Tiny 'hearts' self-assemble in lab dishes and even beat like the real thing

[Judi Lynn]

By Nicoletta Lanese - Staff Writer 3 days ago

Under the watchful eyes of scientists, stem cells in lab dishes assembled themselves into tiny heart "organoids," roughly the size of sesame seeds, and began "beating" like real miniature hearts.

To guide the stem cells into these structures, the research team exposed the cells to a suite of proteins and small molecules that are known to be involved in early human heart development in the womb, according to a new study, published Thursday (May 20) in the journal Cell. These proteins and molecules docked onto receptors on the cell surface and set off a chain reaction, causing the stem cells to differentiate into several different cell types found within the heart.

After one week of development, the cells sorted themselves into hollow, chamber-like structures, analogous to the left ventricle of the heart, the team found. What's more, the walls of the chambers began to contract rhythmically, mimicking a human heartbeat.

"What we're interested in is essentially how human heart development works, and how it fails when we have, for example, congenital heart defects," said senior author Sasha Mendjan, a group leader in the Institute of Molecular Biotechnology at the Austrian Academy of Sciences in Vienna. These defects typically set in fairly early in pregnancy, but scientists cannot look directly into human embryos to see exactly how they occur. "We don't have any access to this window — this is essentially a black box," Mendjan told Live Science.

More:
https://www.livescience.com/sesame-seed-size-heart-organoids.html

[Judi Lynn]

1. This Beating Sesame Seed-Sized 'Human Heart' Grew Itself in a Lab

CARLY CASSELLA 23 MAY 2021

Scientists have successfully grown a bundle of human stem cells into a tiny artificial "heart" the size of a sesame seed.

The pulsating mass is the first self-organizing miniature organ to resemble the human heart, including a hollow chamber enclosed by a wall of cardiac-like tissue.

Simple heart-like organs, or cardioids, have been built in the lab before, but only using a scaffold, a mold, or a matrix for the cells to assemble around.

This new cardioid model spontaneously constructed itself. All scientists had to do was coax the pluripotent stem cells in their dish using six signaling pathways known to coordinate heart development in the human embryo.

Other studies have managed to grow self-organizing eye organoids, self-organizing brain organoids, and self-organizing gut organoids using similar signaling techniques.

"It's not that we are using something different than other researchers, but we are just using all of the signals known," explains biologist Sasha Mendjan from the Austrian Academy of Sciences in Vienna.

More:
https://www.sciencealert.com/scientists-have-built-a-self-organizing-mini-human-heart-that-can-pump-liquid-in-and-out