Researchers often use antibodies to sort cell types in gene-expression studies. The standard way to confirm that cells have been sorted correctly is by fixing them for microscopy or lysing them for PCR or western blotting. New SmartFlare RNA Detection Probes from EMD Millipore offer an alternative option for cell sorting by allowing fluorescent detection of internal RNA species without harm to the cell—no antibodies required.
The probes, oligonucleotides specific to a target RNA that are bound to gold nanoparticles, are incubated with cells overnight. Cells endocytose the nanoparticles, which bind to their complementary RNA target, releasing a fluorophore that can be detected via flow cytometry, microscopy, or any downstream method that relies on fluorescence. The cells exocytose the particles after a few days and thus recover completely from treatment.
“It’s going to revolutionize a lot of things,” says Steve McClellan, who uses the probes at the Mitchell Cancer Institute at the University of South Alabama. McClellan isolates cancer stem cells from dissociated tumors and has found that SmartFlare RNA Detection Probes, which came onto the market in January, allow him to sort out stem cells quickly and easily. He has tested nine different types of cancer, and the probes work in each one. McClellan called the preliminary data “amazing.”
“Being able to work in a live-cell environment opens up a lot of opportunities,” says Victor Koong, SmartFlare product manager at EMD Millipore. The probes are priced at $645 for 250 reactions, and Koong says there should be about 900 different probes available by the end of the year.