Dependence of TIMP-1 Plasma Levels on Preanalytical Specimen Handling

Abstract

Background: Tissue inhibitor of metalloproteinases-1 (TIMP-1) in blood might be a helpful biomarker in various diseases. However, various authors report that TIMP-1 is dependent on preanalytical procedures. Our study was performed to determine how storage conditions and time to centrifugation influence TIMP-1. Materials and Methods: Twenty-six blood specimens were collected from each of 20 volunteers. Two specimens from each person were centrifuged/measured within 1 h after venipuncture and frozen at –80°C. They were thawed once or twice within 72 h. Eight specimens were stored at 20°C in daylight, 8 at 20°C covered and 8 at 4°C in daylight. Four of each of these 8 specimens were mixed once a day until centrifugation. A mixed and an unmixed specimen of each group was centrifuged/measured after 3, 6, 24 and 72 h. Results: TIMP-1 increased after freeze/thaw (p < 0.001). Mixing blood specimens more than once caused increased TIMP-1 (p < 0.001). TIMP-1 increased within 3 h of storage (p < 0.001). The increase was lower in specimens covered and refrigerated (p < 0.001). Conclusion: TIMP-1 is unstable and has to be evaluated carefully. Blood should be centrifuged directly after venipuncture. For routine application, specimen handling must be standardized and carefully followed. Research should be done on specimens handled identically.

Impact of cryopreservation on serum concentration of matrix metalloproteinases (MMP)-7, TIMP-1, vascular growth factors (VEGF) and VEGF-R2 in Biobank samples

“…Our results are concordant with this publication showing moderate susceptibility of MMP-7 to freeze/thaw cycles. On the contrary, another publication stated that TIMP-1 shows an increase after only one freeze/thaw cycle (19). In one, MMP-7 concentrations were rapidly lost after 15 cycles of freezing, while the second showed an increase in MMP-7 up to 143% from initial concentrations after 10 Brought to you by | University of Iowa Libraries Authenticated Download Date | 6/1/15 11:08 PM freeze/thaw cycles.…”