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Free oscillation rheometry in the assessment of platelet quality
Linköping University, Department of Clinical and Experimental Medicine, Transfusion Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Laboratory Medicine, Department of Clinical Immunology and Transfusion Medicine.
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Platelets play an important role in the haemostatic process in order to seal damaged blood vessels. The platelets form a platelet plug at the damaged area and prevent blood loss. Once the damage to the vessel wall has been covered, the platelets retract the coagulum, to allow the blood to flow freely in the vessel. Free oscillation rheometry (FOR) can be used for analysis of coagulation as measured by clotting time and changes in clot elasticity (G'). Clot G' provides information about the fibrin network in the coagulum and the platelets’ ability to retract the coagulum. FOR analysis is performed using the ReoRox® 4 instrument. The blood sample is added to a cylindrical sample cup, which is set into free oscillation. The frequency and damping of the oscillation is recorded over time as the blood coagulates. The change in G' is calculated from the frequency and damping measured. Patients with malignant haematological diseases are often thrombocytopaenic and require platelet transfusions to prevent or stop bleeding. To ensure good haemostatic function in the recipient it is important that the quality of the platelets used for transfusion is well preserved. The aim of this thesis was to determine the quality of platelet concentrates (PCs), during storage, using various in vitro methods, including FOR, and to investigate how various preparation processes affect the quality. We also investigated whether FOR can be used to evaluate the haemostatic status in subjects at risk for thrombosis or bleeding as well as how the haemostatic status was affected by a platelet transfusion.

We show that FOR can provide information about the coagulation properties in subjects at risk of thrombosis (pregnant women) or bleeding (thrombocytopaenic patients). We also show that the coagulation as measured by FOR is influenced by red blood cells and the fibrinogen concentration. However, the presence of functional platelets accounted for 90% of the G'. Furthermore we present data that FOR can provide information on the haemostatic effect of platelet transfusions and on the function of the transfused platelets.

PCs produced by two different cell separators showed similar quality during storage for 7 days as assessed by FOR analysis. Leukocytes in the PCs can cause transfusion-associated graft-versus-host disease which can be prevented by gamma irradiation of the PCs. Gamma irradiation did not affect the quality of PCs during 7 days of storage as analysed by FOR. The clotting time was unchanged during the storage period. The capacity of platelets to retract the coagulum was reduced from days 1 to 5 of storage as seen by a prolonged time to reach maximum G' and the reduced mean change in G' per minute. However, if sufficient time is allowed for the platelets to regain their function, the clot will be fully retracted (as seen by a well maintained maximum G'). The FOR parameters were similar for 5- and 7-day old PCs, which, combined with other in vitro tests (e.g. hypotonic shock response, changes in pH, swirling, lactate and glucose), support the prolongation of the platelet storage period to 7 days. Intercept treatment of PCs can be performed to inhibit replication of contaminating bacteria in PCs. Intercept treatment of PCs did not diminish the clot-promoting capacity of the platelets as assessed by FOR clotting time.

In conclusion, FOR is a promising method for assessing hyper- and hypocoagulability. It can provide information on the haemostatic effect of platelet transfusions and the function of the transfused platelets. FOR was also shown to be useful for analysing PC quality during different preparation and storage conditions.

Place, publisher, year, edition, pages
Linköping University Electronic Press, 2008. , 53 p.
Series
Linköping University Medical Dissertations, ISSN 0345-0082 ; 1056
Keyword [en]
Coagulation, elasticity, platelets, rheology, transfusion
National Category
Other Medical Sciences not elsewhere specified
Identifiers
URN: urn:nbn:se:liu:diva-11525ISBN: 978-91-7393-935-5 (print)OAI: oai:DiVA.org:liu-11525DiVA: diva2:17959
Public defence
2008-05-08, Berzeliussalen, Hälsouniversitetet, Campus US, Linköpings universitet, Linköping, 13:00 (English)
Opponent
Supervisors
Available from: 2008-04-14 Created: 2008-04-14 Last updated: 2015-11-19
List of papers
1. Effects of different blood components on clot retraction analysed by measuring elasticity with a free oscillating rheometer
Open this publication in new window or tab >>Effects of different blood components on clot retraction analysed by measuring elasticity with a free oscillating rheometer
2006 (English)In: Platelets, ISSN 0953-7104, Vol. 17, no 8, 545-554 p.Article in journal (Refereed) Published
Abstract [en]

Free oscillation rheometry (FOR) using the ReoRox® 4 instrument makes it possible, at bedside, to study the coagulation process in blood over time and gives information on clotting time and coagulum elastic properties. In order to find out how various factors influence the FOR analysis we studied the coagulation process and change of elasticity over time in non-anticoagulated and citrated blood samples, plasma samples with various platelet concentrations (0-200 109/l) and blood samples with various haematocrit (0-40%). Blood samples supplemented with fibrinogen were analysed to elucidate the importance of fibrinogen on elasticity. The importance of the GPIIb/IIIa receptor on platelets was investigated by comparing the elasticity development in blood samples in presence and absence of a GPIIb/IIIa receptor inhibitor, abciximab. Anticoagulation with citrate did not have major influence on the viscoelastic properties of the coagulum. Increasing number of platelets and increasing fibrinogen concentration resulted in higher elasticity while increasing haematocrit gave lower elasticity. Blood samples with GPIIb/IIIa receptor inhibitor had very low elasticity indicating the importance of functional GPIIb/IIIa receptors. In conclusion we consider FOR to be a useful method to study the elastic properties of the coagulum. Various factors such as the number of red blood cells and platelets as well as the fibrinogen concentration should be taken into consideration when evaluating the results. The ReoRox® 4 instrument had excellent measuring range and unusually small artefactual effects on clot elasticity induced by the instrument in comparison with published results on other instruments.

Keyword
Coagulation; clot retraction; elasticity; platelets; rheology
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-13164 (URN)10.1080/09537100600759238 (DOI)
Available from: 2008-04-14 Created: 2008-04-14 Last updated: 2015-03-13
2. Free oscillation rheometry detects changes in clot properties in pregnancy and thrombocytopaenia
Open this publication in new window or tab >>Free oscillation rheometry detects changes in clot properties in pregnancy and thrombocytopaenia
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2008 (English)In: Platelets, ISSN 0953-7104, Vol. 19, no 5, 373-378 p.Article in journal (Refereed) Published
Abstract [en]

Improved methods are needed to identify patients at risk for thrombotic or bleeding events. Free oscillation rheometry (FOR) is a technique that offers information on coagulation, based on contributions of all blood components, by measurement of clotting time and changes in clot elasticity. This is the first study that evaluates FOR parameters in subjects likely to represent hypercoagulability (pregnant women) and hypocoagulability (thrombocytopenic patients). Clotting time and blood clot elasticity were measured by FOR in blood samples obtained from women in different pregnancy trimesters (n = 58), in thrombocytopenic patients before and after a platelet transfusion (n = 20) and in healthy blood donors (n = 60). The clotting time was shorter and the clot elasticity higher in pregnant women compared to the non-pregnant female blood donors. The elasticity was higher in late pregnancy compared to early pregnancy. Compared to the blood donors, the thrombocytopenic patients had lower elasticity, which was increased by a platelet transfusion, but there was no difference in clotting time. The results suggest that FOR can provide new information on the haemostatic status of patients at risk of thrombotic or bleeding events as well as information on the haemostatic effect of a platelet transfusion.

Keyword
Clot elasticity, clot retraction, coagulation, platelets
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-13165 (URN)10.1080/09537100802082264 (DOI)
Available from: 2008-04-14 Created: 2008-04-14 Last updated: 2015-03-13
3. The quality of platelet concentrates produced by COBE Spectra and Trima Accel during storage for 7 days as assessed by in vitro methods
Open this publication in new window or tab >>The quality of platelet concentrates produced by COBE Spectra and Trima Accel during storage for 7 days as assessed by in vitro methods
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2008 (English)In: Transfusion, ISSN 0041-1132, E-ISSN 1537-2995, Vol. 48, no 4, 715-722 p.Article in journal (Refereed) Published
Abstract [en]

Background: The quality of PLT concentrates (PCs) can be evaluated using various in vitro methods. A new technique, free oscillation rheometry (FOR), can be used to monitor coagulation properties of PCs and gives information on clotting time and coagulum elasticity. This study compared the quality of apheresis PCs produced by COBE Spectra and Trima Accel during storage for 7 days using in vitro tests including FOR.

Study design and methods: Apheresis PCs were collected with the COBE Spectra (n=10) and Trima Accel (n=10) cell separators. Swirling, blood gases and metabolic parameters were analyzed on day 0. Samples taken on day 1, 5 and 7 were also analyzed for hypotonic shock response (HSR), P-selectin and GPIb expression and evaluation of coagulation by FOR.

Results: Swirling, HSR and percent GPIb expressing PLTs were well maintained for 7 days whereas glucose decreased and lactate increased significantly during storage for both Spectra and Trima PCs. Percent P-selectin expressing cells increased to the same extent in both types of PCs during storage. pH increased between day 0 and 1 but then decreased. The clotting time remained constant throughout the storage period whereas the development of elasticity was reduced on day 5 and 7 compared to day 1 (p<0.05) for both types of PCs.

Conclusion: The results indicate that the PLT quality after storage for 7 days is well preserved although activation of PLTs occurs during storage as assessed by in vitro tests. No difference in platelet quality was observed between Spectra and Trima produced PCs.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-12533 (URN)10.1111/j.1537-2995.2007.01610.x (DOI)
Note
The definitive version is available at www.blackwell-synergy.com: Nahreen Tynngård, Tomas L. Lindahl, Marie Trinks, Monika Studer and Gösta Berlin, The quality of platelet concentrates produced by COBE Spectra and Trima Accel during storage for 7 days as assessed by in vitro methods, 2008, Transfusion, (48), 4, 715-722. Copyright: Blackwell Publishing www.blackwell-synergy.comAvailable from: 2008-09-08 Created: 2008-09-12 Last updated: 2017-12-08Bibliographically approved
4. The effect of gamma irradiation on the quality of apheresis platelets during storage for 7 days
Open this publication in new window or tab >>The effect of gamma irradiation on the quality of apheresis platelets during storage for 7 days
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2008 (English)In: Transfusion, ISSN 0041-1132, E-ISSN 1537-2995, Transfusion, Vol. 48, no 8, 1669-1675 p.Article in journal (Refereed) Published
Abstract [en]

Background:This study compares the quality of gamma-irradiated versus nonirradiated platelet (PLT) concentrates (PCs) during storage for 7 days as assessed by various in vitro methods. A new technique, free oscillation rheometry (FOR), which measures clotting time and coagulum elasticity, was also used to evaluate the PLT function.

Study design and methods: Single-donor PLTs were collected by apheresis technique (n = 20). The PLTs from each donor were divided into two PCs, one gamma-irradiated with 25 Gy and the other used as a nonirradiated control. Blood gases, metabolic variables, and swirling were analyzed from Day 0. Samples taken on Days 1, 5, and 7 were also analyzed for hypotonic shock response (HSR), P-selectin, and glycoprotein (GP)Ib expression by flow cytometry and coagulation by FOR.

Results: Swirling, HSR, and the percentage of GPIb-expressing cells were well maintained for 7 days of storage. pH was always within accepted range (6.4-7.4). Glucose decreased and lactate increased during the storage period (p < 0.05). P-selectin expression increased during storage (p < 0.05). The FOR clotting time remained constant, whereas the build-up of elasticity was slower after storage (p < 0.05). No difference was found between irradiated and nonirradiated PCs.

Conclusion: The results indicate a well-preserved quality of gamma-irradiated apheresis PLTs during storage for 7 days as assessed by in vitro methods, with no difference compared to nonirradiated PLTs.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-13167 (URN)10.1111/j.1537-2995.2008.01746.x (DOI)
Available from: 2008-04-14 Created: 2008-04-14 Last updated: 2017-12-13
5. Effects of intercept pathogen inactivation on platelet function as analysed by free oscillation rheometry
Open this publication in new window or tab >>Effects of intercept pathogen inactivation on platelet function as analysed by free oscillation rheometry
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2008 (English)In: Transfusion and apheresis science, ISSN 1473-0502, E-ISSN 1878-1683, Vol. 38, no 1, 85-88 p.Article in journal (Refereed) Published
Abstract [en]

Introduction: The Intercept Blood System, using InterSol as additive solution, is used for inactivation of contaminating pathogens in PCs, thus reducing the risk for transfusion transmitted infection and making it possible to prolong the storage period. This study aimed at investigating the ability of Intercept treated platelets to induce clot formation, as measured by coagulation time using free oscillation rheometry (FOR), and to compare with that of platelets in concentrates with the additive solution T-Sol or plasma.

Methods: Seventy-four single-donor platelet units were diluted in InterSol (n = 27) or T-Sol (n = 47) to a mean plasma concentration of 38%. The Intercept treatment was performed by addition of amotosalen HCl to the InterSol PCs followed by UVA irradiation and treatment with a compound adsorption device (CAD). Forty-six units were collected and stored in 100% plasma for comparison. Clotting time was measured by FOR in fresh PCs (within 26 h after collection) after stimulation by a platelet activator. Soluble P-selectin was analysed as a marker of platelet activation in the Intercept and T-Sol PCs.

Results: The clotting time was shorter for Intercept treated platelets compared to platelets in T-Sol and plasma (p < 0.05). There was no difference in clotting time between T-Sol and plasma PCs. Soluble P-selectin was higher for Intercept platelets than platelets in T-Sol (p < 0.05).

Conclusions: The platelets treated with the Intercept procedure had good clot promoting capacity.

Keyword
Apheresis, Pathogen inactivation, Platelet concentrates, Platelet function
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-13168 (URN)10.1016/j.transci.2007.12.012 (DOI)
Available from: 2008-04-14 Created: 2008-04-14 Last updated: 2017-12-13

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