Researchers at Karolinska Instittutet in Sweden used a specific brain mapping process known as a single-cell analysis to map a mouse brain and identify genes active in different cell types. The result of their study revealed new and unknown type of brain cells.
It is common knowledge that the nature of a particular cell determines the nature of a particular tissue and the corresponding organ. Cells are almost identical from a larger perspective. From a cellar and molecular perspective however, differentiation in cells is determined by the genes active in their respective DNA. A single-cell analysis is a method of identifying this differentiation using RNA sequencing to analyse and determine the genes active in a specific cell.
Principal investigators Jens Hjerling-Leffler and Sten Linnarson used a large-scale single-cell analysis to map a mouse brain and identify its various cellular constituents. They analysed over 3,000 cells from the cerebral cortex, one at a time, and subsequently, identified which among the 20,000 known genes were active in each one.
“If you compare the brain to a fruit salad, you could say that previous methods were like running the fruit through a blender and seeing what colour juice you got from different parts of the brain,” said Linnarson. “But in recent years we’ve developed much more sensitive methods of analysis that allow us to see which genes are active in individual cells.
“This is like taking pieces of the fruit salad, examining them one by one and then sorting them into piles to see how many different kinds of fruit it contains, what they’re made up of and how they interrelate.”
The researchers identified 47 different kinds of cell, including a large proportion of specialised neurons, some blood vessel cells and glial cells, which take care of waste products, protect against infection and supply nerve cells with nutrients.
Interestingly, the researchers have also identified unknown cell types. These include a nerve cell in the most superficial cortical layer, and six different types of oligodendrocyte, which are cells that form the electrically insulating myelin sheath around the nerve cells.
The study nonetheless presented a new method for examining and analysing organs, tissues, and their constituent cells. This opens newer possibilities for developing treatments against certain types of diseases.
“We have created a much more detailed map of the cells of the brain that describes each cell type in detail and shows which genes are active in it,” said Hjerling-Leffler. “This gives science a new tool for studying these cell types in disease models and helps us to understand better how brain cell respond to disease and injury.”
Further details of the study are found in the article “Cell types in the mouse cortex and hippocampus revealed by single-cell RNA-seq” published in the journal Science.