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Tyrosine kinase inhibitors (TKIs) offer targeted therapy for cancers but can cause severe cardiotoxicities. Determining their dose‑dependent impact on cardiac function is required to optimize therapy and minimize adverse effects. The dose‑dependent cardiotoxic effects of two TKIs, imatinib and ponatinib, were assessed in vitro using H9c2 cardiomyoblasts and in vivo using zebrafish embryos. In vitro , H9c2 cardiomyocyte viability, apoptosis, size, and surface area were evaluated to assess the impact on cellular health. In vivo , zebrafish embryos were analyzed for heart rate, blood flow velocity, and morphological malformations to determine functional and structural changes. Additionally, reverse transcription‑quantitative PCR (RT‑qPCR) was employed to measure the gene expression of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP), established markers of cardiac injury. This comprehensive approach, utilizing both in vitro and in vivo models alongside functional and molecular analyses, provides a robust assessment of the potential cardiotoxic effects. TKI exposure decreased viability and surface area in H9c2 cells in a dose‑dependent manner. Similarly, zebrafish embryos exposed to TKIs exhibited dose‑dependent heart malformation. Both TKIs upregulated ANP and BNP expression, indicating heart injury. The present study demonstrated dose‑dependent cardiotoxic effects of imatinib and ponatinib in H9c2 cells and zebrafish models. These findings emphasize the importance of tailoring TKI dosage to minimize cardiac risks while maintaining therapeutic efficacy. Future research should explore the underlying mechanisms and potential mitigation strategies of TKI‑induced cardiotoxicities.

Cardiac stem cells (CSCs) are important for improving cardiac function following myocardial infarction, with CSC migration to infarcted or ischemic myocardium important for cardiac regeneration. Strategies to improve cell migration may improve the efficiency of myocardial regeneration. Basic fibroblast growth factor (bFGF) is an essential molecule in cell migration, but the endogenous bFGF level is too low to be effective. The effect of exogenously delivered bFGF on CSC migration was observed in vitro and in vivo in the present study. The CSC migration index in response to various bFGF concentrations was demonstrated in vitro. In addition, a murine myocardial infarction model was constructed and bFGF protein expression levels and CSC aggregation following myocardial infarction were observed. To study cell migration in vivo, CM‑Dil‑labeled CSCs or bFGF‑CSCs were injected into the peri‑infarct myocardium following myocardium infarction and cell migration and maintenance in the peri‑infarct/infarct area was observed 1 week later. Protein expression levels of bFGF, CXCR‑4 and SDF‑1 were assessed, as was myocardium capillary density. The Akt inhibitor deguelin was used to assess the role of the PI3K/Akt pathway in vitro and in vivo. The present study demonstrated that bFGF‑promoted Sca‑1+ CSC migration, with the highest migration rate occurring at a concentration of 45 ng/ml. The PI3K/Akt pathway inhibitor deguelin attenuated this increase. The phospho‑Akt/Akt ratio was elevated significantly after 30 min of bFGF exposure. Transplantation of bFGF‑treated Sca‑1+ CSCs led to improved cell maintenance in the peri‑infarct area and increased cell migration to the infarct area, as well as improved angiogenesis. Protein expression levels of bFGF, CXCR‑4 and SDF‑1 were upregulated, and this upregulation was partially attenuated by deguelin. Therefore, bFGF was demonstrated to promote Sca‑1+ CSC migration both in vitro and in vivo, partially through activation of the PI3K/Akt pathway. This may provide a new method for facilitating CSC therapy for myocardium repair after myocardium injury.

Apelin‑13 (APL‑13), a peptide hormone that serves as a ligand for G‑protein coupled receptors, has been demonstrated to be highly expressed in left ventricular hypertrophy rat models. It has been implicated in cardio‑protection under pathological states. The present study aimed to assess the physiological proliferation effect of APL‑13 in cultured H9c2 cardiomyoblast cells, and to elucidate the underlying mechanisms. Cell proliferation was determined by MTT assay. The extracellular signal‑regulated kinase (ERK) 1/2 and protein kinase B (Akt) signaling pathway was identified, and protein expression levels were detected using western blot analysis. The results demonstrated that APL‑13 markedly increased cell proliferation. Western blotting results suggested that APL‑13 significantly enhanced the expression of phosphoinositide ERK1/2 and Akt activation in a dose‑dependent manner. U0126 (10 µM; ERK1/2 inhibitor) and/or 10 µM LY294002 (Akt inhibitor) were used to help to determine the APL‑signaling mechanism. As a result, LY294002 and U0126 partially blocked the APL‑13 induced H9c2 proliferation. In conclusion, these data suggested that APL‑13 has a proliferative effect on myocardium cells via the Akt and ERK1/2 signaling pathways, and provide potential novel pharmaceutical targets for cardiovascular disease.

The aim of the present study was to investigate the protective effect of the selective peroxisome proliferator-activated receptor δ (PPARδ) agonist GW501516 (GW) on lipopolysaccharide (LPS)‑induced apoptosis in the rat cardiomyoblast cell line H9c2, and to investigate the possible underlying mechanisms. Cell viability was estimated using the MTT assay. Apoptosis was estimated by flow cytometry using Annexin V‑fluorescein isothiocyanate/propidium iodide staining and caspase‑3 activity assay. The protein level of heme oxygenase‑1 (HO‑1), cleaved caspase‑3 (CC3), apoptosis regulator Bcl‑2 (bcl‑2), apoptosis regulator BAX (bax) and nuclear factor‑κB (NF‑κB) p65 was measured by western blot analysis. The results demonstrated that pretreatment with GW inhibited the LPS‑induced increase in the rate of apoptosis. Pretreatment with GW also increased the bcl‑2/bax ratio, and decreased CC3 protein expression as well as caspase‑3 activity, in LPS‑stimulated H9c2 cells. Further studies demonstrated that GW inhibited LPS‑induced NF‑κB nuclear translocation in a dose‑dependent manner. In addition, GW induced HO‑1 protein expression in a dose‑dependent manner. ZnPP‑IX, an inhibitor of HO‑1, reversed the inhibitory effect of GW on LPS‑induced NF‑κB activation, leading to the attenuation of PPARδ‑mediated apoptosis resistance. In conclusion, these results suggest that PPARδ activation exerts an anti‑apoptotic effect in LPS‑stimulated H9c2 cardiomyoblasts, potentially through heme oxygenase‑1‑mediated suppression of NF‑κB activation. PPARδ appears to be a promising therapeutic target for the treatment of sepsis‑associated cardiac dysfunction.

Stem cell antigen-1-positive (Sca-1+) cardiac stem cells (CSCs) therapy for myocardial regeneration following acute myocardial infarction (AMI) is limited by insufficient cell viability and a high rate of apoptosis, due to the poor regional microenvironment. Resveratrol, which is a compound extracted from red wine, has been reported to protect myocardial tissue post‑AMI by increasing the expression of angiogenic and chemotactic factors. The present study aimed to investigate the effects of resveratrol on Sca‑1+ CSCs, and to optimize Sca‑1+ CSCs therapy for myocardial regeneration post‑AMI. C57/BL6 mice (age, 6 weeks) were divided into two groups, which received intragastric administration of PBS or 2.5 mg/kg.d resveratrol. The endogenous expression of Sca‑1+ CSCs in the heart was assessed on day 7. Furthermore, C57/BL6 mice underwent left anterior descending coronary artery ligation for the construction of an AMI model, and received an injection of 1x106 CSCs into the peri‑ischemic area (n=8/group). Mice received intragastric administration of PBS or resveratrol (2.5 mg/kg.d) for 4 weeks after cell transplantation. Echocardiography was used to evaluate cardiac function 4 weeks after cell transplantation. Capillary density and cardiomyocyte apoptosis in the peri‑ischemic myocardium were assessed by cluster of differentiation 31 immunofluorescent staining and terminal deoxynucleotidyl transferase‑mediated dUTP nick end labeling assay, respectively. Western blot analysis was conducted to detect the protein expression levels of vascular endothelial growth factor (VEGF) and stromal cell‑derived factor (SDF)‑1α in the myocardium. Treatment with resveratrol increased the number of endogenous Sca‑1+ CSCs in heart tissue after 7 days (PBS vs. Res, 1.85±0.41/field vs. 3.14±0.26/field, P<0.05). Furthermore, intragastric administration of resveratrol significantly increased left ventricle (LV) function 4 weeks after AMI, as determined by an increase in LV fractional shortening (CSCs vs. Res + CSCs, 28.82±1.58% vs. 31.18±2.02%, P<0.05), reduced LV end‑diastolic diameter (CSCs vs. Res + CSCs, 0.37±0.01 mm vs. 0.35±0.02 mm, P<0.05), and reduced LV end‑systolic diameter (CSCs vs. Res + CSCs, 0.26±0.01 mm vs. 0.23±0.02 mm, P<0.05). These protective effects were predominantly achieved via an increase in capillary density (CSCs vs. Res + CSCs, 281.02±24.08/field vs. 329.75±36.69/field, P<0.05) and a reduction in cardiomyocyte apoptosis (CSCs vs. Res + CSCs, 1.5±0.54/field vs. 0.83±0.40/field, P<0.05) in peri‑ischemic myocardium. Western blot analysis indicated that VEGF and SDF‑1α were upregulated in resveratrol‑treated myocardium after a 7 day treatment or 4 weeks after AMI (7 days VEGF PBS vs. Res, 0.89±0.07 vs. 1.21±0.02, P<0.05; SDF‑1α PBS vs. Res, 0.66±0.04 vs. 1.33±0.04, P<0.05; 4 weeks VEGF CSCs vs. Res + CSCs, 0.54±0.03 vs. 0.93±0.13, P<0.05; SDF‑1α CSCs vs. Res + CSCs, 0.53±0.03 vs. 0.93±0.03, P<0.05). Resveratrol activated endogenous CSCs, increased capillary density and decreased cardiomyocyte apoptosis in the peri‑ischemic myocardium, and augmented the effects of CSCs transplantation. These effects may be caused by the upregulation of VEGF and SDF‑1α.

According to previous studies, hyperoside possesses myocardial protective effects. To investigate whether isoquercitrin and isohyperoside have similar functions, the protective effects of isoquercitrin and isohyperoside against H2O2‑induced injury in H9c2 rat cardiomyoblasts were evaluated using a 3‑(4,5‑dimethylthiazol‑2‑yl)‑2,5‑diphenyltetrazolium bromide assay. The mechanism of action was investigated by assessing the leakage of lactate dehydrogenase (LDH) of hyperoside and isoquercitrin‑pretreated H9c2 cardiomyocytes following H2O2‑induced injury, and examining their effects on the levels of malondialdehyde (MDA) and superoxide dismutase (SOD) activity. The isolation of two flavonoid glycosides from H. ascyron was performed, following extraction, using semi‑preparative high performance liquid chromatography. Using the spectral characteristics, the structures of these compounds were identified as isoquercitrin and isohyperoside. This was the first time, to the best of our knowledge, that isohyperoside has been identified from H. ascyron. The results revealed that isoquercitrin and isohyperoside possessed similar protective effects to hyperoside against H2O2‑induced injury in H9c2 cells. The half maximal inhibitory concentration values of hyperoside, isoquercitrin and isohyperoside were 0.0008, 0.0017 and 0.0002 µM, respectively. Based on these results, isohyperoside possessed more marked protective effects against H2O2‑induced injury in the H9c2 cardiomyoblasts. The significant reduction in LDH leakage, decrease in MDA level and increase in SOD activity also provided evidence of the cardioprotective effects of isoquercitrin and isohyperoside. The present study reported for the first time, to the best of our knowledge, the myocardial protective effects of isoquercitrin and isohyperoside. The mechanism of action may involve protection of the cell membrane from oxidative damage.

It has previously been demonstrated that phosphatidylinositol-3-kinase (PI3K)/Akt and cleaved caspase-3 serve critical roles in the apoptosis of cardiac myocytes following ischemia/reperfusion injury. Epigallocatechin-3-gallate (EGCG), the predominant catechin component of green tea, has been reported to have potential cardioprotective effects in primary cultures of cardiac myocytes exposed to I/R injury, mediated through inhibition of signal transducers and activators of transcription-1 activity. In addition, it is also known that the biological behavior of EGCG may be influenced by metal ions, for example the hepatoprotective activity of EGCG has been reported to be enhanced by zinc. In the present study, the protective effects of EGCG with zinc were assessed on cultures of rat cardiac myoblasts exposed to hypoxia/reoxygenation (H/R) injury. H9c2 cells were subjected to 3-h hypoxia, followed by 1-h reperfusion. EGCG and/or zinc were perfused prior to induced hypoxic stress. It was demonstrated that when EGCG interacted with zinc, the anti-apoptotic activity was significantly enhanced. To the best of our knowledge, the current study was the first to demonstrate that EGCG + Zn(2+) protects H9c2 cells against H/R injury through activation of the PI3K/Akt pathway, as determined by western blotting. Since EGCG + Zn(2+) may, at least in part, protect cardiac myocytes against H/R-induced apoptotic cell death, the PI3K/Akt pathway of EGCG may be enhanced by its interactions with zinc during H/R injury. Furthermore, it was suggested that a similar procedure may be implemented in a clinical setting, in order to maximize PI3K/Akt activation levels in patients with acute coronary artery disease. EGCG and zinc may therefore represent effective agents for use in the prevention of I/R injury in clinical practice.