Label-free distinction between platelet and erythrocyte microparticles by Raman microspectroscopy
||E. van der Pol, C.M. Hau, C. Otto, A. Sturk, T.G. van Leeuwen, and R. Nieuwland|
||XXIII Congress of the International Society on Thrombosis and Haemostasis, Kyoto, Japan|
||July 27, 2011|
||Awarded with the Young Investigators Award (YIA)|
Background: The cellular origin of microparticles is usually established by fluorescent antibody labeling, which is laborious, expensive, and involves practical problems (JTH 2010, 8: 2596–607). Using an ultra-modern Raman microspectroscopy setup, we have distinguished platelet from erythrocyte microparticles without labeling.
Methods: Platelet and erythrocyte microparticles were isolated from blood bank concentrates by differential centrifugation and analyzed by flow cytometry, transmission electron microscopy, and Raman microspectroscopy. For Raman microspectroscopy, a 35 mW krypton ion laser operating at a wavelength of 647 nm was focused to a probe volume smaller than 1 μm3 by an Olympus microscope objective with an NA of 0.95. The Stokes shift from light scattered by microparticles diffusing through the probe volume was measured by a sensitive spectrograph dispersing in the range 646–849 nm.
Results: The figure shows that platelet microparticles have a Raman spectrum containing spectral transitions characteristic of phospholipids. The Raman spectrum of erythrocyte microparticles, however, is entirely different.
Conclusions: For the first time, platelet microparticles are distinguished from erythrocyte microparticles without fluorescent antibody labeling.