3D printing incorporating human stem cells might soon become a standard technique for treating heart attack victims, according to US researchers.

Scientists from universities in Minnesota, Wisconsin and Alabama last week unveiled a way of incorporating cells into a bio-printed matrix that will potentially reduce the risk of a second heart attack.

During a heart attack, blood flow to the organ decreases, resulting in massive cell death. These dead cells do not regenerate and are replaced instead by scar tissue – which increases the risk of another adverse event.

The US team, led by biomedical engineer Brenda Ogle at the University of Minnesota, used laser-based 3D printing to bind human stem cells into a matrix that – at least in a Petri dish in the lab – began to beat like heart muscle.

In a further test, the team created 3D-printed heart patches using mouse cells and implanted them into the damaged hearts of lab mice.

After four weeks, the researchers reported "significant increase in functional capacity" in the rodents.

Because the stem cells and supporting proteins used in the biofilm had come originally from each individual animal, the patches became absorbed into each heart. There was no immune system resistance, and no need for follow-up surgery.

Although the technique is still at proof-of-concept stage and faces years of rigorous clinical trials, it represents an important shift towards personalised, regenerative therapies. It also represents a major new direction for 3D printing.

"We were quite surprised by how well it worked given the complexity of the heart," Ogle said. "We were encouraged to see that the cells had aligned in the scaffold and showed a continuous wave of electrical signal that moved across the patch."