A team of scientists from the University of Illinois has developed a method for creating 3D biological samples from living tissue that does not have the drawbacks of typical 3D printing. We are talking about the problem of using scaffolds on which living cells are inoculated. Instead, it was proposed to use a photosensitive hydrogel.
The main difficulties in using frames made of polymers or biodegradable materials when printing living tissues are in agreeing the conditions for the existence of the base and the "filling". It is necessary to choose a lifespan and a way of destroying the framework without harm to the biomaterial, to ensure the supply of nutrients to the growing biomass, to implement all the connections between tissues so that they retain an integral structure even after the support is removed.
In the case of a hydrogel, the needle of a 3D printer penetrates into the material and in the same way places drops of solution with stem cells according to the drawing. Then the entire workpiece is irradiated with ultraviolet light so that the microspheres that make up the hydrogel stick together. This ligament is strong enough to support the weight of the growing structure, but the hydrogel still allows light, air, and water to pass through, which is needed for tissue growth.
The most important advantage of the method: the composition of the hydrogel is selected so that it can be easily programmed for the exact time of biodegradation after the introduction of the process inhibitor. Scientists have complete control over both the rate and nature of the reactions, so there is no risk of damaging printed samples. In this way, parts of the femur and ear cartilage have already been obtained for experimental mice.