The two began working together about two and a half years ago, after Feld invited Suresh to give a talk about the work his lab was doing on malaria cells. After Suresh’s talk, the two decided to combine forces–and instruments–to measure the speed at which healthy and diseased red blood cells vibrate.
They chose malarial cells because of Suresh’s experience working with them, but it meant that Feld’s lab had to be refitted to meet the CDC’s Level 2 biosafety standards. That project was led by one of the researchers on Suresh’s team, Monica Diez-Silva, the only microbiologist in either group.
It takes 48 hours for a malarial invader to run through its life cycle, developing, reproducing, and being expelled from the cell. The researchers thus had to evaluate infected cells from each stage of that 48-hour process, at temperatures that simulated the fever and cooling that the human body experiences during a malarial infection.
Vibrating cell membranes move mere nanometers at a time, and those movements take place in microseconds–millionths of a second. To capture the data from the laser beam passing through the cells, the researchers used Feld’s imaging technique, which stitches multiple images together into a composite. The technique is a species of tomography, the principle that underlies computed-tomography (CT) scans.
Rosakis says that imaging with interference patterns is particularly challenging when looking at red blood cells, which are doughnut-shaped and fluid, constantly changing shape in all directions.
Suresh and Feld’s first set of experiments took almost eight months, including “weeks and weeks” to assemble the 3-D images of the parasites inside the cells. Then they decided to look at hemoglobin levels, which also took months. They spent almost six months writing up the results, which will be published in the Proceedings of the National Academy of Sciences this week.
Suresh says that the research should apply to any other type of living cells. He and Feld want to look at red blood cells with sickle anemia, and possibly cancer cells, although it will be more difficult to study cells that have a nucleus.
Suresh’s and Feld’s techniques can’t yet be used for diagnosing illnesses, but Suresh says that their work “makes the scientific foundation that you can measure” disease at the cellular level.
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