One of the most remarkable applications of 3D printing is tissue bioprinting.
The ability to 3D print living human tissues from stem cells not only opens doors for direct experimentation on human tissue but also provides hope to transplant patients.
We’ve already told you how several large companies like Organovo and Advanced Solutions are working hard to make bioprinting a reality. Last year, Organovo made headlines with its 3D Printed Liver Tissue.
This year, researchers at the University of Melbourne have accomplished an even more astounding feat by 3D printing tiny spheres of the most complex human tissue, the brain.
Printing the Most Complex Tissue
The breakthrough has been accomplished by a team of researchers at the Center of Neural Engineering at the University of Melbourne. Headed by Professor Stan Skafidas, the team has successfully 3D printed spherical pieces of human brain tissue from stem cells using the institute’s specialized bioprinter.
While the spherical structures are quite small (about the size of breadcrumbs), they contain all the six layers of neurons that are normally present in the human brain. Moreover, the neurons even form connections and communicate with one another, just as they do in a real brain. Skafidas says:
“If you’ve got the right microbe environment, the mass starts forming a brain, which would probably be equivalent to a 20-30 day foetus.”
Right now, the printed blobs of brain tissue can remain alive for 30 days but start to die off after that because of lack of nutrients. Researchers are working to extend the life span of the printed brain tissue by devising a better, more efficient system for the provision of oxygen and other nutrients to its neurons. Prof. Skafidas hopes that very soon they’ll be able to form brain tissue, capable of surviving for 100 days or more.
From Stem Cells to Brain Tissue
You’re probably wondering about the process by which brain tissue is 3D printed.
The magic begins with pluripotent stem cells, which are undifferentiated cells capable of forming any tissue of the body.
These stem cells are obtained by reprogramming human skin cells back into an undifferentiated state.
By carefully arranging these stem cells in three-dimension in a dish with the help of a 3D bioprinter and inducing them to form nerve cells by specific chemicals (growth factors), a 3D spherical form of brain tissue is formed.
This spherical tissue represents the brain on a very small scale and hence is termed as brain organoid. Dr. Mirella Dottori, a researcher at the Center of Neural Engineering, explains organoids in the following words:
“…organoids are basically aggregates of cells that very much resemble a tissue or an organ. That’s why they’re called organoids. But the difference is that organoids usually are derived from stem cells that have become the cell types of that organ that they represent.”
The whole process is greatly dependent on the precise three-dimensional arrangement of stem cells accomplished by the help of a 3D bioprinter.
3D Printed Brain Tissue vs 2D Neuron Cultures
To study brain diseases, scientists have traditionally used neuron cultures which are two-dimensional networks of neurons grown in a laboratory. 3D Printed Brain Organoids, made by the researchers at the University of Melbourne, are a huge improvement over traditional 2D cultures because they are able to mimic the complex interactions that are normally found in the brain and thus, can provide valuable information that 2D cultures cannot. Dr. Dottori explains:
“(organoids) are assembled together very much in the way that a tissue is assembled together. So the way the cells are interacting are similar to how cells within that organ interact. Whereas in cell culture as a mono-layer you can’t get that same complexity of interaction in a two dimensional system.”
There are quite a number of implications of 3D printed brain tissue.
The first and the most immediate of these is the experimental value of such printed tissue.
For decades, scientists have conducted experiments on mice or 2D neuron cultures to gain information about human brain diseases and test possible treatments of these diseases.
However, because of the sheer complexity of the human brain, the exact causes of many brain diseases, like schizophrenia and autism, are still unknown. Prof. Skafidas laments our ignorance of these common brain ailments:
“It’s the 21st century and we still don’t know how the brain works”
With access to 3D printed brain tissue, this situation could change drastically. For the first time, scientists will be able to experiment directly on human brain tissue and test all the different theories about brain diseases. They would also be able to test the effects of different drugs on brain tissue. All this could translate into a large-scale revolution in the field of psychiatry. Prof. Skafidas explains:
“One hypothesis for schizophrenia and autism is maternal inflammation early in pregnancy, which starts the trajectory towards these problems later in life. We can now mimic that insult in the dish and see how it ¬affects development. Soon we’ll be able to cut out the hippocampus, experiments that would otherwise be unethical in humans.”
If we look several years into the future, such 3D printed brain tissue may be able to replace damaged parts of the brain in cases of brain stroke or accidents making partial brain transplants a reality.
Even further into the future, advances in 3D bioprinting may enable creation of entire brains which may be used to enhance the intelligence of computers and robots enormously, a possibility that raises interesting ethical questions.
Many of these implications of 3D printed brain tissue are discussed on LipTV’s YouTube channel…
The tiny spheres of 3D printed brain tissue made by Melbourne researchers clearly demonstrate the Limitless Potential of 3D Printing. It is completely changing how we think about our future.
Printing brain tissue, however, comes with its own ethical issues. How far are we willing to go to advance science and technology? Are we ready to make artificial humans or robots that can think and behave just like us? These are some of the questions that we have to face while talking about 3D Printed Brains.
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Thanks for reading.