Salivary Interleukin-13 and Transforming Growth Factor Beta as Potential Biomarkers of Cancer Cachexia.

Cancer cachexia is a syndrome characterized by weight and muscle loss and functional impairment, strongly influencing survival in cancer patients. In this study, we aimed to establish the role of saliva cytokine measurement in cancer cachexia investigation and define two potential independent salivary biomarkers of the condition. METHODS: serum and saliva specimens were obtained from 78 patients. Forty-six patients were non-cachectic, and 32 patients were cachectic (per SCRINIO group criteria), all with metastatic solid tumors. Commercial ELISA kits were used to determine the salivary and serum concentrations of interleukin 13 (IL-13) and transforming growth factor beta (TGF-ß) in two patient groups and healthy controls. Laboratory values were obtained from the hospital information system, and weight and height were measured at the time of sampling. RESULTS: A statistically significant difference was observed between the groups in saliva IL-13 concentrations but no difference in serum concentrations. Statistically significant differences were also observed between the groups in saliva and serum concentrations of TGF-ß. Logistic regression analysis has identified salivary IL-13 and TGF-ß as independent factors for cancer cachexia. CONCLUSIONS: We demonstrated saliva as a valuable specimen for cachexia investigation and established IL-13 and TGF-ß as potential cancer cachexia biomarkers. Further research is needed to evaluate these findings.

Cardiotoxicity of Iron and Zinc and Their Association with the Mitochondrial Unfolded Protein Response in Humans.

This study was designed to examine the association between myocardial concentrations of the trace elements Cu, Fe, Mn, Mo, and Zn and the expression of mitochondrial unfolded protein response (UPRmt) elements and the age of patients who received heart transplantation or a left-ventricular assist device (ageHTx/LVAD). Inductively coupled plasma mass spectrometry was used to determine the concentration of Cu, Fe, Mn, Mo, and Zn in the myocardium of control subjects and patients undergoing heart transplantation or left-ventricular assist device (LVAD) implantation. We used ELISA to quantify the expression of UPRmt proteins and 4-Hydroxynonenal (4-HNE), which served as a marker of oxidative-stress-induced lipid peroxidation. Concentrations of Cu, Mn, Mo, and Zn were similar in the control and heart failure (HF) myocardium, while Fe showed a significant decrease in the HF group compared to the control. A higher cumulative concentration of Fe and Zn in the myocardium was associated with reduced ageHTx/LVAD, which was not observed for other combinations of trace elements or their individual effects. The trace elements Cu, Mn, and Zn showed positive correlations with several UPRmt proteins, while Fe had a negative correlation with UPRmt effector protease YME1L. None of the trace elements correlated with 4-HNE in the myocardium. The concentrations of the trace elements Mn and Zn were significantly higher in the myocardium of patients with dilated cardiomyopathy than in patients with ischemic cardiomyopathy. A higher cumulative concentration of Fe and Zn in the myocardium was associated with a younger age at which patients received heart transplantation or LVAD, potentially suggesting an acceleration of HF. A positive correlation between myocardial Cu, Mn, and Zn and the expression of UPRmt proteins and a negative correlation between myocardial Fe and YME1L expression suggest that these trace elements exerted their actions on the human heart by interacting with the UPRmt. An altered generation of oxidative stress was not an underlying mechanism of the observed changes.

A rare form of LIM domain-binding protein 3 (LDB3) mutation causes hypertrophic cardiomyopathy and myofibrillar myopathy type 4.

Polymorphisms in LDB3 gene can cause various forms of cardiomyopathy and myofibrillar myopathy 4 (MM4). Patient described in this study presented with a hypertrophic cardiomyopathy (HCM) and distal myopathy suggestive of myofibrillar myopathy 4. Genetic analysis using the TruSight Cardio Sequencing Kit (Illumina) revealed suspected LDB3 variant (c.1435G>A, p.(Gly479Arg)). This is the first case in which polymorphism in LDB3 gene is likely responsible for MM4 and HCM in the same patient.

Predictors of prolonged hospitalization of COVID-19 patients.

PURPOSE: Despite the importance of hospital bed network during the pandemic, there are scarce data available regarding factors predictive of prolonged length of hospitalization of COVID-19 patients. METHODS: We retrospectively analyzed a total of 5959 consecutive hospitalized COVID-19 patients in period 3/2020-6/2021 from a single tertiary-level institution. Prolonged hospitalization was defined as hospital stay > 21 days to account for mandatory isolation period in immunocompromised patients. RESULTS: Median length of hospital stay was 10 days. A total of 799 (13.4%) patients required prolonged hospitalization. Factors that remained independently associated with prolonged hospitalization in multivariate analysis were severe or critical COVID-19 and worse functional status at the time of hospital admission, referral from other institutions, acute neurological, acute surgical and social indications for admission vs admission indication of COVID-19 pneumonia, obesity, chronic liver disease, hematological malignancy, transplanted organ, occurrence of venous thromboembolism, occurrence of bacterial sepsis and occurrence of Clostridioides difficile infection during hospitalization. Patients requiring prolonged hospitalization experienced higher post-hospital discharge mortality (HR = 2.87, P < 0.001). CONCLUSIONS: Not only severity of COVID-19 clinical presentation but also worse functional status, referral from other hospitals, certain indications for admission, certain chronic comorbidities, and complications that arise during hospital stay independently reflect on the need of prolonged hospitalization. Development of specific measures aimed at improvement of functional status and prevention of complications might reduce the length of hospitalization.

Human C2a and C6a iPSC lines and H9 ESC line have less efficient cardiomyogenesis than H1 ESC line: Beating enhances cardiac differentiation.

BACKGROUND: Human induced pluripotent stem cells (hiPSCs) need to be thoroughly characterized to exploit their potential advantages in various aspects of biomedicine. The aim of this study was to compare the efficiency of cardiomyogenesis of two hiPSCs and two human embryonic stem cell (hESC) lines by genetic living cardiomyocyte labeling. We also analyzed the influence of spontaneous beating on cardiac differentiation. METHODS: H1 and H9 hESC lines and C2a and C6a hiPSC lines were induced into in vitro directed cardiac differentiation. Cardiomyogenesis was evaluated by the analysis of cell cluster beating, cardiac protein expression by immunocytochemistry, ability of cells to generate calcium transients, and cardiomyocyte quantification by the myosin light chain 2v-enhanced green fluorescent protein gene construct delivered with a lentiviral vector. RESULTS: Differentiation of all cell lines yielded spontaneously beating cell clusters, indicating the presence of functional cardiomyocytes. After the cell dissociation, H1-hESC-derived cardiomyocytes exhibited spontaneous calcium transients, corresponding to autonomous electrical activity and displayed ability to transmit them between the cells. Differentiated hESC and hiPSC cells exhibited striated sarcomeres and expressed cardiac proteins sarcomeric α-actinin and cardiac troponin T. Cardiomyocytes were the most abundant in differentiated H1 hESC line (20% more than in other tested lines). In all stem cell lines, cardiomyocyte enrichment was greater in beating than in non-beating cell clusters, irrespective of cardiomyogenesis efficiency. CONCLUSION: Although C2a and C6a hiPSC and H9 hESC lines exhibited efficient cardiomyogenesis, H1 hESC line yielded the greatest cardiomyocyte enrichment of all tested lines. Beating of cell clusters promotes cardiomyogenesis in tested hESCs and hiPSCs.

Prognostic value of circulating Bcl-2 and anti-p53 antibodies in patients with breast cancer: A long term follow-up (17.5 years).

BACKGROUND: Apoptosis inhibition is a major tumorigenic factor. Bcl-2 dysregulation and TP53 mutation status, which may correlate with autoantibody generation, contribute to impaired apoptosis. OBJECTIVE: This study aimed to investigate the prognostic value of circulating Bcl-2 and anti-p53 antibodies (p53Abs) in a 17.5-year follow-up of breast cancer patients. We also analyzed the correlations of Bcl-2 and p53Abs with various clinicopathological parameters in order to assess their impact on tumor aggressiveness. METHODS: Serum Bcl-2 and p53Abs levels were analyzed by the enzyme-linked immunosorbent assay (ELISA) in 82 patients with invasive breast cancer and twenty individuals without malignancy. RESULTS: Serum Bcl-2 and p53Abs levels in breast cancer patients were significantly higher than those in controls. Patients with high levels of Bcl-2 (cut-off 200 U/ml) had a poorer prognosis (17.5-year survival) than those with lower Bcl-2 values. In combined analysis the subgroup of patients with elevated p53Abs (cut-off 15 U/ml) and elevated Bcl-2 (cut-offs 124 U/ml and 200 U/ml) had the worse prognosis in 17.5-year survival. In correlation analysis p53Abs and Bcl-2 were associated with unfavorable clinicopathological parameters. CONCLUSIONS: Our results suggest that breast cancer patients with high serum levels of p53Abs and Bcl-2 present an especially unfavorable group in a long follow-up.

Mitochondrial ROS Induce Partial Dedifferentiation of Human Mesothelioma via Upregulation of NANOG.

The expression of pluripotency factors is a key regulator of tumor differentiation status and cancer stem cells. The purpose of this study was to examine the expression of pluripotency factors and differentiation status of human mesothelioma and the role of mitochondria in their regulation. We tested the expression of OCT4/POU5F1, NANOG, SOX2, PI3K-AKT pathway and BCL2 genes and proteins in 65 samples of human mesothelioma and 19 samples of normal mesothelium. Mitochondrial membrane potential, reactive oxygen species (ROS) generation and expression of pluripotency factors were also tested in human mesothelioma cell line. Human mesothelium and mesothelioma expressed SOX2, NANOG, PI3K and AKT genes and proteins and POU5F1 gene, whereby NANOG, SOX2 and phosphorylated (activated) AKT were upregulated in mesothelioma. NANOG protein expression was elevated in less differentiated samples of human mesothelioma. The expression of genes of PI3K-AKT pathway correlated with pluripotency factor genes. Mesothelioma cells had functional, but depolarized mitochondria with large capacity to generate ROS. Mitochondrial ROS upregulated NANOG and mitoTEMPO abrogated it. In conclusion, human mesothelioma displays enhanced expression of NANOG, SOX2 and phosphorylated AKT proteins, while elevated NANOG expression correlates with poor differentiation of human mesothelioma. Mitochondria of mesothelioma cells have a large capacity to form ROS and thereby upregulate NANOG, leading to dedifferentiation of mesothelioma.

Mitochondrial unfolded protein response, mitophagy and other mitochondrial quality control mechanisms in heart disease and aged heart.

Mitochondria are involved in crucial homeostatic processes in the cell: the production of adenosine triphosphate and reactive oxygen species, and the release of pro-apoptotic molecules. Thus, cell survival depends on the maintenance of proper mitochondrial function by mitochondrial quality control. The most important mitochondrial quality control mechanisms are mitochondrial unfolded protein response, mitophagy, biogenesis, and fusion-fission dynamics. This review deals with mitochondrial quality control in heart diseases, especially myocardial infarction and heart failure. Some previous studies have demonstrated that the activation of mitochondrial quality control mechanisms may be beneficial for the heart, while others have shown that it may lead to heart damage. Our aim was to describe the mechanisms by which mitochondrial quality control contributes to heart protection or damage and to provide evidence that may resolve the seemingly contradictory results from the previous studies.

Differentiating Between Malignant Mesothelioma and Other Pleural Lesions Using Fourier Transform Infrared Spectroscopy.

Histopathology, despite being the gold standard as a diagnostic tool, does not always provide a correct diagnosis for different pleural lesions. Although great progress was made in this field, the problem to differentiate between reactive and malignant pleural lesions still stimulates the search for additional diagnostic tools. Our research using vibrational spectroscopy and principal component analysis (PCA) statistical modeling represents a potentially useful tool to approach the problem. The objective method this paper explores is based on the correlation between different types of pleural lesions and their vibrational spectra. Obtained tissue spectra recorded by infrared spectroscopy allowed us to categorize spectra in different groups using a created PCA statistical model. The PCA model was built using tissues of known pathology as the model group. The validation samples were then used to confirm the functionality of our PCA model. Student's t-test was also used for comparing samples in paired groups. The PCA model was able to clearly differentiate the spectra of mesothelioma, metastasis and reactive changes (inflammation), and place them in discrete groups. Thus, we showed that Fourier transform infrared spectroscopy combined with PCA can differentiate pleural lesions with high sensitivity and specificity. This new approach could contribute in objectively differentiating specific pleural lesions, thus helping pathologists to better diagnose difficult pleural samples but also could shed additional light into the biology of malignant pleural mesothelioma.

Non-linear actions of physiological agents: Finite disarrangements elicit fitness benefits.

Finite disarrangements of important (vital) physiological agents and nutrients can induce plethora of beneficial effects, exceeding mere attenuation of the specific stress. Such response to disrupted homeostasis appears to be universally conserved among species. The underlying mechanism of improved fitness and longevity, when physiological agents act outside their normal range is similar to hormesis, a phenomenon whereby toxins elicit beneficial effects at low doses. Due to similarity with such non-linear response to toxins described with J-shaped curve, we have coined a new term "mirror J-shaped curves" for non-linear response to finite disarrangement of physiological agents. Examples from the clinical trials and basic research are provided, along with the unifying mechanisms that tie classical non-linear response to toxins with the non-linear response to physiological agents (glucose, oxygen, osmolarity, thermal energy, calcium, body mass, calorie intake and exercise). Reactive oxygen species and cytosolic calcium seem to be common triggers of signaling pathways that result in these beneficial effects. Awareness of such phenomena and exploring underlying mechanisms can help physicians in their everyday practice. It can also benefit researchers when designing studies and interpreting growing number of scientific data showing non-linear responses to physiological agents.

Targeted Modification of Mitochondrial ROS Production Converts High Glucose-Induced Cytotoxicity to Cytoprotection: Effects on Anesthetic Preconditioning.

Contradictory reports on the effects of diabetes and hyperglycemia on myocardial infarction range from cytotoxicity to cytoprotection. The study was designed to investigate acute effects of high glucose-driven changes in mitochondrial metabolism and osmolarity on adaptive mechanisms and resistance to oxidative stress of isolated rat cardiomyocytes. We examined the effects of high glucose on several parameters of mitochondrial bioenergetics, including changes in oxygen consumption, mitochondrial membrane potential, and NAD(P)H fluorometry. Effects of high glucose on the endogenous cytoprotective mechanisms elicited by anesthetic preconditioning (APC) and the mediators of cell injury were also tested. These experiments included real-time measurements of reactive oxygen species (ROS) production and mitochondrial permeability transition pore (mPTP) opening in single cells by laser scanning fluorescence confocal microscopy, and cell survival assay. High glucose rapidly enhanced mitochondrial energy metabolism, observed by increase in NAD(P)H fluorescence intensity, oxygen consumption, and mitochondrial membrane potential. This substantially elevated production of ROS, accelerated opening of the mPTP, and decreased survival of cells exposed to oxidative stress. Abrogation of high glucose-induced mitochondrial hyperpolarization with 2,4 dinitrophenol (DNP) significantly, but not completely, attenuated ROS production to a level similar to hyperosmotic mannitol control. DNP treatment reversed high glucose-induced cytotoxicity to cytoprotection. Hyperosmotic mannitol treatment also induced cytoprotection. High glucose abrogated APC-induced mitochondrial depolarization, delay in mPTP opening and cytoprotection. In conclusion, high glucose-induced mitochondrial hyperpolarization abolishes APC and augments cell injury. Attenuation of high glucose-induced ROS production by eliminating mitochondrial hyperpolarization protects cardiomyocytes. J. Cell. Physiol. 232: 216-224, 2017. © 2016 Wiley Periodicals, Inc.

Cardioprotection during diabetes: the role of mitochondrial DNA.

BACKGROUND: Diabetes alters mitochondrial bioenergetics and consequently disrupts cardioprotective signaling. The authors investigated whether mitochondrial DNA (mtDNA) modulates anesthetic preconditioning (APC) and cardiac susceptibility to ischemia-reperfusion injury by using two strains of rats, both sharing nuclear genome of type 2 diabetes mellitus (T2DN) rats and having distinct mitochondrial genomes of Wistar and fawn-hooded hypertensive (FHH) rat strains (T2DN(mtWistar) and T2DN(mtFHH), respectively). METHODS: Myocardial infarct size was measured in Wistar, T2DN(mtWistar), and T2DN(mtFHH) rats with or without APC (1.4% isoflurane) in the presence or absence of antioxidant N-acetylcysteine. Flavoprotein fluorescence intensity, a marker of mitochondrial redox state, 5-(and-6)-chloromethyl-2',7'-dichlorofluorescein fluorescence intensity, a marker of reactive oxygen species generation, and mitochondrial permeability transition pore opening were assessed in isolated rat ventricular cardiomyocytes with or without isoflurane (0.5 mmol/l). RESULTS: Myocardial infarct size was decreased by APC in Wistar and T2DN(mtWistar) rats (to 42 ± 6%, n = 8; and 44 ± 7%, n = 8; of risk area, respectively) compared with their respective controls (60 ± 3%, n = 6; and 59 ± 9%, n = 7), but not in T2DN(mtFHH) rats (60 ± 2%, n = 8). N-acetylcysteine applied during isoflurane treatment restored APC in T2DN(mtFHH) (39 ± 6%, n = 7; and 38 ± 5%, n = 7; 150 and 75 mg/kg N-acetylcysteine, respectively), but abolished protection in control rats (54 ± 8%, n = 6). Similar to the data on infarct size, APC delayed mitochondrial permeability transition pore opening in T2DN(mtWistar) but not in T2DN(mtFHH) cardiomyocytes. Isoflurane increased flavoprotein and 5-(and-6)-chloromethyl-2',7'-dichlorofluorescein fluorescence intensity in all rat strains, with the greatest effect in T2DN(mtFHH) cardiomyocytes. CONCLUSION: Differences in the mitochondrial genome modulate isoflurane-induced generation of reactive oxygen species which translates into differential susceptibility to APC and ischemia-reperfusion injury in diabetic rats.

Apolipoprotein A-1 mimetic D-4F enhances isoflurane-induced eNOS signaling and cardioprotection during acute hyperglycemia.

Acute hyperglycemia (AHG) decreases the availability of nitric oxide (NO) and impairs anesthetic preconditioning (APC)-elicited protection against myocardial infarction. We investigated whether D-4F, an apolipoprotein A-1 mimetic, rescues the myocardium by promoting APC-induced endothelial NO signaling during AHG. Myocardial infarct size was measured in mice in the absence or presence of APC [isoflurane (1.4%)] with or without AHG [dextrose (2 g/kg ip)] and D-4F (0.12 or 0.6 mg/kg ip). NO production, superoxide generation, protein compartmentalization, and posttranslational endothelial NO synthase (eNOS) modifications were assessed in human coronary artery endothelial cells cultured in 5.5 or 20 mM glucose with or without isoflurane (0.5 mM) in the presence or absence of D-4F (0.5 µg/ml). Myocardial infarct size was significantly decreased by APC (36 ± 3% of risk area) compared with control (54 ± 3%) in the absence, but not presence, of AHG (49 ± 4%). D-4F restored the cardioprotective effect of APC during AHG (36 ± 3% and 30 ± 3%, 0.12 and 0.6 mg/kg, respectively), although D-4F alone had no effect on infarct size (53 ± 3%). Isoflurane promoted caveolin-1 and eNOS compartmentalization within endothelial cell caveolae and eNOS dimerization, concomitant with increased NO production (411 ± 28 vs. 68 ± 10 pmol/mg protein in control). These actions were attenuated by AHG (NO production: 264 ± 18 pmol/mg protein). D-4F reduced superoxide generation and enhanced caveolin-1 and eNOS caveolar compartmentalization and posttranslational eNOS modifications, thus restoring NO production during isoflurane and AHG (418 ± 36 pmol/mg protein). In conclusion, D-4F restored the cardioprotective effect of APC during AHG, possibly by decreasing superoxide generation, which promoted isoflurane-induced eNOS signaling and NO biosynthesis.

Preconditioning by isoflurane elicits mitochondrial protective mechanisms independent of sarcolemmal KATP channel in mouse cardiomyocytes.

Cardiac mitochondria and the sarcolemmal (sarc)KATP channels contribute to cardioprotective signaling of anesthetic-induced preconditioning. Changes in mitochondrial bioenergetics influence the sarcolemmal ATP-sensitive K (sarcKATP) channel function, but whether this channel has impacts on mitochondria is uncertain. We used the mouse model with deleted pore-forming Kir6.2 subunit of sarcKATP channel (Kir6.2 KO) to investigate whether the functional sarcKATP channels are necessary for isoflurane activation of mitochondrial protective mechanisms. Ventricular cardiomyocytes were isolated from C57Bl6 wild-type (WT) and Kir6.2 KO mouse hearts. Flavoprotein autofluorescence, mitochondrial reactive oxygen species production, and mitochondrial membrane potential were monitored by laser-scanning confocal microscopy in intact cardiomyocytes. Cell survival was assessed using H2O2-induced stress. Isoflurane (0.5 mM) increased flavoprotein fluorescence to 180% ± 14% and 190% ± 15% and reactive oxygen species production to 118% ± 2% and 124% ± 6% of baseline in WT and Kir6.2 KO myocytes, respectively. Tetramethylrhodamine ethyl ester fluorescence decreased to 84% ± 6% in WT and to 86% ± 4% in Kir6.2 KO myocytes. This effect was abolished by 5HD. Pretreatment with isoflurane decreased the stress-induced cell death from 31% ± 1% to 21% ± 1% in WT and from 44% ± 2% to 35% ± 2% in Kir6.2 KO myocytes. In conclusion, Kir6.2 deletion increases the sensitivity of intact cardiomyocytes to oxidative stress, but does not alter the isoflurane-elicited protective mitochondrial mechanisms, suggesting independent roles for cardiac mitochondria and sarcKATP channels in anesthetic-induced preconditioning by isoflurane.

Comparison of cardiomyogenic potential among human ESC and iPSC lines.

We recently reported that, following induction of clumps of pluripotent H1 human embryonic stem cells (hESCs) with activin-A and Bmp4 in defined medium for 5 days, widespread differentiation of rhythmically contracting cardiomyocytes occurs within 3-4 weeks. In this study, the same approach was used to assess whether human induced pluripotent stem cells (hiPSCs), which may theoretically provide an unlimited source of patient-matched cells for transplantation therapy, can similarly undergo cardiomyocyte differentiation. Differentiation of four pluripotent cell lines (H1 and H9 hESCs and C2a and C6a hiPSCs) was compared in parallel by monitoring rhythmic contraction, morphologic differentiation, and expression of cardiomyogenic genes. Based on expression of the cardiomyogenic lineage markers MESP1, ISL1, and NKX2-5, all four cell lines were induced into the cardiomyogenic lineage. However, in contrast to the widespread appearance of striations and rhythmic contractility seen in H9 and especially in H1 hESCs, both hiPSC lines exhibited poor terminal differentiation. These findings suggest that refined modes of generating hiPSCs, as well as of inducing cardiomyogenesis in them, may be required to fulfill their potential as agents of cardiac regeneration.

Complex I and ATP synthase mediate membrane depolarization and matrix acidification by isoflurane in mitochondria.

Short application of the volatile anesthetic isoflurane at reperfusion after ischemia exerts strong protection of the heart against injury. Mild depolarization and acidification of the mitochondrial matrix are involved in the protective mechanisms of isoflurane, but the molecular basis for these changes is not clear. In this study, mitochondrial respiration, membrane potential, matrix pH, matrix swelling, ATP synthesis and -hydrolysis, and H(2)O(2) release were assessed in isolated mitochondria. We hypothesized that isoflurane induces mitochondrial depolarization and matrix acidification through direct action on both complex I and ATP synthase. With complex I-linked substrates, isoflurane (0.5mM) inhibited mitochondrial respiration by 28 ± 10%, and slightly, but significantly depolarized membrane potential and decreased matrix pH. With complex II- and complex IV-linked substrates, respiration was not changed, but isoflurane still decreased matrix pH and depolarized mitochondrial membrane potential. Depolarization and matrix acidification were attenuated by inhibition of ATP synthase with oligomycin, but not by inhibition of mitochondrial ATP- and Ca(2+)-sensitive K(+) channels or uncoupling proteins. Isoflurane did not induce matrix swelling and did not affect ATP synthesis and hydrolysis, but decreased H(2)O(2) release in the presence of succinate in an oligomycin- and matrix pH-sensitive manner. Isoflurane modulated H(+) flux through ATP synthase in an oligomycin-sensitive manner. Our results indicate that isoflurane-induced mitochondrial depolarization and acidification occur due to inhibition of the electron transport chain at the site of complex I and increased proton flux through ATP synthase. K(+) channels and uncoupling proteins appear not to be involved in the direct effects of isoflurane on mitochondria.

Marked hyperglycemia attenuates anesthetic preconditioning in human-induced pluripotent stem cell-derived cardiomyocytes.

INTRODUCTION: Anesthetic preconditioning protects cardiomyocytes from oxidative stress-induced injury, but it is ineffective in patients with diabetes mellitus. To address the role of hyperglycemia in the inability of diabetic individuals to be preconditioned, we used human cardiomyocytes differentiated from induced pluripotent stem cells generated from patients with or without type 2 diabetes mellitus (DM-iPSC- and N-iPSC-CMs, respectively) to investigate the efficacy of preconditioning in varying glucose conditions (5, 11, and 25 mM). METHODS: Induced pluripotent stem cells were induced to generate cardiomyocytes by directed differentiation. For subsequent studies, cardiomyocytes were identified by genetic labeling with enhanced green fluorescent protein driven by a cardiac-specific promoter. Cell viability was analyzed by lactate dehydrogenase assay. Confocal microscopy was utilized to measure opening of the mitochondrial permeability transition pore and the mitochondrial adenosine 5'-triphosphate-sensitive potassium channels. RESULTS: Isoflurane (0.5 mM) preconditioning protected N-iPSC- and DM-iPSC-CMs from oxidative stress-induced lactate dehydrogenase release and mitochondrial permeability transition pore opening in 5 mM and 11 mM glucose. Isoflurane triggered mitochondrial adenosine-5'-triphosphate-sensitive potassium channel opening in N-iPSC-CMs in 5 mM and 11 mM glucose and in DM-iPSC-CMs in 5 mM glucose; 25 mM glucose disrupted anesthetic preconditioning-mediated protection in DM-iPSC- and N-iPSC-CMs. CONCLUSIONS: The opening of mitochondrial adenosine 5'-triphosphate-sensitive potassium channels are disrupted in DM-iPSC-CMs in 11 mM and 25 mM glucose and in N-iPSC-CMs in 25 mM glucose. Cardiomyocytes derived from healthy donors and patients with a specific disease, such as diabetes in this study, open possibilities in studying genotype- and phenotype-related pathologies in a human-relevant model.

Biphasic effect of nitric oxide on the cardiac voltage-dependent anion channel.

Nitric oxide (NO·) effects on the cardiac mitochondrial voltage-dependent anion channel (VDAC) are unknown. The effects of exogenous NO· on VDAC purified from rat hearts were investigated in this study. When incorporated into lipid bilayers, VDAC was inhibited directly by an NO· donor, PAPA NONOate, in a concentration-dependent biphasic manner. This was prevented by an NO· scavenger, 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide. The effect paralleled that of NO() in delaying the opening of the mitochondrial permeability transition (PT) pore. These biphasic effects on the cardiac VDAC and the mitochondrial PT pore reveal a tandem impact of NO() on the two mitochondrial entities.

Isoflurane preconditioning elicits competent endogenous mechanisms of protection from oxidative stress in cardiomyocytes derived from human embryonic stem cells.

BACKGROUND: Human embryonic stem cell (hESC)-derived cardiomyocytes potentially represent a powerful experimental model complementary to myocardium obtained from patients that is relatively inaccessible for research purposes. We tested whether anesthetic-induced preconditioning (APC) with isoflurane elicits competent protective mechanisms in hESC-derived cardiomyocytes against oxidative stress to be used as a model of human cardiomyocytes for studying preconditioning. METHODS: H1 hESC cell line was differentiated into cardiomyocytes using growth factors activin A and bone morphogenetic protein-4. Living ventricular hESC-derived cardiomyocytes were identified using a lentiviral vector expressing a reporter gene (enhanced green fluorescent protein) driven by a cardiac-specific human myosin light chain-2v promoter. Mitochondrial membrane potential, reactive oxygen species production, opening of mitochondrial permeability transition pore, and survival of hESC-derived cardiomyocytes were assessed using confocal microscopy. Oxygen consumption was measured in contracting cell clusters. RESULTS: Differentiation yielded a high percentage (∼85%) of cardiomyocytes in beating clusters that were positive for cardiac-specific markers and exhibited action potentials resembling those of mature cardiomyocytes. Isoflurane depolarized mitochondria, attenuated oxygen consumption, and stimulated generation of reactive oxygen species. APC protected these cells from oxidative stress-induced death and delayed mitochondrial permeability transition pore opening. CONCLUSIONS: APC elicits competent protective mechanisms against oxidative stress in hESC-derived cardiomyocytes, suggesting the feasibility to use these cells as a model of human cardiomyocytes for studying APC and potentially other treatments/diseases. Our differentiation protocol is very efficient and yields a high percentage of cardiomyocytes. These results also suggest a promising ability of APC to protect and improve engraftment of hESC-derived cardiomyocytes into the ischemic heart.