Thrombin-induced platelet microparticles improved the aggregability of cryopreserved platelets

Authors: Xiao H.¹; Jepkorir C.J.²; Harvey K.²; Remick D.G.¹

Source: Cryobiology, Volume 44, Number 2, April 2002 , pp. 179-188(10)

Publisher: Academic Press

Abstract:

Platelets were activated with freezing/thawing and thrombin stimulation, and platelet microparticles generated following platelet activation were isolated with ultracentrifugation. The effects of platelet microparticles on platelet activation were studied with annexin V assay, protein tyrosine phosphorylation, and platelet aggregation. Freezing-induced platelet microparticles decreased but thrombin-induced platelet microparticles increased platelet annexin V binding and aggregation. Freshly washed platelets were cryopreserved using epinephrine and dimethyl sulfoxide (Me₂SO) as combined cryoprotectants, and stimulated with thrombin-induced platelet microparticles. Following incubation of thrombin-induced platelet microparticles, the reaction time of platelets to agonists decreased but the percentages of aggregation increased, such as washed platelets from44%±30 to92%±7,p<0.001, and cryopreserved platelets from66%±10 to77%±7,p<0.02. By increasing platelet aggregability, platelet microparticles recovered after thrombin stimulation improved platelet function for transfusion. A 53-kDa platelet microparticle protein showed little phosphorylation if it was released from resting platelets or platelets stimulated with ADP, epinephrine, propyl gallate or dephosphorylation if it was derived from ionophore A 23187—stimulated platelets. However, the same protein released from frozen platelets showed significant tyrosine phosphorylation. Since a microparticle protein with 53 kDa was compatible with protein tyrosine phosphatase-1B (PTP-1B), its phosphorylation suggests the inhibition of enzyme activity. The microparticle proteins derived from thrombin-stimulated platelets were significantly phosphorylated at 64 kDa and pp60c-src, suggesting that the activation of tyrosine kinases represents a possible mechanism of thrombin-induced platelet microparticles to improve platelet aggregation.

© 2002 Elsevier Science (USA)

Language: English

Document Type: Research article

Affiliations: 1: Department of Pathology, University of Michigan Medical School, Ann Arbor, MI 48109-0602, USA 2: Methodist Research Institute, 1701 N. Senate Blvd., P.O. Box 1367, Indianapolis, IN 46206-1367, USA

Publication date: 2002-04-01

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• In this Subject: Anatomy & Physiology ,  Chemical Engineering
• By this author: Xiao H. ;  Jepkorir C.J. ;  Harvey K. ;  Remick D.G.

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