01 Human organs in a petri dish
The human body is like a continuous working machine, and the various organs of the body are the components. Human organs are often composed of a variety of different cells, all kinds of cells or the collection of cells play different roles, and there are a large number of blood vessels, nerves, various types of pipelines and other structures in the organ together with the cells to achieve the complex functions in the body.
With the help of 3-D cell cultures, scientists have been able to create miniature versions of “mini” organs — professionally known as “organoid organs” — in laboratory dishes, including the liver, pancreas, stomach, heart, kidney, and even the breast.
Organ analogs are highly similar to the source tissues and organs, having the ability to self-renew and self-organize, and to reproduce part of the physiological functions of the source organs. With organoids, researchers can better understand biological development and the causes of disease, and have achieved remarkable results in drug screening, precision medicine, regenerative medicine and other applications.
In vitro culture of “mini” stomach
Image credit: ScienceMag
02 Is the quasi-organ a microcosm of the real organ?
Although very small, these lab-made “mini” organs are not random aggregations of cells. Instead, they already have complex structures that resemble real organs, such as the tiny blood vessels on the kidneys, the folds in the cerebral cortex, and the mucous membranes and villi inside the small intestine that can be seen under a microscope. Organs can also grow and function just like real tissues in the body! However, quasi-organs cannot be completely called “miniature versions” of real organs. Some structural features closely related to the function and development of real organs, such as the lack of vascular system, are still not available to quasi-organs. However, a few kinds of organ like culture have been successfully vascularized, and scientists are still actively exploring the possibility that in the near future, organ like with blood vessels for transplantation will be constructed in vitro for the benefit of human beings.
03 Organ like can cry, and maybe think?
With the deepening of organoid research, more and more functions of organoid have been reported, and the achievements of organoid are even more exciting.
The tear-producing culture, published in Cell Stem Cell on March 16, 2021, is the first “organoid” of the lacrimal gland — a three-dimensional collection of cells that resembles a miniature organ. The glandular organs that produce tears could be used to study and eventually treat diseases that cause dry eye, including an autoimmune disorder known as Sjogren syndrome.
At first, it takes a long time to make the cells cry — up to a whole day. But with experience and a little prodding, researchers were eventually able to make cells cry in as little as half an hour.
The lacrimal glands produce tear-like fluid (red).
Image: Yorick Post/The Hubrecht Institute in the Netherlands
The “crying” organs swell with tears
Image: MarieBannier-Helaouet/The Hubrecht Institute in the Netherlands
And, according to media reports, a Petri dish filled with what looks like tiny pearls at the University of California, San Diego, may be thinking — at least that’s what a machine-learning algorithm says when it detects a spike in neural activity. The study, published in the August 29, 2019 issue of Cell Stem Cell, could help scientists better understand how the human brain develops. The researchers described in detail how a group of tiny brains (classified as organoids) grown in the lab for nine months began to produce electrical patterns similar to those of premature babies. The researchers point out that this is the first time this has been done in a petri dish.
A 10-month-old human brain-like organ the size of a pea grain
Image: Muotri Lab
Alyssson R. Muotri, co-senior author of the study, said that while they were initially shocked, they were cautious.
Muotri points out that these tiny brains are nowhere near as functional as the full cerebral cortex, even in babies.
To measure the activity of organoids, the researchers used data from babies born three and a half months prematurely. They then developed an algorithm that could predict the age of the captured electrical signals from an electroencephalogram. The results showed that the nine-month-old organoid showed similar characteristics to a premature baby born at 40 weeks old.
The researchers say their findings could open new doors to understanding mental illness and epilepsy.
Post time: Jun-23-2021