Artificial hearts for transplantation could be here sooner than we think

Heart disease is the number one killer in the United States and around the world. In most cases, a heart transplant is the best way to save someone’s life and give them the opportunity to live a longer, healthier life. But unfortunately there are not enough hearts compared to the amount that is needed. About 20 percent of patients who need a heart transplant die on the waiting list, and many still have to deal with possible complications like transplant rejection even if they receive a new heart.

One possible solution to this problem is to circumvent it entirely (no pun intended) – 3D print artificial human hearts or other methods when a patient needs a transplant. Using 3D printing, researchers are developing techniques to print cells onto scaffolds to make parts of the heart, hoping to one day create a full human heart. Newer methods of making an artificial heart are also being developed that are similar to 3D printing but can have significant benefits.

Each of these projects could one day revolutionize heart health as we know it. But first they have to prove they can work.

The advent of 3D printing is something that organ researchers are watching very closely — and with good reason. If we could print structurally healthy human hearts using real heart cells, we could create something that is patient-specific and doesn’t require an organ donor at all. The likelihood of organ rejection would be extremely low.

But building a human heart from scratch is as difficult a task as you can imagine. The human heart is, after all, one of the most complex organs that has ever evolved on Earth – largely because its mechanics are so unique to its functions.

At its core, the heart is a pump that pumps blood through the lungs to be oxygenated and then to the rest of the body to deliver that oxygen to every single cell. But this pump doesn’t just expand and contract. It actually rotates as it contracts so it can expel more blood. Twisting gives the heart some torque – similar to wringing out a wet cloth. If researchers want to create a working human heart, they need to replicate that heart’s function.

Kit Parker, a bioengineer at Harvard University, has spent much of the past few decades working to develop the systems needed to create artificial human hearts. Earlier this year, he unveiled a breakthrough: a new way to create a heart chamber (one of the two types of chambers in the organ) that actually deviates from traditional 3D printing. This method, called Focused Rotary Jet Spinning (FRJS), can produce the ventricle much faster.

In FRJS, a liquid polymer is spun in a jet and collected on a scaffold, where it then solidifies and turns into fibers. Using this technique, Parker is able to recreate the spiral structure of the heart, which allows it to twist. The temporary scaffold, which is eventually dissolved, can then receive a layer of heart cells.

The cells are what are known as “induced pluripotent stem cells,” meaning they can be made by taking some skin cells from a patient, converting them back to the stem cell state, and then manipulating them to produce heart cells. Since the original skin cells used come directly from the patient, the transplant is not rejected as with a donor.

“You want these cells to feel like they’re in a real heart. You have to create a microenvironment or scaffold that creates the same kind of geometric constraints and the same kind of chemical constraints,” Parker told The Daily Beast. “We can do that with these fibers.”

According to Parker, it would take weeks to 3D print a viable human heart valve. FRJS can produce one in an hour. That kind of timing could be the difference between life and death for a patient in need where every minute counts. He thinks we could use FRJS to make parts of hearts for patients within a few years; and full hearts within a decade or so. The modularity of FRJS also means it can be used to fix a specific problem – there is no need to wait for a whole donor heart when a specific tissue or part of the organ can be replaced.

“What we’re trying to understand now is do you build this modularly and together like Lego, or do you build everything at once? It’s probably going to be a version of a modular heart,” Parker said.

However, much testing and troubleshooting remains to be done before FRJS or any other method of building an artificial heart can be used in real patients.

“We are learning how the cells organize and form muscle tissue. We understand how an embryo forms the heart, but we don’t try it that way. We are trying to create a full size heart. We can’t have normal development,” Adam Feinberg, a biomedical engineer at Carnegie Mellon University in Pittsburgh, told The Daily Beast. “Part of this is the creation of vessels in the heart. We’re learning how to do that.”

One of the problems that researchers face when attempting to make a heart is the investment of time and money required to simply make the heart cells. A human heart contains many different types of cells – from muscle cells to pacemaker cells – and Feinberg said making them is a laborious process.

“A full-size adult heart will likely have between 10 and 50 billion cells,” Feinberg said. “With today’s technology, that will probably cost between $100,000 and $150,000 just for the cells alone, and it will take two or three months to grow them” before they can be assembled into a heart. That means even if we’re able to make artificial human hearts, most people probably won’t be able to afford a heart built specifically for them.

However, Feinberg believes that once the technology becomes more widespread, costs will come down relatively quickly. As technology becomes more widespread, the supply chain expands, and the process becomes more refined, the price will come down.

“I don’t think it’s going to be very accessible in the short term, but I think over the long term — maybe 10 years after it’s released — we’ll see it become widely available,” Feinberg said. Artificial hearts for transplantation could be here sooner than we think

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