Strontium-containing nanostructured hydroxyapatite microspheres for bone regeneration

Abstract

The aim of this study was to analyze the biological behavior and osteogenic potential of nanostructured hydroxyapatite microspheres substituted with strontium (nHASr). Therefore, twenty adult male Wistar rats were randomly distributed into two groups: GnHASr – critical bone defect filled with nHASr microspheres; e CG (control group) – critical bone defect without implantation of biomaterial; evaluated at the biological points of 30 and 60 days. The collected specimens were processed and stained with hematoxylin-eosin (HE) and Masson-Goldner trichrome (TG) and examined by light microscopy. Posteriorly, they were analyzed histomorphometrically to measure the percentage of neoformed osteoid matrix (%OM). In both groups studied, at all biological points, deposition of reparative osteoid matrix (OM) was observed near the bone edges; discrete chronic inflammatory response; connective tissue formation and neovascularization in the residual area of the defect. In the GnHASr, in the two evaluated periods, the deposition of OM was also noticed, both around and inside the microspheres. At 60 days, an area of 7.54% of OM deposition in relation to the total defect area was evidenced in the GnHASr, while in the CG this value was 6.80%. It is concluded that the nHASr microspheres evaluated were biocompatible, biodegradable, bioresorbable, bioactive and osteoconductive. In both groups, the formation of neomineralized tissue occurred in a limited way, which indicates that the concentration of metal used in the replacement did not favor greater osteogenic potential for the biomaterial. The evaluated biomaterial it's adequate for use as a filling material.

Biological evaluation of critical bone defect regeneration using hydroxyapatite/ alginate composite granules

“…However, the biomaterial implanted group had a chronic granulomatous type of tissue response, due to granules, re perceived by the organism as foreign bodies 10 - 13 . These findings corroborate with results demonstrated by some studies 1 - 4 , 10 , 11 , which used different biomaterials for bone regeneration. Throughout our study, the inflammatory response was discrete and regressive, resulting in scarce inflammatory cells at the biological endpoint, highlighting biocompatibility of the evaluated composite.…”

“…Limited formation of bone tissue in CG was associated with reduced arrival of growth factors and osteogenic cells on the central region of the defect. Histomorphological pattern found for this group is compatible with critical bone defect, which, according to Schimdzt and Hollinger 16 , does not regenerate throughout animal’s life and has been extensively reported by different studies evaluating biomaterials for bone regeneration 2 - 4 , 10 , 11 , 17 , 18 . This type of defect in rat calvaria is a widely accepted model for studies in bone tissue bioengineering, as it allows verifying the biocompatibility and effect of biomaterials on bone neoformation 1 , 11 , 19 .…”

“…Animals were euthanized 15, 45 and 120 days postoperative with intraperitoneal lethal dose of ketamine hydrochloride (300 mg/kg) associated with xylazine hydrochloride (30 mg/Kg). The biological points were defined following previous research by this research group 1 - 4 , 10 , 11 . The upper portion of calvaria bone was removed, discarding all surrounding soft tissue, and fixed in 4% formaldehyde for 72 hours.…”

“…However, scientific and technological advances of the last few decades made it possible exponential development and use of biomaterials. Although the osseous tissue is dynamic and has an excellent regenerative and remodeled capacity, when it comes to great tissue loss, the regenerative capacity becomes limited and its repair usually is made with fibrous connective tissue 1 - 4 . Many of these tissue losses affects function and aesthetics which, consequently, interferers on wellbeing of the affected individuals.…”