Pittsburgh - US researchers have developed technology for 3-D printers with which complex anatomical structures up to the heart of newborn can be produced from collagen. A model of ventricle presented in Science (2019; 365: 482-487) was even capable of (very weak) contractions after colonization with stem cells. Heart valves could be first application.
Collagen is the basic building material of the extracellular matrix that makes up human connective tissue. The possibility of “pouring” collagen into any shape with 3-D printer could therefore open up wide range of possibilities. A team led by Adam Feinberg from Carnegie Mellon University in Pittsburgh immediately decided on one of the most difficult tasks, the reconstruction of human heart.
The researchers succeeded in producing complete heart the size of newborn with the to produce four chambers and heart valves. The FRESH ("Freeform Reversible Embedding of Suspended Hydrogel") printing process developed by the researchers prints the collagen molecules in hydrogel, which later dissolves when heated. The shape of the hydrogel enables porous structures to be built that could later serve as framework for functional tissue. The cavities would then be colonized by stem cells from which blood vessels and organ cells could develop.
The researchers have not yet been able to bring complete heart to life. However, an elliptoid model of heart chamber has been successfully turned into heart muscle tissue. The ventricles began to contract spontaneously at rate of 1 or 2 Hertz, i.e. 60 to 120 times per minute. The ventricles were reduced in size by up to 14 percent. However, unlike the natural heart, these actions did not take place against an existing filling pressure. As replacement part for an insufficient heart muscle, they are currently out of the question.
Deutsches Ärzteblatt print
Other applications seem to be more realistic. With resolution of only 20 µm, compact structures can also be produced with FRESH. The researchers show this on models of heart valves that withstand pressures in laboratory experiments, such as those found in the pulmonary circulation. According to Fiebert, the valves withstood pressure differences of 40 mm Hg when closed with regurgitation of less than 15 percent. However, it is unclear whether they would be able to cope with the demands of tricuspid or pulmonary valve in the long term.Animal experiments have apparently not yet been carried out.
The biofabrication of human tissue is advancing rapidly. Researchers from Israel recently reported on the production of human heart tissue on 3D printer. The researchers succeeded in constructing muscle patch with “contractile potential” and mini heart.