Analysis of simulations of rhBMP-2 reconstructions in polydioxanone scaffolds: in vivo study

Abstract

The objective of this project will be to analyze the bioactive potential of a Polydioxanone (PDO) scaffold with association of rhBMP-2 in reconstructions after simulation of bone resection in rats. Therefore, 24 adult male rats (Rattus novergicus albinus Wistar), 6 months old, will be submitted to bilateral femoral resection and reconstruction simulation. Initially, stabilization will be performed with the fixation of plates with intermediate and titanium screws of the 1.5 mm system and then a 5 mm gap will be made. The reconstruction will be performed with rhBMP-2 (Infuse) carried in collagen sponge (6.5 µg), with a titanium mesh, for the titanium group (n=12) (control group), acting as a framework, keeping the sponge with rhBMP-2 in its position. And for the PDO group (n=12) (test group), reconstruction will also be performed with the rhBMP-2 loaded into a collagen sponge (6.5 µg), but the framework will be provided by a PDO scaffold. The animals will be submitted to euthanasia (n=6 per group) in the periods of 14 and 60 days after the reconstruction surgery, by means of anesthetic dosage and their femurs will be removed, reduced and stored in 70% alcohol (Titanium Group and PDO Group) to be later sent for analysis in a computerized digital microtomography system, to evaluate the volumetric parameters of bone (BV and BV/TV) and bone quality (Tb.Th, Tb.Sp and Tb.N). After scanning by computed microtomography, the pieces will continue in processing to perform analysis of decalcified tissues. Decalcification will then be performed in EDTA (10%) to obtain slides with sections of 5 ¼m thickness, and the even slides will be destined for histological evaluation by means of hematoxylin and eosin (HE) staining, while the odd slides will follow for immunohistochemical analysis through the Runx2, Col-1, OPG, RANKL, OCN and BMP2 proteins.All quantitative data will be submitted to the normality curve to establish the best statistical test (parametric or non-parametric), considering p<0.05 the level of significance.