The bioprinting g-code file is a computer program with commands necessary to print bionic pancreas. It contains information about the geometry of the printed model saved as a list of printhead movements. In our case, it is a list of about 30,000 instructions divided into movements of printheads (bioink A, bioink B and crosslinking head). The programs were optimized with many laboratory tests using dedicated bioinks. The following parameters were optimized: path shape for all heads, fill shape and density, sequence of consecutive movements, crosslinking time and speed, removal of collision sterile movements. Below, the visualizations of the printhead movement prepared from the g-code file and a fragment text content of g-code file are attached.
During the developmental process of a bionic pancreas, the composition and properties of two independent bioinks (A and B) were determined – a bioink A, containing pancreatic cells and islets, and bioink B consisting of endothelial cells and fibroblasts, used as a temporary support for the vessels and washed out immediately after bio-printing the entire organ. Bioink A is a decellularized ECM (dECM)-based hydrogel containing methacrylated gelatin, methacrylated hyaluronic acid, glycerol and other additives improving its functionality. Vascular bioink B contains dECM hydrogel with the addition of microbial gelatin, carboxymethylcellulose (CMC), fibronectin and others. Both bioinks are suitable for printing process of live biological material using appropriate parameters, such as temperature, pressure and dosing speed of component to obtain a functional prototype of bionic pancreas.
A bioreactor is a device dedicated to ensure the physiologically relevant conditions for organs after a bio-printing process. It allows to control the processes such as: temperature, pH, velocity and pressure of the flow, as well as it assures a proper oxygenation, nutrient and drugs dosage. It was created by the scientists working in the Foundation of Research and Science Development.