Now, spring-like fibres to repair heart tissue

Researchers have developed new spring-like fibres that will enable engineered cardiac tissue in damaged hearts to help the organ function normally.
The threat from a heart attack doesn't end with the event itself. Blockage of blood flow to the heart can cause irreversible cell death and scarring, researchers said.
With transplants scarce, half the people who live through a heart attack die within five years. Scientists are trying to address this problem by engineering cardiac tissue to patch up damaged areas.
Researchers Sharon Fleischer and Ron Feiner working with Dr Tal Dvir from Tel Aviv University have fabricated fibres shaped like springs that allow engineered cardiac tissue to pump more like the real thing.

"Until now, when scientists have tried to engineer cardiac tissue, they've used straight fibres to support the contracting cells," said Dvir.
"However, these fibres prevent the contraction of the engineered tissue. What we did was mimic the spring-like fibres that promote contraction and relaxation of the heart muscle. We found that by growing tissues on these fibres, we got more functional tissues," said Dvir.

Cardiac tissue is engineered by allowing cells taken from the hearts of patients or animals to grow on a three-dimensional scaffold, which replaces the extracellular matrix, a collagen grid that naturally supports the cells in the heart.

Over time, the cells come together to form a tissue that generates its own electrical impulses and expands and contracts spontaneously. The tissue can then be surgically implanted to replace damaged tissue and improve heart function in patients.
More recently, the researchers identified spiral-shaped collagen fibres in the extracellular matrix of rat hearts. Seeing the potential for an advance, they set out to recreate them for the first time.
After fabricating the spring-like fibres using advanced techniques, they subjected them to a variety of tests.
As the researchers predicted, the spring-like fibres showed better mechanical properties than straight fibres, with especially improved elasticity.

And compared to tissue engineered with straight fibres, the tissue engineered with spring-like fibres contracted with greater force and less mechanical resistance.
"These properties are very important, because we want to transplant the tissue into the human heart, which expands and contracts constantly," said Fleischer.
The study was published in the journal Biomaterials.