Translating molecular medicine into clinical tools: doomed to fail by neglecting basic preanalytical principles

Journal of Translational Medicine BioMed Central Commentary Open Access Translating molecular medicine into clinical tools: doomed to fail by neglecting basic preanalytical principles Klaus Jung*1,2, Ferdinando Mannello3 and Michael Lein1,2 Address: 1Department of Urology, Charité - Universitätsmedizin Berlin, Campus Mitte, Schumannstr. 20/21, 10117 Berlin, Germany, 2Berlin Institute for Urologic Research, Berlin, Germany and 3Department of Biomolecular Sciences, Section of Clinical Biochemistry, University "Carlo Bo", Urbino, Italy Email: Klaus Jung* - ; Ferdinando Mannello - ; Michael Lein - * Corresponding author Published: 14 October 2009 Journal of Translational Medicine 2009, 7:87 doi:10.1186/1479-5876-7-87 Received: 19 August 2009 Accepted: 14 October 2009 This article is available from: http://www.translational-medicine.com/content/7/1/87 © 2009 Jung et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Abstract This commentary discusses a study on measurements of matrix metalloproteinase 9 (MMP-9) in serum of pseudoxanthoma elasticum patients recently published in Journal of Molecular Medicine. This study can be considered the typical "obstacle" to effective translational medicine as previously documented in JTM journal. Although serum has been frequently proven as inappropriate sample for determining numerous circulating MMPs, among them MMP-9, there are over and over again studies, as in this case, that measure MMP-9 in serum. Comparative measurements in serum and plasma samples demonstrated higher concentrations for MMP-9 in serum due to the additional release from leukocytes and platelets following the coagulation/fibrinolysis process. From this example it can be concluded that translating basic research discoveries into clinical tools needs a more intensive exchange between basic biomedical research and clinical scientists already in an early stage. Otherwise a lost of translation, as discussed in JTM journal, seems to be inevitable. Commentary Diekmann et al. [1] recently reported data in the Journal of Molecular Medicine on the increased serum concentrations of circulating matrix metalloproteinases 2 and 9 (MMP-2; MMP-9) in patients suffering from pseudoxanthoma elasticum. This genetic disorder, caused by mutations in the transporter gene ABCC6, is characterized by alterations in the extracellular matrix, especially in the skin, retina, and the vascular system. The authors reported that MMP-9 in serum was found both in male and female patients about 2.5-times higher than that in healthy controls, whereas MMP-2 was elevated only in female patients. On this basis, the authors hypothesized that the development of the symptoms of pseudoxanthoma elasticum could be attributed to the action of MMPs, since these enzymes are well known to be involved in the initial step of damage and/or the following remodelling, repairing processes of extracellular matrix [2]. The authors concluded that the measurement of serum MMP-2 and MMP9 could be applied for non-invasive monitoring of matrixdegradative processes in pseudoxanthoma elasticum. In this respect, the use of MMP-2 and MMP-9 as surrogate biomarkers suggested by Diekmann et al. [1] may be appreciated as a nice example of translational medicine, defined as "the transfer of new understandings of disease mechanisms gained in the laboratory into the development of new methods for diagnosis, therapy, and prevention and their first testing in humans" [3] or "effective translation of the new knowledge, mechanisms, and techniques generated by advances in basic science research into new approaches for prevention, diagnosis, and treatment of disease ....for improving health" [4]. Page 1 of 4 (page number not for citation purposes) Journal of Translational Medicine 2009, 7:87 The study of Diekmann et al. [1] deals with an interesting topic and shows the potential of basic science discovery to improve clinical medicine. However, a closer and accurate re-examination of this "bench-to-bedside" example manifests that Diekmann et al. [1] have neglected the opposite "bedside-to-bench" effort of translational medicine as second part of its "two-way road" principle [5]. According to growing literature evidence demonstrating that blood sampling strongly influences the measurement and recovery of "true" circulating matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs), we would like to draw attention on the preanalytical impact of blood collection/handling methods in order to limit technical pitfalls that may lead to misinterpretations. In particular, the authors did not consider that serum was demonstrated as inappropriate sample for measuring circulating MMP-9. Noteworthy, the misuse of serum as sample for determining circulating MMP-9 was frequently considered inadequate, both in clinical and biochemical/ analytical journals [6-11]. It was additionally pointed out that technical details of sampling and handling procedures (like the time between venipuncture and centrifugation of blood samples as well as the use of different anticoagulants) must be taken into consideration with more attention and have to be reported due to their known crucial influence on the concentrations and activation/inhibition patterns of MMP-9 [12,13]. Thus, the fundamental significance of blood processing as important preanalytical determinant of accurate measurements of really circulating MMPs in peripheral blood, especially for MMP-9, has been clearly overlooked by Diekmann et al. [1]. It is a typical example that may be considered as of one of the significant "obstacles" to effective translational medicine contributing to the "lost of translation" as well documented in JTM journal [14]. To highlight the role and effects of preanalytical conditions, we summarized in Figure 1 some of our own data of MMP-2 and MMP-9 measurements in serum and plasma samples collected under different conditions [15]. Briefly, from 10 healthy adults (all with normal leukocyte count and profile), venous blood samples were simultaneously collected in plastic tubes (Monovette Systems, Sarstedt AG, Nümbrecht, Germany). All subjects, informed about the objectives of the study, participated on a voluntary basis and provided informed consent. Tubes either without additives or with kaolin-coated granulate as clot activator were used to prepare native serum (serum(-)) or serum after enhanced coagulation (serum(+)), respectively; tubes with lithium heparin or sodium citrate were used to collect plasma samples. The blood specimens were centrifuged within 30 min after venipuncture at 1600 × g and 4°C for 15 min and the supernatants were carefully removed and stored at -80°C until analysis. MMPs were measured i (...truncated)