Release of growth factors from liposomes immobilized on electrospun nanofibers targeting tissue engineering applications

The ability to manipulate and control the surface properties is of crucial importance in the designing of Tissue Engineering (TE) scaffolds. Electrospun nanofibers with a high surface area to volume ratio have received much attention due to their potential as biomedical devices, TE scaffolds, and drug delivery carriers. In this work, polycaprolactone (PCL) nanofiber meshes (NFM) and membranes (M) were functionalized using UV-O irradiation and amine groups were covalently bonded onto their surface by aminolysis. The amine surface groups were thiolated (SH) with 2-iminothiolane and SH quantification was performed using the Ellman’s reagent method. The SH spatial distribution on the surface of the NFM and M was studied by fluorescence microscopy using SH-reactive probes. Dexamethasone (DEX)-loaded liposomes were covalently immobilized at the surface of the PCL NFMs and Ms. Under this approach, different lipid formulations were studied and DEX encapsulation was decreased by the presence of cholesterol. In vitro studies demonstrated a sustained release of DEX after an initial burst effect. The bioactivity of the released DEX was assessed by cultivating human bone marrow mesenchymal stem cells (hBMSCs) on DEX-loaded liposomes immobilized on PCL NFMs and Ms, under DEX-absent osteogenic differentiation medium formulation. Biological data, namely the cell viability and proliferation, the protein synthesis and the expression of alkaline phosphatase (an osteblastic marker), suggests the DEX-loaded liposomes immobilized on PCL NFMs performs better than the DEX-loaded liposomes immobilized on Ms. Concluding, that these multi functionalized systems can be used as carriers for the sustained release of growth/differentiation factors relevant for bone tissue engineering strategies.