Improved platelet survival after cold storage by prevention of glycoprotein Ibα clustering in lipid rafts.
BACKGROUND
Storing platelets for transfusion at room temperature increases the risk of microbial infection and decreases platelet functionality, leading to out-date discard rates of up to 20%. Cold storage may be a better alternative, but this treatment leads to rapid platelet clearance after transfusion, initiated by changes in glycoprotein Ibα, the receptor for von Willebrand factor.


METHODS
We examined the change in glycoprotein Ibα distribution using Förster resonance energy transfer by time-gated fluorescence lifetime imaging microscopy.


RESULTS
Cold storage induced deglycosylation of glycoprotein Ibα ectodomain, exposing N-acetyl-D-glucosamine residues, which sequestered with GM1 gangliosides in lipid rafts. Raft-associated glycoprotein Ibα formed clusters upon binding of 14-3-3ζ adaptor proteins to its cytoplasmic tail, a process accompanied by mitochondrial injury and phosphatidyl serine exposure. Cold storage left glycoprotein Ibα surface expression unchanged and although glycoprotein V decreased, the fall did not affect glycoprotein Ibα clustering. Prevention of glycoprotein Ibα clustering by blockade of deglycosylation and 14-3-3ζ translocation increased the survival of cold-stored platelets to above the levels of platelets stored at room temperature without compromising hemostatic functions.


CONCLUSIONS
We conclude that glycoprotein Ibα translocates to lipid rafts upon cold-induced deglycosylation and forms clusters by associating with 14-3-3ζ. Interference with these steps provides a means to enable cold storage of platelet concentrates in the near future.
Thrombosis and Hemostasis Laboratory, Department of Clinical Chemistry and Hematology, University Medical Center Utrecht, Utrecht, the Netherlands.
Eelo
E
Gitz
Cornelis A
CA
Koekman
Dave J
DJ
van den Heuvel
Hans
H
Deckmyn
Jan W
JW
Akkerman
Hans C
HC
Gerritsen
Rolf T
RT
Urbanus
D048948:14-3-3 Proteins / Q000378:metabolism*; D017209:Apoptosis; D001792:Blood Platelets / Q000166:cytology / Q000378:metabolism*; D003080:Cold Temperature; D031541:Fluorescence Resonance Energy Transfer; D005677:G(M1) Ganglioside / Q000378:metabolism*; D006031:Glycosylation; D006490:Hemostatics; D006801:Humans; D021962:Membrane Microdomains / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D019038:Platelet Glycoprotein GPIb-IX Complex / Q000378:metabolism*; D021381:Protein Transport
D048948:14-3-3 Proteins; D006490:Hemostatics; D019038:Platelet Glycoprotein GPIb-IX Complex; D005677:G(M1) Ganglioside