Development of porous scaffolds with oriented macro-channels network: association of bubbling-effect and three-dimensional printing techniques

Abstract

The development of scaffolds for mineralized tissues (bone and dentin) regeneration by cell homing is an innovative alternative aimed at the establishment of minimally invasive therapies capable to accelerate tissue repair and regeneration. For that, development of bioactive composition and an architectural pattern capable of favoring the infiltration and interaction of precursor cells, along with angiogenesis, are crucial. Thus, this project has a proposal to associate simple and cost effective technologies to develop chitosan scaffolds containing an bioactive mineral phase, and presenting a macro-architecture composed by an interconnected network of pore and channels. In the first phase, chitosan scaffolds in association with calcium hydroxide, calcium carbonate, calcium phosphate and calcium silicate will be formulated by bubbling effect technique, in order to stablish compositions with an organized and interconnected macro-porous network. The scaffolds will be assessed by morphological analysis (SEM/EDS, microCT) and physical-chemical-mechanical assays (FTIR, degradability degree, calcium release, porosity pattern, swelling, modulus of elasticity, compressive strength). The biological characterization will be performed by cultivating human dental pulp cells (HDPC) and an osteoblastic cell lineage (SAOS-2) onto scaffolds, and by cultivating the cells with extracts collected from the materials. Therefore, direct cell-material interaction and its modulation potential at distance will be evaluated, an essential characteristic for cell homing therapies. In phase 2, negative molds will be made through three-dimensional (3D) printing to obtain scaffolds with macro-channels of different diameters and distribution, creating thus infiltration paths inside the materials, which will be interconnected to the macro-pore created by bubbling effect. The morphological, physical-chemical-mechanical and biological analysis in a static culture model with HDPCs and SAOS-2 will be performed. Additionally, adhesion and spread of endothelial cells (HUVEC) on macro-structure will be evaluated. Subsequently, selected formulations will be evaluated in perfusion bioreactor by means of a dynamic culture model, and the constructs will be implanted in the subcutaneous of immunocompromised mice to evaluate cell migration, tissue deposition, vascular organization and integration with host tissue, through histological analyses. Finally, in phase 3, scaffolds will be implanted in critical calvary defects in rats to assess the formation of mineralized tissue in vivo (histology, microCT). Qualitative data will be descriptively analysed and quantitative data will be submitted to specific statistical analysis. (AU)