Organ donation is always a burning issue. The waiting lists for receiving a transplant are endless and many people die before being able to see the end. Several nations, such as Austria, Argentina, and England, have adopted the so-called opt-out system to solve the problem. This policy requires all people to be donors unless they expressly declare that they do not want to become donors. This rule has had the desired results, just think that 99.98% of Austrians are donors. In Germany, on the other hand, where the opt-in system is in force, which requires the citizen’s availability to donate, only 12% of the population gave their consent.
Despite the progress made with the adoption of the opt-out system, finding a compatible body available as soon as possible is always a problematic issue. In this regard, the entire scientific community has recently been displaced by a new, revolutionary technique devised by bioengineers of the University of Washington and Rice University. The group of researchers was, in fact, able to create models of functional tissue using 3D printing, using materials suitable for our body.
The technique is called projection stereolithography and this is the first time we try to use it in the field of biology, despite the fact that already in the 1980s it was a known and widespread technology. During the process, layers of liquid resin are bombarded with blue light, which allows solidification in hydrogels. The latter is composed of sequences of polymeric molecules, ie molecules made up of many molecular groups chained together by a covalent bond.
Subsequently, the polymeric molecules form a structure on which live cells are implanted. The step forward made by these bioengineers is that they have managed to keep these cells alive, thus allowing the fabric models created to perform certain functions. In this way, it is possible to simulate the action performed by the different organs, as in this case from a pulmonary alveolus. The researchers in fact succeeded in recreating the pneumonic vascular network, allowing the exchange of oxygen between separate channels for air and blood cells.
The success of the experiment, however, was not at all obvious. Many risks have been avoided by adopting this technique, which, being faster than a normal 3D printer, avoids cell death. This is possible because, immediately after printing the structure mentioned above, it starts sending oxygen and nutrients to the cells, keeping them alive. So the only possible way to create the delicate and intricate vascular system of the organs is precisely the stereolithography.
Another obstacle to overcome was finding a way to avoid the use of photoreactive chemicals, necessary for 3D printing with stereolithography. The goal was difficult to achieve because until then only these carcinogens had been used because they were sure of their successful use. Furthermore, these reagents could not be dispensed with because they allow the targeted solidification of some areas of the liquid resin. By doing so, the areas left soft could be removed simply by washing them away. In order for the experiment to be successful, a safe but above all water-soluble photoreagent was needed.
The brilliant intuition of the group of researchers, led by the bioengineering professor Jordan Miller, was to use food coloring. In fact, in addition to working well with light (absorbing the necessary wavelengths), it is also biocompatible. Bioengineers have used tartrazine (E102), a commonly used yellow coloring additive, readily available at the supermarket. During the experiment, a dye kit bought in a common store was used, so much was the hurry of the researchers to find out if their idea could be realized or not.
Scientists’ lighting could not be more correct. Even tartrazine, in addition to the necessary requirements such as biocompatibility and safety, is very easily removed from the remaining structure. The only problem that it could cause would be the deterioration of the hyperactivity of children only if they were already predisposed. The substance does not seem to harm the health of patients.
In addition to creating a pulmonary alveolus, bioengineers have also formed hepatocyte-injected liver tissue models. The samples were subsequently inserted into live mice that had hepatic lesions and in healthy mice. This test, like any other, was successful. Intravascular valves were also produced which proved to be functional. They have in fact preserved their structure, thus allowing the various liquids to flow freely.
Obviously, for scientists this is not the end of the story, and there is a need for many other tests and experiments to really understand how far this technique can go. For this reason, the bioengineering group of this study has given the green light to other researchers for the use of this technology. Indeed, a start-up that sells the materials necessary for the printing was created by Miller and colleagues.