Coaxial electrospinning of PEEU/gelatin to fiber meshes with enhanced mesenchymal stem cell attachment and proliferation

Microfibers with a core-shell structure can be produced by co-axial electrospinning, allowing for the functionalization of the outer layer with bioactive molecules. In this study, a thermoplastic, degradable polyesteretherurethane (PEEU), consisting of poly(p-dioxanone) (PPDO) and poly(epsilon-caprolactone) (PCL) segments with different PPDO to PCL weight ratios, were processed into fiber meshes by co-axial electrospinning with gelatin. The prepared PEEU fibers have a diameter of 1.3 +/- 0.5 mu.m and an elastic modulus of around 5.1 +/- 1.0 MPa as measured by tensile testing in a dry state at 37 degrees C, while the PEEU/Gelatin core-shell fibers with a gelatin content of 12 +/- 6 wt% and a diameter of 1.5 +/- 0.5 mu.m possess an elastic modulus of 15.0 +/- 1.1 MPa in a dry state at 37 degrees C but as low as 0.7 +/- 0.7 MPa when hydrated at 37 degrees C. Co-axial electrospinning allowed for the homogeneous distribution of the gelatin shell along the whole microfiber. Gelatin with conjugated Fluorescein (FITC) remained stable on the PEEU fibers after 7 days incubation in Phosphate-buffered saline (PBS) at 37 degrees C. The gelatin coating on PEEU fibers lead to enhanced human adipose tissue derived mesenchymal stem cell (hADSC) attachment and a proliferation rate 81.7 +/- 34.1 % higher in cell number in PEEU50/Gelatin fibers after 7 days of cell culture when compared to PEEU fibers without coating. In this work, we demonstrate that water-soluble gelatin can be incorporated as the outer shell of a polymer fiber via molecular entanglement, with a sustained presence and role in enhancing stem cell attachment and proliferation.