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Biological Cartographers Seek To Map The Trillions Of Cells In The Human Body


Your body has around 37 trillion cells - no, really, we've counted, all bodies do, including BJ Leiderman, who writes our theme music - heart cells, liver cells, bone cells. NPR's Nell Greenfieldboyce reports scientists are now using a powerful technology to discover the kinds of cells that weren't previously recognized, and their goal is to build an atlas of every cell in the human body.

NELL GREENFIELDBOYCE, BYLINE: At the Broad Institute of MIT and Harvard in Boston, I watch a researcher named Julia Waldman consider some bits of what looks like orange Styrofoam. It's skin - frozen, human skin. She selects one of them.

JULIA WALDMAN: I'll put the rest back so we can freeze them and save them for later.

GREENFIELDBOYCE: I don't think I've ever seen frozen skin before. I bet you've...

WALDMAN: (Laughter) Most people haven't.

GREENFIELDBOYCE: I bet you've seen a lot of frozen things.

WALDMAN: I have. I have seen many frozen tissues.

GREENFIELDBOYCE: And fresh tissue samples, too, from human brains, lungs, kidneys, prostates, livers, the gut, fat. They were sent here by clinicians and other researchers because this lab is part of an international effort to look at all these tissues in a radical new way. Waldman kind of crushes the skin in a test tube filled with a chemical solution.

WALDMAN: You can see it's getting cloudy, so the tissue is starting to break up.

GREENFIELDBOYCE: After some more processing to strip away the cell membranes, she's left with nothing but cell nuclei, the control center of each cell. She counts them under a microscope.

WALDMAN: So we have roughly 500,000 nuclei per milliliter, which is great.

GREENFIELDBOYCE: She puts thousands of them into a special device. It encases each cell nucleus in a separate droplet of oil along with a tiny bead of gel that has a unique barcode. When these droplets get run through a machine, the contents of each individual cell nucleus can be analyzed separately, thousands of them all at once.

AVIV REGEV: Whereas before, you know, with very hard work, one person could process a handful.

GREENFIELDBOYCE: Aviv Regev runs this lab. She says, this kind of technology to probe individual cells has only been available in the last few years. She says, every cell in the body basically has the same DNA, the same set of genetic instructions.

REGEV: But every cell reads only a portion of these instructions. And that's why the cells in our liver are different from the cells in our brain and are different from the cells in our skin and so on.

GREENFIELDBOYCE: Now scientists can easily find out what genetic instructions each cell is following, and they can do this on a massive scale. Already, millions of individual cells have been analyzed, and new types of cells have been found in, for example, the lining of the windpipe. Regev and some of her colleagues plan to catalogue every single cell type in the human body. They call it the Human Cell Atlas.

REGEV: We don't need to analyze every individual cell out of 37 trillion because the cells kind of repeat themselves. All we need to do is sample enough of them from enough region in order to get comprehensive coverage.

GREENFIELDBOYCE: The effort started a couple years ago, and it will take years to complete. But the payoff could be huge with new insights into all kinds of diseases. Sarah Teichmann is head of cellular genetics at the Wellcome Trust Sanger Institute in Cambridge, England. She's one of the leaders of the Human Cell Atlas, and she and her colleagues recently took a close look at kidney cancer. They analyzed 72,000 cells from healthy and cancerous human kidneys.

SARAH TEICHMANN: And so that was really exciting, both in terms of the basic understanding of the kidney cells but also for the cancer community in terms of understanding where these tumor cells come from.

GREENFIELDBOYCE: A child who had kidney cancer, for example, seemed to come from aberrant fetal cells while some adult cancers came from a different, little-studied subset of cells.

TEICHMANN: I mean, the methods are just so powerful. It really is mind-boggling, incredibly exciting and, you know, I need to pinch myself sometimes.

GREENFIELDBOYCE: She says the human body contains more than 50 different tissues. Some get a lot of attention, like the brain. Others are kind of ignored.

TEICHMANN: There are some that you probably haven't even heard of, you know, funny stuff like omentum.

GREENFIELDBOYCE: That's a sheet of fatty tissue that wraps around the intestines. The Human Cell Atlas wants to get everything from that to the inner ear. The whole plan staggers folks who study cells and tissues in more traditional ways, like with microscopes and stained slides. Rosy Jurjus is an associate professor of anatomy and cell biology at George Washington University. She recently attended a workshop for folks who are mapping the human body at the cellular level.

ROSY JURJUS: And I remember actually being very excited all through the workshop because it's groundbreaking. It's new, and it's the future.

GREENFIELDBOYCE: Meanwhile, researchers have been building complete cell atlases of creatures that are commonly studied in the lab to give insights on human biology. They've already finished one for a famous laboratory worm, C. elegans. Unlike humans, it has hundreds rather than trillions of cells. Nell Greenfieldboyce, NPR News. Transcript provided by NPR, Copyright NPR.

Nell Greenfieldboyce
Nell Greenfieldboyce is a NPR science correspondent.