Capillary vessels distinguish themselves by very small and complicated structures. Up to now, the replication of the fine branching and hollows was very difficult for the researchers. The artificial production wasn't possible on conventional way. However, now scientists of five Fraunhofer institutes have succeeded in building up complicated 3D models, with the help of the 3D printing established in Rapid Prototyping and the multi photons polymerisation developed in the polymer science, and in transferring them on elastic biomaterials.
Small printed tubes
„Everything we need is a 3D inkjet printer and a special ink fortified with polymers,“ explains Christian Nüsser of the Fraunhofer ILT. „The printer applies the liquid polymers in layers and the integrated laser makes sure that the single layers are only chemically connected at certain places by free radicals.“ However, to achieve a perfect result, this technology must be combined with the multi photons polymerisation.
Short, intensive laser pulses hit the material and stimulate the single molecules in such a strong way that these combine themselves to longer chains. The resulted structures polymerise and become solid. Nevertheless, they remain as elastic as natural materials. This reaction can be controlled so specifically that the construction of the finest structures is possible according to a three-dimensional plan.
„In order to make sure that the later blood vessels are biocompatible, the synthetic tubes have to be enriched with cells afterwards,“ says Nüsser. For that to happen, the scientists integrate modified biological structures and anchor proteins into the inner walls. In the second step, endothelium cells can attach themselves in the tube systems. These cells form the most internal wall layer of every vessel in the body. „This procedure is important so that the blood can be transported unimpeded through the vessels and does not stick,“ explains Nüsser.
Chances for medicine
The construction of elastic three-dimensional formed biomaterials is still in the early stages of development. „Our next step will be to combine these blood vessels with already producible cells, as for example skin cells, so that these can be supplied with nutrients,“ says Nüsser. This is also valid for completely artificial organs, which aren't suited for transplantation up to now. However, in this manner, animal testing could be substituted and even the treatment of bypass patients with artificial vessels is conceivable.
„It is our long-term aim to produce organs of own stem cells and blood vessels in the laboratory so that maybe one day organ donations may not be waived,“ Nüsser dares a preview. „Because it would then be body’s own material, the danger of repulsion would be virtually zero.“ However, until technology is good enough that this vision can be translated into reality reliably, it will still take some time.