Catalan researchers print a piece of a beating heart for the first time.

BarcelonaCatalan scientists from the Bellvitge Biomedical Research Institute (IDIBELL) have, for the first time, created a piece of heart tissue that can grow, mature, and survive long-term inside an animal. Until now, these types of experiments failed because these tissues are very complex, and if they don't receive enough blood and nutrients, they don't mature properly and eventually die. Now these researchers have achieved this goal using a 3D bioprinter: they have created small blood vessels with this tool, allowing the tissue to integrate perfectly into the circulatory system and survive for a month after implantation. Until now, the life expectancy of these tissues was no more than two weeks, so the researchers believe that using this technique, heart patches could be manufactured to replace affected parts of a patient's organ and help the patient regain its functionality.

Specifically, the researchers have created a small piece of myocardium, one of the muscles responsible for pumping blood, and have verified that the tissue was beating correctly and new blood vessels had been generated, supplying it with blood and nutrients. Today, they have achieved this with an animal, but they believe that in the future it could be applied to humans as a therapy for people suffering from cardiovascular disease. "To be able to bring this therapy to the first patient, we estimate that it would require about four more years of research and collaboration with other research centers. We have applied for a European project, but they have not granted it, therefore, we will have to look for other ways to move forward," explains Ángel Raya, leader of the study.

The "recipe" for printing

3D bioprinting allows for the creation of different layers that provide good structure and stability to the tissue so it can survive. This tool uses bioink, a material made from stem cells to create cardiac tissue. The "recipe" that researchers have found to make the formula work and for the tissue to adapt correctly to the heart is to place three layers of muscle bioink between two layers of vascular bioink. These materials are composed of gelatin, which provides consistency and plasticity to the tissue, but also a protein called fibrinogen and hyaluronic acid, which provide structure, flexibility, and support to the cells.

Finally, the bioink also includes microbial transglutaminase, an enzyme that promotes the creation of bonds between cell layers, an essential characteristic for the stability of the tissue once implanted. From this base, the two inks can be generated separately. On the one hand, muscle bioink requires adding muscle cells called cardiomyocytes to the bioink, while vascular bioink uses vascular microfragments extracted from the patient themselves.