Scientists in the US have grown, in a lab, the first functioning mini-human heart models to help identify cardiac disorders.

The human heart organoids (hHOs), which have functioning chambers and vascular tissue, were created with stem cells to mimic the ‘nuts and bolts’ of how a fetal heart develops in the womb.

The tiny hHOs, which grew up to around 0.04 inches (1mm) in diameter after just 15 days, started beating at only around six days old.

Researchers say their little spherical hearts are the ‘most faithful human cardiovascular organoid model’ grown in vitro to date.

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Lab-made mini-human heart models will help scientists better understand how defects like congenital heart disease develop, which affect one percent of all live births.

“With our heart organoids, we can study the origin of congenital heart disease and find ways to stop it,” said Aitor Aguirre, assistant professor of biomedical engineering at Michigan State University.

“These mini-hearts constitute incredibly powerful models in which to study all kinds of cardiac disorders with a degree of precision unseen before.”

The hHOs showed very high similarity to human fetal hearts, both morphologically – in terms of structure – and cell-type complexity and have ‘sophisticated, interconnected internal chambers’.

One of the main issues facing the study of fetal heart development and congenital heart defects is access to a developing heart.

Researchers have previously been restricted to using of mammalian models and donated fetal remains.

‘Now we can have the best of both worlds, a precise human model to study these diseases – a tiny human heart – without using fetal material or violating ethical principles,’ Aguirre said.

The team used induced pluripotent stem cells (iPSCs) – adult cells taken from a patient – to trigger embryonic-like heart development in a dish. MailOnline

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