It doesn’t come as a big surprise when we see most of the 3D printing applications in biomedical field. The reason being that 3D printing allows the experts to 3D print organs down to the last minute detail and that changes everything, drastically. We’ve already seen 3D printing being used for helping with transplanting a kidney. What’s the recent feat of 3D printing? Well, scientists from Harvard University have 3D printed a fake gel brain and then observed it ‘grow’ thus discovering and understanding how the human cortex develops the iconic folds.
This discovery has been published in the journal Nature Physics and is a major step towards understanding the structure of grey matter that will help in subsequent understanding of certain disorders that could be attributed to over-folding or under-folding of brain.
Ellen Kuhl of Stanford University writes in a commentary that researchers ‘have provided the first experimental evidence of the theory of differential growth and demonstrated that physical forces — not just biochemical processes alone — play a critical role in neurodevelopment. Their findings could have far-reaching clinical consequences for diagnosing, treating and preventing a wide variety of neurological disorders.’
Human fetuses begin the developing of these folds once they are about 23 weeks in gestation and the final touches are imparted on the network after they the child is born. Scientists have been able to deduce in the past that the folded nature of the brain gives it certain benefits; it enables for increased connectivity across the cortex – the surface layer of brain that is composed of gray matter.
Kuhl wrote, “Each cortical neuron is connected to 7,000 other neurons, resulting in 0.15 quadrillion connections and more than 150,000 km of nerve fibers.” However, scientists have failed to ascertain that what causes the development of these folds. A number of researchers have tried to determine the biochemical and cellular processes at work, however, Lakshminarayanan Mahadevan decided to go with the physics of the structure itself. Mahadevan is a physicist and applied mathematician at Harvard University and says, ““I have a longstanding interest in trying to understand how the body or bodies of animals organize themselves. I approach these problems from a mathematical perspective.”
The basic problem lies with the fact that there is no way to observe an actual brain during its development phase and thus the lack of understanding persists. Enter 3D printing that was used to build a physical model of the brain by making ingenious use of materials. Scientists made use of MRI from a fetal brain at 22 weeks of gestation and then 3D printed a cast to create a fake brain from gel. The ‘white matter’ was covered with a thin coat of rubbery gel in order to mimic the grey matter. It was then subjected to a liquid solvent that allowed the cortex like layer to begin its growth and the brain-like folds formed eventually allowing the team to gain an insight.
So what really happens? The cortical tissue intends to continue growing, however, the white matter inhibits it and the expansion of cortex causes collapse of the tissue thus evoking the gyri (round features) and sulci (deep grooves) that cover the surface.
Mahadevan says, “In the end, all of them are related. If I think about the shape of the folds in a fetal brain then yes, there are molecular processes: There are biochemical processes which cause cells to move, cause cells to divide, cause cells to change shape and cause cells to change in number.”
Kuhl said, “Making these connections can help us identify topological markers for the early diagnosis of autism, schizophrenia or Alzheimer’s disease, and, ultimately, design more effective treatment strategies.” 3D printing has helped achieve this feat and we are really excited to see what else can be achieved by this amazing technology.