DNA Barcodes Make for Better Single-Cell Analysis
Posted on by Dr. Francis Collins
Imagine how long it would take to analyze the 37 trillion or so cells that make up the human body if you had to do it by hand, one by one! Still, single-cell analysis is crucial to gaining a comprehensive understanding of our biology. The cell is the unit of life for all organisms, and all cells are certainly not the same. Think about it: even though each cell contains the same DNA, some make up your skin while others build your bones; some of your cells might be super healthy while others could be headed down the road to cancer or Alzheimer’s disease.
So, it’s no surprise that many NIH-funded researchers are hard at work in the rapidly emerging field known as single-cell analysis. In fact, one team recently reported impressive progress in improving the speed and efficiency of a method to analyze certain epigenetic features of individual cells . Epigenetics refers to a multitude of chemical and protein “marks” on a cell’s DNA—patterns that vary among cells and help to determine which genes are switched on or off. That plays a major role in defining cellular identity as a skin cell, liver cell, or pancreatic cancer cell.
The team’s rather simple but ingenious approach relies on attaching a unique combination of two DNA barcodes to each cell prior to analyzing epigenetic marks all across the genome, making it possible for researchers to pool hundreds of cells without losing track of each of them individually. Using this approach, the researchers could profile thousands of individual cells simultaneously for less than 50 cents per cell, a 50- to 100-fold drop in price. The new approach promises to yield important insights into the role of epigenetic factors in our health, from the way neurons in our brains function to whether or not a cancer responds to treatment.
DNA Barcodes Interrogate Cancer Cells
Posted on by Dr. Francis Collins
The proteins speckling the surface of a cancer cell reveal critical clues—the type of cancer cell and a menu of possible mutations that may have triggered the malignancy. Since these proteins are exposed on the outside of the cell, they are also ideal targets for so-called precision cancer therapies (especially monoclonal antibodies), optimized for the particular individual. But in the past, to analyze and identify these different proteins, large samples of tissue have been needed. Typically, these are derived from surgical biopsies. But biopsies are expensive and invasive. Furthermore, they aren’t a practical option if you want to monitor the effects of a drug in a patient closely over time.
Using a minimally invasive method of cell sampling called fine needle aspiration, physicians can collect miniscule cell samples frequently, cheaply, and safely. But, until now, these tiny samples only provided enough material to analyze a handful of cell surface proteins. So, it comes as particularly good news that NIH-funded researchers at Massachusetts General Hospital in Boston have developed a new technology that quickly identifies hundreds of these proteins simultaneously, using just a few of the patient’s cells . The key to this new method is a clever adaptation of the familiar barcode.