3D IMPRINTED HYDROGEL WITH DRUG DELIVERY SYSTEM OF STRONIUM RANELATE AND RALOXYFEN for BONE REPAIR IN OVARIECTOMIZED RATS: In vitro and in vivo study.

Abstract

This project will investigate the influence of drug delivery systems using hydrogels incorporated with bioglass particles functionalized with drugs in the regeneration of critical bone defects in femurs of ovariectomized rats. The drugs used to functionalize the bioglass particles will be raloxifene and strontium ranelate, which are expected to act locally. Initially, the synthesis and characterization of the bioglass will be performed, followed by its functionalization with the drugs, through the sonochemical route. Sequentially, the characterization of the hydrogel produced by means of the 3D printing technique and incorporated with the functionalized bioglass will be performed. Next, the cytotoxicity test of the different hydrogels will be performed, using mesenchymal cells differentiated into osteoblasts, isolated from femurs of ovariectomized rats. Subsequently, an in vivo experiment will be performed. For this, young adult female Wistar rats (n=8 for each subgroup) will be divided into 2 groups: S- submitted to sham surgery (bilateral ovariectomy), OVX- submitted to bilateral ovariectomy. After 8 weeks of the surgeries, all animals will undergo critical bone defect in the distal epiphysis of the femurs bilaterally, which will be filled with clot, hydrogel embedded with bioglass particles, and hydrogel embedded with bioglass particles functionalized with the drugs raloxifene or strontium ranelate. All animals, Sham and OVX, will receive the same hydrogel in both femurs, which will be printed with 4x4mm cylinder design for filling the defect. The animals will be euthanized 4 weeks after the surgical procedure, at which time 5 mL of blood will be taken from each animal for cytokine analysis. After euthanasia, the right femurs will be submitted to computed microtomography analysis for the morphometric evaluation of the bone formed in the area of the critical defect. While the pieces from the left femurs will undergo laboratory processing for histological, histomorphometric and immunohistochemical analysis to evaluate the quality and quantity of neoformed bone tissue in the defect area, as well as the presence of TRAP, osteocalcin and osteoprotegerin markers. The quantitative data will be submitted to normality test for the selection of the appropriate statistical test (parametric or non-parametric), with a significance level of 5%.