Polycaprolactone Electrospun Fiber Mats Prepared Using Benign Solvents: Blending with Copper(II)-Chitosan Increases the Secretion of Vascular Endothelial Growth Factor in a Bone Marrow Stromal Cell Line

Abstract

Inducing the formation of new blood vessels (angiogenesis) is an essential requirement for successful tissue engineering. Approaches have been proposed to enhance angiogenesis using growth factors and other biomolecules; however, this approaches present drawbacks in terms of high cost and patient safety. Copper is known to effectively regulate angiogenesis and can offer a more cost-effective alternative than the direct use of growth factors. With this study, a strategy to incorporate copper in electrospun fibrous scaffolds with pro-angiogenic properties is presented. Polycaprolactone (PCL) and copper(II)-chitosan are electrospun using benign solvents. The morphological and physicochemical properties of the fiber mats are investigated through scanning electron microscopy (SEM), static contact angle measurements, energy dispersive X-ray, and Fourier-transform infrared spectroscopies. Scaffold stability in phosphate buffered saline at 37 °C is monitored over 1 week. A bone marrow stromal cell line (ST-2) is cultured for 7 days and its behavior is evaluated using SEM, fluorescence microscopy and a tetrazolium salt-based colorimetric assay. Results confirm that PCL/copper(II)-chitosan is suitable for electrospinning. The fiber mats are biocompatible and favor cell colonization and infiltration. Most notably, the angiogenic potential of PCL/copper(II)-chitosan blends is confirmed by a three-fold increase in VEGF secretion by ST-2 cells in the presence of copper(II)-chitosan.