Scaffold fabrication

A cylindrical scaffold 10 × 6 mm in size with an empty area inside of 6 × 2 mm was designed with SolidWorks 2012 (Waltham, MA, USA) CAD software (Fig. 2a). The scaffolds were designed to enable the fibers restricting the empty area on one side to be easily cut to allow the scaffold to be opened like a chest to place it on the vascular pedicle (Fig. 2b). Next, 36 poly-ε-caprolactone (PCL) scaffolds were produced with a 3D printer (Bioscaffolder, SYS+ENG, Salzgitter-Bad, Germany) using the fused deposition modelling technique. One scaffold contained 50 layers of fibers, with a fiber pattern that repeated every 5 layers. The fiber pattern used in the first 5 layers is shown in Fig. 2c. Prior to implantation, the scaffolds were sterilized in 70% ethanol.

Scaffold design (a–c) and scaffold implantation (d–i): a Scaffold dimensions. b Place in the opening of the scaffold (blue line) used to insert the vascular pedicle inside (μCT 3D reconstruction model). c The fibre pattern was repeated every five layers during scaffold printing. d Incision markings. e Isolation of the vascular pedicle with the surrounding fascia. f Insertion of the vascular pedicle inside the scaffold. g Scaffold “closing” on the vascular pedicle. h Classic prefabrication group—insertion of the scaffold in the proximity of the vascular pedicle. i Correct placement of scaffolds: on the left side—vascular pedicle is inside the scaffold (flow-through prefabrication group); on the right side, vascular pedicle is outside but close to the scaffold (classic prefabrication group)