The influence of autologous bone marrow stem cell transplantation on matrix metalloproteinases in patients treated for acute ST-elevation myocardial infarction

TIMP-1 expression in coronary thrombi associate with myocardial injury in ST-elevation myocardial infarction patients

BACKGROUND

Matrix metalloproteinases (MMPs) and their inhibitors (TIMPs) are considered important both in atherosclerosis and remodeling after acute myocardial infarction (AMI). We aimed to study genetic expression and presence of MMP-2, MMP-9, TIMP-1, TIMP-2 and the extracellular MMP-inducer (EMMPRIN) in coronary thrombi. Circulating levels and genetic expression in circulating leukocytes were also assessed, and relations to degree of myocardial injury measured by troponin T and time from symptom to PCI were explored. Expression of cell markers were also analyzed, indicating relations to cell types.

METHODS

Intracoronary thrombi were aspirated from 33 patients with ST-elevation myocardial infarction (STEMI). Blood samples with Pax-gene tubes were drawn at end of PCI and the next day. RNA was isolated from thrombi and leukocytes, and genes were relatively quantified by RT-PCR. Each thrombus was preserved for histology and immunohistochemistry analyzes.

RESULTS

Genes coding for the five markers were present in 84-100% of thrombi and immunohistochemically stained in 96-100%. Expression of TIMP-1 in thrombi and in leukocytes correlated significantly to peak troponin T ( r = 0.393 P = 0.026, r = 0.469 P = 0.006, respectively). No significant correlations between genes expressed in thrombi and time from symptom to PCI were observed. TIMP-1 was connected mainly to monocytes/macrophages in the thrombi.

CONCLUSION

MMP-2, MMP-9, TIMP-1, TIMP-2 and EMMPRIN were highly expressed in human coronary thrombi. The correlation between troponin T and the expression of TIMP-1 both in thrombi and in leukocytes at time of PCI indicates that TIMP-1 plays a role in myocardial damage early post-MI.

Construction of engineered myocardial tissues in vitro with cardiomyocyte‑like cells and a polylactic‑co‑glycolic acid polymer

The aim of the present study was to explore the feasibility of the construction of engineered myocardial tissues in vitro with cardiomyocyte‑like cells derived from bone marrow mesenchymal stem cells (BMMSCs) and a polylactic‑co‑glycolic acid (PLGA) polymer. The PLGA polymer was sheared into square pieces (10x10x1 mm), sterilized by Co60 irradiation, and hydrated in Dulbecco's modified Eagle's medium for 1 h. BMMSCs were isolated from the bone marrow of Sprague‑Dawley rats and the third passage cells were induced by 5‑azacytidine (5‑aza). Following successful induction, the cells were trypsinized and suspended at a density of 1x109/ml. Then, the cell suspension was added to the PLGA scaffold and cultured for 14 days. The morphological changes of BMMSCs were observed using phase contrast microscopy. Immunofluorescence staining was used to identify the cardiomyocyte‑like cells. Hematoxylin and eosin (H&E) and immunohistochemical staining were used to observe the morphology of the engineered myocardial tissues. The cell adhesion rates and scanning electron microscopy were used to observe the compatibility of the cardiomyocyte‑like cells and PLGA. Transmission electron microscopy was used to view the ultrastructure of the engineered myocardial tissues. BMMSCs in primary culture presented round or short spindle cell morphologies. Following induction by 5‑aza, the cells exhibited a long spindle shape and a parallel arrangement. Analysis of the cell adhesion rates demonstrated that the majority of the cardiomyocyte‑like cells had adhered to the PLGA scaffolds at 24 h. H&E staining suggested that the cardiomyocyte‑like cells with spindle nuclei were evenly distributed in the PLGA scaffold. Immunofluorescence staining revealed that the cardiomyocyte‑like cells were positive for cardiac troponin I. Scanning electron microscopy demonstrated that the inoculated cells were well attached to the PLGA scaffold. Transmission electron microscopy indicated that the engineered myocardial tissues contained well‑arranged myofilaments, desmosomes, gap junction and Z line‑like structures. The present study successfully constructed engineered myocardial tissues in vitro with a PLGA polymer and cardiomyocyte‑like cells derived from BMMSCs, which are likely to share various structural similarities with the original heart tissue.

MMP-9 and Its Regulators TIMP-1 and EMMPRIN in Patients with Acute ST-Elevation Myocardial Infarction: A NORDISTEMI Substudy

OBJECTIVES

The extracellular matrix is involved in wound repair after acute myocardial infarction (AMI). We investigated whether matrix metalloproteinase (MMP)-9, tissue inhibitor of metalloproteinases (TIMP)-1, and the MMP inducer (EMMPRIN) are associated with infarct size, left ventricular function, and clinical outcome in ST-elevation-MI (STEMI).

METHODS

In 243 STEMI patients, circulating EMMPRIN, MMP-9, and TIMP-1 were analyzed 3 days and 3 months post-AMI. Infarct size and left ventricular ejection fraction were assessed by single-photon emission computed tomography (SPECT) (n = 230/226) and MRI (n = 111/167) at 3 months.

RESULTS

EMMPRIN, MMP-9, and TIMP-1 levels and the MMP-9/TIMP-1 ratio declined from day 3 to 3 months (p < 0.001, all). TIMP-1 levels at day 3 correlated significantly with SPECT- and MRI-based infarct size, troponin T (p < 0.04, all), and amino-terminal pro-B-type natriuretic peptide (NT-proBNP; p < 0.001). The upper quartile of day 3 TIMP-1 levels showed an adjusted odds ratio of 5.0 (95% confidence interval 1.2-20.6) for having a large infarct size. An insignificant relationship between MMP-9 and clinical events within 1 year (death, AMI, or stroke) (n = 15) was observed, probably due to the lack of statistical power.

CONCLUSION

The decline in EMMPRIN, MMP-9, and TIMP-1 3 months after acute STEMI is probably due to initial acute-phase processes. The associations between TIMP-1, infarct size, and NT-proBNP indicate a role for TIMP-1 in cardiac remodeling.

Stem cell treatment for acute myocardial infarction

BACKGROUND

Cell transplantation offers a potential therapeutic approach to the repair and regeneration of damaged vascular and cardiac tissue after acute myocardial infarction (AMI). This has resulted in multiple randomised controlled trials (RCTs) across the world.

OBJECTIVES

To determine the safety and efficacy of autologous adult bone marrow stem cells as a treatment for acute myocardial infarction (AMI), focusing on clinical outcomes.

SEARCH METHODS

This Cochrane review is an update of a previous version (published in 2012). We searched the Cochrane Central Register of Controlled Trials (CENTRAL 2015, Issue 2), MEDLINE (1950 to March 2015), EMBASE (1974 to March 2015), CINAHL (1982 to March 2015) and the Transfusion Evidence Library (1980 to March 2015). In addition, we searched several international and ongoing trial databases in March 2015 and handsearched relevant conference proceedings to January 2011.

SELECTION CRITERIA

RCTs comparing autologous bone marrow-derived cells with no cells in patients diagnosed with AMI were eligible.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened all references, assessed the risk of bias of the included trials and extracted data. We conducted meta-analyses using random-effects models throughout. We analysed outcomes at short-term (less than 12 months) and long-term (12 months or more) follow-up. Dichotomous outcomes are reported as risk ratio (RR) and continuous outcomes are reported as mean difference (MD) or standardised MD (SMD). We performed sensitivity analyses to evaluate the results in the context of the risk of selection, performance and attrition bias. Exploratory subgroup analysis investigated the effects of baseline cardiac function (left ventricular ejection fraction, LVEF) and cell dose, type and timing of administration, as well as the use of heparin in the final cell solution.

MAIN RESULTS

Forty-one RCTs with a total of 2732 participants (1564 cell therapy, 1168 controls) were eligible for inclusion. Cell treatment was not associated with any changes in the risk of all-cause mortality (34/538 versus 32/458; RR 0.93, 95% CI 0.58 to 1.50; 996 participants; 14 studies; moderate quality evidence), cardiovascular mortality (23/277 versus 18/250; RR 1.04, 95% CI 0.54 to 1.99; 527 participants; nine studies; moderate quality evidence) or a composite measure of mortality, reinfarction and re-hospitalisation for heart failure (24/262 versus 33/235; RR 0.63, 95% CI 0.36 to 1.10; 497 participants; six studies; moderate quality evidence) at long-term follow-up. Statistical heterogeneity was low (I(2) = 0% to 12%). Serious periprocedural adverse events were rare and were generally unlikely to be related to cell therapy. Additionally, cell therapy had no effect on morbidity, quality of life/performance or LVEF measured by magnetic resonance imaging. Meta-analyses of LVEF measured by echocardiography, single photon emission computed tomography and left ventricular angiography showed evidence of differences in mean LVEF between treatment groups although the mean differences ranged between 2% and 5%, which are accepted not to be clinically relevant. Results were robust to the risk of selection, performance and attrition bias from individual studies.

AUTHORS' CONCLUSIONS

The results of this review suggest that there is insufficient evidence for a beneficial effect of cell therapy for AMI patients. However, most of the evidence comes from small trials that showed no difference in clinically relevant outcomes. Further adequately powered trials are needed and until then the efficacy of this intervention remains unproven.