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

Abstract

The activity and the distribution of osteogenic cells around octacalcium phosphate (OCP) granules combined with gelatin matrix (OCP/Gel) onlaid on rat calvaria were analyzed histomorphometrically and immunohistochemically during vertical bone augmentation under mechanical or nonmechanical environment until 8 weeks. OCP/Gel disk was placed in subperiosteal pocket on the calvaria with or without polytetrafluoroethylene (PTFE) support. The latter is a nonmechanical stress model to alleviate the mechanical stress from the subcutaneous tissues. Onlay grafts of gelatin (Gel) sponge disk and OCP granules were also carried out for the comparison purpose. When bone augmentation was evaluated in first area from bone surface (area until 150 μm high from bone surface) and second area above the newly formed bone (area until 150 µm high from the first area), bone formation was enhanced most in first area followed by second area of OCP/Gel with PTFE. The appearance of tartrate-resistant acid phosphatase (TRAP)-positive osteoclast-like cells was suppressed more in the newly formed tissue with PTFE than those without PTFE with an emphasis of the presence of gelatin. Although Runx2 positive-cells were accumulated more in both OCP/Gel with and without PTFE, osteocalcin-positive cells were abundant in OCP/Gel with PTFE than that without PTFE, suggesting that nonmechanical stress condition is more suitable for osteoblast differentiation. The appearance of receptor activator of nuclear factor (NF)-kappaB ligand (RANKL)-positive cells was restrained in OCP/Gel and Gel with PTFE while osteoprotegerin-positive cells were most accumulated in OCP/Gel without PTFE. The results suggest that OCP/Gel composite under the mechanical stress-alleviated condition can enhance bone augmentation through balanced osteoblastic and osteoclastic cellular activities. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1322-1333, 2018.

Octacalcium phosphate/gelatin composite facilitates bone regeneration of critical-sized mandibular defects in rats: A quantitative study

“…The effect of the gelatin matrix with OCP might have also accelerated the biodegradation of the OCP particles. 39 Studies showed that highly resorbable and osteoconductive biomaterials, such as OCP/Gel composite, have potential use in clinical practice, which is consistent with those of the present study. Further studies are necessary to investigate the relationship between the rapid biodegradability and bone regenerative capacity of the OCP/Gel composite.…”

Calcium Orthophosphate (CaPO4) Containing Composites for Biomedical Applications: Formulations, Properties, and Applications

“…For example, OCP granules were combined with gelatin and the prepared composites were spread on rat calvaria. Those composites were found to promote bone growth due to the balanced cellular activity of osteoblasts and osteoclasts [473]. There is also an excellent review on OCP/polymer biocomposites with a controlled hierarchical structure from the macro to the nanoscale [474].…”