Impact of blood sampling on the circulating matrix metalloproteinases 1, 2, 3, 7, 8, and 9

Protein signatures of centenarians and their offspring suggest centenarians age slower than other humans

Using samples from the New England Centenarian Study (NECS), we sought to characterize the serum proteome of 77 centenarians, 82 centenarians' offspring, and 65 age-matched controls of the offspring (mean ages: 105, 80, and 79 years). We identified 1312 proteins that significantly differ between centenarians and their offspring and controls (FDR < 1%), and two different protein signatures that predict longer survival in centenarians and in younger people. By comparing the centenarian signature with 2 independent proteomic studies of aging, we replicated the association of 484 proteins of aging and we identified two serum protein signatures that are specific of extreme old age. The data suggest that centenarians acquire similar aging signatures as seen in younger cohorts that have short survival periods, suggesting that they do not escape normal aging markers, but rather acquire them much later than usual. For example, centenarian signatures are significantly enriched for senescence-associated secretory phenotypes, consistent with those seen with younger aged individuals, and from this finding, we provide a new list of serum proteins that can be used to measure cellular senescence. Protein co-expression network analysis suggests that a small number of biological drivers may regulate aging and extreme longevity, and that changes in gene regulation may be important to reach extreme old age. This centenarian study thus provides additional signatures that can be used to measure aging and provides specific circulating biomarkers of healthy aging and longevity, suggesting potential mechanisms that could help prolong health and support longevity.

MMP-2 and MMP-9 in Human Peripheral Blood: Optimizing Gelatinase Calibrator for Degradome Research and Discovering a Novel Gelatinolytic Enzyme

Matrix metalloprotease-2 and -9 (gelatinase A and B, respectively) are enzymes crucially involved in a plethora of physiopathological conditions. Gelatin zymography is considered one of the major qualitative/semiquantitative assays for simultaneously determining zymogenic, active, and complexed forms of gelatinases. Critical steps are represented by variations in sample collection methods, molecular weight standard calibrators, and different zymography assay protocols. A normalization of these aspects is required for reducing discrepancies in technical procedures and interpreting results among different laboratories. In this study, we describe a novel protocol for gelatin zymography with increased pore size, which improves the separation of gelatinases with different molecular weights. A new method for obtaining gelatinase calibrator for gelatin zymography, by extracting MMP-2 and MMP-9 from peripheral blood, is also reported. Our method provides a gelatinase calibrator with enhanced stability both at room temperature and during multiple freeze-thaw cycles. This calibrator preparation is also suitable for in vitro post-translational modifications. For the first time, the improved zymography protocol allowed us to reveal in human peripheral blood samples new gelatinolytic bands resolved at very high molecular weight, likely complexes of MMP-9, undetectable with classical zymography protocols.

Cellular and Molecular Effects of High-Molecular-Weight Heparin on Matrix Metalloproteinase 9 Expression

Blood sampling with different anticoagulants alters matrix metalloproteinase (MMP-) 9 expression, thus influencing its concentration and diagnostic validity. Here, we aimed to evaluate the effects of different anticoagulants on MMP-9 regulation. MMP-9 expression was assessed in response to ethylenediaminetetraacetic acid, citrate, and high-/low-molecular-weight heparin (HMWH, LMWH) in co-culture experiments using THP-1, Jurkat, and HT cells (representing monocytes, T, and B cells). Triple and double cell line co-culture experiments revealed that HMWH treatment of THP-1 and Jurkat led to a significant MMP-9 induction, whereas other anticoagulants and cell type combinations had no effect. Supernatant of HMWH-treated Jurkat cells also induced MMP-9 in THP-1 suggesting monocytes as MMP-9 producers. HMWH-induced cytokine/chemokine secretion was assessed in co-culture supernatant, and the influence of cytokines/chemokines on MMP-9 production was analyzed. These experiments revealed that Jurkat-derived IL-16 and soluble intercellular adhesion molecule (sICAM-) 1 are able to induce MMP-9 and IL-8 production by THP-1. As a consequence, the increased MMP-9 expression found in HMWH blood samples may be influenced by HMWH-dependent secretion of IL-16 and sICAM-1 by T cells resulting in an increased production of MMP-9 and IL-8 by monocytes. IL-8, in turn, may support MMP-9 and its own expression in a positive autocrine feedback loop.

Matrix Metalloproteinases in Pulmonary and Central Nervous System Tuberculosis-A Review

Tuberculosis (TB) remains the single biggest infectious cause of death globally, claiming almost two million lives and causing disease in over 10 million individuals annually. Matrix metalloproteinases (MMPs) are a family of proteolytic enzymes with various physiological roles implicated as key factors contributing to the spread of TB. They are involved in the breakdown of lung extracellular matrix and the consequent release of Mycobacterium tuberculosis bacilli into the airways. Evidence demonstrates that MMPs also play a role in central nervous system (CNS) tuberculosis, as they contribute to the breakdown of the blood brain barrier and are associated with poor outcome in adults with tuberculous meningitis (TBM). However, in pediatric TBM, data indicate that MMPs may play a role in both pathology and recovery of the developing brain. MMPs also have a significant role in HIV-TB-associated immune reconstitution inflammatory syndrome in the lungs and the brain, and their modulation offers potential novel therapeutic avenues. This is a review of recent research on MMPs in pulmonary and CNS TB in adults and children and in the context of co-infection with HIV. We summarize different methods of MMP investigation and discuss the translational implications of MMP inhibition to reduce immunopathology.

Stability of matrix metalloproteinase-9 as biological marker in colorectal cancer

Matrix metalloproteinases (MMPs) are believed to be of importance in the growth and spread of colorectal cancer (CRC). MMP-9 level has been suggested as a biological predictor of prognosis in CRC as well as in other types of cancer such as breast and cervical cancer. The purpose of this study was to investigate the stability over time of MMP-9 in cryopreserved plasma, colorectal tumor tissue extract and macroscopically tumor-free colon mucosa tissue extract samples. Plasma and tissue samples were taken from patients at primary CRC surgery and analyzed for MMP-9. Aliquots of samples from the same patients were stored at – 80 °C pending analysis. These aliquots were analyzed using identical methods after storage periods of nine (plasma) and twelve (tissue) years. No significant difference in plasma MMP-9 concentration was seen between baseline samples and those after 9 years of cryopreservation (median values 9.9 and 9.7 ng/mL, respectively; p > 0.05). MMP-9 levels in the tumor-free tissue extracts had increased to baseline (median values 7.1 and 8.1 ng/mL, respectively; p < 0.01). MMP-9 levels in the tumor tissue extracts had also increased significantly (median values 89.9 and 133.5 ng/mL, respectively; p < 0.01). We have demonstrated that MMP-9 levels in frozen citrated plasma are stable if stored at − 80 °C, whereas MMP-9 levels in extracts from tumor tissue and tumor-free intestinal mucosa appear to increase with time. We conclude that MMP-9 levels in cryopreserved plasma may be considered stable over time and are thus suitable for comparison purposes in consecutive series.

Circulating Biomarkers Predictive of Postoperative Atrial Fibrillation

Postoperative atrial fibrillation (PoAF), a common complication of cardiac surgery, contributes significantly to morbidity, mortality, and increasing healthcare costs. Despite advances in surgical and medical management, the overall incidence of PoAF has not changed significantly, partly because of the limited understanding of mechanisms underlying acute surgery-related factors, such as myocardial injury, inflammation, sympathetic activation, and oxidative stress, which play an important role in the initiation of PoAF, whereas a preexisting atrial substrate appears to be more important in the maintenance of this dysrhythmia. Thus, in a majority of patients, PoAF becomes a manifestation of an underlying arrhythmogenic substrate that is unmasked after acute surgical stress. As such, the ability to identify which patients have this proarrhythmic substrate and are, therefore, at high risk for developing AF postoperatively, is important for the improved selection for prophylactic interventions, closer monitoring for complications, and establishing the probability of AF in the long term. This review highlights the role of the underlying substrate in promoting PoAF, proposed mechanisms, and the potential role of serum biomarkers to identify patients at risk for PoAF.

Validation of the prognostic value of MMP-7 in idiopathic pulmonary fibrosis

BACKGROUND AND OBJECTIVE

Idiopathic pulmonary fibrosis (IPF) is a progressive disease with poor prognosis and variable clinical course. Although matrix metalloproteinase-7 (MMP-7) is emerging as an important IPF biomarker, reproducibility across studies is unclear. We aimed to determine whether a previously reported prognostic threshold for MMP-7 was predictive of mortality in an independent cohort of IPF patients.

METHODS

MMP-7 concentrations obtained from heparinized plasma samples were determined by ELISA in 97 patients with IPF and 41 healthy controls. The association of the previously published heparin plasma MMP-7 threshold of 12.1 ng/mL with all-cause mortality or transplant-free survival (TFS) was determined, either as an independent biomarker or as part of the modified personal clinical and molecular mortality index (m-PCMI).

RESULTS

MMP-7 plasma concentrations were significantly higher in IPF patients compared to healthy controls (14.40 ± 6.55 ng/mL vs 6.03 ± 2.51 ng/mL, P < 0.001). The plasma MMP-7 threshold of 12.1 ng/mL was significantly associated with both all-cause mortality and TFS (unadjusted Cox proportional hazard ratio (HR) = 25.85 and 15.49, 95% CI: 10.91-61.23 and 5.41-44.34, respectively, P < 0.001). MMP-7 concentrations, split by 12.1 ng/mL, were significantly (P < 0.05) predictive of mortality and TFS after adjusting for age, gender, smoking and baseline pulmonary function parameters, in a multivariate Cox proportional hazards model. MMP-7 concentrations were negatively correlated with diffusing lung capacity of carbon monoxide (DL_CO ) (r = -0.21, P = 0.02), and positively with a mortality risk scoring system (GAP) that combines age, gender, forced vital capacity (FVC) and DL_CO (r = 0.32, P = 0.001).

CONCLUSION

This study confirms that MMP-7 concentrations could be used to accurately predict outcomes across cohorts and centres, when similar collection protocols are applied.

Adapting extracellular matrix proteomics for clinical studies on cardiac remodeling post-myocardial infarction

Following myocardial infarction (MI), the left ventricle (LV) undergoes a series of cardiac wound healing responses that involve stimulation of robust inflammation to clear necrotic myocytes and tissue debris and induction of extracellular matrix (ECM) protein synthesis to generate a scar. Proteomic strategies provide us with a means to index the ECM proteins expressed in the LV, quantify amounts, determine functions, and explore interactions. This review will focus on the efforts taken in the proteomics research field that have expanded our understanding of post-MI LV remodeling, concentrating on the strengths and limitations of different proteomic approaches to glean information that is specific to ECM turnover in the post-MI setting. We will discuss how recent advances in sample preparation and labeling protocols increase our successes at detecting components of the cardiac ECM proteome. We will summarize how proteomic approaches, focusing on the ECM compartment, have progressed over time to current gel-free methods using decellularized fractions or labeling strategies that will be useful for clinical applications. This review will provide an overview of how cardiac ECM proteomics has evolved over the last decade and will provide insight into future directions that will drive forward our understanding of cardiac ECM turnover in the post-MI LV.

Levels of matrix metalloproteinases differ in plasma and serum - aspects regarding analysis of biological markers in cancer

BACKGROUND

There are inconsistencies in the use of serum or plasma when analysing the matrix metalloproteinases (MMPs) as diagnostic or prognostic markers. The purpose of this study was to compare the concentration of MMP-1, -2, -7, -8, -9 and -13 in serum vs plasma samples.

METHODS

Blood samples were obtained from sixty-five men and women. Samples were analysed for levels of MMPs in corresponding citrate plasma and serum.

RESULTS

All MMPs expressed higher concentration in serum compared with plasma (P<0.01). There were no differences between genders.

CONCLUSIONS

Present study demonstrated significant differences regarding concentrations of some MMPs using plasma vs serum. We conclude that future studies regarding MMPs as biological markers in cancer should consider the use of citrate plasma instead of serum.

Matrix Metalloproteinases and Subclinical Atherosclerosis in Chronic Kidney Disease: A Systematic Review

Background. Cardiovascular disease (CVD) remains a significant problem in Chronic Kidney Disease (CKD). Subclinical atherosclerosis identified by noninvasive methods could improve CVD risk prediction in CKD but these methods are often unavailable. We therefore systematically reviewed whether circulating levels of Matrix Metalloproteinases (MMPs) and tissue inhibitors (TIMPs) are associated with subclinical atherosclerosis in CKD, as this would support their use as biomarkers or pharmacologic targets. Methods. All major electronic databases were systematically searched from inception until May 2015 using appropriate terms. Studies involving CKD patients with data on circulating MMPs levels and atherosclerosis were considered and subjected to quality assessment. Results. Overall, 16 studies were identified for qualitative synthesis and 9 studies were included in quantitative synthesis. MMP-2 and TIMP-1 were most frequently studied while most studies assessed carotid Intima-Media Thickness (cIMT) as a measure of subclinical atherosclerosis. Only MMP-2 demonstrated a consistent positive association with cIMT. Considerable variability in cIMT measurement methodology and poor plaque assessment was found. Conclusions. Although MMPs demonstrate great potential as biomarkers of subclinical atherosclerosis, they are understudied in CKD and not enough data existed for meta-analysis. Larger studies involving several MMPs, with more homogenized approaches in determining the atherosclerotic burden in CKD, are needed.

The importance of sample collection when using single cytokine levels and systemic cytokine profiles as biomarkers--a comparative study of serum versus plasma samples

BACKGROUND

Cytokines, soluble adhesion molecules and metalloproteinases can be detected in human serum or plasma samples. Such systemic levels are widely used as biomarkers in epidemiological and clinical studies.

METHODS

We prepared serum samples and three types of plasma samples (EDTA, heparin, citric acid) from 20 healthy individuals. The levels of 31 cytokines, four soluble adhesion molecules and eight matrix metalloproteinases were analyzed by Luminex technology.

RESULTS

Most mediators showed detectable levels in both plasma and serum. Several mediators that can be released by platelets showed increased serum levels, especially CCL5 and CD40L, but for the other mediators the serum levels did not correlate with peripheral blood platelet counts and for these last mediators serum and plasma levels often showed strong correlations. The use of bivalirudin for anticoagulation significantly increased and citric acid combined with platelet inhibitors (ticagrelor, acetylsalicylic acid plus prostaglandin E2) did not alter plasma levels of platelet-store mediators compared with citric acid alone. The impact of sample preparation differed between mediators; for many mediators strong correlations were seen between serum and plasma levels even when absolute levels differed. Soluble adhesion molecule levels showed only minor differences between samples. Unsupervised hierarchical clustering suggested that the effect of sampling/preparation was strongest for serum and heparin plasma samples.

CONCLUSION

Careful standardization of sample preparation is usually necessary when analyzing systemic mediator levels, and differences caused by sample preparation should be considered as a possible explanation if studies show conflicting results.

Translational research in pediatrics II: blood collection, processing, shipping, and storage

Translational research often involves tissue sampling and analysis. Blood is by far the most common tissue collected. Due to the many difficulties encountered with blood procurement from children, it is imperative to maximize the quality and stability of the collected samples to optimize research results. Collected blood can remain whole or be fractionated into serum, plasma, or cell concentrates such as red blood cells, leukocytes, or platelets. Serum and plasma can be used for analyte studies, including proteins, lipids, and small molecules, and as a source of cell-free nucleic acids. Cell concentrates are used in functional studies, flow cytometry, culture experiments, or as a source for cellular nucleic acids. Before initiating studies on blood, a thorough evaluation of practices that may influence analyte and/or cellular integrity is required. Thus, it is imperative that child health researchers working with human blood are aware of how experimental results can be altered by blood sampling methods, times to processing, container tubes, presence or absence of additives, shipping and storage variables, and freeze-thaw cycles. The authors of this review, in an effort to encourage and optimize translational research using blood from pediatric patients, outline best practices for blood collection, processing, shipment, and storage.

Novel association between plasma matrix metalloproteinase-9 and risk of incident atrial fibrillation in a case-cohort study: the Atherosclerosis Risk in Communities study

Background

Previous cross-sectional studies have suggested that biomarkers of extracellular matrix remodelling are associated with atrial fibrillation (AF), but no prospective data have yet been published. Hence, we examine whether plasma matrix metalloproteinases (MMP) and their inhibitors are related to increased risk of incident AF.

Methods

We used a case-cohort design in the context of the prospective Atherosclerosis Risk in Communities (ARIC) study. From 13718 eligible men and women free from AF in 1990-92, we selected a stratified random sample of 500 individuals without and 580 with incident AF over a mean follow-up of 11.8 years. Using a weighted proportional hazards regression model, the relationships between MMP-1, MMP-2, MMP-9, tissue inhibitor of matrix metalloproteinase (TIMP)-1, TIMP-2 and C-terminal propeptide of collagen type-I with incident AF were examined after adjusting for confounders.

Results

In models adjusted for age, sex and race, all biomarkers were associated with AF, but only the relationship between plasma MMP-9 remained significant in the fully-adjusted model: each one standard deviation increase in MMP-9 was associated with 27% (95% Confidence Interval: 7% to 50%) increase in risk of AF with no evidence of an interaction with race or sex. Individuals with above mean levels of MMP-9 were more likely to be male, white and current smokers.

Conclusions

The findings suggest that elevated levels of MMP-9 are independently associated with increased risk of AF. However, given the lack of specificity of MMP-9 to atrial tissue, it remains to be determined whether the observed relationship reflects the impact of atrial fibrosis or more generalized fibrosis on risk of incident AF.

The behavior of matrix metalloproteinases and their inhibitors in colorectal cancer

Matrix metalloproteinases (MMPs) play an important role in the degradation of extracellular matrix components crucial for tumor growth, invasion and metastasis. MMPs are controlled by natural inhibitors called tissue inhibitors of metalloproteinases (TIMPs). We and others have demonstrated that MMPs and TIMPs are especially important in the process of tumor invasion, progression and the metastasis of colorectal cancer (CRC). It has been proposed that MMPs and TIMPs might play a part not only in tumor invasion and initiation of metastasis but also in carcinogenesis from colorectal adenomas. Several recent studies demonstrated that high preoperative serum or plasma MMP-2, MMP-9 and TIMP-1 antigen levels are strong predictive factors for poor prognosis in patients with CRC and their determination might be useful for identification of patients with higher risk for cancer recurrence. MMP-9 and TIMP-1 have significant potential tumor marker impact in CRC. Their diagnostic sensitivity is consistently higher than those of conventional biomarkers. The pharmacological targeting of CRC by the development of a new generation of selective inhibitors of MMPs, that is highly specific for certain MMPs, is a promising and challenging area for the future.

Serum matrix metalloproteinase 9 and colorectal neoplasia: a community-based evaluation of a potential diagnostic test

Background:

A blood test may be a more acceptable routine colorectal cancer (CRC) screening test than faecal occult blood test, flexible sigmoidoscopy or colonoscopy, and could be safer and cheaper. We evaluated the accuracy of a serum matrix metalloproteinase (MMP9) test for CRC in a non-presenting symptomatic population.

Methods:

A cohort, aged 50–69 with lower gastrointestinal symptoms, was identified by community-based survey. Accuracy of serum MMP9 was assessed by comparison with colonoscopy. Logistic regression identified predictors of neoplasia and receiver operating characteristic curve analyses determined the cutoff to maximise the sensitivity.

Results:

Data were available for 748 patients. Overall, 46 cases of neoplasia were identified. Univariate analysis demonstrated that demographic characteristics, behavioural factors, clinical symptoms and raised serum MMP9 concentration were all significantly associated with the presence of neoplasia. Our final logistic regression model had a sensitivity of 79% and specificity of 70%.

Conclusion:

We demonstrated a significant association between serum MMP9 concentration and the presence of neoplasia. Serum MMP9 levels are raised in those with cancer and high-risk adenomas, although MMP9 estimation is likely to have the greatest predictive utility when used as part of a panel of biomarkers. Further work is required to identify biomarkers that are sufficiently accurate for implementing into routine practice.

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

OBJECTIVES

Matrix 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 METHODS

Blood 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.

RESULTS

In 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.

CONCLUSIONS

Preanalytics plays a key role for determination of MMP-9. EDTA seems to be a valid anticoagulant for MMP-9 protein measurement.

Translational research in pediatrics: tissue sampling and biobanking

Translational research is expanding and has become a focus of National Research funding agencies, touted as the primary avenue to improve health care practice. The use of human tissues for research on disease etiology is a pillar of translational research, particularly with innovations in research technologies to investigate the building blocks of disease. In pediatrics, translational research using human tissues has been hindered by the many practical and ethical considerations associated with tissue procurement from children and also by a limited population base for study, by the increasing complexities in conducting clinical research, and by a lack of dedicated child-health research funding. Given these obstacles, pediatric translational research can be enhanced by developing strategic and efficient biobanks that will provide scientists with quality tissue specimens to render accurate and reproducible research results. Indeed, tissue sampling and biobanking within pediatric academic settings has potential to impact child health by promoting bidirectional interaction between clinicians and scientists, helping to maximize research productivity, and providing a competitive edge for attracting and maintaining high-quality personnel. The authors of this review outline key issues and practical solutions to optimize pediatric tissue sampling and biobanking for translational research, activities that will ultimately reduce the burden of childhood disease.

Serum MMP-8 levels increase in colorectal cancer and correlate with disease course and inflammatory properties of primary tumors

Matrix metalloproteinases (MMPs) form a family of zinc-dependent endoproteases participating in cancer pathogenesis by promoting invasion and regulating growth signaling, apoptosis, angiogenesis and immune responses. MMP-8 is an intriguing MMP with recently discovered antitumor activity and immunoregulatory properties, but its role in colorectal cancer (CRC) has not been studied extensively. Preoperative serum MMP-8 levels (S-MMP-8) of 148 CRC patients and 83 healthy controls were measured using an immunofluorometric assay and related to clinical and pathological parameters. The patients had higher S-MMP-8 than the controls (median 63.0 vs. 17.2 ng/ml, p = 1.5E - 9), and a receiver operating characteristics analysis yielded an area under the curve of 0.751 in differentiating the groups. In univariate analyses, S-MMP-8 correlated positively with disease stage (p = 4.5E - 4), the degree of primary tumor necrosis (p = 0.0024) and blood neutrophil count (Pearson r = 0.523, p = 2.5E - 9). Particular interest was also addressed to the inflammatory properties of the tumors, and both variables studied, peritumoral tumor-destructing inflammatory infiltrate and Crohn's-like lymphoid reaction (CLR), showed a negative correlation with S-MMP-8 (p = 0.041 and p = 0.0057, respectively). In a multiple linear regression analysis, high S-MMP-8 associated with elevated blood neutrophil count, distant metastases, low-grade CLR and low body mass index. Overall, our results indicate that MMP-8 is involved in the course and progression of CRC influencing the immune response against the tumor and contributing to the resolution of necrosis. Serum or plasma MMP-8 may prove to be a worthy biomarker for CRC.

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°C.

CONCLUSION

Active MMP-9 and TIMP-1 appear to be stable seasonally, and in storage for at least three years.

Matrix metalloproteinases and their clinical relevance in urinary bladder cancer

Matrix metalloproteinases (MMPs) have important roles in several cancer-supporting cellular processes, such as extracellular matrix (ECM) remodeling, angiogenesis, apoptosis, epithelial-to-mesenchymal transition and cell proliferation. This broad range of activity has led to considerable interest in the use of MMPs in the clinical setting as diagnostic or prognostic biomarkers and as therapeutic targets. Levels of the different MMPs can be measured in several sample types, including paraffin-embedded or fresh frozen tissue, serum, plasma and urine, and by various analytical methodologies, such as immunohistochemistry, real-time PCR, western and northern blot analyses, enzyme-linked immunosorbent assay and zymography. Several MMPs have been identified as having potential diagnostic or prognostic utility, whether alone or in combination with currently available diagnostic tests or imaging modalities. Although the early broad-spectrum anti-MMP agents showed a lack of efficacy, our continually improving understanding of the complex physiologic and pathologic roles of MMPs might enable the development of new MMP-specific and tumor-specific therapies. Accordingly, MMPs will continue to be the subjects of intensive research in bladder cancer.

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

BACKGROUND

Blood biomarkers are subject to pre-analytical variability. In many cases, the stability of important new tissue biomarkers during freeze cycles and storage has not been studied sufficiently.

METHODS

To test the stability of matrix metalloproteinases-7 (MMP-7) and their tissue inhibitors (TIMP-1), vascular growth factors (VEGF) and VEGF-receptor, serum samples were frozen and then thawed up to six times. The impact of storage temperature was investigated using an accelerated stability testing protocol. Stability at -20°C and -75°C was calculated using the Arrhenius equation.

RESULTS

The average concentration of TIMP-1 was stable, even after six freeze/thaw cycles. One thawing did not change the concentration of MMP-7 and VEGF-receptor. However, repeated freeze/thaw cycles increased the measured values significantly. Decreases in VEGF concentrations were dramatic, even after the first freeze/thaw cycle. According to the Arrhenius calculation, MMP-7 showed excellent stability, at least 5 years at -20°C and several 100 years at -75°C. The VEGF-receptor maintains 90% of its initial concentration at -20°C over 3 months, and decades at -75°C. TIMP-1 and VEGF showed poor stability with cryopreservation, even at -75°C.

CONCLUSIONS

The stability of MMP-7, TIMP-1, VEGF or VEGF-receptor in biobanking is highly variable, and this should be taken into account in the interpretation of results. A temperature -20°C is unsuitable for prolonged storage of the biomarkers investigated, and repeated thawing of sera is not recommended. VEGF is especially unstable and should be quantitated using serum that has never been frozen.

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

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.

Heparin affects matrix metalloproteinases and tissue inhibitors of metalloproteinases circulating in peripheral blood

OBJECTIVES

Blood sampling/handling alters matrix metalloproteinases (MMP) and tissue inhibitors of metalloproteinases (TIMP) expression. The aim of this study is to evaluate the effects of high molecular weight heparin on MMP and TIMP expression in blood.

DESIGN AND METHODS

We analyzed by gelatin zymography and ELISA assays the effects of different heparin salts, dose- and time-dependence of MMP and TIMP concentrations in plasma and sera collected with and without clot-accelerator in plastic tubes from 50 healthy donors.

RESULTS

The levels and zymography of MMP-2 did not show significant changes among all samples, and during time- and dose-dependent heparin treatments. MMP-9 and TIMP-2 expression were strongly affected by heparin, with significant increase of their content and gelatinolytic activity both in time- and in dose-dependent fashion. Addition of heparin allowed also the displacement of MMP-2 prodomain, favouring zymogen activation.

CONCLUSIONS

Heparin has direct and indirect effects, altering MMP/TIMP complexes circulating in blood, and increasing the release of TIMP-2. To avoid misinterpretations due to MMP/TIMP complex alteration and MMP prodomain displacement, heparin should be cautiously used in blood collection procedures.

Plasma matrix metalloproteinase-7 as a metastatic marker and survival predictor in patients with renal cell carcinomas

We evaluated the clinical usefulness of plasma matrix metalloproteinase-7 (MMP-7) as a diagnostic and prognostic biomarker in patients with renal cell carcinoma (RCC). MMP-7 was quantified in plasma of 50 healthy subjects and 97 RCC patients using a Fluorokine MultiAnalyte Profiling assay. RCC patients were stratified into the following groups: without metastases (N0M0; n = 39), with lymph nodes (N1M0; n = 13), and with distant metastases (M1; n = 45). Diagnostic performance of MMP-7 was analyzed by the receiver operating characteristics (ROC) curve. Kaplan-Meier analysis and the Cox regression model were used to estimate the impact of MMP-7 on the cancer-specific survival outcome of RCC patients. MMP-7 was significantly higher in both metastatic groups N1M0 and M1 (medians, 3.82 and 3.34 microg/L) compared to N0M0 group or controls (medians, 1.85 and 1.64 microg/L; all P < 0.001). In ROC analysis, the area under the ROC curve of MMP-7 was 0.80 in the detection of metastases in RCC (P < 0.0001). In the Kaplan-Meier analysis, patients with MMP-7 above the 95th percentile of controls showed less favorable survival rates compared to those with normal MMP-7 (log-rank test, 15.7; P < 0.0001). High MMP-7 was associated with cancer-related mortality estimated by univariate Cox regression (risk ratio, 4.34, 95% CI, 1.12-10.6; P = 0.032). The multivariate Cox regression model determined MMP-7 (risk ratio, 2.70, 95% CI, 1.39-5.24; P = 0.003) and metastases (risk ratio, 5.81, 95% CI, 2.77-12.2; P < 0.0001) as independent determinants of cancer-related survival outcomes. In conclusion, increased plasma MMP-7 could be related to metastatic disease and poor prognosis in patients with RCC.