You probably know that our body is made up of cells. Lots of them. And those cells all work together to build tissues and organs and hair and teeth and all the things that make a human a human. You probably also know that genes are what controls how those pieces all fit together. But until recently, scientists haven't been able to really put those two things together - to look at the genes of a single cell. Instead they've looked at the genes of a whole body, a birds eye view of genetics.
That's because genetic analysis and sequencing simply hasn't been good enough to analyze single cells in a meaningful way. They could look at single celled organisms. They could sequence their genes. But they couldn't really say much about the single cells of a larger organism like us.
But, as it tends to do, the technology has improved. In a paper published today in the journal Nature Biotechnology, researchers have demonstrated a smarter way to take a peek into the mysterious genetic world of the individual cell.
The press release puts it this way:
Only by viewing a Seurat painting at close range can you appreciate the hidden complexities of pointillism – small, distinct dots of pure color applied in patterns to form an image from a distance. Similarly, biologists and geneticists have long sought to analyze profiles of genes at the single cell level but technology limitations have only allowed a view from afar until now.
The technology, called SmartSeq started by understanding something called splicing. When a cell splices, it means that it takes the raw copy of a gene and copies and pastes a bunch of different configurations. Those different configurations then all go on to produce the same protein, but in different ways. Which means that two cells from the same tissue might have proteins that arose in totally different ways - and that their genetic signatures might be different.
From there, the researchers figured out how to map the gene expression of each cell to see which genes are turned on, and which aren't. So if the genes in one cell in, say, your liver, are turned on, but they're turned off in another cell in your liver, that might tell doctors something about both what those genes do and how they might break down.
If you're thinking: hey, this might be useful for cancer, you're totally right. In cancer, cells within a tissue go rogue and start behaving badly. Scientists hope to use this technique to understand how one liver cell and another might express genes differently. Or, how one liver cell goes bad and another doesn't.
They've already tested this on a certain type of cancer, in fact. In the study, they took tumor cells from a patient with malignant melanoma. Using Smart Seq they could see that in the tumor cells, genes for things called "membrane proteins" were turned on, while in the normal cells they weren't. Membrane proteins help cells evade the system that regulates the body, and allow cells to spread from their home base into the blood or lymph fluids in the body.
Image: Wikimedia Commons