A look inside the organ: For the first time, researchers have succeeded in making human organs completely transparent. Thanks to their process, the complex structure of these tissues can be visualized and analyzed down to the cellular level. This enables accurate mapping of the organs – and could one day help create functional artificial replicas.
Whether brain, heart or kidney: human organs are incredibly complex. Doctors now know the basic structure and function of these tissues. Deciphering its structure in every detail has always been a challenge. Because technologies to make organ structures visible down to the cellular level were missing.
That should change with so-called tissue clearing. This process makes organs transparent and thus enables complex 3D images of them to be generated. So far, however, this has only been possible with tissues from mice. The problem: In the course of time, insoluble molecules such as collagen accumulate in human organ tissue and make it stiff. Common cleaning agents can therefore make mouse organs transparent – but they fail, especially on human tissue in adults.
A look into the brain, kidney and co
Shan Zhao from Helmholtz Zentrum München and her colleagues have now succeeded in making the apparently impossible: They have made intact human organs transparent. “We had to take a completely new path and start all over again to find a chemical that could also make human organs transparent,” reports the researcher.
After a series of experiments, the scientists came up with the solution: They found that a detergent called CHAPS can create small holes in the stiff organs. This makes them more permeable to other solutions, which then penetrate the fabric down to a centimeter and convert it into transparent structures. In this way, Zhao’s team managed, among other things, a unique look into a human brain and kidney.
“Key for mapping”
In order to be able to examine the transparent organs in detail, the researchers developed a new laser scanning microscope with a particularly large recording capacity and a self-learning algorithm. As they report, the microscope can take pictures of entire human organs up to the size of a kidney. The algorithm is then used to analyze the millions of cells imaged.
Zhao and her colleagues summarize their entire method under the name SHANEL (Small-micelle-mediated human organ efficient clearing and labeling). “SHANEL could become a key technology for mapping intact human organs in the near future. This would enable us to quickly understand much better how organs such as our brain develop and how they function in a healthy and sick state, ”explains Zhao’s colleague Ali Ertürk.
Alternative to donor organs?
According to the scientists, this will result in exciting new possibilities for 3D printing of organs. Because cellular three-dimensional maps of human organs could in future serve as templates for such artificially produced tissues. To achieve this goal, the team is already working on mapping the most important human organs, starting with the pancreas, heart and kidney.
If one day the detailed replication of human organs succeeds, patients who depend on a donor organ in particular could benefit. “There is an enormous shortage of donor organs for hundreds of thousands of people,” emphasizes Ertürk. Tissues from the 3D printer could be a suitable substitute here: “With detailed knowledge of the cell structure of human organs, we are taking an important step closer to the artificial production of functional organs on demand,” emphasizes the researcher. (Cell, 2020; doi: 10.1016 / j.cell.2020.01.030)
Source: Helmholtz Zentrum München