There has been extensive interest in using cell-based therapy to treat patients with myocardial infarction and ischemic heart failure^1,2 via hypothetical mechanisms involving the generation of new myocardial tissue^3,4 or to release molecules⁵ and exosomes⁶ that harness endogenous repair mechanisms.⁷ Cells can be delivered by intramyocardial, intracoronary, and retrograde coronary venous injection to cardiac tissue. However, the cell delivery techniques used thus far have all been fraught with poor efficiency⁸ and have led to poor engraftment, retention, and survival of transplanted cells in heart tissue.⁹

Background: Human-induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) have shed great light on cardiac regenerative medicine and specifically myocardial repair in heart failure patients. However, the treatment efficacy and the survival of iPSC-CMs in vivo after transplantation have yielded inconsistent results. Objectives: The objective of this study was to evaluate the ability of human iPSC-CMs to improve myocardial function in a rat postinfarction heart failure model. Methods: Eight-week-old male Sprague-Dawley rats were randomly selected to receive an intramyocardial injection of 5% albumin solution with or without 1 × 10⁷ human iPSC-CMs 10 days after undergoing left anterior descending (LAD) coronary artery ligation. Cyclosporine A and methylprednisolone were administered before iPSC-CM injection and until the rats were killed to prevent graft rejection. Cardiac function was evaluated by echocardiography. The survival of grafted cardiomyocytes was confirmed by observing the fluorescent cell tracer Vybrant™ CM-DiI or expression of the enhanced green fluorescent protein (eGFP) in transplanted cells, or survival was demonstrated by polymerase chain reaction (PCR)-based detection of human mitochondrial DNA. Sirius red stain was used to evaluate the fibrosis ratio. Hematoxylin-eosin staining was used to observe the formation of teratomas. Results: Four weeks after intramyocardial injection of iPSC-CMs, animals undergoing iPSC-CM transplantation had lower mortality than the control group. Animals injected with cell-free solution (control group) demonstrated significant left ventricular (LV) functional deterioration, whereas grafting of iPSC-CMs attenuated this remodeling process. In the control group, the ejection fraction deteriorated by 10.11% (from 46.36 to 41.67%), and fractional shortening deteriorated by 9.23% (from 24.37 to 22.12%) by 4 weeks. In the iPSC-CM injection group, the ejection fraction improved by 18.86% (from 44.09 to 52.41%), and fractional shortening improved by 23.69% (from 23.08 to 28.54%). Cell labeling, tracking, and molecular biology techniques indicated that the grafted cardiomyocytes survived in the rat heart 1 month after iPSC-CM transplantation. Myocardial fibrosis was also attenuated in the iPSC-CM treatment group. Conclusions: Human iPSC-CM grafts survived in infarcted rat hearts and restored myocardial function 4 weeks after transplantation. Cell replacement therapy also reversed ventricular remodeling, indicating the potential of iPSC-CMs for cardiac repair strategies.

BACKGROUND: S-Nitrosylation (SNO), a prototypic redox-based posttranslational modification, is involved in cardiovascular disease. Aortic aneurysm and dissection are high-risk cardiovascular diseases without an effective cure. The aim of this study was to determine the role of SNO of Septin2 in macrophages in aortic aneurysm and dissection. METHODS: Biotin-switch assay combined with liquid chromatography–tandem mass spectrometry was performed to identify the S-nitrosylated proteins in aortic tissue from both patients undergoing surgery for aortic dissection and Apoe ^−/− mice infused with angiotensin II. Angiotensin II–induced aortic aneurysm model and β-aminopropionitrile–induced aortic aneurysm and dissection model were used to determine the role of SNO of Septin2 (SNO-Septin2) in aortic aneurysm and dissection development. RNA-sequencing analysis was performed to recapitulate possible changes in the transcriptome profile of SNO-Septin2 in macrophages in aortic aneurysm and dissection. Liquid chromatography–tandem mass spectrometry and coimmunoprecipitation were used to uncover the TIAM1-RAC1 (Ras-related C3 botulinum toxin substrate 1) axis as the downstream target of SNO-Septin2. Both R-Ketorolac and NSC23766 treatments were used to inhibit the TIAM1-RAC1 axis. RESULTS: Septin2 was identified S-nitrosylated at cysteine 111 (Cys111) in both aortic tissue from patients undergoing surgery for aortic dissection and Apoe ^−/− mice infused with Angiotensin II. SNO-Septin2 was demonstrated driving the development of aortic aneurysm and dissection. By RNA-sequencing, SNO-Septin2 in macrophages was demonstrated to exacerbate vascular inflammation and extracellular matrix degradation in aortic aneurysm. Next, TIAM1 (T lymphoma invasion and metastasis-inducing protein 1) was identified as a SNO-Septin2 target protein. Mechanistically, compared with unmodified Septin2, SNO-Septin2 reduced its interaction with TIAM1 and activated the TIAM1-RAC1 axis and consequent nuclear factor-κB signaling pathway, resulting in stronger inflammation and extracellular matrix degradation mediated by macrophages. Consistently, both R-Ketorolac and NSC23766 treatments protected against aortic aneurysm and dissection by inhibiting the TIAM1-RAC1 axis. CONCLUSIONS: SNO-Septin2 drives aortic aneurysm and dissection through coupling the TIAM1-RAC1 axis in macrophages and activating the nuclear factor-κB signaling pathway–dependent inflammation and extracellular matrix degradation. Pharmacological blockade of RAC1 by R-Ketorolac or NSC23766 may therefore represent a potential treatment against aortic aneurysm and dissection.

Idiopathic pulmonary fibrosis (IPF) was considered as a telomere-mediated disease. TERT and TERC correlated with telomere length. Although telomerase gene mutations were associated with IPF, majority patients did not carry mutations. The mechanism by which telomerase expression was regulated in IPF are still unclear. In this study, we aimed to delineate the mechanisms that how TERT protein expression were regulated in alveolar epithelial cells (AECs) in pulmonary fibrosis. Here, we found that P16, P21 and fibrosis markers (αSMA and Collagen-I) were prominently increased in lung tissues of IPF patients and bleomycin-induced mouse models, while the expression of KLF4 and TERT were decreased in AECs. In vivo experiments, AAV-6 vectors mediated KLF4 over-expression with specific SP-C promoter was constructed. Over-expression of KLF4 in AECs could protect TERT expression and suppress the development of pulmonary fibrosis in bleomycin-induced mouse models. In the mechanism exploration of TERT regulation, KLF4 and TERT were both down-regulated in bleomycin-induced senescent MLE-12 and BEAS-2B cells. Compared with control group, small-interfering RNA targeting KLF4 significantly reduced the TERT expression and telomerase activity, while overexpression of KLF4 can increased the expression of TERT and telomerase activity in senescent AECs. Furthermore, ChIP showed that KLF4 protein could bind to the TERT promoter region in MLE-12 cells, suggesting that KLF4 could implicate in pathogenesis of lung fibrosis through regulating TERT transcription in AECs. Taken together, this study identified that KLF4 might be a promising potential target for further understanding the mechanism and developing novel strategy for the treatment of lung fibrosis in IPF.

Ischemia/reperfusion (I/R) injury is an inevitable process during heart transplant and suppressing I/R injury could greatly improve the survival rate of recipients. Mesenchymal stem cells (MSCs) have positive effects on I/R. We aimed to investigate the mechanisms underlying the protective roles of MSCs in I/R. Both cell model and rat model of myocardial I/R were used. MTT assay and flow cytometry were used to measure cell viability and apoptosis, respectively. QRT-PCR and western blotting were employed to measure levels of lncRNA HCP5 (HLA complex P5), miR-497, apoptosis-related proteins, and insulin-like growth factor (IGF1)/PI3K/AKT pathway. Dual luciferase assay was used to validate interactions of HCP5 and miR-497, miR-497 and IGF1. Echocardiography was performed to evaluate cardiac function of rats. Serum levels of CK-MB and LDH were measured. H&E and Masson staining were used to examine morphology of myocardial tissues. hBMSC-derived exosomes (hBMSC-Exos) increased the viability of cardiomyocytes following hypoxia/reperfusion (H/R) and decreased apoptosis. H/R diminished HCP5 expression in cardiomyocytes while hBMSC-Exos recovered the level. Overexpression of HCP5 in hBMSC-Exos further enhanced the protective effects in H/R while HCP5 knockdown suppressed. HCP5 directly bound miR-497 and miR-497 targeted IGF1. miR-497 mimics or si-IGF1 blocked the effects of HCP5 overexpression. Further, hBMSC-Exos alleviated I/R injury in vivo and knockdown of HCP5 in hBMSC-Exos decreased the beneficial effects. AntagomiR-497 blocked the effects of HCP5 knockdown. HCP5 from hBMSC-Exos protects cardiomyocytes against I/R injury via sponging miR-497 to disinhibit IGF1/PI3K/AKT pathway. These results shed light on mechanisms underlying the protective role of hBMSC-Exos in I/R.

Background: The sivelestat is a neutrophil elastase inhibitor thought to have an effect against acute lung injury (ALI) in patients after scheduled cardiac surgery. However, the beneficial effect of sivelestat in patients undergoing emergent cardiovascular surgery remains unclear. We aim to evaluate the effect of sivelestat on pulmonary protection in patients with ALI after emergent cardiovascular surgery.Methods: Firstly, a case-control study in 665 patients undergoing emergent cardiovascular surgery from January 1^st, 2020 to October 26^th, 2022 was performed. 52 patients who received sivelestat (0.2mg/kg/h for 3 days) and 613 age- and sex-matched controls. Secondly, a propensity-score matched cohort (sivelestat vs control: 50 vs 50) was performed in these 665 patients. The primary outcome was a composite of adverse outcomes, including 30-day mortality, ECMO, continuous renal replacement therapy (CRRT) and IABP, etc. The secondary outcome included pneumonia, ventricular arrhythmias and mechanical ventilation time, etc.Results: In propensity-matched patients, the 30-day mortality (16% vs 24%, P=0.32), stroke (2% vs 8%, P=0.17), ECMO(6% vs 10%, P=0.46), IABP(4% vs 8%, P=0.40) and CRRT(8% vs 20%, P=0.08) had no differences between sivelestat and control group; sivelestat could significantly decrease pneumonia (40% vs 62%, P=0.03), mechanical ventilation time (median: 96hours, IQR:72-120hours vs median:148hours, IQR:110-186hours, P<0.01), bilateral pulmonary infiltrates (P<0.01), oxygen index (P<0.01), interleukin-6(P=0.02), procalcitonin(P<0.01) and C-reactive protein(P<0.01).Conclusion: Administration of sivelestat might improve postoperative outcomes in patients with ALI after emergent cardiovascular surgery. Our results show that sivelestat may be considered to protect pulmonary function against inflammatory injury by CPB.Registration: http://www.chictr.org.cn/showproj.aspx?proj=166643, identifier ChiCTR2200059102.