Seasonal variation and stability of matrix metalloproteinase-9 activity and tissue inhibitor of matrix metalloproteinase-1 with storage at-80 °C

Objective: To determine whether active matrix metalloproteinase (MMP)-9 and tissue inhibitor of matrix metalloproteinase (TIMP)-1 displayed seasonal variation and were stable in storage. Methods: Plasma active MMP-9 and TIMP-1 were measured at three time-points in 163 individuals. Result: There was no evidence for seasonal variation or declining levels for up to three years of storage at -80 degrees C. Conclusion: Active MMP-9 and TIMP-1 appear to be stable seasonally, and in storage for at least three years. (C) 2011 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.