The brain of an embryo in a test tube
Scientists have grown the brain of a human embryo from stem cells
Scandinavian scientists have created a human embryo brain model from stem cells in order to use its example to see how different brain regions are formed during early development. This will help accelerate the development of new stem cell treatments for a number of serious neurological diseases. The results are published in the journal Nature Biotechnology (Rifes et al., Modeling neural tube development by differentiation of human embryonic stem cells in a microfluidic WNT gradient).
Studies of how the human brain develops at the earliest stages – from the second to the seventh week after fertilization – have so far been absent, since scientists did not have access to human embryonic tissue at such an early stage. Therefore, all conclusions were based on experiments on flies, chickens and mice.
However, the properties of the human brain are very different from those of animals, and knowledge of how each individual nerve cell is formed in the brain of an embryo is necessary in order to develop effective treatment for neurological diseases such as Parkinson's disease, epilepsy and stroke.
Knowing how nerve cells are formed at different stages of development, researchers will be able to develop treatments for each specific disease. For example, the therapy of Parkinson's disease requires a specific type of nerve cells that are lost in this disease – dopaminergic nerve cells.
Danish scientists from the Novo Nordisk Center for Stem Cell Biology, in collaboration with colleagues from the University of Copenhagen and bioengineers from Lund University in Sweden, have created a model from stem cells that simulates the early stages of human brain development. The cells were grown in a special microfluidic chamber, where conditions were created similar to the environment in which the embryo's brain develops.
"We know that in the early embryonic stage, the brain is exposed to changing concentrations of growth factors that cause the formation of different brain regions. Using microfluidic methods, we can, under controlled conditions, recreate tissue resembling an embryonic brain at a very early stage – about 4-5 weeks after fertilization of an egg – a stage that we have not been able to study until now," the words of the first author of the article, associate professor Pedro Rifes, are quoted in a press release from the University of Copenhagen.
The researchers plan to use a new model to map the development of brain cells – a kind of "development tree" of the brain, which will show how different nerve cells in the human brain are formed in the early embryonic stages.
"As soon as we have a map, we will be able to better reproduce human neural cells in the laboratory, which can be used for transplantation, regenerative therapy, as well as for the treatment of various diseases," says the head of the study, Associate Professor Agnete Kirkeby.
Kirkeby is well aware of the importance of the task being solved, as she has been working for ten years with colleagues from Lund and Cambridge on the development of stem cell therapy for Parkinson's disease. With the new model, researchers expect that similar studies will be conducted much faster in the future.
"If we understand exactly how the brain develops in the early stages, we will be better able to direct stem cells in the right direction when producing human nerve cells in the laboratory. This will allow us to develop cellular therapies faster and more efficiently," says Kirkeby.
The authors note that the model can serve other useful purposes. It can be used to study how the brain cells of an embryo react to certain chemicals that surround us in everyday life – in the environment, consumer products or medicines that pregnant women take.
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