Evaluation of biocement based on calcium aluminate cement incorported with bioglass and strontium: in vitro and in vivo study

Abstract

Bone biocements have been used to repair bone tissue defects, as well as fix orthopedic implants, acting as fillers in the space between the implant and living tissues. Among these materials, calcium aluminate cement (CAC) highlight for having superior mechanical properties and being a promising material for bone regeneration. It exhibits chemical similarity with bone tissue, biocompatibility, bacteriostatic properties, moisture tolerance, dimensional stability, but is not bioactive. On the other hand, bioglass represents one of the most promised for bone repair materials, due to its biocompatibility, osteoinductivity and great bioactivity due to its dissolution when in contact with body fluids, accelerating the regeneration of injured tissues of the human body. Another bioactive element that has been studied to stimulate the regeneration of injured bone tissue is strontium, which in low doses increases bone formation. In this context, the objective in this present study will be to produce composites based on CAC cement incorporated with bioglass and strontium in order to optimize osteogenesis and bone tissue repair. The composites obtained will be characterized for viscosity, injectability, workability/prey time. Next, the biological behavior of these materials will be evaluated through in vitro cell culture using the MG63 cell line. The tests of adhesion, cell viability, total protein content, alkaline phosphatase (ALP) activity, formation of mineralization nodules and genotoxicity will be performed to verify the influence of these samples on osteoblastic activity and differentiation. For the in vivo study, 18 Wistar rats will be used, which will be submitted to a monocortical critical bone defect in each femur. The defects on the right side will be filled with clot (group C), while the defects on the left side will be randomly divided according to the filling of the bone defect (n=6): a) C Group: CAC biocement; b) CBv Group: CAC/Bioglass biocement; c) CBvE Group: CAC/Bioglass/Strontium biocement. After the period of 03 weeks, all animals will be euthanized and the pieces will be submitted to histological and histomorphometric analyses to visualize the bone tissue-samples interface and also quantification of bone neoformation. The control group in the in vitro tests will be the bottom of the plate and in the in vivo tests it will be the filling of the defect with clot. The data will be statistically analyzed, initially through the normality test aiming at the application of the appropriate statistical test. The significance level adopted will be the conventional value of 5%.