Fibronectin (nano)fibrils induced by materials: from 2D to 3D microenvironments

Abstract

Event Abstract Back to Event Fibronectin (nano)fibrils induced by materials: from 2D to 3D microenvironments Laia León-Boigues1, Antonio Sánchez-Laosa1, Luis Gómez-Estrada2, José Luis Gómez Ribelles1, 3, Manuel Salmerón-Sánchez4, Gloria Gallego Ferrer1, 3 and Roser Sabater I Serra1 1 Universitat Politècnica de València, Center for Biomaterials and Tissue Engineering, Spain 2 Ikasia Technologies SL, Spain 3 Biomedical Research Networking Centre (CIBER), Spain 4 University of Glasgow, Division of Biomedical Engineering, School of Engineering, United Kingdom Introduction: Biomaterials play a key role in regenerative medicine, acting as a synthetic extracellular matrix. However, synthetic biomaterials, biologically inert, have to be functionalised to become bioactive. Adsorption of adhesive proteins, as fibronectin (FN), on the biomaterial surface is one of the strategies commonly used to enhance bioactivity[1],[2]. It have been shown that certain materials, such as poly(ethyl acrylate), PEA, are able to induce the organization of FN in a biomimetic way. A physiological-like FN nanonetwork is organised upon simple adsorption of FN from a protein solution as consequence of protein-material interactions[3]. The novelty of this work is to show the ability of PEA to induce the formation of fibronectin (nano)fibrils in 3D-like environments, as it has been shown only on 2D substrates. For this purpose, PEA scaffolds with interconnected pores larger than 300 µm were synthesised, to be afterwards 3D-coated with FN to promote vascularization and new bone formation[4]. The distribution of the adsorbed FN within the walls of the scaffold surface was studied by AFM. Experimental Methods: PEA scaffolds were obtained by radical polymerization (1 wt% of benzoyl peroxide initiator). 2 wt% ethylene glycol dimethacrylate, EGDMA, was used as crosslinker to improve PEA mechanical properties. Polyvinyl alcohol templates, obtained by rapid-prototyping, were used as porogen. The polymerization was carried out at 60 ºC for 24h. Then, the template was dissolved in water. 2D substrates (films) with 0 and 2 wt% EGDMA were also prepared to be used as 2D controls. Scaffold mechanical properties, morphology and porosity were studied by compression tests, SEM and a liquid displacement method, respectively. The distribution of FN (10 µg/mL PBS solution, 10 min) was investigated by AFM. Results and Discussion: PEA scaffolds show a homogeneous structure, with channels (ca. 350 µm of diameter) in orthogonal directions and distance between channels ca. 400 µm (Fig. 1); the overall porosity is ca. 50%. The elastic modulus is ~ 2.5 MPa. Figure 1. SEM images. Cross-section of PEA scaffolds (2 %wt EGDMA)) AFM images (Fig. 2) show FN distribution after adsorption on 3D substrates (Fig. 2c) and 2D uncrosslinked and crosskinked films (Fig. 2a and 2b respectively). Similar interconnected FN nanofibrils were found on both 2D surfaces, indicating that the process of material-driven FN assembly is unaffected by the crosslinking process. FN fibrils induced in 3D substrates show no significant differences with the ones induced on 2D PEA films. Figure 2. AFM phase (1 μm x 1 μm). a) film (0 wt% EGDMA), b) film (2 wt% EGDMA), c) scaffold (2 wt% EGDMA). Conclusion: We demonstrated that PEA is able to induce the formation of fibronectin (nano)fibrils in 3D environments. Bioactive scaffolds with homogeneous channels and suitable pore size for bone regeneration have been engineered. The support of the project MAT2012-38359-C03-01 (including the FEDER financial support) as well as CIBER is acknowledged. CIBER-BBN is an initiative funded by the VI National R&D&I Plan 2008-2011, Iniciativa Ingenio 2010, Consolider Program, CIBER Actions and financed by the Instituto de Salud Carlos III with the assistance from the European Regional Development Fund.