One of the biggest mysteries in science over the past century is how one fertilised cell can divide, grow and differentiate to form a vast number of different cell types which make up a complete organism (in humans there are over 200 different types of cells!).

The cells contained in an embryo, referred to as stem cells, are pluripotent. This means that they have the potential to differentiate into any other type of cell. Once a cell has differentiated it becomes specialised as a specific mature cell type. Stem cells are of huge value in medical research due to the potential to become any other cell type but the ethical concerns surrounding embryonic stem cells has been a big hurdle to this process and a continuing debate in science.

In the last decade, there have been huge advances made in the field of cell differentiation, with the 2012 Nobel prize going to Shimya Yamanaka and Sir John Gurdon for the discovery that mature cells can be reprogrammed to become pluripotent (undifferentiated).

This was a huge finding, not only because it demonstrated the power of molecular biology to manipulate cells, but because it showed great potential for medical applications, such as tissue regeneration.

This was a huge finding, not only because it demonstrated the power of molecular biology to manipulate cells, but because it showed great potential for medical applications, such as tissue regeneration.

Using this information, scientists have been able to grow 3D structures in the lab called organoids. This approach opens up a vast range of potential scientific developments, not least as a tool to study the brain. Brains are infinitely complicated. Our vast and intricate brain network is what sets us apart from other animals, having the ability to think freely, talk and even fall in love.

The complexity of the human brain makes it very difficult to carry out research into brain-associated diseases, but the use of organoids has taken us another step closer to looking directly at the human brain without having to cut someone open to doing so.

Organoids are the closest thing we currently have to replicate an organ outside of a host organism and are essentially 3-D groups of cells which mimic an organ. This means that we now have a new tool to do things we couldn’t before, such as observe how neurons develop and function and how they are affected by different drugs. And it’s not just brain organoids, which have been successfully grown, demonstrating the flexibility and scope of this approach.

Using this process, scientists have been able to form brain organoids from patient cells, first triggering a state of pluripotency, then incubating them in such a way that they form brain cells. This approach has allowed researchers to pin-point stages in brain development which differ in diseased patients compared to healthy individuals, enabling us to begin to gain a greater understanding of brain disorders, such as microcephaly.

Madeline Lancaster, the scientist who first created brain organoids puts it best by saying that her ultimate goal is to one day discover “what makes us human” and the secret to this is likely locked away in our brains.

Chloe is a health and fitness enthusiast undertaking a Ph.D. in Molecular Biology at UCL. To check out her blog visit www.runningwithscience.com