A team of scientists developed a functioning heart tissue in a lab, made from donated hearts' regenerated cells. While scientists are still far from growing a functional human heart in a lab, the findings can help in growing tissue patches made from the patient's own cells.

The procedure involved a detergent solution that can strip living cells out of a donor organ. The method was created by Dr. Harald Ott in 2008. Ott, the paper's senior author, is from the Massachusetts General Hospital's Center for Regenerative Medicine and Department of Surgery.

To grow a heart tissue, the cells need a scaffold to give them shape. This is known as the extracellular matrix, which is made from the proteins that cells secrete.

But growing this natural scaffold takes time, so they used 73 donor hearts that were deemed unfit for transplant by the New England Organ Bank. The researchers stripped the cells from the donor hearts and grew a new heart tissue by seeding the leftover neutral extracellular matrix.

In the seeding process, the researchers utilized a new technique wherein the messenger RNA (mRNA) was used to degenerate skin cells back to stem cells. The mRNA is an RNA subtype wherein the molecules transport a part of a DNA code to other cells parts for processing. The resulting pluripotent stem cells are then coaxed to grow into cardiac muscle cells.

For 120 days, the coaxed cardiac muscle cells were seeded into the extracellular matrix. The growing cardiac tissue was exposed to various conditions that replicated those surrounding a living heart.

"Generating personalized functional myocardium from patient-derived cells is an important step towards novel device-engineering strategies," said Ott, who is also an assistant professor of surgery at the Harvard Medical School.

During the electrical stimulation in the tissue analysis, the grown heart tissue demonstrated functional contraction as a response. The study was published in the journal Circulation Research.

"Regenerating a whole heart is most certainly a long-term goal that is several years away," said Jacques Guyette, lead author, who is also from the Massachusetts General Hospital's Center for Regenerative Medicine.