Sustained release of MCP-1 from an electrospun scaffold by incorporation of mesoporous silica nanoparticles

Abstract

Event Abstract Back to Event Sustained release of MCP-1 from an electrospun scaffold by incorporation of mesoporous silica nanoparticles Shraddha Thakkar1, 2, Oliver Wiltschka3, Patricia Dankers1, 4, Carlijn Bouten1, 2, Mika Linden3 and Cecilia Sahlgren1, 2 1 Eindhoven University of Technology, Institute for Complex Molecular Systems, Netherlands 2 Eindhoven University of Technology, Department of Biomedical Engineering, Soft Tissue Biomechanics & Tissue Engineering, Netherlands 3 University of Ulm, Institute for Inorganic Chemistry II, Germany 4 Eindhoven University of Technology, Department of Biomedical Engineering, Laboratory of Chemical Biology, Netherlands In-situ tissue engineering is an emerging approach that relies on the regenerative capacity of the body to create living tissues at the site of implantation of a scaffold. The implanted scaffold will trigger an immune response, which can be modulated by incorporating bioactive moieties in the scaffold[1] . It is envisioned that a sustained release of cytokine moieties, such as monocyte chemoattracant protein-1 (MCP-1), guide recruitment of cells and improved tissue regeneration. In this study, electrospun scaffolds were fabricated with bisurea-modified polycaprolactone (PCL-BU)[2]. To achieve sustained release from the scaffolds we incorporated mesoporous silica nanoparticles (MSNs), which have a high drug carrying potential, in the scaffold and subsequently loaded the MSNs-PCL-BU scaffold with MCP-1[3]. Fibrous scaffolds were fabricated by electrospinning PCL-BU (provided by SyMO-Chem) in chloroform:methanol (w/w 85:15). The fiber diameter was determined to 5.1 ± 0.33µm by scanning electron microscopy (SEM)(Fig. 1). Aminopropyl functionalized MSNs were synthesised as previously described[4]. SEM verified homogenous morphology and a size distribution of 350 ± 0.40 nm (Fig. 1). The size distribution was further verified by transmission electron microscopy (TEM) and pore size was determined to 3 nm by nitrogen sorption (data not shown). MSN were incorporated in the scaffold by drop casting. MSNs resuspended in ethanol attached onto the scaffold by physisorption, at a concentration of 1mg/50µL, followed by ethanol evaporation. MCP-1 was subsequently loaded to the MSNs-scaffold by adding 300 ng/mL MCP-1 in PBS, onto the scaffold, followed by rinsing in PBS. PCL -BU scaffolds (bare), PCL-BU scaffolds with MSNs without MCP-1 and medium with MCP-1 were used as controls for this study. All scaffolds were incubated in medium and the concentration of MCP-1 released in the medium was measured by enzyme-linked immunosorbent assay (ELISA). Media was collected at 1hr, 4hrs, 24hrs, 3 days, 5 days and 7 days. The bioactivity of the released MCP-1 was evaluated by migration of peripheral blood mononuclear cell (hPBMCs) towards the scaffolds in a Boyden chamber, and the presence of cells on scaffolds was accessed by staining of the cell nuclei (DAPI). MCP-1 is expected to be released in medium through a slow diffusion from MSNs. A net cumulative release of 16ng MCP-1 untill 7 days was observed (Fig. 2) . The MSN-scaffold incorporated with MCP-1 exhibited an initial burst release within the first hour followed by a sustained release of MCP-1 for a week. Migration of cells towards, the scaffolds confirms the release of active MCP-1. The presence of the cells in the scaffolds was shown by DAPI staining (Fig. 3). In conclusion: we showed that a desired prolonged release of MCP-1 can be achieved by loading MCP-1 into MSNs incorporated in electrospun PCL-BU scaffolds. This MSN-scaffold may also be extended to serve as a reservoir for sustained release of other cytokines. The Netherlands Institute for Regenerative Medicine (NIRM)