Matrix metalloproteinases (MMP): determination of different forms by different techniques may require different preanalytical strategies

In our report, we employed, for the first time, an activity assay to assess CSF and serum concentrations of active MMP-9 in patients with MS . All serum samples analysed were processed and stored under the same conditions. In this connection, conflicting findings were found when the effects of storage procedure on stability and preservation of MMPs were tested. Some investigators described a time-dependent, progressive reduction in both activity and concentrations of MMPs in samples stored at /808C up to 43 months before the assay Conversely, others demonstrated that storage temperature and repeated freeze thaw cycles did not affect the measurement of MMP activity In conclusion, the possibility that different methods for MMP detection in blood samples, such as ELISA, zymography and activity assays, may require different preanalytical strategies should be take into account.