Dataset Information

Automated quantification of myocardial salvage in a rat model of ischemia-reperfusion injury using 3D high-resolution magnetic resonance imaging (MRI).

ABSTRACT:

Background

Quantification of myocardial "area at risk" (AAR) and myocardial infarction (MI) zone is critical for assessing novel therapies targeting myocardial ischemia-reperfusion (IR) injury. Current "gold-standard" methods perfuse the heart with Evan's Blue and stain with triphenyl tetrazolium chloride (TTC), requiring manual slicing and analysis. We aimed to develop and validate a high-resolution 3-dimensional (3D) magnetic resonance imaging (MRI) method for quantifying MI and AAR.

Methods and results

Forty-eight hours after IR was induced, rats were anesthetized and gadopentetate dimeglumine was administered intravenously. After 10 minutes, the coronary artery was re-ligated and a solution containing iron oxide microparticles and Evan's Blue was infused (for comparison). Hearts were harvested and transversally sectioned for TTC staining. Ex vivo MR images of slices were acquired on a 9.4-T magnet. T2* data allowed visualization of AAR, with microparticle-associated signal loss in perfused regions. T1 data demonstrated gadolinium retention in infarcted zones. Close correlation (r=0.92 to 0.94; P<0.05) of MRI and Evan's Blue/TTC measures for both AAR and MI was observed when the combined techniques were applied to the same heart slice. However, 3D MRI acquisition and analysis of whole heart reduced intra-observer variability compared to assessment of isolated slices, and allowed automated segmentation and analysis, thus reducing interobserver variation. Anatomical resolution of 81 ?m(3) was achieved (versus ?2 mm with manual slicing).

Conclusions

This novel, yet simple, MRI technique allows precise assessment of infarct and AAR zones. It removes the need for tissue slicing and provides opportunity for 3D digital analysis at high anatomical resolution in a streamlined manner accessible for all laboratories already performing IR experiments.

SUBMITTER: Grieve SM

PROVIDER: S-EPMC4310382 | biostudies-literature | 2014 Jul

REPOSITORIES: biostudies-literature

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Publications

Automated quantification of myocardial salvage in a rat model of ischemia-reperfusion injury using 3D high-resolution magnetic resonance imaging (MRI).

Grieve Stuart M SM Mazhar Jawad J Callaghan Fraser F Kok Cindy Y CY Tandy Sarah S Bhindi Ravinay R Figtree Gemma A GA

Journal of the American Heart Association 20140723 4

<h4>Background</h4>Quantification of myocardial "area at risk" (AAR) and myocardial infarction (MI) zone is critical for assessing novel therapies targeting myocardial ischemia-reperfusion (IR) injury. Current "gold-standard" methods perfuse the heart with Evan's Blue and stain with triphenyl tetrazolium chloride (TTC), requiring manual slicing and analysis. We aimed to develop and validate a high-resolution 3-dimensional (3D) magnetic resonance imaging (MRI) method for quantifying MI and AAR.<h ...[more]

PMID: 25146703

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Project description:ObjectiveThe incidence of acute myocardial infarction (AMI) is increasing yearly. With the use of thrombolysis or percutaneous coronary intervention (PCI), the mortality rate of acute myocardial infarction has been significantly reduced. However, reperfusion can cause additional myocardial injury. There is still a lack of effective drugs to treat I/R injury, and it is urgent to find new therapeutic drugs.MethodsIn this study, network pharmacology was used to predict potential targets and biological processes involved in Muscone-mediated treatment of acute myocardial infarction. To model ischemia‒reperfusion injury, a hypoxia-reoxygenation model and in vivo ischemia‒reperfusion injury C57BL/6 mice model was constructed. Mice were treated with Muscone i.p. for 4 weeks. We detected the cardiac function on day 28.The expression levels of the apoptotic proteins Caspase-3 and Bax and the anti-apoptotic protein Bcl-2 were detected by immunoblotting after Muscone treatment of AC16 cells and in vivo. Additionally, the gene expression levels of the PUMA and p53 were analyzed by qRT‒PCR. Molecular docking was used to evaluate the binding energy between Muscone and NLRP3-related proteins. Immunoblotting and qRT‒PCR were used to assess the expression levels of NLRP3 signaling pathway-related proteins (NLRP3, ASC, and Caspase-1) and the NLRP3 gene, respectively. Moreover, the extracellular acidification rate of AC16 cells was measured using the Seahorse system to evaluate glycolysis levels after Muscone treatment. The expression of the key glycolytic enzyme PKM2 was analyzed by immunoblotting and qRT‒PCR. Finally, ChIP‒qPCR was performed to determine the levels of histone modifications (H3K4me3, H3K27me3, and H2AK119Ub) in the PKM2 promoter region.ResultsGO functional enrichment analysis revealed that muscone was involved in regulating the biological processes (BP) of AMI, which mainly included negative regulation of the apoptosis signaling pathway, the response to lipopolysaccharide, and blood pressure regulation. The cellular components (CC) involved in muscone-mediated regulation of AMI mainly included lipid rafts, membrane microdomains, and membrane regions. The molecular functions (MF) involved in muscone-mediated regulation of AMI mainly included oxidoreductase activity, nuclear receptor activity, and transcription factor activity. In vitro results indicated that muscone treatment could inhibit the expression levels of Bax and Caspase-3 in AC16 cells after ischemia‒reperfusion while increasing the expression level of the antiapoptotic protein Bcl-2. Muscone significantly suppressed the transcription levels of p53 and PUMA in AC16 cells. Molecular docking suggested that muscone could bind well with the Cryo-EM structure of NEK7(PDB ID:6NPY). Further investigation of inflammatory pathways revealed that muscone could inhibit the expression level of NLRP3 in AC16 cells and reduce the expression levels of Caspase-1 and Caspase recruitment domain. Fluorescent quantitative PCR experiments showed that muscone significantly inhibited the transcription of NLRP3. Moreover, we found that muscone could enhance the glycolytic efficiency of AC16 cells, which may be related to the increased protein expression of PKM2 in AC16 cells. Fluorescent quantitative PCR showed that muscone could increase the transcription level of PKM2. Chromatin immunoprecipitation assays showed that muscone treatment increased the expression level of H3K4me3 in the PKM2 promoter region and inhibited the levels of H3K27me3 and H2AK119Ub in the PKM2 promoter region.ConclusionMuscone promoted myocardial glycolysis and inhibited NLRP3 pathway activation to improve myocardial ischemia‒reperfusion injury.

Project description:Myocardial ischemia-reperfusion (I/R) results in the generation of free radicals, accumulation of lipid peroxidation-derived unsaturated aldehydes, variable angina (pain), and infarction. The transient receptor potential ankyrin 1 (TRPA1) mediates pain signaling and is activated by unsaturated aldehydes, including acrolein and 4-hydroxynonenal. The contribution of TRPA1 (a Ca2+-permeable channel) to I/R-induced myocardial injury is unknown. We tested the hypothesis that cardiac TRPA1 confers myocyte sensitivity to aldehyde accumulation and promotes I/R injury. Although basal cardiovascular function in TRPA1-null mice was similar to that in wild-type (WT) mice, infarct size was significantly smaller in TRPA1-null mice than in WT mice (34.1?±?9.3 vs. 14.3?±?9.9% of the risk region, n = 8 and 7, respectively, P < 0.05), despite a similar I/R-induced area at risk (40.3?±8.4% and 42.2?±?11.3% for WT and TRPA1-null mice, respectively) after myocardial I/R (30 min of ischemia followed by 24 h of reperfusion) in situ. Positive TRPA1 immunofluorescence was present in murine and human hearts and was colocalized with connexin43 at intercalated disks in isolated murine cardiomyocytes. Cardiomyocyte TRPA1 was confirmed by quantitative RT-PCR, DNA sequencing, Western blot analysis, and electrophysiology. A role of TRPA1 in cardiomyocyte toxicity was demonstrated in isolated cardiomyocytes exposed to acrolein, an I/R-associated toxin that induces Ca2+ accumulation and hypercontraction, effects significantly blunted by HC-030031, a TRPA1 antagonist. Protection induced by HC-030031 was quantitatively equivalent to that induced by SN-6, a Na+/Ca2+ exchange inhibitor, further supporting a role of Ca2+ overload in acrolein-induced cardiomyocyte toxicity. These data indicate that cardiac TRPA1 activation likely contributes to I/R injury and, thus, that TRPA1 may be a novel therapeutic target for decreasing myocardial I/R injury. NEW & NOTEWORTHY Transient receptor potential ankyrin 1 (TRPA1) activation mediates increased blood flow, edema, and pain reception, yet its role in myocardial ischemia-reperfusion (I/R) injury is unknown. Genetic ablation of TRPA1 significantly decreased myocardial infarction after I/R in mice. Functional TRPA1 in cardiomyocytes was enriched in intercalated disks and contributed to acrolein-induced Ca2+ overload and hypercontraction. These data indicate that I/R activation of TRPA1 worsens myocardial infarction; TRPA1 may be a potential target to mitigate I/R injury.

Project description:PurposeTo assess the performance of an automated myocardial T2 and extracellular volume (ECV) quantification method using transfer learning of a fully convolutional neural network (CNN) pretrained to segment the myocardium on T1 mapping images.Materials and methodsA single CNN previously trained and tested using 11 550 manually segmented native T1-weighted images was used to segment the myocardium for automated myocardial T2 and ECV quantification. Reference measurements from 1525 manually processed T2 maps and 1525 ECV maps (from 305 patients) were used to evaluate the performance of the pretrained network. Correlation coefficient (R) and Bland-Altman analysis were used to assess agreement between automated and reference values on per-patient, per-slice, and per-segment analyses. Furthermore, transfer learning effectiveness in the CNN was evaluated by comparing its performance to four CNNs trained using manually segmented T2-weighted and postcontrast T1-weighted images and initialized using random-weights or weights of the pretrained CNN.ResultsT2 and ECV measurements using the pretrained CNN strongly correlated with reference values in per-patient (T2: R = 0.88, 95% confidence interval [CI]: 0.85, 0.91; ECV: R = 0.91, 95% CI: 0.89, 0.93), per-slice (T2: R = 0.83, 95% CI: 0.81, 0.85; ECV: R = 0.84, 95% CI: 0.82, 0.86), and per-segment (T2: R = 0.75, 95% CI: 0.74, 0.77; ECV: R = 0.76, 95% CI: 0.75, 0.77) analyses. In Bland-Altman analysis, the automatic and reference values were in good agreement in per-patient (T2: 0.3 msec ± 2.9; ECV: -0.3% ± 1.7), per-slice (T2: 0.1 msec ± 4.6; ECV: -0.3% ± 2.5), and per-segment (T2: 0.0 msec ± 6.5; ECV: -0.4% ± 3.5) analyses. The performance of the pretrained network was comparable to networks refined or trained from scratch using additional manually segmented images.ConclusionTransfer learning extends the utility of pretrained CNN-based automated native T1 mapping analysis to T2 and ECV mapping without compromising performance. Supplemental material is available for this article. © RSNA, 2020.

Dataset Information

Automated quantification of myocardial salvage in a rat model of ischemia-reperfusion injury using 3D high-resolution magnetic resonance imaging (MRI).

Background

Methods and results

Conclusions

Publications

Automated quantification of myocardial salvage in a rat model of ischemia-reperfusion injury using 3D high-resolution magnetic resonance imaging (MRI).

Similar Datasets

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