Polycaprolactone/gelatin-based scaffolds with tailored performance: in vitro and in vivo validation

Nanofibrous scaffolds composed of polycaprolactone (PCL) and gelatin (Ge) were obtained through a hydrolytic assisted electrospinning process. The PCL-to-Ge proportion (100/0 to 20/80), as well as the dissolution time (24, 48, 72, 96, 120 h) into a 1:1 formic/acetic acid solvent before electrospinning were modified to obtain the different samples. A strong influence of these factors on the physicochemical properties of the scaffolds was observed. Higher Ge percentage reduced crystallinity, allowed a uniform morphology and increased water contact angle. The increase in the dissolution time considerably reduced the molar mass and, subsequently, fibre diameter and crystallinity were affected. During in vitro biocompatibility tests, higher cell adhesion and proliferation were found for the 60/40, 50/50 and 40/60 PCL/Ge compositions that was corroborated by MTT assay, fluorescence and microscopy. A weakened structure, more labile to the in vitro degradation in physiologic conditions was found for these compositions with higher dissolution times (72 and 96 h). Particularly, the 40/60 PCL/Ge scaffolds revealed an interesting progressive degradation behaviour as a function of the dissolution time. Moreover, these scaffolds were non-inflammatory, as revealed by the pyrogen test and after the 15-day subcutaneous in vivo implantation in mice. Finally, a reduction of the scar tissue area after infarction was found for the 40/60 PCL/Ge scaffolds electrospun after 72 h implanted in rat hearts. These results are especially interesting and represent a feasible way to avoid undesired inflammatory reactions during the scaffold assimilation.