{"id":1519,"date":"2013-07-25T18:29:24","date_gmt":"2013-07-25T18:29:24","guid":{"rendered":"https:\/\/mtlsites.mit.edu\/annual_reports\/2013\/?p=1519"},"modified":"2013-07-25T18:29:24","modified_gmt":"2013-07-25T18:29:24","slug":"iso-dielectric-separation-of-cells-and-particles","status":"publish","type":"post","link":"https:\/\/mtlsites.mit.edu\/annual_reports\/2013\/iso-dielectric-separation-of-cells-and-particles\/","title":{"rendered":"Iso-dielectric Separation of Cells and Particles"},"content":{"rendered":"

The development of new techniques to separate and characterize cells with high throughput has been essential to many of the advances in biology and biotechnology over the past few decades.\u00a0 We are developing a novel method for the simultaneous separation and characterization of cells based upon their electrical properties.\u00a0 This method, iso-dielectric separation (IDS), uses dielectrophoresis (the force on a polarizable object[1<\/a>]<\/sup> and a medium with spatially varying conductivity to sort electrically distinct cells while measuring their effective conductivity (Figure 1).\u00a0 It is similar to iso-electric focusing, except that it uses DEP instead of electrophoresis to concentrate cells and particles to the region in a conductivity gradient where their polarization charge vanishes[2<\/a>]<\/sup>[3<\/a>]<\/sup>[4<\/a>]<\/sup>.<\/p>\n

Sepsis is a clinical condition caused by infection and, despite state-of-the-art facilities and treatments, it has a mortality rate of ~30%. Sepsis induces inflammation and organ failure; a possible treatment would require removing inflammatory agents, such as activated neutrophils, from whole blood. We used a CLP mouse model of sepsis (Figure 2a) and PMA-activated human granulocytes (Figure 2b) to monitor electrical differences between septic blood and leukocytes. With human granulocytes we saw a shift in their average isodielectric position (IDP) at high frequencies. Based on these results we did an IDP profile of leukocytes in healthy mouse blood and established a gate for the activated leukocytes. Applying the same gate under the same conditions with blood from CLP mice (n=4), we saw an increase in the number of activated leukocytes (Figure 2c). Finally we took aliquots of the same samples from healthy and CLP mice and measured common activation biomarkers with flow cytometry. Comparing both results, we see good correlation between our estimation of activated cells and the number of activated granulocytes measured in flow cytometry.<\/p>\n\n\t\t