At first glance, any observer may not be able to realize that he is seeing a retina growing on a Petri dish. For researchers at Johns Hopkins University, however, this cultivated organoid holds many secrets .
Among them are the secrets of macular degeneration, or color blindness . This artificial organ is practically identical to a natural one, explain the scientists, and is helping to show that organoids are the most effective medicine future.
Cultivating eyes in Petri dishes
“How can we see color? ? And how do the cells of our eyes develop to make it possible? ” With these questions, Kiara Eldred presents her latest study published in Science. The protagonist of this work is a piece of retina, the “tapestry” that covers the inside of our eyes. Thanks to this fabric we can see. It is also thanks to him that we can distinguish colors.
Your ultimate goal is understand the secrets of the vision to be able to develop effective therapies that help cure color blindness or degeneration of the macula. While the former prevents the colors from being correctly appreciated, the latter causes the loss of sharpness and vision. Until recently, none had a solution. Now we begin to see the first treatments. Studies like this are the ones that are paving the way to his cure.
On the other hand, if we look at the cultivated “eyes” of Eldred, we probably do not distinguish much. This is because researchers are working with a retinal organoid . That is, they have taken stem cells and turned them into a practically complete retina. “Everything we examine looks like an eye in normal development, it only grows on a plate,” explained Robert Johnston evolutionary biologist and director of the Johns Hopkins University lab where Kiara works.
These researchers focus on the cells of the retina that allow to see blue, red and green . These cells are known as cones, and are part of the photoreceptors that make up the retina. Thanks to the combination of these three, the human eye is able to perceive the colors of the visible spectrum.
To understand it better, the study has worked on the development of the cells, that is, how is determined what type will the stem cells become as the eye grows .
“The Trichromatic vision differentiates us from most mammals, “explained Kiara Eldred. “What we are trying to find out is what path these cells take to give us that special color vision.”
Cells that detect blue appear first, followed by those that detect red and green
A Over the months, as the cells grew on the plate, the team discovered that the cells that detect blue appear first, followed by those that detect red and green . In this development, the thyroid hormone plays a fundamental role, they observed.
The most curious thing is that in the plaque there is no thyroid gland . Therefore, it is the retina itself that produces the hormone to control the growth of some cells or others. By understanding the role of the amount of thyroid hormone in the eye, the team managed to create eyes that were only able to see blue, red or green.
Opening doors to new solutions
Premature babies suffer a higher incidence of vision disorders. This, explains the team, is related to thyroid hormone. “If we know what factors drive a cell to its final role, we will be closer to restoring color vision in people with damaged photoreceptors ,” Eldred said.
With the hormone, the team has begun to walk towards the answers. In addition to color deficiencies, which could help cure color blindness, they also want to help with macular degeneration. The macula deteriorates over time or due to external factors. The macula is responsible for visual acuity.
Also what happens with the cones, if we can determine how the macula appears, we could instruct the cells to repair the damage caused by macular degeneration. Currently, this disease is one of the leading causes of blindness in the world.
These are just some examples. The truth is that the team has demonstrated the usefulness of organoids in the study of difficult to treat diseases. In the future, they indicate, they would like to use these organoids to learn even more about the vision of color and the mechanisms involved in the creation of other regions of the retina, which may lead to new treatments . ] Organoids, the future of medicine
The retina grown by the Eldred team is what is known as “organoid”. Organoids are artificial organs, created from stem cells and an adequate cocktail of substances . In our body, starting from a few stem cells begin to appear all kinds of tissues.
Organoids are artificial organs, created from stem cells and a suitable cocktail of substances
All cells carry the same DNA , so, how does each one know what it has to become? The instructions for each one to fulfill their function are received according to the position they occupy. This they “know” by their companions. They transmit a series of chemical signals. When they receive the right signals, the cells know what to become and, in turn, produce new substances.
This is basically what happens in an organoid. Take a handful of cells and give them a chemical cocktail that begins the formation of a tissue. From there, the organoid itself, if well fed, finishes its formation. These “plaque organs” are very important in the study of diseases.
In itself, they function as a realistic model of many diseases and processes. This has been shown with this eye in a Petri dish, but they are not the only ones. There are already laboratories building “robots” capable of designing new organoids automatically.
This will allow us to build all kinds of tiny organs in which to make valuable tests without having to resort to the Experimentation with humans or animals . And this, in turn, will open the doors to the development of treatments for diseases that until now seem impossible to cure.