Aims: To investigate the effect of survivin (SVV)-engineered mesenchymal stem cells (MSCs) on post-infarction cardiac performance and remodelling in rats. Methods and results: Mesenchymal stem cells from male Sprague–Dawley rat bone marrow were infected with the self-inactive lentiviral vector GFP-wre-CMV/LTR and Flap-Ubiqutin promoter (GCFU) carrying green fluorescent protein (GFP) gene and SVV recombinant vector (GCFU-SVV). In vitro, modification with SVV increased the secretion of vascular endothelial growth factor (VEGF) by 1.28-fold under hypoxic conditions. In vivo, after permanent left anterior descending artery occlusion, rats were randomized (n = 18 per group) to receive intra-myocardial injections of 100 µL of phosphate-buffered saline without cells (group vehicle) or containing 2 million MSCGFP (group MSCGFP) or MSCSVV (group MSCSVV) cells. Cellular survival assessed by reverse transcriptase–polymerase chain reaction for GFP in the MSCSVV group was 2.5-fold higher at 7 days and 4.3-fold higher at 28 days after transplantation than in the MSCGFP group. When compared with transplantation with MSCGFP, transplantation with MSCSVV further upregulated VEGF expression at 7 and 28 days after myocardial infarction (MI), increased capillary density by 38%, reduced the infarct size by 12.7%, significantly inhibited collagen deposition, and further improved cardiac function at 28 days after MI. Conclusion: Transplantation with SVV-engineered MSCs by lentiviral vector leads to better prognosis for MI by enhancing cellular survival.

Vascular smooth muscle cell (VSMC) phenotype switching is a pathological hallmark in various cardiovascular diseases. N4-acetylcytidine (ac4C) catalyzed by N-acetyltransferase 10 (NAT10) is well conserved in the enzymatic modification of ribonucleic acid (RNA). NAT10-mediated ac4C acetylation is involved in various physiological and pathological processes, including cardiac remodelling. However, the biological functions and underlying regulatory mechanisms of mRNA ac4C modifications in vascular diseases remain elusive. By combining in-vitro and in-vivo vascular injury models, NAT10 was identified as a crucial protein involved in the promotion of post-injury neointima formation, as well as VSMC phenotype switching. The potential mechanisms of NAT10 in the vascular neointima formation were clarified by RNA sequence (RNA-seq), acetylated mRNA immunoprecipitation sequence (acRIP-seq), and RNA binding protein immunoprecipitation sequence (RIP-seq). NAT10 and ac4C modifications were upregulated in injured human and rodent arteries. Deletion of NAT10 in VSMCs effectively reduced post-injury neointima formation and VSMC phenotype switching. Further RNA-seq, RIP-seq, and acRIP-seq revealed that NAT10, by its ac4C modification, directly interacts with genes, including integrin-β1 (ITGB1) and collagen type I alpha 2 chain (Col1a2) mRNAs. Taking ITGB1 as one example, it showed that NAT10-mediated ac4C consequently increased ITGB1 mRNA stability and its downstream focal adhesion kinase (FAK) signaling, directly influencing the proliferation of VSMCs and vascular remodelling. The regulation of NAT10 on the VSMC phenotype is of translational significance because the administration of Remodelin, a NAT10 inhibitor, effectively prevents neointima formation by suppressing VSMC proliferation and downregulating ITGB1 expression and deactivating its FAK signaling. This study reveals that NAT10 promotes vascular remodelling via mRNA ac4C acetylation, which may be a promising therapeutic target against vascular remodelling. N-acetyltransferase 10 (NAT10)-mediated N4-acetylcytidine (ac4C) mRNA acetylation regulates vascular smooth muscle cell (VSMC) phenotype switching and vascular remodelling. Stress, such as injury, upregulates NAT10, which directly interacts with downstream target genes, including integrin-β1 (ITGB1) mRNA. NAT10-mediated ac4C mRNA acetylation subsequently increases ITGB1 mRNA stability and downstream focal adhesion kinase (FAK) signaling, thereby inducing the phenotype switching of VSMCs, leading to vascular remodelling. Remodelin is a NAT10 acetyltransferase inhibitor. AKT, serine–threonine protein kinase; Col1a2, collagen type I alpha 2 chain; ERK, extracellular signal-regulated kinase; FAK, focal adhesion kinase; PDGF, platelet-derived growth factor; SRC, steroid receptor coactivator.

Objectives CD4⁺CD25⁺ regulatory T cells (Tregs) play a key role in the prevention of various inflammatory and autoimmune disorders by suppressing immune responses. The beneficial effect of statins on myocardial ischemia-reperfusion injury (IRI) depends in part on their immunomodulatory and anti-inflammatory mechanisms. We aimed to determine whether Tregs contribute to statin-induced cardioprotection against myocardial IRI. Methods Thirty-two rats were divided into four groups: sham, ischemia-reperfusion (IR), rosuvastatin (RSV)/IR, and mevalonic acid (MVA)+RSV/IR. Myocardial IR was induced by a 30-min coronary occlusion, followed by a 48-h reperfusion. RSV (5 mg/kg) was administered intravenously 18 h before IR. The rats were killed after 48-h reperfusion. Serum cardiac troponin I (cTnI) was measured by ELISA, infiltration of inflammatory cells in myocardium by hematoxylin and eosin staining, expression of FoxP3 protein by western blotting, accumulation of Tregs in myocardium by immunohistochemical examination, and infarct size by TTC staining. Results Significant elevation in serum cTnI, enlarged infarct size, and marked infiltration of inflammatory cells in myocardium were observed in the IR group. The administration of RSV significantly reduced the serum cTnI level, attenuated the accumulation of inflammatory cells, decreased infarct size, and increased the FoxP3 expression and Treg accumulation in myocardium compared with the IR group. The combination of RSV and MVA pretreatment partially abolished the anti-inflammatory and infarct size-limiting effects and completely reversed Treg accumulation in myocardium induced by RSV. The accumulation of inflammatory cells was negatively correlated with FoxP3 expression and Treg accumulation in the ischemic myocardium. Conclusion RSV pretreatment was associated with more Treg accumulation, less inflammatory response, and myocardial injury, suggesting that such cardioprotection against IRI was partially mediated by Treg-negative modulation of inflammation response, probably through the HMG-CoA reductase pathway.

Myocardial ischemia-reperfusion injury (MIRI) is a highly complex disease with high morbidity and mortality. Studying the molecular mechanism of MIRI and discovering new targets are crucial for the future treatment of MIRI. We constructed the MIRI rat model and hypoxia/reoxygenation (H/R) injury cardiomyocytes model. RT-PCR and Western blot were used to investigate the expression of the fat mass and obesity-associated (FTO) gene. Electrocardiogram, echocardiography, triphenyltetrazolium chloride (TTC) staining and hematoxylin-eosin (HE) staining were used to assess the model and the effect of FTO overexpression. The generation of reactive oxygen species (ROS) and the levels of superoxide dismutase (SOD2), mitochondrial transcription factor (TFAM) and cytochrome c oxidase I (COXI) were detected to assess the oxidative stress and mitochondrial biogenesis. RNA immunoprecipitation (RIP) and RNA pulldown assays were used to identify the interaction of FTO and PGC-1a. The m6A dot blot, methylated RNA immunoprecipitation PCR (MeRIP-PCR) and RNA stability analysis were used to analyze the regulation of methylation of PGC-1a by FTO. FTO was downregulated in MIRI rats and H/R induced cardiomyocytes. Overexpression of FTO inhibited ROS level and increased the expression of SOD2, TFAM and COXI in vitro and in vivo. In addition, PGC-1a was identified as a downstream target of FTO. FTO enhanced the stability of PGC-1a mRNA through removing the m6A modification. Our study revealed the role of FTO regulates the oxidative stress and mitochondrial biogenesis via PGC-1a in MIRI, which may provide a new approach to mitigating MIRI.