06 April 2018

A piece of the heart

Mature heart tissue was grown from stem cells for the first time

Anatoly Glossev, Vesti

Biologists have grown tissue from stem cells that reproduces the properties of a healthy human heart with unprecedented accuracy. In addition, it was obtained in record time: cultivation took nine times less time than usual. A new technology has helped scientists in this. The achievement is described in a scientific article published in the journal Nature by a team led by Gordana Vunjak-Novakovic from Columbia University in the USA (Advanced maturation of human cardiac tissue grown from pluripotent stem cells).

Induced pluripotent stem cells are an indispensable tool for physicians and biologists. Recall that pluripotency is the ability of such a cell to develop into a cell of any organ and tissue. The word "induced" means that stem cells were forced to become such: they were obtained by "reprogramming" ordinary somatic cells (the technology has existed since 2009).

Specialists grow different tissues from such cells in order to test drugs on them. Unfortunately, the applicability of this method is still limited. The fact is that so far "tissues from a test tube" do not demonstrate all the properties of their natural analogues.

Against this background, the achievement of the Vunyak-Novakovich group looks particularly impressive.

"The resulting bioengineered tissue is truly unprecedented in its similarity to functioning human tissue," the press release of the study quotes the words of Seila Selimovic, director of the program under which the study was funded.

Kacey Ronaldson-Bouchard, Gordana Vunjak-Novakovic/Columbia Engineering

It is all the more surprising that the fabric was able to grow in record time. The procedure took not nine months, as usual, but only four weeks. Both the growth rate and the functionality of the "product" should be thanked for the new technology.

Recall that a stem cell can become a "brick" of any organ. To create artificial hearts, researchers naturally take cells that turn into cardiomyocytes – muscle cells of the heart. However, such a metamorphosis is a gradual and multi–stage process, and the question remains at what stage to take "test subjects".

"The general approach in our field is that the more mature the starting cardiomyocytes are, the better," explains the first author of the study, Kacey Ronaldson–Bouchard from Columbia University. "However, we found that very young cells, whose development is still plastic, will respond better to external influences that we carry out to stimulate maturation."

The "embryos" of the heart, measuring about six millimeters, developed in a system known as "organ-on-a-chip". In addition to biochemical effects, the researchers used electrical stimulation to make the growing muscle tissue contract. This is a standard procedure, but the innovation was in the mode of supplying electrical signals. The frequency of induced contractions was increased literally every day.


As a result, the brainchild of the researchers copied mature healthy heart tissue for a number of parameters. These are the pattern of gene expression, sarcomere length, mitochondrial density, the presence of transverse tubules in the cell membrane, the ratio of strength and frequency of contractions, oxidative metabolism and biochemical turnover of calcium.

Such an accurate analogue of a living heart significantly expands the possibilities of drug testing, making them safer and more effective as a result. In addition, it can be useful in the study of hereditary diseases of the human "flame motor". By reproducing the desired mutation in cells, scientists will be able to investigate its consequences and ways to combat them.

Unfortunately, the current achievement does not yet allow us to grow a full-fledged heart for transplantation to a patient. According to a number of electromechanical parameters, the resulting tissue is still too different from the natural one. However, if technology develops at a similar pace, the day is not far off when it will become possible.

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