New technique generates detailed protein-expression profiles (inset) of cancer cells (background)COURTESY OF RALPH WEISSLEDERThe technique: Researchers from Massachusetts General Hospital have developed an approach that enables the in-depth characterization of the proteins present in small numbers of cells. The antibody barcoding with photocleavable DNA (ABCD) platform, which the team described today (January 15) in Science Translational Medicine, first involves passing collected cells through a microfluidic device that uses antibodies to bind to isolate cells of interest—in this case, cancer cells. The target cells are then incubated with a cocktail of more than 90 antibodies attached by a photocleavable linker to DNA “barcodes”—specific 70 nucleotide long sequences from the potato genome, which were chosen to avoid cross reactions with human DNA. Next, the unbound antibodies are washed away, and the linkers on the remaining antibodies are cleaved both enzymatically and with UV light. The linkers can then be detected using a second, complementary barcode conjugated to five fluorescent proteins in variable order, and visualized using a sensitive fluorescent camera.
The team validated its ABCD platform as a profiling tool in both cell lines and in cells from human cancer patients, before and after they underwent treatment. The ABCD platform accurately profiled protein expression even in single cells. “This technology . . . enables one to do much more comprehensive analysis on way fewer cells,” said senior author Ralph Weissleder, who directs the Center for Systems Biology at Mass General.
What’s new: Traditional methods for assessing protein levels in cancer samples are time-consuming and require large amounts of tissue or amplification, which can both skew results. The ABCD platform analysis can be completed in a matter of hours, instead of the days that traditional immunohistochemistry approaches take. It also avoids amplification.
“Here you’re able to, ...
