The research team of the Centre for Organismal Studies (COS) has succeeded in obtaining retinas from embryonic stem cells of various fish.
The scientists were thus able to gain many new insights into the development of retinas and the general development of cell structures at Heidelberg University.
The Research Process At A Glance
To begin with, pluripotent stem cells from various bony fish (zebra and medaka fish) were extracted. These cells do not yet have any special properties and can develop into different cell types in the course of their development
These pluripotent stem cells of an embryo then merged in a Petri dish within one day to form a large retina. From this union, different types of cells developed in a very short time, which is remarkable in this efficiency. In total, several hundred retinal organoids developed, making it possible to narrow down the requirements for structures resembling a head and two eyes.
What Is An Organoid?
An organoid is a microstructure that can be artificially synthesized. They can be “manufactured” from tissue cells or pluripotent stem cells under the right conditions. They serve a variety of purposes and are often used as a support in drug development or disease research.
Fish organoids are more reproducible than mammalian organoids and develop faster, so they offer many advantages for this research. Only in this way is a comparison with real fish embryos realistic.
Why Are The Results So Important?
There are already studies that indicate promising findings with stem cells of bony fish, but cultures of the cells have never been able to assemble into a complex structure in this way
By analyzing the development of this process, new potentials open up, especially with regard to the “manipulation” of stem cells. The first step has thus been taken towards synthetically reproducing highly complex structures. Thus, a major advance has been made in research with organoids, which gives hope for more to come.
In particular, the results obtained can still become valuable in research on diseases and in drug development.
Validation Of The Results
The result obtained is extremely promising, however, appearances can be deceiving: The external appearance of a highly complex retina does not yet mean that this compound really behaves like a retina. To check the behavior of the specially created retina, movement and other behaviors were monitored through a state-of-the-art microscope.
Analysis showed that a “real” retina showed no differences from the retina in the experiment, and research on the new organoid can continue.
The research is based on medaka and zebrafish, which are fundamentally evolutionarily different. By the strongly similar results of both fishes, it can be concluded that the development of the eyes, especially the retina, shows a strong similarity and has little evolutionary difference in the genetics of the different fish species.
The finding that embryonic stem cells can independently develop organoids such as retinal tissue implies that other highly complex structures can also be produced in a Petri dish.
For this reason, the results are a major step in organoid research, but also in general stem cell research.
Source: L. Zilova, V. Weinhardt, T. Tavhelidze, C. Schlagheck, T. Thumberger, J. Wittbrodt: Fish primary embryonic pluripotent cells assemble into retinal tissue mirroring in vivo early eye development, eLife (12 July 2021)