Jinling Chen

Improving the efficacy of therapeutic angiogenesis by UTMD-mediated Ang-1 gene delivery to the infarcted myocardium

This study aimed to verify the feasibility and efficacy of ultrasound-targeted microbubble destruction (UTMD)-mediated angiopoietin-1 (Ang-1) gene delivery into the infarcted myocardium. Microbubbles carrying anti-intercellular adhesion molecule-1 (ICAM-1) antibody were prepared and identified. The microbubbles carrying anti-ICAM-1 antibody selectively adhered to the interleukin (IL)-1β-stimulated ECV304 cells and to the ischemic vascular endothelium, and the infarct area was examined to evaluate the targeting ability of ICAM-1 microbubbles in vitro and in vivo. The intravenous administration of the Ang-1 gene was carried out by UTMD in rabbits with acute myocardial infarction (AMI). The rabbits were divided into the control (no treatment), non-targeted microbubble destruction (non-TMB) and the ICAM-1 TMB (TMB) group. Gene delivery by direct intramyocardial injection (IMI) served as a reference. Two weeks later, regional myocardial perfusion and cardiac function were evaluated by echocardiography, and Ang-1 gene-mediated angiogenesis was assessed histologically and biochemically. The results revealed that the ICAM-1-targeted microbubbles selectively adhered to the IL-1β-stimulated ECV304 cells in vitro and to the ischemic vascular endothelium in the infarct area of the rabbits with AMI. Two weeks after the delivery of the Ang-1 gene, compared with the non-TMB group, left ventricular function and myocardial perfusion at the infarct area had improved in the TMB and IMI group (p<0.01). Ang-1 gene expression was detectable in the non-TMB, TMB and IMI group, while its expression was higher in the latter 2 groups (all p<0.01). The microvascular density (MVD) of the infarct area in the non-TMB, TMB and IMI group was 65.6±4.4, 96.7±2.1 and 100.7±3.6, respectively (p<0.01). The findings of our study indicate that UTMD-mediated gene delivery may be used to successfully deliver the Ang-1 gene to the infarcted myocardium, thus improving the efficacy of therapeutic angiogenesis. This may provide a novel strategy for future gene therapy.

Injection of composite with bone marrow-derived mesenchymal stem cells and a novel synthetic hydrogel after myocardial infarction: A protective role in left ventricle function

A number of studies have shown that the transplantation of bone marrow‐derived mesenchymal stem cells (BMSCs) into the thinned infarct wall improves regional wall motion. In this study, we hypothesized that the injection of biomaterials and MSCs into the infarcted myocardium can preserve left ventricular (LV) function. To test this hypothesis, anterior acute myocardial infarction (AMI) was induced in 34 rabbits and BMSCs with hydrogel composite were prepared. One week after inducing AMI, 28 of the 34 rabbits were divided into four groups (Groups A–D; three rabbits were used for bone marrow aspiration, and three rabbits died) and all received an epicardial injection. Group A received BMSCs with hydrogel composite marked by 5‐bromodeoxyuridine (BrdU); Group B received BMSCs only marked by BrdU; Group C received hydrogel only marked by BrdU; and Group D was the control group, which received fetal bovine serum. Echocardiography was performed before AMI was induced, 1 week after AMI, and 4 weeks after the epicardial injection. The results were compared with those before AMI, and the rabbits of all the four groups had significantly larger LV end‐diastolic diameter (LVDd), thinner anterior wall (AW), lower LV ejection fraction (LVEF), lower VS and VE (p < 0.05) 1 week after AMI, which were more significant in Group A (p < 0.05). Compared with 1 week after AMI, Group A and Group B had significantly smaller LVDd, thicker AW, larger LVEF, larger VS and VE (p < 0.05) 4 weeks after the epicardial injection, which were more significant in Group A (p < 0.05); however, there was no significant difference in Group C and Group D. These results suggested that BMSCs with hydrogel composite could serve as an injectable biomaterial that prevents LV remodeling and dilation, and improves local systolic and diastolic function after AMI.

Ultrasound microbubbles combined with the NFκB binding motif increase transfection efficiency by enhancing the cytoplasmic and nuclear import of plasmid DNA

Inefficient gene delivery poses a challenge for non‑viral gene therapy. Cytoplasmic and nuclear membrane barriers are responsible for the inefficiency as they restrict the import of exogenous genes. The present study aimed to improve the transfection efficiency using a novel gene delivery system, which consisted of two components: ultrasound microbubbles and the nuclear factor κB (NFκB) binding motif. Ultrasound-targeted microbubble destruction (UTMD) was used to enhance the cytoplasmic import of plasmids and the NFκB binding motif was added to promote the nuclear intake of the plasmid from the cytoplasm. In the present study, human umbilical vein endothelial cells were transfected using UTMD with two different Cy3-labeled plasmids, phSDF-1α and phSDF‑1α‑NFκB. phSDF-1α-NFκB was constructed by inserting a specific DNA targeting sequence (five optimal repeats of the binding motif for the inducible transcription factor NFκB) into phSDF‑1α. The nuclear import and gene expression efficiency of phSDF-1α-NFκB were compared with those of phSDF-1α to investigate the effect of the NFκB binding motif on transfection. The results showed that UTMD significantly increased the cytoplasmic intake of pDNA and maintained high cell viability. The nuclear import and gene expression of phSDF-1α‑NFκB‑transfected cells were significantly higher than those transfected with phSDF-1α. Compared with the NFκB‑free plasmids, the quantity of NFκB plasmids in the nucleus increased 6.5-fold and the expression of SDF-1α was 4.4-fold greater. These results suggest that UTMD combined with NFκB binding motif significantly improve transfection efficiency by enhancing the cytoplasmic and nuclear import of exogenous plasmid DNA.

Optimization of transfection parameters for ultrasound/Sonovue microbubble-mediated hAng-1 gene delivery in vitro

This study aimed to explore the effects of microbubble concentration, gene dosage, cell-microbubble mixing mode and fetal bovine serum (FBS) on gene delivery. 293T cells were transfected with Sonovue microbubbles carrying the hAng-1 gene via ultrasound irradiation. Various ultrasound exposure parameters and microbubble and DNA concentrations were investigated. In addition, FBS and the cell suspension or adherent mode was explored. Transfection efficiency and cell viability were used to determine the optimal transfection parameters. hAng-1 gene transfection efficiency gradually increased with elongation of ultrasound exposure and increasing microbubble concentration. However, if ultrasound irradiation exceeded 1.5 W/cm² and 30 sec or the microbubble concentration was over 20%, hAng-1 gene expression was significantly decreased, coupled with extensive cell death. Gene transfection levels were low under DNA concentrations less than 15 µg/ml. Furthermore, the gene transfer rate was significantly increased under cell suspension mode; FBS had no effect on hAng-1 gene transfection. The integrity of hAng-1 DNA was not affected by ultrasonic irradiation under optimal conditions. The optimal transfection parameters for the hAng-1 gene and Sonovue microbubble were ultrasound exposure of 1.5 W/cm² and 30 sec, 20% microbubbles, 15 µg/ml of DNA and under cell suspension mode.

Stable cavitation using acoustic phase-change dodecafluoropentane nanoparticles for coronary micro-circulation thrombolysis

BACKGROUND The thrombolysis in micro-circulation after acute myocardial infarction has been an unsolved issue, as elimination effect of acute thrombolysis and primary intervention were unsatisfied. Stable cavitation using acoustic phase-change nanoparticles may have potential for thrombolysis. Therefore, we sought to investigate a novel treatment method with dodecafluoropentane (DDFP) nanoparticles for rapid and effective thrombolysis in an in-vitro artificial vascular system, as a mimicking preparation of coronary circulation. METHODS To simulate thrombus embolism in coronary circulation, an in-vitro artificial vascular system was established with cavitation effect using DDFP nanoparticles. For PBS blank control (group A), SonoVue microbubbles (group B) and DDFP nanoparticles (group C), the durations for cavitation effect were recorded and the thrombolysis efficiency with low intensity focused ultrasound irradiation in the in-vitro vascular system were analyzed with weight loss and pathological changes of thrombus before and after thrombolysis. RESULTS The optimal conditions for acoustic cavitation effect were power of 6 W for 20 min by ultrasound irradiation at 37 °C. The weight loss and weight loss rates of thrombus in group C (189.4 ± 30.2 mg and 34.2 ± 5.7%) were higher than those in group A (30.2 ± 16.0 mg and 5.2 ± 2.1%) and group B (84.0 ± 20.4 mg and 14.6 ± 1.5%) (P < 0.01, all). The duration for cavitation effect in group C (32.8 ± 3.9 min) was also longer than those in group A (0.0 ± 0.0 min) and group B (5.3 ± 0.3 min) (P < 0.01, all). CONCLUSIONS By stable and sustaining cavitation in targeted area, DDFP nanoparticles with ultrasound irradiation have significantly increased the thrombolysis efficiency, which has provided a powerful experimental foundation for potential coronary thrombolysis.

The differences in left atrial function between ischemic and idiopathic dilated cardiomyopathy patients: A two‐dimensional speckle tracking imaging study

To evaluate left atrial (LA) function in patients with ischemic (ICM) or idiopathic dilated (DCM) cardiomyopathy via two‐dimensional speckle‐tracking imaging.

The predictive value of intra-left atrial mechanical delay for 1-year recurrence of atrial fibrillation after catheter ablation: A clinical follow-up study using dual Doppler echocardiography

The availability of dual Doppler echocardiography (DDE), which facilitates the simultaneous recording of Doppler waveforms at two different sites, has enhanced ability to assess single‐beat atrial mechanical delay. We sought to investigate the predictive value of intra‐left atrial mechanical delay for atrial fibrillation (AF) recurrence after radiofrequency catheter ablation (RFCA) with DDE.

Prediction for Improvement and Remodeling in First-Onset Myocardial Infarction by Speckle Tracking Echocardiography: Is Global or Regional Selection Better?

Cardiac function improvement and chamber remodeling after the onset of acute myocardial infarction (AMI) is crucial as it is closely related to the outcomes of patients. We sought to investigate the predictive value of left ventricular (LV) global and region of interest (ROI) assessment for prognosis of AMI patients by speckle tracking echocardiography (STE). We prospectively enrolled 81 first-onset AMI patients for baseline and 6-mo follow-up analysis. The echocardiography-derived parameters were compared in receiver operator characteristics (ROC) analysis for prediction of LV remodeling (LVR) (a minimum 20% increase of LV end-diastolic volume) and cardiac function improvement (a minimum 5% increase of LV ejection fraction). The ROI strain was selected by wall motion score index (WMSI) scores ≥2. The time of whole analysis process was recorded. Cut-off values of -9.92% for global circumferential strain (CS) and -5.53% for ROI CS predicted LVR. Cut-off values of -10.40% for global longitudinal strain (LS) and -5.33% for ROI LS predicted cardiac function improvement. Areas under curves of global and ROI parameters were comparable in ROC analysis (p > 0.05, all). The time of global analysis was less than the time of ROI analysis (p < 0.05) and the reproducibility of global analysis was slightly better than the ROI analysis. Our results demonstrated that STE was valuable for the prediction of LVR and cardiac function improvement after AMI. Compared with ROI parameters, global parameters were more integral and efficient as predictive factors with high predictive power, less analysis time and better reproducibility.

Evaluating the morphology of the left atrial appendage by a transesophageal echocardiographic 3-dimensional printed model

Abstract The novel 3-dimensional printing (3DP) technique has shown its ability to assist personalized cardiac intervention therapy. This study aimed to determine the feasibility of 3D-printed left atrial appendage (LAA) models based on 3D transesophageal echocardiography (3D TEE) data and their application value in treating LAA occlusions. Eighteen patients with transcatheter LAA occlusion, and preprocedure 3D TEE and cardiac computed tomography were enrolled. 3D TEE volumetric data of the LAA were acquired and postprocessed for 3DP. Two types of 3D models of the LAA (ie, hard chamber model and flexible wall model) were printed by a 3D printer. The morphological classification and lobe identification of the LAA were assessed by the 3D chamber model, and LAA dimensions were measured via the 3D wall model. Additionally, a simulation operative rehearsal was performed on the 3D models in cases of challenging LAA morphology for the purpose of understanding the interactions between the device and the model. Three-dimensional TEE volumetric data of the LAA were successfully reprocessed and printed as 3D LAA chamber models and 3D LAA wall models in all patients. The consistency of the morphological classifications of the LAA based on 3D models and cardiac computed tomography was 0.92 (P < .01). The differences between the LAA ostium dimensions and depth measured using the 3D models were not significant from those measured on 3D TEE (P > .05). A simulation occlusion was successfully performed on the 3D model of the 2 challenging cases and compared with the real procedure. The echocardiographic 3DP technique is feasible and accurate in reflecting the spatial morphology of the LAA, which may be promising for the personalized planning of transcatheter LAA occlusion.

Comparison of Intracoronary and Intravenous Ultrasound-targeted Microbubble Destruction–mediated Ang1 Gene Transfection on Left Ventricular Remodeling in Canines With Acute Myocardial Infarction

Abstract: Intravenous ultrasound-targeted microbubble destruction (IV-UTMD) has made distinct but limited progress in gene therapy. Intracoronary (IC) injection may lead to more gene transfection than IV injection. This study compared the therapeutic effects of IC-UTMD–mediated and conventional IV-UTMD–mediated gene transfection in acute myocardial infarction (MI). A canine MI model was successfully established through transcatheter coronary artery embolism, and the animals were divided into several treatment groups: IC injection with UTMD and the negative control plasmid (IC-UTMD); IC injection of the angiopoietin 1 (Ang1) plasmid (IC-Ang1); IC injection with UTMD and the Ang1 plasmid (IC-UTMD-Ang1); and IV injection with UTMD and the Ang1 plasmid (IV-UTMD-Ang1). At 12 hours after injection, more green fluorescence was observed from the fluorescein isothiocyanate-labeled Ang1 plasmid in the IC-UTMD-Ang1 group. After 1 month, compared with the IV-UTMD-Ang1 group, echocardiography showed that the IC-UTMD-Ang1 group exhibited increased left ventricular systolic function and myocardial infusion, with lower fibrous tissue levels and higher blood vessel density and Ang1 mRNA and protein levels. Similar cardiac troponin I and N-terminal pro-B type natriuretic peptide levels were observed in all groups. Compared with IV-UTMD, IC-UTMD can enhance Ang1 plasmid transfection efficiency after MI, promote gene expression and angiogenesis, and improve left ventricular remodeling without decreasing safety.