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Updated: Apr 26, 2026
Author Spotlight: High-Sensitivity Tissue Factor Activity Assay for Plasma Diagnosis
Published on: December 29, 2023
Effects of freezing on tissue factor activity in a thromboelastography assay
Jennifer L Scruggs1, Bente Flatland, Ann Reed
1Department of Biomedical and Diagnostic Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN, USA.
Background:
Human recombinant tissue factor (TF) can be used to activate viscoelastic coagulation assays. Although the package insert indicates that TF should not be frozen, published scientific data are not available. Ability to store frozen aliquots of TF would increase laboratory efficiency and decrease costs associated with performing TF-activated assays.
Objective:
The objectives of this study were to determine the effects of freezing and storage time on TF's ability to activate commercially available quality control material in thromboelastography (TEG).
Methods:
TF was diluted and frozen at -20°C and -70°C for 72 hours, one week, 2 weeks, 3 months, and 6 months, and used for TEG after thawing. TF activation of control material was also assessed after TF storage at room temperature for 0, 24, and 48 hours. Time to fibrin formation (R), rate of clot formation (K and angle α), and clot strength (MA) were measured, and ANOVA used to identify differences.
Results:
There were no significant differences in mean α and MA regardless of storage time or temperature. Means for R were not significantly increased at any time point after storage at room temperature or -70°C, but significant increases in mean R were observed after storage at -20°C starting after one week and continuing up to 6 months.
Conclusion:
TF can be stored at room temperature for at least 48 hours, stored at -20°C for 72 hours, and stored at -70°C for up to 6 months without significant loss of activity for TEG.
