Granule Size–Dependent Bone Regenerative Capacity of Octacalcium Phosphate in Collagen Matrix

Abstract

The present study was designed to determine whether the osteoconductivity of octacalcium phosphatecollagen (OCP/Col) composite can be improved by controlling the granule size of OCP. The granules of synthetic OCP, with diameters in the range of 53 to 300, 300 to 500, and 500 to 1000 mm, were used as an inorganic source of composite materials mixed with atelo-Col. After vacuum dehydrothemal treatment, OCP/Col disks were implanted into critical-sized calvaria defects in Wistar rats for 4, 8, and 12 weeks and examined radiographically, histologically, histomorphometrically, and histochemically. The materials were characterized according to mercury intrusion porosimetry and scanning electron microscopy. X-ray diffraction was performed before and after implantation. The dissolution of OCP crystals in a Col matrix was determined by immersing OCP/Col disks in a culture medium. OCP/Col had a constant pore size (*30 mm) regardless of OCP granule size. OCP in the Col matrix tended to convert to hydroxyapatite (HA) during the implantation. OCP/Col with the smallest granules of OCP enhances both bone regeneration and biodegradation the most through tartrateresistant acid phosphatase (TRAP)-positive osteoclastic cellular resorption of OCP granules. The smallest OCP granules in the Col matrix showed the highest dissolution and had the greatest potential to form HA. The results indicated that the size of the included OCP granules can controll the osteoconductivity of OCP/Col. The overall results suggest that the physicochemical property of OCP crystals is a factor that determines the bone regenerative capacity of OCP/Col in critical-sized calvaria large bone defects in rats.

Osteogenic cellular activity around onlaid octacalcium phosphate‐gelatin composite onto rat calvaria

“…The previous study by OCP implantation in the granule form in mouse calvaria criticalsized defect, which could be a nonloading locus, showed that bone formation became higher with increasing the granule size accompanied by higher appearance of TRAPpositive cells. 38 Similar result was observed in the implantation of OCP/Gel composite in rat calvaria defect. 30 An interesting finding in the present results is that the appearance of osteoclast-like cells was suppressed in OCP/ Gel with PTFE (Fig.…”

“…3). 14,35,38,[42][43][44] However, because OCP small crystals-co-precipitated gelatin composite induced TRAPpositive cells during bone regeneration in rat calvaria defect, 39 the activity of OCP probably associated with the size of the OCP granules, may be involved in accumulation of the osteoclast-like cells in the present OCP/Gel composites. 11 This may be stemmed from the difference of the matrix materials between gelatin and collagen, in which the appearance of TRAP-positive cells by onlaid Gel sponges was almost inhibited in both the mechanical stress conditions with and without PTFE support (Fig.…”

Adsorption of Chromium (VI) on Calcium Phosphate: Mechanisms and Stability Constants of Surface Complexes

“…Two surface species were always formed when hydration equilibrium was reached; deprotonated ( > SCrO 4 ) and protonated (> SHCrO 4 ) complexes, which were more stable in near neutral, than acidic, solution. This was consistent with modeling adsorption data, indicating a mixture of both monodentate and bidentate chromate surface complexes on goethite [62,63].…”

A Novel BMP2‐Coprecipitated, Layer‐by‐Layer Assembled Biomimetic Calcium Phosphate Particle: A Biodegradable and Highly Efficient Osteoinducer

“…27 After 5 weeks, 60 to 82% of BioCaP degraded ( Figure 6B), which indicated a significantly higher degradability of BioCaP than most of the clinically used CaP-based bone-filling materials. 27 After 5 weeks, 60 to 82% of BioCaP degraded ( Figure 6B), which indicated a significantly higher degradability of BioCaP than most of the clinically used CaP-based bone-filling materials.…”