 24 h in air to remove organic components.…”

“…Furthermore, we believe that ideal scaffolds for bone engineering should be bioabsorbable, mimetic and hydrophilic which can allow the permeation of liquid components, such as blood and/or operation 8,9) . The b-HAp ceramics with a porosity of 60-80%…”

Effects of Functionally Graded Hydroxyapatite for Large Mandibular Defects in Adult Rabbits

“…In this step, reprecipitated HAp (r-HAp) was deposited on b-HAp from cancellous bone (fg-HAp) ( Figure 1B, 2B) 1) .…”

“…Specifically, we have developed a form of hydroxyapatite that has a functionally graded crystalline structure that extends from its deepest layer toward its surface layer and called it functionally graded hydroxyapatite (fg-HAp) 1) . The fgHAp consists of an interconnected porous structure similar to cancellous bone.…”

Bone Augmentation Using Novel Unidirectional Porous Hydroxyapatite with Bone Morphogenetic Protein-2 on Rat Skull

“…One of the important points in clinical use of biomaterials is that they must be not only biocompatible but also stable immediately after they are implanted. To facilitate bone formation and shorten the time for bone union, recombinant human bone morphogenetic proteins (rhBMPs) are available, which are known to induce ectopic bone formation in skeletal and nonskeletal sites [5][6][7][8] . The present study was designed to evaluate osteogenic effect of a newly developed UDPHAp as a carrier of rhBMP-2 in the rat onlay graft model.…”