Sunitinib malate induces cell death in adult human cardiac progenitor cells.

Sunitinib malate is known to cause cardiotoxicity in a sub-population of patients, with heart failure seen in more severe cases. Cardiac progenitor cells (CPCs) have been identified in adult human myocardium and contribute to overall tissue maintenance, with previous work identifying negative impacts of sunitinib on these cells. This study aimed to characterise the toxic effects of sunitinib in human CPCs, applying sunitinib concentrations equivalent to clinical plasma levels to these cells in vitro. Cell viability was reduced by 26.5 ± 6.6 % by 2 µM sunitinib for 24 h (p < 0.01); this concentration also induced fold-change increases in gene expression of: calpain (3.1 ± 0.73, p < 0.05), FAS (2.3 ± 0.8, p < 0.05) and BAX (1.9 ± 0.2, p < 0.05), and a decrease in BCL-2 (3.5 ± 0.0, p < 0.001), vs. control (1.0 ± 0.0). This was affirmed by sunitinib inducing fold changes in protein expression of: calpain-1 (2.5 ± 0.5, p < 0.05); FAS receptor (2.1 ± 0.2, p < 0.05) and BAX (2.1 ± 0.2, p < 0.05) vs. control (1.0 ± 0.0). These results indicated that sunitinib induced apoptosis in CPCs, but negative annexin V staining and lack of protection by caspase inhibitors indicated this was not the cell death pathway activated. Further investigation found sunitinib was concentrated in the lysosomes and autophagosomes within CPCs, but did not induce accumulation of acidic organelles. In conclusion, these data confirm that cell death is caused by sunitinib in CPCs at concentrations equivalent to clinical plasma levels, inducing cell death pathway signals that lead to non-apoptotic cell death.

Imatinib Mesylate Induces Necroptotic Cell Death and Impairs Autophagic Flux in Human Cardiac Progenitor Cells.

The receptor tyrosine kinase inhibitor imatinib improves patient cancer survival but is linked to cardiotoxicity. This study investigated imatinib's effects on cell viability, apoptosis, autophagy, and necroptosis in human cardiac progenitor cells in vitro. Imatinib reduced cell viability (75.9 ± 2.7% vs. 100.0 ± 0.0%) at concentrations comparable to peak plasma levels (10 µM). Imatinib reduced cells' TMRM fluorescence (74.6 ± 6.5% vs. 100.0 ± 0.0%), consistent with mitochondrial depolarisation. Imatinib increased lysosome and autophagosome content as indicated by LAMP2 expression (2.4 ± 0.3-fold) and acridine orange fluorescence (46.0 ± 5.4% vs. 9.0 ± 3.0), respectively. Although imatinib increased expression of autophagy-associated proteins and also impaired autophagic flux, shown by proximity ligation assay staining for LAMP2 and LC3II (autophagosome marker): 48 h of imatinib treatment reduced visible puncta to 2.7 ± 0.7/cell from 11.3 ± 2.1 puncta/cell in the control. Cell viability was partially recovered by autophagosome inhibition by wortmannin, with the viability increasing 91.8 ± 8.2% after imatinib-wortmannin co-treatment (84 ± 1.5% after imatinib). Imatinib-induced necroptosis was associated with an 8.5 ± 2.5-fold increase in mixed lineage kinase domain-like pseudokinase activation. Imatinib-induced toxicity was rescued by RIP1 inhibition: 88.6 ± 3.0% vs. 100.0 ± 0.0% in the control. Imatinib applied to human cardiac progenitor cells depolarises mitochondria and induces cell death through necroptosis, recoverable by RIP1 inhibition, with a partial role for autophagy.

Receptor tyrosine kinase inhibitors negatively impact on pro-reparative characteristics of human cardiac progenitor cells.

Receptor tyrosine kinase inhibitors improve cancer survival but their cardiotoxicity requires investigation. We investigated these inhibitors' effects on human cardiac progenitor cells in vitro and rat heart in vivo. We applied imatinib, sunitinib or sorafenib to human cardiac progenitor cells, assessing cell viability, proliferation, stemness, differentiation, growth factor production and second messengers. Alongside, sunitinib effects were assessed in vivo. Inhibitors decreased (p < 0.05) cell viability, at levels equivalent to 'peak' (24 h; imatinib: 91.5 ± 0.9%; sunitinib: 83.9 ± 1.8%; sorafenib: 75.0 ± 1.6%) and 'trough' (7 days; imatinib: 62.3 ± 6.2%; sunitinib: 86.2 ± 3.5%) clinical plasma levels, compared to control (100% viability). Reduced (p < 0.05) cell cycle activity was seen with imatinib (29.3 ± 4.3% cells in S/G2/M-phases; 50.3 ± 5.1% in control). Expression of PECAM-1, Nkx2.5, Wnt2, linked with cell differentiation, were decreased (p < 0.05) 2, 2 and 6-fold, respectively. Expression of HGF, p38 and Akt1 in cells was reduced (p < 0.05) by sunitinib. Second messenger (p38 and Akt1) blockade affected progenitor cell phenotype, reducing c-kit and growth factor (HGF, EGF) expression. Sunitinib for 9 days (40 mg/kg, i.p.) in adult rats reduced (p < 0.05) cardiac ejection fraction (68 ± 2% vs. baseline (83 ± 1%) and control (84 ± 4%)) and reduced progenitor cell numbers. Receptor tyrosine kinase inhibitors reduce cardiac progenitor cell survival, proliferation, differentiation and reparative growth factor expression.

Receptor tyrosine kinase inhibitors cause dysfunction in adult rat cardiac fibroblasts in vitro.

The anti-cancer receptor tyrosine kinase inhibitors include known cardiotoxins: a component of this toxicity may be mediated by effects on cardiac fibroblasts (CFs). We hypothesised that imatinib mesylate (imatinib) and sunitinib malate (sunitinib) cause significant dysfunction in adult CFs. Following in vitro treatments with imatinib or sunitinib, adult rat CF viability was assessed by fluorescein diacetate assay, proliferation measured by bromodeoxyuridine nuclear incorporation and changes to the expression of CF secretome components determined by real time quantitative RT-PCR. Imatinib and sunitinib significantly reduced cell viability over 48 h, with EC50 values of 11.0 µM (imatinib) and 4.5 µM (sunitinib) respectively. Imatinib reduced CF proliferation from 35.5 ±â€¯3.2% in control to 23.0 ±â€¯5.5% (3 µM; p < 0.001) and to 9.4 ±â€¯2.5% (10 µM; p < 0.001), whereas sunitinib reduced proliferation to 22.9 ±â€¯3.1% (1 µM; p < 0.001) and to 15 ±â€¯1.0% (3 µM; p < 0.001). Further, 10 µM imatinib increased mRNA expression of TGFB1 7-fold, (p < 0.01), IL6 6-fold (p < 0.01), and IL1B 7-fold (p < 0.05) and reduced PDGFD 15-fold (p < 0.01); whereas sunitinib specifically reduced IL1B mRNA expression 17-fold (p < 0.01). Overall, these findings show tyrosine kinase inhibitors cause significant dysfunction in CFs. These data point to an important role for the PDGF pathway in governing CF functions, including survival and proliferation.

Left main coronary artery originating from the proper sinus but with acute angulation and an intramural course, leading to critical stenosis.

Because of the variety of their anatomy and clinical implications, coronary anomalies tend to confuse many observers. Recently, our group and other investigators have proposed that only 1 specific type of anomaly, by means of a specific mechanism, is able to cause both symptoms of myocardial ischemia and sudden death. This anomaly is known as anomalous origin of a coronary artery from the opposite sinus of Valsalva, with intramural course (ACAOS). Its defining pathophysiologic feature is that the proximal section of the ectopic artery has an intramural course, which leads to variable degrees of functional obstruction. Herein, we describe an unusual, previously unreported coronary anomaly: a "normal origin" of the left main coronary artery from the left sinus of Valsalva that resulted in progressive, critical ischemia. The proximal few millimeters of this artery were intramural, embedded into the aortic-sinus wall, and laterally compressed. Therefore, this anomaly may be regarded also as "ACAOS of the left coronary artery without an ectopic origin." Angiography and intravascular ultrasonography revealed a variable degree of obstruction without intimal thickening and, likely, without spasm. Surgical repair, including ostioplasty, completely relieved the patient's clinical symptoms.

Sub-10 nm nanoimprint lithography by wafer bowing.

We introduce the concept of wafer bowing to affect nanoimprinting. This approach allows a design that can fit the key imprinting mechanism into a compact module, which we have constructed and demonstrated with an overlay and resolution of <0.5 microm and <10 nm, respectively. In the short term, this wafer bowing approach makes nanoimprint lithography much more accessible to a broad range of researchers. More importantly, this approach eliminates machine movement other than wafer bowing and shortens the mechanical path; these will enable the achievement of excellent patterning and overlay at a much lower cost. In the long term, wafer bowing is extensible to step-and-repeat printing for volume manufacturing.

Symptomatic anomalous origination of the left coronary artery from the opposite sinus of valsalva. Clinical presentations, diagnosis, and surgical repair.

Anomalous origination of a coronary artery can have serious, even fatal, consequences. Intravascular ultrasonography has recently provided new insights into anomalous coronary artery origination from the opposite sinus of Valsalva. On the basis of these insights, we describe 3 typical forms of this anomaly with left coronary artery involvement, including clinical presentations, diagnostic methods (particularly intravascular ultrasonography), and details of surgical treatment. In this case series, the left coronary artery originated from the noncoronary sinus in 1 patient and from the right sinus in another patient. In the 3rd patient, both the left and right coronary arteries originated from the ascending aorta above the sinotubular junction. Baseline areas of stenosis ranged from 48.6% to 70.1%. Intravascular ultrasonography was the only method that enabled us to clarify the mechanisms and the severity of the anomaly. Pharmacologic challenge was useful to predict worsening that might have occurred under physiologic conditions. We found that, in cases of symptomatic left anomalous coronary artery origination from the opposite sinus of Valsalva, the proximal segment of the left coronary artery consistently has (1) an intramural course inside the aortic wall; (2) hypoplasia, as determined by its circumference; and (3) a cross-sectional ovaloid deformity (lateral compression) with phasic and exercise-induced worsening of the deformity With regard to surgical treatment, ostioplasty is preferable to coronary bypass. To establish sound guidelines for managing these anomalies, a larger series should be studied prospectively with quantitative parameters and long-term follow-up.