Effects of chitosan isolated or associated with mesenchymal stem cells on consolidation of critical-sized bone defects in rats

• Grant number: 15/23632-8
• Support type: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): April 01, 2016
• Effective date (End): December 31, 2016
• Field of knowledge: Interdisciplinary Subjects
• Principal researcher: Karina Nogueira Zambone Pinto Rossi
• Grantee: Caio Almeida Batista de Oliveira
• Home Institution: Centro de Ciências Biológicas e da Saúde (CCBS). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil

Abstract

Biomaterials may be defined as materials projected to be used in medical devices, which will interact with biological systems. Recently, their enormous potential has been highlighted as a therapy option in several cases, whether those are for substitution or to favour tissue repair. Chitosan, especially, has been shown promising because of its already presented biocompatibility, in vitro and in vivo. Obtained from chitin - via chemical treatment or enzymatic treatment -, chitosan is used in different forms and with varied objectives, among which its applicability in hydrogel form has been brought out, for treatment of joint and bone diseases and traumas, with or without cell load in its interior. Thus, it will be objective of this study to evaluate the efficacy of chitosan hydrogel implant, associated or not to mesenchymal stem cells (MSCs), in repair of critical sized bone defect, induced on rats' scalp. Thirty male Wistar rats were used, randomly distributed in three groups (control, isolated chitosan and chitosan loaded with MSCs). The control received no treatment and was compared to the other two groups. The chitosan used in this project is commercially available, and its final concentration was 2,5% (w/v). The surgery was performed in all animals, using a trephine-like dental drill to produce the eight millimetre in diameter bone lesion. After 21 days, they were euthanized by anaesthetic lethal dose. The scalps were dissected and, in sequence, they were subjected to fixation and decalcification in order to perform future analysis. Scanning electron microscopy (SEM) of the samples will be carried out, in order to acquire images of tissue lesion and biomaterial implant. It will also be performed histological processing of the samples and the slides will be stained with haematoxylin-eosin for tissue qualitative analysis by morphological description. The bone defect area morphometric analysis will be performed using slides stained with Masson's trichrome. It will also be performed immunohistochemical analysis to verify the expression of COX-2 enzyme and RUNX-2 transcription factor, which are related to osteoblast differentiation and activation. This test will use polyclonal primary antibodies anti-COX-2 and anti-RUNX-2 on rehydrated histological slides, analysing the proportion of immunoexpression area in comparison to total area. The statistical analysis will use the ANOVA method or the Kruskal-Wallis test for group comparison. (AU)