Organoid of the embryonic heart
For the first time, stem cells were turned into an analog of the heart of a mouse embryo
Molecular biologists have created the first full-fledged miniature copy of the heart of a mouse embryo. To do this, they used miniature analogues of embryos grown from stem cells – organoids. An article describing the work was published by the scientific journal Cell Stem Cell (Rossi et al., Capturing Cardiogenesis in Gastruloids).
"The main advantage of embryonic organoids is that many different tissues develop inside them in parallel. They exchange among themselves the same signals that are critical for the proper growth of the embryo. The heart cells growing in them are in the same environment in which they would be located in a real embryo," explained Juliana Rossi, a molecular biologist from the Swiss Federal Polytechnic School and one of the authors of the work.
Over the past ten years, scientists have repeatedly tried using embryonic or stem cells to create artificial liver analogues. The first such experiments ended with success back in 2012. Then Japanese scientists reproduced some of the liver functions of mice with the help of artificially grown organoid–like organs.
Subsequently, biologists created and tested several other variants of such an "artificial" liver and other organs. All such experiments were carried out on animal cell cultures, which is why researchers are not yet sure whether it is possible to grow human organs in a similar way.
Test Tube Heart
Rossi and her colleagues have taken the first big step towards growing a heart in vitro. They figured out how to cultivate full-fledged miniature analogs of the heart from mouse stem cells.
Analyzing the sets of signals that are needed to turn stem cells into various body tissues, scientists noticed that the heart is the first organ that begins to form and work inside the multicellular embryo. Guided by this idea, Swiss researchers tried to grow not an "adult" heart, but its embryonic counterpart, creating a so-called gastruloid.
This is what scientists call a miniature analogue of the embryo. In its structure, it resembles the so–called gastrula - a hollow spherical structure that is formed in the first phases of embryo development. Having grown several similar mini-embryos from stem cells, the scientists treated them with a mixture of ascorbic acid and VEGF-165 and FGF proteins, which stimulate the growth of the heart and blood vessels.
As a result, in the vast majority of gastruloids, first "blanks" of heart muscle cells began to form, and then the organ itself appeared. He began to contract, as well as to produce and perceive signals characteristic of the forming heart. In addition, scientists have recorded signs that blood vessels began to grow around this organoid, and cells that participate in the formation of the left and right half of the heart began to emerge inside it.
Scientists hope that in the course of further experiments with gastruloids they will understand how to turn such a structure into a full-fledged human heart. They also hope to find out how violations occur in his work. To do this, it will be necessary to grow artificial copies of the circulatory systems of people with congenital cardiac diseases.
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