German scientists have 3D-printed vascular tissue on a durable polymer frame. This has been reported by the Utrecht University medical centre.
Modern 3D printers allow printing with living stem cells, making it possible to achieve similarity of living tissues (some even suitable for implantation into the body). In this case, as a rule, during printing, cells are seeded on a biogel that supports their vital activity. The presence of biogel weakens the final strength of the tissue and therefore it is difficult, for example, to obtain high-pressure vessels using this technology.
Gabriel Grosbacher and colleagues solved this problem by changing the substrate for planting the cells. Instead of soft biogel, they used a solid polymer formed into a tubular frame with electrowriting to form the vessels. In electrowriting, the printer “writes” a three-dimensional structure by directing a thin stream of fast-curing hot material. A biogel is then applied to this frame and the living cells are already printed on it.
During the experiment, the authors managed to create a prototype vessel using stem cells. It has high strength and does not collapse when bent. Some of the prototype veins were bifurcated or could have functioned as venous valves to maintain unidirectional flow. In order for the blood to perform its function, it is necessary to adjust its permeability by creating holes in the vessel walls.
In the future, the authors plan to add muscle and fibrous tissue cells to stem cells to make the vessel functional.