Complexation of Injectable Biphasic Calcium Phosphate with Phosphoserine-Presenting Dendrons with Enhanced Osteoregenerative Properties.

Injectable biphasic calcium phosphates have been proposed as a solution in the treatment of a range of clinical applications including as fillers in the augmentation of osteoporotic bone. To date, various biodegradable natural or synthetic organics have been used as a polymer component of bone materials to increase their cohesiveness. Herein, a novel bone material was developed combining osteoconductive biphasic calcium phosphate (BCP) nanoparticles with phosphoserine-tethered generation 3 poly(epsilon-lysine) dendron (G3-K PS), a class of hyperbranched peptides previously shown to induce biomineralization and stem cell osteogenic differentiation. Strontium was also incorporated into the BCP nanocrystals (SrBCP) to prevent bone resorption. Within 24 h, an antiwashout behavior was observed in G3-K PS-integrated pure BCP group (BCPG3). Moreover, both in vitro tests by relevant cell phenotypes and an in vivo tissue regeneration study by an osteoporotic animal bone implantation showed that the integration of G3-K PS would downregulate Cxcl9 gene and protein expressions, thus enhancing bone regeneration measured as bone mineral density, new bone volume ratio, and trabecular microarchitectural parameters. However, no synergistic effect was found when Sr was incorporated into the BCPG3 bone pastes. Notably, results indicated a concomitant reduction of bone regeneration potential assessed as reduced Runx2 and PINP expression when bone resorptive RANKL and CTX-I levels were reduced by Sr supplementation. Altogether, the results suggest the potential of injectable BCPG3 bone materials in the treatment of osteoporotic bone defects.

A degradable soybean-based biomaterial used effectively as a bone filler in vivo in a rabbit.

The 'gold standard' for bone filling is currently the bone autograft, but its use is limited by material availability and by the possible risks of infection or other donor site morbidity. Materials proposed so far as bone fillers do not show all the characteristics which are desirable. These are (a) osteoconductivity, (b) controlled biodegradation and (c) ease of adaptation to the implantation site. Recently, a new class of biodegradable material based on soybeans has been presented which shows good mechanical properties and an intrinsic bioactivity on inflammatory and tissue cells in vitro. The authors investigated the morphology in vivo of bone response in repairing a surgical lesion in the presence of granules of a novel soybean-based biomaterial (SB), comparing it with a sham-operated contralateral lesion of critical size (non-healing model); 26 operations were performed in New Zealand White rabbits, with back scattered electron microscopy as the analysis technique of choice. Implantation of SB granules over 8 weeks produced bone repair with features distinct from those obtained by healing in a non-treated defect. New and progressively maturing trabeculae appeared in the animal group where SB granules were implanted, while sham operation produced only a rim of pseudo-cortical bone still featuring a large defect. The trabeculae forming in the presence of SB granules had features typical of reticular bone. These findings suggest that the bone regeneration potential of SB granules and their intrinsic bioactivity, combined with their relatively easy and cost-effective preparation procedures, make them suitable candidates as a bone filler in clinical applications.

Bone regeneration potential of a soybean-based filler: experimental study in a rabbit cancellous bone defects.

Autologous and allogenic bone grafts are considered as materials of choice for bone reconstructive surgery, but limited availability, risks of transmittable diseases and inconsistent clinical performances have prompted the development of alternative biomaterials. The present work compares the bone regeneration potential of a soybean based bone filler (SB bone filler) in comparison to a commercial 50:50 poly(D: ,L: lactide-glycolide)-based bone graft (Fisiograft((R)) gel) when implanted into a critical size defect (6-mm diameter, 10-mm length) in rabbit distal femurs. The histomorphometric and microhardness analyses of femoral condyles 4, 8, 16 and 24 weeks after surgery showed that no significant difference was found in the percentage of both bone repair and bone in-growth in the external, medium and inner defect areas. The SB filler-treated defects showed significantly higher outer bone formation and microhardness results at 24 weeks than Fisiograft((R)) gel (P < 0.05). Soybean-based biomaterials clearly promoted bone repair through a mechanism of action that is likely to involve both the scaffolding role of the biomaterial for osteoblasts and the induction of their differentiation.