"One of the big plusses with our system is that it's a non-labeling approach for studying living cells," says Berger.
IRAM differs from most standard procedures where markers are inserted in, or attached to cells. If a marker sticks to one cell, and not the other, you can tell which cell is which on the basis of specific binding properties.
While markers are often adequate for studying cells at a single point in time, monitoring a cell over time as it changes is more problematic, since the marker can affect dynamic cell activities, like membrane transport. And internal markers actually involve punching holes in the membrane, damaging or killing the cell in the process.
"Our method uses only light to effectively reach inside the cell," says Smith. "We can classify internal differences in the cell without opening it up, attaching anything to it, or preparing it in any special way. It's really just flipping a switch."
Despite being relatively intense, the light used with IRAM does not harm or inhibit normal cell functionality. This is because the wavelength of the light can be precisely calibrated to minimize absorption by the cells. The near-infrared spectrum has proven particularly optimal for allowing almost all of the light to pass through the cells.
With the availability of a technique where making a measurement does not alter cellular activity, scientists will be able to better observe individual cell responses to stimuli, which Berger and Smith suspect may have far reaching implications for current understandings of cell activation and development.
"In the cell sensing community it's currently a pretty hot area to figure out how to analyze activation responses on a cell-by-cell basis," says Berger. "If individual information was available on top of existing ensemble data, you'd have a richer understanding of immune responses."
Perfecting IRAM has been a stepping stone process
|Contact: Evan Wendel|
University of Rochester