An image analysis-based workflow for 3D bioprinting of anatomically realistic retinal vascular patterns

Abstract There is an enduring need for vascularization of bioprinted constructs with vascular networks optimized for distribution of nutrient-containing fluids, both for in vitro applications and in vivo implantation. However, most of the efforts in this field were directed so far towards generation of simple linear channels, often lined with endothelial cells only, and thus lacking the anatomical details of real vascular networks. To start addressing this need, here we explored the possibility of using actual vascular patterns derived from human ocular fundus for instructing the 3D printing activity. In order to assign to these patterns the organ-specific topology, and eventually vessel branch-defined cellular composition, we describe the use of the branching analysis program VESGEN 2D for planning a workflow that links the primary vascular images with their 3D printing with bioinks. To this end, we show how to process flat vascular images and, for an even more realistic representation, how to retro-engineer concave retinal patterns from flat images and to print them in a supporting hydrogel. This work opens the possibility of bioprinting more anatomically realistic vascular networks, and thus to eventually improve the vascularization of living tissue-engineered constructs.