From housewares, to toys, to high fashion, 3-D printers can be used to make many different things. Printing one layer at a time, 3-D printers use materials like plastics and metals to build intricate and complex objects, such as tools, replacement parts, even prosthetics. In engineering, this type of construction is referred to as additive manufacturing. In Pittsburgh, one biomedical engineer has even invented a way to 3D print human tissue, an innovation that could one day allow us to print a working human heart. The actual human heart is incredibly complex, and we don’t necessarily need to mimic every feature in there. What we’re trying to create is a minimum feature set that really recreates the core properties of heart muscle tissue. Adam Feinberg, a professor at Carnegie Mellon University, received a 2015 Career award from the National Science Foundation for his work on 3D bioprinting. His research touches upon a crucial aspect of innovation, how scientists and engineers improve upon the work of others to make things better, faster and cheaper. Feinberg didn’t dream up the idea of 3D printing, but he is improving and adapting the technology to solve big needs. We really pull understanding, knowledge, technologies from anywhere we need them, and combine them to solve what we need to solve. And I think out of that process comes innovation. The problem Feinberg hopes to solve is a method for bioprinting human heart tissue and growing it outside of the body, an achievement that could help millions of people who suffer from heart disease, an affliction that kills more than 600,000 people in the United States every year. Heart disease is the number one cause of death worldwide. And really, the problem is that the heart doesn’t regenerate. If your heart becomes damaged, the heart muscle cells inside just cannot divide and regrow that damage. So once the damage occurs, through a heart attack or a lot of other diseases, it’s permanent. Since the 1960s, artificial hearts have helped patients live longer. However, artificial hearts can cause blood to clot and are still a continuing problem. Heart transplants offer another option for patients, but there are a limited number of hearts available for donation every year. Feinberg thought he might be able to bioprint new heart muscle tissue using 3D printers. But first, he had to figure out how to get them to print soft tissue-like material. Soft materials deform under their own weight and air. So when you go to 3D-print that, you’re going to lay down one layer, and if you come down to put the next layer on top, that first layer will now have moved. If that first layer moves, you can’t put the second layer on top. After a lot of trial and error, Feinberg invented a process that prints a soft gel inside a second support gel. This allowed him to print delicate soft structures that could support heart muscle tissue without it collapsing onto itself. The support is really what we 3D print into. It’s made out of a gelatin slurry, which is really just these tiny particles of gelatin. You can think of them like grains of sand. In this demo, Feinberg starts with a 3D image of the coronary artery, a major artery which supplies critical blood flow to the heart. Instead of printing with actual heart tissue, he uses alginate, a polymer material derived from algae, which he prints into the support gel. After the artery is printed, the support gel is melted, leaving an exact replica of the artery. This replica acts as a scaffold to grow human heart cells. Like the scaffolding that surrounds a building while it’s being built. You can either print cells in the scaffold during this process, or you can basically coat the scaffold with cells afterwards. While we are still many years away from bioprinting a full human heart, Feinberg says that within five years he may be able to print heart tissue, a breakthrough that could allow researchers to test drugs on 3D-printed heart tissue, instead of through costly human trials. We can make human heart muscle in the dish that you can test these drugs on, and the human heart muscle basically has all the unique properties of the actual human heart. Feinberg has seven patents issued by the U.S. Patent and Trademark Office. He hopes that other scientists and engineers will take his innovations and improve upon them even further. The way we look at it is, we don’t want to hold the technologies in. We patent it essentially so companies will be motivated to take the technology and move it forward. Technology, improved by innovation, that is only just beginning to make a big impact, and could one day save lives.