Researchers at MIT, Bringham, and Women's Hospital have designed a cell-sorting microchip that takes advantage of a natural cell-rolling mechanism. The device takes in mixtures of cells that flows through tiny channels that are coated with sticky molecules. Cells with specific receptors, called the P-selection, slightly attach itself to the molecules, roll away from the flow, and out into a separated receptacle.
Cell rolling is a common mechanism cells use to navigate through the body. During inflammation, the endothelial cells that line the blood vessels present certain molecules that attract white blood cells to divert them from the rest of the vessel's cellular traffic. White blood cells then slow down by rolling along the vessel wall which is what heals inflamed areas.
"We're working on a disposable device where your wouldn't even need a syringe pump to drive the separation," Rohit Karnik, a d'Arbelogg Assistant Professor of Mechanical Engineering at MIT, said about his project. "You could potentially buy a $5 or $10 kit and get the cells sorted without needing any kind of [additional] instrument."
The device can be replicated and stacked to organize large batches of cells at a low cost. Karnik is hoping to apply the device to organize other blood cells and specific types of cancer cells for diagnostic applications as well as stem cells for therapeutic applications. To do that, Karnik and his team is investigating molecules similar to the P-selection. In the future, they envision tailor-made cell rolling molecules and surfaces that slightly attach itself to any desired type of cells.
"It's really the ability to design molecules to separate cells of interest that will be powerful," Karnik said. "There is no reason to believe it cannot be done, because nature has already done it."
While current cell-sorting technologies separate large batches of cells quickly and efficiently, they have several limitations. The commonly used fluorescence-activated cell sorting requires lasers and voltage to organize cells based on their electric charge. Researchers have used both fluorescent markers and magnetic beads that bind to desired cells, making them easy to spot and sift out. However, once the cells are collected they need to be separated from the beads and markers, and this added step is risking an adjustment of the samples.