Anticoagulants affect matrix metalloproteinase 9 levels in blood samples of stroke patients and healthy controls

ObjectivesMatrix metalloproteinase-9 (MMP-9) represents a promising marker for acute stroke management. In clinical studies MMP-9 has been quantified by ELISA using differing protocols. We aimed to establish a valid protocol by evaluation of preanalytics.Design and methodsBlood from stroke patients (n = 28) and healthy controls (n = 28) was drawn into tubes containing different anticoagulants (EDTA, citrate, lithium-heparin (heparin) and heparin with proteinase inhibitors) and processed after 0, 60 and 240 min. MMP-9 plasma protein and mRNA from mononuclear leukocytes were determined.ResultsIn regard to anticoagulants used, samples showed different MMP-9 protein baseline values and kinetics. Stable MMP-9 protein concentrations were only measured from EDTA samples. Particularly in samples with proteinase inhibitors protein and mRNA concentrations increased over time. Kinetics did not differ between patients and controls.ConclusionsPreanalytics plays a key role for determination of MMP-9. EDTA seems to be a valid anticoagulant for MMP-9 protein measurement.

► Preanalytics of MMP-9 protein and mRNA measurement in stroke patients and controls. ► Different anticoagulants used affect MMP-9 protein baseline values and kinetics. ► Only EDTA plasma samples show stable MMP-9 protein values. ► Considerably increased MMP-9 values in heparin samples with proteinase inhibitors. ► Kinetics in MMP-9 without qualitative differences between patients and controls.