Development of polycaprolactone grafts with improved physical properties and body stability using a screw extrusion-type 3D bioprinter

Three-dimensional (3D) bioprinter including screw extruder was developed, and the polycaprolactone (PCL) grafts fabricated by screw-type and pneumatic pressure-type bioprinters were comparatively evaluated. The density and tensile strength of the single layers printed by the screw-type were 14.07% and 34.76% higher, respectively, than those of the single layers produced by the pneumatic pressure-type. The adhesive force, tensile strength, and bending strength of the PCL grafts printed by the screw-type bioprinter were 2.72 times, 29.89%, and 67.76% higher, respectively, than those of the PCL grafts prepared by the pneumatic pressure-type bioprinter. By evaluating the consistency with the original image of the PCL grafts, we found that it had a value of about 98.35%. The layer width of the printing structure was 485.2 ± 0.004919 µm, which was 99.5% to 101.8% compared to the set value (500 µm), indicating high accuracy and uniformity. The printed graft had no cytotoxicity, and there were no impurities in the extract test. In the in vivo studies, the tensile strength of the sample 12 months after implantation was reduced by 50.37% and 85.43% compared to the initial point of the sample printed by the screw-type and the pneumatic pressure-type, respectively. Through observing the fractures of the samples at 9- and 12-month samples, we found that the PCL grafts prepared by the screw-type had better in vivo stability. Therefore, the printing system developed in this study can be used as a treatment for regenerative medicine.