Loss of m6A demethylase ALKBH5 alleviates hypoxia-induced pulmonary arterial hypertension via inhibiting Cyp1a1 mRNA decay.

BACKGROUND: Hypoxia-induced pulmonary artery hypertension (HPH) is a complication of chronic hypoxic lung disease and the third most common type of pulmonary artery hypertension (PAH). Epigenetic mechanisms play essential roles in the pathogenesis of HPH. N6-methyladenosine (m6A) is an important modified RNA nucleotide involved in a variety of biological processes and an important regulator of epigenetic processes. To date, the precise role of m6A and regulatory molecules in HPH remains unclear. METHODS: HPH model and pulmonary artery smooth muscle cells (PASMCs) were constructed from which m6A changes were observed and screened for AlkB homolog 5 (Alkbh5). Alkbh5 knock-in (KI) and knock-out (KO) mice were constructed to observe the effects on m6A and evaluate right ventricular systolic pressure (RVSP), left ventricular and septal weight [RV/(LV + S)], and pulmonary vascular remodeling in the context of HPH. Additionally, the effects of Alkbh5 knockdown using adenovirus were examined in vitro on m6A, specifically in PASMCs with regard to proliferation, migration and cytochrome P450 1A1 (Cyp1a1) mRNA stability. RESULTS: In both HPH mice lung tissues and hypoxic PASMCs, a decrease in m6A was observed, accompanied by a significant up-regulation of Alkbh5 expression. Loss of Alkbh5 attenuated the proliferation and migration of hypoxic PASMCs in vitro, with an associated increase in m6A modification. Furthermore, Alkbh5 KO mice exhibited reduced RVSP, RV/(LV + S), and attenuated vascular remodeling in HPH mice. Mechanistically, loss of Alkbh5 inhibited Cyp1a1 mRNA decay and increased its expression through an m6A-dependent post-transcriptional mechanism, which hindered the proliferation and migration of hypoxic PASMCs. CONCLUSION: The current study highlights the loss of Alkbh5 impedes the proliferation and migration of PASMCs by inhibiting post-transcriptional Cyp1a1 mRNA decay in an m6A-dependent manner.

Association Between Serum Uric Acid Levels and Neoatherosclerosis.

Neoatherosclerosis is a major cause of stent failure after percutaneous coronary intervention. Metabolism such as hyperuricemia is associated with in-stent restenosis (ISR). However, the association between serum uric acid (sUA) levels and in-stent neoatherosclerosis (ISNA) has never been validated.A total of 216 patients with 220 ISR lesions who had undergone optical coherence tomography (OCT) of culprit stents were included in this study. According to their sUA levels, eligible patients were divided into two groups [normal-sUA group: sUA < 7 mg/dL, n = 126, and high-sUA group: sUA ≥ 7 mg/dL, n = 90]. OCT findings were analyzed and compared between the normal- and high-sUA groups.The incidence of ISNA (63.0% versus 43.0%, P = 0.004) was significantly higher in the high-sUA group than in the normal-sUA group. Lipid plaques (66.3% versus 43.0%, P < 0.001) and thin-cap fibroatheroma (38.0% versus 18.0%, P = 0.001) were observed more frequently in the restenotic tissue structure in patients in the high-sUA group than in those in the normal-sUA group. Meanwhile, univariate (OR: 1.208, 95% CI: 1.037-1.407; P = 0.015) and multivariate (OR: 1.254, 95% CI: 1.048-1.501; P = 0.013) logistic regression analyses indicated that sUA levels were an independent risk factor for ISNA after adjusting for relevant risk factors.The high-sUA levels were an independent risk factor for the occurrence of neoatherosclerosis in patients with ISR via OCT.

[Role of CGRP modified mesenchymal stem cells in restenosis in rat model with carotid angioplasty].

OBJECTIVE: To explore the role of calcitonin gene-related peptide (CGRP) in the proliferation of vascular smooth muscle cells (VSMCs) and restenosis. METHODS: The high-expression CGRP lentivirus [Lenti-green fluorescent protein (GFP)-CGRP] was constructed. And mesenchymal stem cells (MSCs) were transfected with Lenti-GFP-CGRP, Lenti-GFP and phosphate buffer saline (PBS). Reverse transcription-polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA) were used to determine the CGRP gene and protein expression level of smooth muscle cells in each group respectively. Then MSCs were co-cultured with VSMCs. Experimental groups were MSCs(CGRP+/+)+VSMCs, MSCs(CGRP-/-)+VSMCs and MSCs(PBS)+VSMCs groups. The method of methyl thiazolyl tetrazolium (MTT) was employed to detect the proliferation of smooth muscle cells. Sacculus damaged atherosclerotic carotid was prepared according to the previous study. MSCs were transfected with Lv-CGRP-EGFP and Lv-CGRP and then transplanted into rat model. At Day 7 post-transplantation, injured carotid artery was harvested to detect the C expression of GRP by Western blot and the expression of CD31 by immunofluorescence. At Day 28 post-transplantation, injured carotid artery was harvested to assess organization morphology by hematoxylin and eosin stain and detect the expression of proliferating cell nuclear antigen (PCNA) by immunohistochemical stain. RESULTS: As compared with control and Lenti-GFP groups, the expressions of CGRP protein and CGRP mRNA increased at 72 h after transfecting with Lenti-GFP-CGRP (P < 0.05). After 72-hour co-culturing with VSMCs, the proliferation ability of VSMCs was the lowest in MSCs(CGRP+/+)+VSMCs group versus other three groups (P < 0.05). At Day 7 post-transplantation, as compared with control and Lenti-GFP groups, the expression of CGRP proteins increased significantly in MSCs-CGRP group (P < 0.05). A continuous expression of CD31 was found in damaged carotid intima in MSCs-CGRP group, but not in control group. At Day 28 post-transplantation, the area of intimal hyperplasia was smaller in MSCs-CGRP group than that in control and Lenti-GFP groups. Also the expression of PCNA decreased more in MSCs-CGRP group than control and Lenti-GFP groups (P < 0.05). CONCLUSIONS: CGRP protein and CGRP mRNA are expressed after CGRP transfection. And CGRP can suppress the proliferation of VSMCs and reduce intimal hyperplasia so as to facilitate a recovery of damaged endothelium.

[Expression of SDF-1/CXCR4 in acute infarct myocardium after implantation of bone marrow mesenchymal stem cells in rats].

OBJECTIVE: To explore the role of stromal cell derived factor-1 (SDF-1)/CXCR4 axis in acute infarct myocardium after an implantation of bone marrow mesenchymal stem cells (MSCs) in rats. METHODS: The animals were anesthetized by an intraperitoneal injection of pentobarbital sodium. Left anterior thoracotomy through 3/4 intercostals region was performed and then left anterior descending coronary arteries were ligated for modeling acute myocardial infarction. The MSCs were injected into the area of acute infarct myocardium after a 10-minute ligation of left anterior descending coronary artery. The different concentration and expression of SDF-1/CXCR4 in the area of acute myocardial infarction and left ventricular function were analyzed. RESULTS: At day 28 post-transplantation, the vascular density in MSCs implant group were significantly higher than that in control group (P<0.05). And left ventricular function in MSCs implant group improved significantly than that in control group too (P<0.05). At the same time, the expressions of SDF-1 and CXCR4 in topical injection sites of infarct myocardium were significantly higher than those in control group (P<0.05). In MSCs implant group, the level of SDF-1/CXCR4 peaked at Day 1 post-transplantation and then it declined. CONCLUSIONS: After the implantation of MSCs into acute infarct myocardium, there is vascular regeneration and the level of SDF-1/CXCR4 increases so that left ventricular function improves. And the mechanism may be due to an up-regulation of SDF-1/CXCR4 axis.

miR-613 regulates cholesterol efflux by targeting LXRα and ABCA1 in PPARγ activated THP-1 macrophages.

Cholesterol efflux from macrophages is a critical mechanism to prevent the development of atherosclerosis. Although PPARγ is known to be a potent sterol sensor that play a fundamental role in cholesterol metabolism, the potential effects of PPARγ responsive miRNA still need to be revealed. In this study, we found that miR-613 is inversely correlated with LXRα and ABCA1 in PPARγ activated THP-1 cells. PPARγ negatively regulates the expression of miR-613 at transcriptional level, and miR-613 suppressed LXRα and ABCA1 by targeting the 3'-UTR of their mRNAs. Furthermore, downregulation of LXRα and ABCA1 by miR-613 inhibited cholesterol efflux from PPARγ activated THP-1 macrophages. These results revealed an alternative mechanism for PPARγ regulation and provided a potential target for the treatment of cholesterol metabolic diseases.

Thin-cap fibroatheroma in acute coronary syndrome: Implication for intravascular imaging assessment.

Acute coronary syndrome (ACS), a significant cardiovascular disease threat, has garnered increased focus concerning its etiological mechanisms. Thin-cap fibroatheroma (TCFA) are central to ACS pathogenesis, characterized by lipid-rich plaques, profuse foam cells, cholesterol crystals, and fragile fibrous caps predisposed to rupture. While TCFAs may be latent and asymptomatic, their pivotal role in ACS risk is undeniable. High-resolution imaging techniques like Optical coherence tomography (OCT) and Intravascular ultrasound (IVUS) are instrumental for effective TCFA detection. Therapeutic strategies encompass pharmacological and interventional measures, including antiplatelet agents, statins, and Percutaneous Coronary Intervention (PCI), aiding in plaque stabilization, inflammation reduction, and rupture risk mitigation. Despite the strong correlation between TCFAs and adverse prognoses in ACS patients, early detection and rigorous treatment significantly enhance patient prognosis and diminish cardiovascular events. This review aims to encapsulate recent advancements in TCFA research within ACS, covering formation mechanisms, clinical manifestations, and prognostic implications.

Association of the monocytes to high-density lipoprotein cholesterol ratio with in-stent neoatherosclerosis and plaque vulnerability: An optical coherence tomography study.

BACKGROUND: Monocyte-to-high-density lipoprotein cholesterol ratio (MHR) is an independent predictor of atherosclerosis and in-stent restenosis (ISR). However, the association between MHR and the incidence of in-stent neoatherosclerosis (ISNA) remains to be validated. METHODS: This study included 216 patients with acute coronary syndrome who had 220 ISR lesions and had undergone optical coherence tomography (OCT). All eligible patients were divided into three groups according to their MHR tertile level. OCT characteristics were comparatively analyzed between groups of different MHR levels, and univariate and multivariate logistic regression analyses were constructed to assess correlations between MHR level and ISNA as well as in-stent thin-cap fibroatheroma (TCFA). A receiver operating characteristic curve was used to determine the optimal MHR thresholds for predicting ISNA and in-stent TCFA. RESULTS: The incidence of ISNA (70.3% vs. 61.1% vs. 20.3%, P < 0.001) and in-stent TCFA (40.5% vs. 31.9% vs. 6.8%, P < 0.001) was the highest in the third tertile, followed by the second and first tertiles, respectively. Multivariate analysis revealed that MHR was independently associated with ISNA (odds ratio [OR], 7.212; 95% confidence interval [CI], 1.287-40.416; P = 0.025) and in-stent TCFA (OR, 5.610; 95% CI, 1.743-18.051; P = 0.004) after adjusting for other clinical factors. The area under the curve was 0.745 (95% CI, 0.678-0.811; P < 0.001) for the prediction of ISNA and 0.718 (95% CI, 0.637-0.778; P < 0.001) for the prediction of in-stent TCFA. CONCLUSION: MHR levels are an independent risk factor for ISNA.

Association between periprocedural myocardial injury and neointimal characteristics in patients with in-stent restenosis: an optical coherence tomography study.

Background: The relationship between neointimal characteristics of in-stent restenosis (ISR) and periprocedural myocardial injury (PMI) remains unclear. Therefore, this study aimed to investigate the relationship between PMI and neointimal characteristics of ISR by using optical coherence tomography (OCT). Methods: This was a retrospective study. We enrolled 140 patients diagnosed with ISR with normal baseline high-sensitivity troponin T (hs-cTnT) levels who underwent OCT and subsequent revascularization by means of drug-coated balloon (DCB) or drug-eluting stent (DES) between October 2018 and October 2022 in the Affiliated Hospital of Zunyi Medical University. Based on the 4th universal definition of myocardial infarction, patients whose hs-cTnT were increased five times above the upper reference limit (URL) after percutaneous coronary interventions (PCI) were deemed to PMI. The patients were subdivided into PMI (n=53) and non-PMI (n=87) groups. In the univariable analysis, variables in the baselines, angiography characteristics and OCT findings were analyzed with binary logistic regression. A P value of <0.2 was included in the multivariable model. Multivariable logistic regression analysis was used to identify the independent predictors of PMI. Results: The prevalence of intra-intimal microvessels in patients with PMI was higher than in those without PMI (58.5% vs. 32.2%, P=0.003). The ratio of intra-stent plaque rupture (PR) was also higher in patients with PMI (60.4% vs. 40.2%, P=0.021). Multivariable logistic regression analysis showed that intra-intimal microvessels [odds ratio (OR): 3.193, 95% confidence interval (CI): 1.280-7.966; P=0.013] and intra-stent PR (OR: 2.124, 95% CI: 1.153-4.732; P=0.035) were independently associated with PMI. Conclusions: Intra-intimal microvessels and intra-stent PR were independently associated with PMI. Accurate identification and recognition of intra-intimal microvessels and intra-stent PR may be helpful in preventing PMI.

[Effects of CGRP and CGRP receptor modified mesenchymal stem cells on proliferation and phenotypic transformation of vascular smooth muscle cells].

OBJECTIVE: To explore the effects and mechanism of secretory calcitonin gene-related peptide (CGRP) and CGRP receptor modified mesenchymal stem cells on proliferation and phenotypic transformation of vascular smooth muscle cell. METHODS: Firstly (Lenti-GFP-CGRP, referred to CGRP (+/+)) MSCs were transfected with high expression lentivirus vector of CGRP (MSCs(CGRP+/+)). Protein secretion in the above-mentioned MSCs(CGRP+/+) supernatant was detected with enzyme-linked immunosorbent assay (ELISA). And then MSCs(CGRP+/+) was co-cultured with VSMCs(RAMP1)(+/+) and VSMCs(RAMP1-/-) respectively. Experimental groups were as follows: MSCs +VSMCs MSCs(CGRP+/+) +VSMCs, MSCs(CGRP+/+) +VSMCs(RAMP1)(+/+) and MSCs(CGRP+/+) + VSMCs (RAMP1-/-). Flow cytometry was applied to detect the cycle variation of smooth muscle cells, thiazolyl blue tetrazolium bromide method for detecting the proliferation of smooth muscle cells and Western blot for examining the expression changes of spectrin α-SM-actin and synthetic protein OPN in each group respectively. RESULTS: After the transfection of CGRP(+/+), MSCs(CGRP+/+) secreted and expressed CGRP protein, the secretory volume of CGRP protein in MSCs(CGRP+/+) increased significantly compared with the control group (19.530 ± 0.498 vs 3.133 ± 0.160 and 3.120 ± 0.001, P < 0.05) . After a 72 h co-culturing with VSMCs, the proliferation of VSMCs in MSCs(CGRP+/+) +VSMCs(RAMP1)(+/+)group declined significantly (0.270 ± 0.263 vs 0.413 ± 0.070, P < 0.05) and the number of cells staying in G0 phase significantly increased (93.51% ± 0.38% vs 84.48% ± 0.31%, P < 0.05) , the expression of contractile phenotype protein α-SM-actin increased and intermediate phenotype OPN declined significantly as compared with MSCsCGRP(+/+) +VSMCs group { (α-SM-actin 102 946 ± 3847 vs 51 759 ± 635, P < 0.05), OPN (26 026 ± 2595 vs 44 201 ± 2811, P < 0.05) }; but compared with MSCs(CGRP+/+)+VSMCs(RAMP1)(+/+)group, the proliferation of VSMCs in MSCs(CGRP+/+) +VSMCs(RAMP1)-/-group significantly increased (0.601 ± 0.04 vs 0.270 ± 0.263, P < 0.05) while the number of cells staying in G0 phase significantly declined (78.57% ± 0.68% vs 93.51% ± 0.38%, P < 0.05) . The expression of contractile phenotype protein α-SM-actin declined while intermediate phenotype OPN increased significantly in MSCs(CGRP+/+)+VSMCs(RAMP1)-/-group {α-SM-actin (34 400 ± 2179 vs 102 946 ± 3847, P < 0.05), OPN (53 933 ± 1192 vs 26 026 ± 2595, P < 0.05)}. CONCLUSIONS: CGRP gene-modified MSCs may secrete target protein stably. And CGRP-modified MSCs inhibits VSMCs phenotypic transformation and cell proliferation. It is probably associated with enhanced CGRP effect due to an up-regulation of CGRP receptor.

Hypoxia Induces M2 Macrophages to Express VSIG4 and Mediate Cardiac Fibrosis After Myocardial Infarction.

M2 macrophage-mediated tissue repair plays an important role in acute myocardial infarction (AMI). Additionally, VSIG4, which is mainly expressed on tissue-resident and M2 macrophages, is crucial for the regulation of immune homeostasis; however, its effects on AMI remain unknown. In this study, we aimed to investigate the functional significance of VSIG4 in AMI using VSIG4 knockout and adoptive bone marrow transfer chimeric models. We also determined the function of cardiac fibroblasts (CFs) through gain- or loss-of-function experiments. We showed that VSIG4 promotes scar formation and orchestrates the myocardial inflammatory response after AMI, while also promoting TGF-ß1 and IL-10. Moreover, we revealed that hypoxia promotes VSIG4 expression in cultured bone marrow M2 macrophages, ultimately leading to the conversion of CFs to myofibroblasts. Our results reveal a crucial role for VSIG4 in the process of AMI in mice and provide a potential immunomodulatory therapeutic avenue for fibrosis repair after AMI.

ANNEXIN A2 FACILITATES NEOVASCULARIZATION TO PROTECT AGAINST MYOCARDIAL INFARCTION INJURY VIA INTERACTING WITH MACROPHAGE YAP AND ENDOTHELIAL INTEGRIN Β3.

ABSTRACT: Cardiac macrophages with different polarization phenotypes regulate ventricular remodeling and neovascularization after myocardial infarction (MI). Annexin A2 (ANXA2) promotes macrophage polarization to the repair phenotype and regulates neovascularization. However, whether ANXA2 plays any role in post-MI remodeling and its underlying mechanism remains obscure. In this study, we observed that expression levels of ANXA2 were dynamically altered in mouse hearts upon MI and peaked on the second day post-MI. Using adeno-associated virus vector-mediated overexpression or silencing of ANXA2 in the heart, we also found that elevation of ANXA2 in the infarcted myocardium significantly improved cardiac function, reduced cardiac fibrosis, and promoted peri-infarct angiogenesis, compared with controls. By contrast, reduction of cardiac ANXA2 exhibited opposite effects. Furthermore, using in vitro coculture system, we found that ANXA2-engineered macrophages promoted cardiac microvascular endothelial cell (CMEC) proliferation, migration, and neovascularization. Mechanistically, we identified that ANXA2 interacted with yes-associated protein (YAP) in macrophages and skewed them toward pro-angiogenic phenotype by inhibiting YAP activity. In addition, ANXA2 directly interacted with integrin ß3 in CMECs and enhanced their growth, migration, and tubule formation. Our results indicate that increased expression of ANXA2 could confer protection against MI-induced injury by promoting neovascularization in the infarcted area, partly through the inhibition of YAP in macrophages and activation of integrin ß3 in endothelial cells. Our study provides new therapeutic strategies for the treatment of MI injury.

Hypoxia-induced signaling in the cardiovascular system: pathogenesis and therapeutic targets.

Hypoxia, characterized by reduced oxygen concentration, is a significant stressor that affects the survival of aerobic species and plays a prominent role in cardiovascular diseases. From the research history and milestone events related to hypoxia in cardiovascular development and diseases, The "hypoxia-inducible factors (HIFs) switch" can be observed from both temporal and spatial perspectives, encompassing the occurrence and progression of hypoxia (gradual decline in oxygen concentration), the acute and chronic manifestations of hypoxia, and the geographical characteristics of hypoxia (natural selection at high altitudes). Furthermore, hypoxia signaling pathways are associated with natural rhythms, such as diurnal and hibernation processes. In addition to innate factors and natural selection, it has been found that epigenetics, as a postnatal factor, profoundly influences the hypoxic response and progression within the cardiovascular system. Within this intricate process, interactions between different tissues and organs within the cardiovascular system and other systems in the context of hypoxia signaling pathways have been established. Thus, it is the time to summarize and to construct a multi-level regulatory framework of hypoxia signaling and mechanisms in cardiovascular diseases for developing more therapeutic targets and make reasonable advancements in clinical research, including FDA-approved drugs and ongoing clinical trials, to guide future clinical practice in the field of hypoxia signaling in cardiovascular diseases.

Association of LDL-C level with neoatherosclerosis and plaque vulnerability in patients with late restenosis: an optical coherence tomography study.

Neoatherosclerosis (NA) is a significant contributor to late stent failure; however, predictors of late in-stent restenosis (ISR) with NA have not been systematically reported. This study aimed to identify predictors of NA incidence and plaque vulnerability in patients with late ISR and the role of low-density lipoprotein cholesterol (LDL-C) levels in this process. A total of 216 patients with 216 lesions who underwent optical coherence tomography (OCT) before interventional procedure for late drug-eluting stent ISR were enrolled and divided into NA and non-NA groups based on OCT findings. Results showed that higher LDL-C levels were associated with NA, thin-cap fibroatheroma (TCFA), intimal disruption, plaque erosion, and thrombosis. Multivariate regression analysis revealed that the LDL-C level was an independent risk factor for NA and TCFA. The LDL-C levels exhibited a significant predictive value for NA and TCFA, surpassing other factors such as stent age and other lipid types. In conclusion, a high LDL-C level is an independent predictor of NA incidence and plaque vulnerability in patients with late ISR.

[Effects of hRAMP1 modified mesenchymal stem cells on restenosis and heart function in rabbit model of carotid angioplasty and myocardial infarction].

OBJECTIVE: To observe the effects of mesenchymal stem cells (MSC) modified by human receptor activity-modifying protein 1 (hRAMP1) on restenosis and cardiac function post-myocardial infarction (MI) and explore the therapeutic safety for gene modification of MSC. METHODS: The double-injury rabbit model with MI reperfusion and sacculus damaged atherosclerotic carotid were established according to the previous study. MSC were transfected with adenovirus vector with enhanced green fluorescence protein (EGFP) and then introduced into rabbit model. The animals were randomly divided into Ad-EGFP-hRAMP1-MSC transfection group (hRAMP1-MSC group, n = 24) and Ad-EGFP-MSC transfection group (MSC group, n = 24), and PBS transfection group (C group, n = 24). At Day 28 post-transplantation, the injured carotid arteries and infarction myocardium were harvested to detect the expression of EGFP-positive MSC and assess organization morphology by hematoxylin and eosin, triphenyltetrazolium chloride or immunohistochemical stains and heart function by echocardiography. RESULTS: On flow cytometry, most cells expressed CD29 and CD90 while few ones expressed CD45. MSC with EGFP and a continuous expression of CD31 were found in intima of damaged carotid of both hRAMP1-MSC and MSC, but the expression of EGFP was not found in the control group. At Day 28 post-transplantation, the improvement of heart function and the decrease of infarct size were found in the hRAMP1-MSC and MSC groups compared with that in the control group(EF: 60.6% ± 1.5%,50.8% ± 3.2% vs 38.2% ± 2.0%, infarct size: 20.7% ± 1.4%, 33.2% ± 3.7% vs 35.6% ± 2.7%, all P < 0.05), especially much higher in hRAMP1-MSC group. At Day 28 post-transplantation, the area of intima hyperplasia and the rate of neointima and media in the hRAMP1-MSC group were lower than those in the MSC and C groups (0.15 ± 0.05 and 0.33 ± 0.08 vs 0.77 ± 0.11, 0.24 ± 0.07 and 0.51 ± 0.11 vs 1.09 ± 0.23, all P < 0.05). Also the expression of α-SMA was found in the hyperplasia intima. The expression of proliferating cell nuclear antigen significantly decreased in the hRAMP1-MSC group than those of the MSC and control groups (0.120 ± 0.028 vs 0.366 ± 0.013 and 0.627 ± 0.049, both P < 0.05). And it was much lower in the MSC group than that in the control group. CONCLUSIONS: Compared with MSC alone, hRAMP1-modified MSC have the potency not only of more improvement on cardiac function and the recovery of damaged endothelium, but also of significant inhibition of the proliferation of vascular smooth muscle cells. The recombinant hRAMP1 adenovirus vectors do not affect the differentiation potential MSC into endothelial cells.

[Effect of gene modified mesenchymal stem cells overexpression human receptor activity modified protein 1 on inflammation and cardiac repair in a rabbit model of myocardial infarction].

OBJECTIVE: To investigate the effect of mesenchymal stem cells (MSCs) overexpressing human receptor activity modified protein 1 (hRAMP1) by adenovirus vector on infarction related inflammation and cardiac repair in a rabbit model of myocardial infarction (MI). METHODS: Thirty rabbits underwent coronary artery ligation for 60 minutes followed by 24 hours reperfusion and divided into MSC(hRAMP1) group (intravenously injection of MSCs transfected with adenovirus vector encoding hRAMP1 gene enhanced green fluorescent protein, EGFP, n = 10), MSC(null) group (MSCs transfected with adenovirus vector encoding only EGFP without hRAMP1 gene, n = 10) and control group (equally volume of phosphate buffered saline, PBS, n = 10). The plasma level of tumor necrosis factor-α (TNF-α) and interleukin-10 (IL-10) were quantified by ELISA assay at before and 1, 3, 7, 28 days after induction of MI. The expression of nuclear factor-κB (NF-κB) and hRAMP1 in infracted myocardium were measured by Western blot at 1, 3, 7, 28 day following MI. The area of MI and collagen deposition and fibrosis were evaluated by TTC staining and Masson staining, respectively. RESULTS: Area of MI and collagen content were significantly reduced in MSC(hRAMP1) group compared those in MSC(null) and control group [(10.1 ± 2.9)% vs. (30.6 ± 2.7)% and (22.5 ± 3.2)%, P < 0.05]. Myocardial expression of NF-κB and plasma TNF-α[7 days after transplantation: (97.2 ± 6.7) pg/ml vs. (207.6 ± 12.7) pg/ml and (153.2 ± 9.9) pg/ml, P < 0.05] were also lower while plasma level of IL-10 [7 days after transplantation: (238.5 ± 17.5) pg/ml vs. (177.3 ± 19.8) pg/ml and (244.6 ± 27.3) pg/ml, P < 0.05] was significantly higher in MSC(hRAMP1) group than in MSC(null) and control group. CONCLUSION: MSCs overexpression hRAMP1 could further reduce area of MI possibly through inhibiting the myocardial expression of NF-κB and reducing the plasma TNF-α level and raising plasma IL-10 level.

CircERBB2IP promotes post-infarction revascularization via the miR-145a-5p/Smad5 axis.

Myocardial infarction is one of the leading diseases causing death and disability worldwide, and the revascularization of damaged tissues is essential for myocardial-injury repair. Circular RNAs (circRNAs) are widely involved in physiological and pathological processes in various systems throughout the body, and the role of circRNAs in cardiovascular disease is gaining attention. In this study, we determined that circERBB2IP is highly expressed in the hearts of newborn mice. Silencing or overexpression of circERBB2IP inhibited and promoted angiogenesis in vivo and in vitro, respectively. Mechanistically, the transcription factor GATA4 promotes the production of circERBB2IP. Furthermore, circERBB2IP functioned as an endogenous miR-145a-5p sponge and was able to sequester and repress miR-145a-5p activity, which led to an increased expression level of Smad5. In summary, circERBB2IP can promote angiogenesis after myocardial infarction through the miR-145a-5p/Smad5 axis. These data suggest that circERBB2IP may be a potential therapeutic target for the treatment of myocardial infarction.

Exosomal MiR-29a in Cardiomyocytes Induced by Angiotensin II Regulates Cardiac Microvascular Endothelial Cell Proliferation, Migration and Angiogenesis by Targeting VEGFA.

BACKGROUND: Exosomes released from cardiomyocytes (CMs) potentially play an important role in angiogenesis through microRNA (miR) delivery. Studies have reported an important role for miR-29a in regulating angiogenesis and pathological myocardial hypertrophy. However, whether CMderived exosomal miR-29a is involved in regulating cardiac microvascular endothelial cell (CMEC) homeostasis during myocardial hypertrophy has not been determined. METHODS: Angiotensin II (Ang II) was used to induce CM hypertrophy, and ultracentrifugation was then used to extract exosomes from a CM-conditioned medium. CMECs were cocultured with a conditioned medium in the presence or absence of exosomes derived from CMs (Nor-exos) or exosomes derived from angiotensin II-induced CMs (Ang II-exos). Moreover, a rescue experiment was performed using CMs or CMECs infected with miR-29a mimics or inhibitors. Tube formation assays, Transwell assays, and 5-ethynyl-20-deoxyuridine (EdU) assays were then performed to determine the changes in CMECs treated with exosomes. The miR-29a expression was measured by qRT-PCR, and Western blotting and flow cytometry assays were performed to evaluate the proliferation of CMECs. RESULTS: The results showed that Ang II-induced exosomal miR-29a inhibited the angiogenic ability, migratory function, and proliferation of CMECs. Subsequently, the downstream target gene of miR- 29a, namely, vascular endothelial growth factor (VEGFA), was detected by qRT-PCR and Western blotting, and the results verified that miR-29a targeted the inhibition of the VEGFA expression to subsequently inhibit the angiogenic ability of CMECs. CONCLUSION: Our results suggest that exosomes derived from Ang II-induced CMs are involved in regulating CMCE proliferation, migration, and angiogenesis by targeting VEGFA through the transfer of miR-29a to CMECs.

Role of Mydgf in the regulation of hypoxia/reoxygenation-induced apoptosis in cardiac microvascular endothelial cells.

We aimed to explore the effects of myeloid-derived growth factor (Mydgf) on the regulation of hypoxia/reoxygenation (HR)-induced apoptosis of cardiac microvascular endothelial cells (CMECs). CMECs were exposed to hypoxia for 24 h and reoxygenation for 6 h to establish an HR cell model. Subsequently, an adenovirus was used to overexpress Mydgf in CMECs. Flow cytometry and TUNEL staining were used to detect the extent of apoptosis, whereas qPCR was used to detect the relative expression of Mydgf mRNA. Western blotting was also performed to detect the expression of apoptosis-related proteins and endoplasmic reticulum stress (ERS)-related proteins, including C/EBP Homologous Protein (CHOP), glucose-regulated protein 78 (GRP 78), and cleaved Caspase-12. The endoplasmic reticulum stress agonist tunicamycin (TM) was used to stimulate CMECs for 24 h as a rescue experiment for Mydgf. Flow cytometry revealed that the HR model effectively induced endothelial cell apoptosis, whereas qPCR and western blotting showed that Mydgf mRNA and protein levels decreased significantly after HR treatment (P < 0.05). Overexpression of Mydgf in cells effectively reduced apoptosis after HR. Furthermore, western blotting showed that HR induced a significant upregulation of CHOP, GRP78, and cleaved-Caspase-12 expression in CMECs, whereas HR-treated cells downregulated the expression of CHOP, GRP78, and cleaved-Caspase-12 after Mydgf overexpression. Under HR conditions, TM significantly reversed the protective effect of Mydgf on CMECs. Mydgf may reduce CMEC apoptosis induced by HR by regulating oxidative stress in ERS.

Methyltransferase like 3-mediated N6-methylatidin methylation inhibits vascular smooth muscle cells phenotype switching via promoting phosphatidylinositol 3-kinase mRNA decay.

N6-methylatidine (m6A) is involved in post-transcriptional metabolism and a variety of pathological processes. However, little is known about the role of m6A in vascular proliferative diseases, particularly in vascular smooth muscle cells (VSMCs) phenotype switching-induced neointimal hyperplasia. In the current study, we discovered that methyltransferase like 3 (METTL3) is a critical candidate for catalyzing a global increase in m6A in response to carotid artery injury and various VSMCs phenotype switching. The inhibited neointimal hyperplasia was obtained after in vivo gene transfer to knock-down Mettl3. In vitro overexpression of Mettl3 resulted in increased VSMC proliferation, migration, and reduced contractile gene expression with a global elevation of m6A modification. In contrast, Mettl3 knockdown reversed this facilitated phenotypic switch in VSMCs, as demonstrated by downregulated m6A, decreased proliferation, migration, and increased expression of contractile genes. Mechanistically, Mettl3 knock-down was found to promote higher phosphatidylinositol 3-kinase (Pi3k) mRNA decay thus inactivating the PI3K/AKT signal to inhibit VSMCs phenotype switching. Overall, our findings highlight the importance of METTL3-mediated m6A in VSMCs phenotype switching and offer a novel perspective on targeting METTL3 as a therapeutic option for VSMCs phenotype switching modulated pathogenesis, including atherosclerosis and restenosis.

[Effect of mesenchymal stem cells on cardiac function and restenosis of injured artery after myocardial infarction].

OBJECTIVE: Although earlier studies have shown that the transplantation of mesenchymal stem cells (MSCs) might improve cardiac functions after myocardial infraction, its role on vascular restenosis after percutaneous coronary intervention (PCI) remains controversial. The aim of this study was to investigate the effects of MSCs on the restenosis of injured artery following balloon angioplasty in a rabbit model with both myocardial infarction reperfusion and atherosclerotic stenosis carotid artery by balloon injury. METHODS: After the animal model was established for myocardial infraction reperfusion and atherosclerotic stenosis carotid artery by balloon injury, the rabbits received an intravenous transplantation of MSCs. And an equal volume of phosphate buffered solution was administered for the control group. The animal vascular tissue and myocardium tissue were excised at different time points post-transplantation and used to detect the homing of MSCs and the expressions of platelet-endothelial cell adhesion molecule-1 (CD31) and proliferating cell nuclear antigen (PCNA) by immunohistochemical staining. Four weeks later, vascular restenosis was analyzed by angiography of bilateral carotid arteries and the vascular tissues were used for histological studies. RESULTS: At one week post-transplantation, the 4',6-diamidino-2-phenylindole (DAPI)-labeled MSCs could be detected in myocardial infarction and injured intima. And the intimal expression of CD31 was observed at 2 weeks in the MSCs transplantation group. Yet the expression of PCNA was significantly lower in the MSCs transplantation group than that in the control group (50.5% ± 3.6% vs 23.4% ± 2.8%, P < 0.05). At 4 week post-transplantation, the neointimal area of injured vessels and the vascular restenosis were significantly lower in the MSCs transplantation group than those in the control group (0.092 ± 0.009 vs 0.189 ± 0.007, P < 0.05; 41.7 ± 3.7 vs 61.3 ± 1.6, P < 0.05). Furthermore the MSCs transplantation group demonstrated improved cardiac functions, reduced myocardial infarct size (21.7% ± 2.2% vs 34.3% ± 1.8%, P < 0.05) and significantly increased capillary density around infarction foci (33.6% ± 2.1% vs 20.8% ± 2.6%, P < 0.05) versus the control group. CONCLUSION: The transplantation of MSCs plays significant roles in cardiac repairing in terms of improved cardiac functions, accelerated repair of injured vessels, suppression of neointimal hyperplasia and reduced restenosis of injured vessels.