Multiple biomolecules viewed in a single human cell

US researchers have found a way to generate snapshots of dozens of different biomolecules within a single human cell.

The Harvard University team claim such images will help scientists better understand the processes that take place within a cell and pave the way for better ways to diagnose and monitor diseases.

Current technology can only identify three or four types of the many different cellular processes happening at any one time because the gap between the molecules is so small it is impossible to see with visible light.

‘If you can see only a few things at a time, you are missing the big picture,’ said Peng Yin, one of the researchers from Harvard’s Wyss Institute of Biologically Inspired Engineering.

Scientists have previously used combinations of specialised optics, fluorescent proteins or dyes that tag cellular components, to visualise a small number of separate molecules.

The Harvard team modified this technique to take a series of images, each with a different molecule highlighted with fluorescent dye. They then assigned each highlighted molecule a false colour and combined the images show all the molecules could be seen at once, something that wouldn’t be possible if different molecules were simultaneously labelled with different dyes.

The “Exchange-PAINT” technique relies on the use of DNA tags attached to each biomolecule. The DNA strands each momentarily bind to a corresponding partner strand carrying a fluorescent dye that lights up when the two pair up, effectively causing the biomolecule to flash at a rate the researchers can control and use to obtain sharp images.

The team used the method to capture detailed images of fixed human cells, with each colour tagging up to 10 important cellular components such as microtubules, mitochondria, Golgi apparatus and peroxisomes. They expect that further development will allow them to visualise dozens of cellular components at once.