CaMKII inhibition mitigates ischemia/reperfusion-elicited calpain activation and the damage to membrane skeleton proteins in isolated rat hearts.

Ca2+/calmodulin-dependent protein kinase II (CaMKII) has been implicated in myocardial ischemia/reperfusion (IR) injury. The aim of this study was to determine the effect of CaMKII on the damage to membrane skeleton proteins, which is an important cause of IR injury. Isolated rat hearts were subjected to 45-min global ischemia/2-h reperfusion. Both KN-62 and KN-93 were used to inhibit CaMKII. Compared with controls, the hearts in the IR group exhibited remarkable myocardial injury area, LDH release, cell apoptosis and contractile dysfunction, along with an increase in the phosphorylation of CaMKII and its substrate phospholamban. Treatment with either KN-62 or KN-93 mitigated both the heart injury and the phosphorylation of CaMKII and phospholamban. The analysis of cell skeleton proteins revealed that IR injury resulted in an increase in the 150-kDa fragments resulting from the degradation of α-fodrin and dystrophin translocating from the sarcolemmal membrane to the cytosol and a decrease in the 220-kDa isoform of ankyrin-B. As expected, Evans blue dye staining showed an increase in membrane permeability or membrane rupture in the IR group. All of these alterations were alleviated by treatment with either KN-62 or KN-93. In addition, both KN-62 and KN-93 blocked the activity and membrane recruitment of calpain, a key protease responsible for destroying cell skeleton proteins during IR injury. In conclusion, our data provide evidence that damage to membrane skeleton proteins via calpain is a destructive downstream event of CaMKII activation in the setting of myocardial IR injury.

2,3,5,4'-Tetrahydroxystilbene-2-O-ß-D-glucoside protects murine hearts against ischemia/reperfusion injury by activating Notch1/Hes1 signaling and attenuating endoplasmic reticulum stress.

2,3,5,4'-Tetrahydroxystilbene-2-O-ß-D-glucoside (TSG) is a water-soluble active component extracted from Polygonum multiflorum Thunb. A number of studies demonstrate that TSG exerts cardioprotective effects. Since endoplasmic reticulum (ER) stress plays a key role in myocardial ischemia/reperfusion (MI/R)-induced cell apoptosis, we sought to determine whether modulation of the ER stress during MI/R injury was involved in the cardioprotective action of TSG. Male mice were treated with TSG (60 mg·kg-1·d-1, ig) for 2 weeks and then were subjected to MI/R surgery. Pre-administration of TSG significantly improved post-operative cardiac function, and suppressed MI/R-induced myocardial apoptosis, evidenced by the reduction in the myocardial apoptotic index, serum levels of LDH and CK after 6 h of reperfusion. TSG (0.1-1000 µmol/L) did not affect the viability of cultured H9c2 cardiomyoblasts in vitro, but pretreatment with TSG dose-dependently decreased simulated ischemia/reperfusion (SIR)-induced cell apoptosis. Furthermore, both in vivo and in vitro studies revealed that TSG treatment activated the Notch1/Hes1 signaling pathway and suppressed ER stress, as evidenced by increasing Notch1, Notch1 intracellular domain (NICD), Hes1, and Bcl-2 expression levels and by decreasing p-PERK/PERK ratio, p-eIF2α/eIF2α ratio, and ATF4, CHOP, Bax, and caspase-3 expression levels. Moreover, the protective effects conferred by TSG on SIR-treated H9c2 cardiomyoblasts were abolished by co-administration of DAPT (the Notch1 signaling inhibitor). In summary, TSG ameliorates MI/R injury in vivo and in vitro by activating the Notch1/Hes1 signaling pathway and attenuating ER stress-induced apoptosis.

Glutamate protects against Ca(2+) paradox-induced injury and inhibits calpain activity in isolated rat hearts.

This study determined the effects of glutamate on the Ca(2+) paradoxical heart, which is a model for Ca(2+) overload-induced injury during myocardial ischaemia and reperfusion, and evaluated its effect on a known mediator of injury, calpain. An isolated rat heart was retrogradely perfused in a Langendorff apparatus. Ca(2+) paradox was elicited via perfusion with a Ca(2+) -free Krebs-Henseleit (KH) solution for 3 minutes followed by Ca(2+) -containing normal KH solution for 30 minutes. The Ca(2+) paradoxical heart exhibited almost no viable tissue on triphenyltetrazolium chloride staining and markedly increased LDH release, caspase-3 activity, cytosolic cytochrome c content, and apoptotic index. These hearts also displayed significantly increased LVEDP and a disappearance of LVDP. Glutamate (5 and 20 mmol/L) significantly alleviated Ca(2+) paradox-induced injury. In contrast, 20 mmol/L mannitol had no effect on Ca(2+) paradox. Ca(2+) paradox significantly increased the extent of the translocation of µ-calpain to the sarcolemmal membrane and the proteolysis of α-fodrin, which suggests calpain activation. Glutamate also blocked these effects. A non-selective inhibitor of glutamate transporters, dl-TBOA (10 µmol/L), had no effect on control hearts, but it reversed glutamate-induced cardioprotection and reduction in calpain activity. Glutamate treatment significantly increased intracellular glutamate content in the Ca(2+) paradoxical heart, which was also blocked by dl-TBOA. We conclude that glutamate protects the heart against Ca(2+) overload-induced injury via glutamate transporters, and the inhibition of calpain activity is involved in this process.

Berberine protects rat heart from ischemia/reperfusion injury via activating JAK2/STAT3 signaling and attenuating endoplasmic reticulum stress.

AIM: Berberine (BBR), an isoquinoline-derived alkaloid isolated from Rhizoma coptidis, exerts cardioprotective effects. Because endoplasmic reticulum (ER) stress plays a pivotal role in myocardial ischemia/reperfusion (MI/R)-induced apoptosis, it was interesting to examine whether the protective effects of BBR resulted from modulating ER stress levels during MI/R injury, and to define the signaling mechanisms in this process. METHODS: Male rats were treated with BBR (200 mg · kg(-1) · d(-1), ig) for 2 weeks, and then subjected to MI/R surgery. Cardiac dimensions and function were assessed using echocardiography. Myocardial infarct size and apoptosis was examined. Total serum LDH levels and CK activities, superoxide production, MDA levels and the antioxidant SOD activities in heart tissue were determined. An in vitro study was performed on cultured rat embryonic myocardium-derived cells H9C2 exposed to simulated ischemia/reperfusion (SIR). The expression of apoptotic, ER stress-related and signaling proteins were assessed using Western blot analyses. RESULTS: Pretreatment with BBR significantly reduced MI/R-induced myocardial infarct size, improved cardiac function, and suppressed myocardial apoptosis and oxidative damage. Furthermore, pretreatment with BBR suppressed MI/R-induced ER stress, evidenced by down-regulating the phosphorylation levels of myocardial PERK and eIF2α and the expression of ATF4 and CHOP in heart tissues. Pretreatment with BBR also activated the JAK2/STAT3 signaling pathway in heart tissues, and co-treatment with AG490, a specific JAK2/STAT3 inhibitor, blocked not only the protective effects of BBR, but also the inhibition of BBR on MI/R-induced ER stress. In H9C2 cells, treatment with BBR (50 µmol/L) markedly reduced SIR-induced cell apoptosis, oxidative stress and ER stress, which were abolished by transfection with JAK2 siRNA. CONCLUSION: BBR ameliorates MI/R injury in rats by activating the AK2/STAT3 signaling pathway and attenuating ER stress-induced apoptosis.

Effects of Sevoflurane Inhalation During Cardiopulmonary Bypass on Pediatric Patients: A Randomized Controlled Clinical Trial.

The effects of sevoflurane inhalation during cardiopulmonary bypass (CPB) on postoperative courses and serum cardiac troponin I (cTnI) concentrations in pediatric patients undergoing cardiac surgery have not been extensively investigated. In this single-center, prospective, randomized trial, an anesthetic regimen containing 2% sevoflurane used throughout the CPB process was compared with a total intravenous anesthesia (TIVA) regimen. One hundred and three patients undergoing congenital heart defect repair with CPB were included in this prospective randomized controlled study. They were randomized into two groups: the sevoflurane group, who received 2% sevoflurane during CPB via an oxygenator, and the control group, who received only an oxygen-air mixture. The pre- and intra-operative parameters were comparable between the two groups. There was a slight but significant increase of arterial diastolic pressure in the sevoflurane group immediately after CPB compared with control patients (46.9 ± 9.3 mm Hg vs. 43.6 ± 8.9 mm Hg; p = 0.033). There was no death in either group. The postoperative ventilation time (in mean [95% confidence interval]) was shorter in the sevoflurane group than that in the control group (26.1 [19.2, 33.0] h vs. 37.7 [24.4, 50.9] h; p = 0.014). The postoperative ICU time, hospital days, and serial serum cTnI concentrations were not significantly different between the two groups. Inhalation of 2% sevoflurane during CPB is beneficial to the recovery of pediatric patients undergoing cardiac surgery but has no significant effect on postoperative cTnI release.

The Blockade of Transmembrane Cl⁻ Flux Mitigates I/R-Induced Heart Injury via the Inhibition of Calpain Activity.

AIMS: The aim of this study was to determine whether calpain is involved in Cl(-)-induced myocardial ischemia/reperfusion (I/R) injury. METHODS: Isolated rat hearts were subjected to either 45 min of global no-flow ischemia followed by reperfusion or successive perfusion with Ca(2+)-free KH solution for 3 min and normal KH solution for 30 min, also known as Ca(2+) paradox. RESULTS: The hearts in the I/R group exhibited increases in myocardial injury area, LDH release, caspase 3 activity and apoptotic indices and a marked decline in cardiac performance. As was the case regarding the effects of MDL 28170, an inhibitor of calpain, treatment with 5 µM NPPB, 5 µM DIDS and low Cl(-) significantly attenuated cardiac injury. Moreover, each of the treatments significantly protected against Ca(2+) overload-induced injury in the setting of Ca(2+) paradox. The Western blot and immunofluorescence data revealed that there was an increase in the percentages of calpain membrane-positive cells and the numbers of fragments resulting from the calpain-mediated proteolysis of α-fodrin in both the I/R and the Ca(2+) paradox, indicating that the activation of calpain occurred. More importantly, these effects were mitigated by the blockade of transmembrane Cl(-) flux, as was accomplished via MDL 28170. CONCLUSION: Our results provide evidence that the blockade of transmembrane Cl(-) flux mitigates I/R-induced cardiac injury via the inhibition of calpain activity. They also indicate that intracellular Ca(2+) overload regulates calpain activation in the setting of Cl(-)-induced injury.

The myocardial protective effects of a moderate-potassium blood cardioplegia in pediatric cardiac surgery: a randomized controlled trial.

BACKGROUND: We investigated the myocardial protective effect of a moderate-potassium cold blood cardioplegic solution (K+, 10 mmol/L) in pediatric cardiac surgery. METHODS: Sixty-eight pediatric patients with congenital heart disease and undergoing open heart surgery with cardiopulmonary bypass were randomly allocated to the high potassium (HP [K+, 20 mmol/L, n=31]) cold blood cardioplegia group or the moderate potassium (MP [K+, 10 mmol/L, n=37]) cold blood cardioplegia group. Heart arresting time, rhythm recovery time, mechanical ventilation time, inotropic drug use in the intensive care unit, perioperative serum cardiac troponin I concentrations, morbidities, and mortalities were compared between the two groups. RESULTS: There were no differences in cardiopulmonary bypass time, aorta cross-clamping time, cardioplegia volume, lowest body temperature during cardiopulmonary bypass, total volume of cardioplegia delivered, hematocrit value, and fluid output during the operation between the two groups. However, there was a longer arresting time and a shorter rhythm recovery time in the MP group (35.6±2.4 s, and 30.8±3.1 s) when compared with that in the HP group (24.7±2.7 s, and 42.0±4.0 s, both p<0.05). The total mediastinal drainage volume, the length of stay in the intensive care unit, the postoperative inotropic drug use, and the postoperative hospital time were similar between the two groups, but the number of patients with a long postoperative mechanical ventilation time (>24 hours) in the MP group (6 of 36) was less than that in HP group (13 of 30; p<0.05). At 1 hour, 3 hours, and 6 hours after myocardium reperfusion, the serum concentration of cardiac troponin I significantly decreased in the MP group (in ng/mL: 15.18±3.57, 24.83±4.91, and 19.62±3.93, respectively) when compared with that in the HP group (in ng/mL: 32.67±5.31, 39.26±7.43, and 30.52±5.17, respectively, p<0.05). CONCLUSIONS: The present study demonstrated that the M (10 mmol/L) cold blood cardioplegia formula is associated with better myocardial protective effects when compared with conventional HP cardioplegia in pediatric patients.

The association between OGG1 Ser326Cys polymorphism and lung cancer susceptibility: a meta-analysis of 27 studies.

BACKGROUND: Numerous studies have investigated association of OGG1 Ser326Cys polymorphism with lung cancer susceptibility; however, the findings are inconsistent. Therefore, we performed a meta-analysis based on 27 publications encompass 9663 cases and 11348 controls to comprehensively evaluate such associations. METHODS: We searched publications from MEDLINE and EMBASE which were assessing the associations between OGG1 Ser326Cys polymorphism and lung cancer risk. We calculated pooled odds ratio (OR) and 95% confidence interval (CI) by using either fixed-effects or random-effects model. We used genotype based mRNA expression data from HapMap for SNP rs1052133 in normal cell lines among 270 subjects with four different ethnicities. RESULTS: The results showed that individuals carrying the Cys/Cys genotype did not have significantly increased risk for lung cancer (OR = 1.15, 95% CI = 0.98-1.36) when compared with the Ser/Ser genotype; similarly, no significant association was found in recessive, dominant or heterozygous co-dominant model (Ser/Cys vs. Cys/Cys). However, markedly increased risks were found in relatively large sample size (Ser/Ser vs. Cys/Cys: OR = 1.29, 95% CI = 1.13-1.48, and recessive model: OR = 1.19, 95% CI = 1.07-1.32). As to histological types, we found the Cys/Cys was associated with adenocarcinoma risk (Ser/Ser vs. Cys/Cys: OR = 1.32, 95% CI = 1.12-1.56; Ser/Cys vs. Cys/Cys: OR = 1.19, 95% CI = 1.04-1.37, and recessive model OR = 1.23, 95% CI = 1.08-1.40). No significant difference of OGG1 mRNA expression was found among genotypes between different ethnicities. CONCLUSIONS: Despite some limitations, this meta-analysis established solid statistical evidence for an association between the OGG1 Cys/Cys genotype and lung cancer risk, particularly for studies with large sample size and adenocarcinoma, but this association warrants additional validation in larger and well designed studies.

Calpain inhibitor MDL 28170 protects against the Ca2+ paradox in rat hearts.

The calcium paradox represents an important model in which to study myocardial injuries due to intracellular Ca(2+) overload. In a previous study, calpain was transiently activated in Ca(2+) -paradoxic hearts. The aim of the present study was to determine the role of calpain in myocardial dysfunction in hearts subjected to the Ca(2+) paradox and to elucidate the underlying mechanisms. Rat hearts were isolated, Langendorff perfused and subjected to the Ca(2+) paradox, which was induced by 3 min Ca(2+) depletion followed by 30 min Ca(2+) repletion, in the presence or absence of the calpain inhibitor 10 umol/L MDL 28170. Cardiac function was evaluated. Furthermore, cell death and the degradation of troponin I (TnI) were assessed and calpain activity was determined by measurement of the α-fodrin fragment and confocal image analysis. Upon Ca(2+) repletion, the hearts immediately deteriorated, exhibiting a marked depression in cardiac function and an enlarged myocardial injury area. This was accompanied by significant increases in lactate dehydrogenase, mitochondrial release of cytochrome c, the apoptotic index and degraded TnI. These changes were significantly inhibited by MDL 28170, with the exception of TnI degradation. Compared with the control group, Ca(2+) -paradoxic hearts showed a marked increase in cleaved 150 kDa fragments resulting from specific calpain-mediated proteolysis of α-fodrin. This effect was attenuated by MDL 28170. Confocal image analysis revealed the translocation of both µ- and m-calpain to the sarcolemmal membrane in Ca(2+) -paradoxic hearts, indicating increased activity of both isoforms. The results suggest that the Ca(2+) paradox promotes calpain activity, leading to necrosis, apoptosis and myocardial dysfunction.

Different roles for contracture and calpain in calcium paradox-induced heart injury.

The Ca(2+) paradox represents a good model to study Ca(2+) overload injury in ischemic heart diseases. We and others have demonstrated that contracture and calpain are involved in the Ca(2+) paradox-induced injury. This study aimed to elucidate their roles in this model. The Ca(2+) paradox was elicited by perfusing isolated rat hearts with Ca(2+)-free KH media for 3 min or 5 min followed by 30 min of Ca(2+) repletion. The LVDP was measured to reflect contractile function, and the LVEDP was measured to indicate contracture. TTC staining and the quantification of LDH release were used to define cell death. Calpain activity and troponin I release were measured after Ca(2+) repletion. Ca(2+) repletion of the once 3-min Ca(2+) depleted hearts resulted in almost no viable tissues and the disappearance of contractile function. Compared to the effects of the calpain inhibitor MDL28170, KB-R7943, an inhibitor of the Na(+)/Ca(2+) exchanger, reduced the LVEDP level to a greater extent, which was well correlated with improved contractile function recovery and tissue survival. The depletion of Ca(2+) for 5 min had the same effects on injury as the 3-min Ca(2+) depletion, except that the LVEDP in the 5-min Ca(2+) depletion group was lower than the level in the 3-min Ca(2+) depletion group. KB-R7943 failed to reduce the level of LVEDP, with no improvement in the LVDP recovery in the hearts subjected to the 5-min Ca(2+) depletion treatment; however, KB-R7943 preserved its protective effects in surviving tissue. Both KB-R7943 and MDL28170 attenuated the Ca(2+) repletion-induced increase in calpain activity in 3 min or 5 min Ca(2+) depleted hearts. However, only KB-R7943 reduced the release of troponin I from the Ca(2+) paradoxic heart. These results provide evidence suggesting that contracture is the main cause for contractile dysfunction, while activation of calpain mediates cell death in the Ca(2+) paradox.

[Clinical follow-up of staged hybrid approach for patients with ventricular septal defects combined with patent ductus arteriosus and pulmonary hypertension].

OBJECTIVE: To evaluate the safety and efficacy of staged hybrid approach in treating ventricular septal defect (VSD) patients combined with patent ductus arteriosus (PDA) and pulmonary artery hypertension (PAH). METHODS: From July 2004 to July 2009, 22 VSD patients with PDA and PAH were enrolled and received staged hybrid approach treatment (transcatheter PDA occlusion and elective open surgery for VSD several days after PDA occlusion). All patients were followed up to examine rhythm change, residual shunt, shape of occlude, possible valve regurgitation, and aortic stenosis by echocardiography. RESULTS: After transcatheter PDA occlusion, pulmonary arterial systolic pressure decreased from (76.2 ± 25.8) mm Hg (1 mm Hg = 0.133 kPa) to (55.4 ± 20.6) mm Hg (P = 0.005), mean pulmonary artery pressure decreased from (53.5 ± 23.5) mm Hg to (36.2 ± 17.8) mm Hg (P = 0.049), total pulmonary resistance decreased from (8.2 ± 4.9) wood units to (6.9 ± 4.3) wood units (P = 0.037), and pulmonary-to-systemic flow ratio (Qp/Qs) increased from 2.8 ± 2.3 to 3.4 ± 1.7 (P = 0.045) post transcatheter interventional PDA occlusion. After VSD repair, pulmonary arterial systolic pressure decreased from (64.5 ± 22.3) mm Hg to (43.1 ± 18.9) mm Hg (P = 0.001) and mean pulmonary artery pressure decreased from (40.2 ± 18.7) mm Hg to (29.5 ± 15.8) mm Hg (P = 0.040). There was no death or right heart failure during the follow-up. CONCLUSION: Staged hybrid approach is an effective and safe strategy for treating VSD patients with PDA and PAH.

The myocardial protective effects of a moderate-potassium adenosine-lidocaine cardioplegia in pediatric cardiac surgery.

OBJECTIVES: We sought to evaluate a moderate-potassium cardioplegic solution using adenosine and lidocaine as the arresting and protecting cardioprotective combination in pediatric cardiac surgery. METHODS: One hundred thirty-four patients with congenital heart disease were randomly allocated to one of 3 groups according to the cardioplegia formula used: the high-potassium (HP) group (K(+), 20 mmol/L), 46 patients; the high-potassium adenosine-lidocaine (HPAL) group (K(+), 20 mmol/L; adenosine, 0.7 mmol/L; and lidocaine, 0.7 mmol/L), 44 patients; and the moderate-potassium adenosine-lidocaine (MPAL) group (K(+), 10 mmol/L; adenosine, 0.7 mmol/L; and lidocaine, 0.7 mmol/L), 44 patients. Hemodynamic data during the operation and postoperative data were recorded. Serum cardiac troponin I concentrations were examined at the time points of before cardiopulmonary bypass and 1, 3, 6, 12, and 24 hours after aortic crossclamp removal. RESULTS: At the end of cardiopulmonary bypass and modified ultrafiltration, the systolic and pulse pressures of the MPAL group were significantly increased compared with the respective values of the HP group. At the time points of 1 to 12 hours after reperfusion, the levels of serum cardiac troponin I were significantly decreased in the MPAL group compared with those in the HP and HPAL groups. CONCLUSIONS: The MPAL cardioplegia formula was associated with better myocardial protective effects.

Tanshinone IIA: a new activator of human cardiac KCNQ1/KCNE1 (I(Ks)) potassium channels.

Tanshinone IIA, one of the main active components from Chinese herb Danshen, is widely used to treat cardiovascular diseases including arrhythmia in Asian countries especially in China. However, the mechanisms underlying its anti-arrythmia effects are not clear. In this study we investigate the effects of tanshinone IIA on human KCNQ1/KCNE1 potassium channels (I(Ks)), human ether-a-go-go-related gene potassium channels (hERG), Kv1.5 potassium channels, inward rectifier potassium channels (I(K1)) expressed in HEK 293 cells using patch clamp technique. Tanshinone IIA potently and reversibly enhanced the amplitude of I(Ks) in a concentration dependent manner with an EC(50) of 64.5 microM, accelerated the activation rate of I(Ks) channels, decelerated their deactivation and shifted the voltage dependence of I(Ks) activation to negative direction. Isoproteronol, a stimulator of beta-adrenergic receptor, at 1 microM and sodium nitroprusside (SNP), a NO donor, at 1 mM, had no significant effects on the enhancement of I(Ks) by 30 microM tanshinone IIA. N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide (H89), a selective protein kinase A inhibitor, at 0.1 microM and 1H-(1,2,4)oxadiazolo(4,3-a)quinoxalin-1-one (ODQ), a selective nitric oxide-sensitive guanylyl cyclase inhibitor, at 10 microM, also had no significant effects on the enhancement of I(Ks) by 30 microM tanshinone IIA. Tanshinone IIA did not affect expressed hERG channels, Kv1.5 channels and I(K1) channels. These results indicate that tanshinone IIA directly and specifically activate human cardiac KCNQ1/KCNE1 potassium channels (I(Ks)) in HEK 293 cell through affecting the channels' kinetics.

Postconditioning the human heart with adenosine in heart valve replacement surgery.

BACKGROUND: The effect of adenosine postconditioning on myocardial protection in cardiac surgery remains uncertain. The present study evaluated the safety, feasibility, and beneficial effect of adenosine postconditioning as an adjunct to predominantly used cold-blood cardioplegic myocardial protection method in the setting of heart valve replacement operations. METHODS: Sixty patients with rheumatic heart valve disease undergoing heart valve replacement operations were randomized to an adenosine (1.5 mg/kg) or saline (as control) bolus injection through an arterial catheter immediately after the aorta cross-clamp was removed. The surgical indications were similar in both groups, and heart valve replacement was successful in all patients. RESULTS: The extubation time and postoperative hospital time were similar in both groups. Compared with the control group, however, the inotrope scores in the intensive care unit (ICU) were much lower (p < 0.01), and the ICU time was significantly shorter (p < 0.05) in adenosine group. More important, cardiac troponin I release was less in the adenosine group, especially at 12 and 24 hours after reperfusion (p < 0.01), and total cardiac troponin I release estimated with the area under curve was also significantly reduced during the first 24 hours after reperfusion (p < 0.01). CONCLUSIONS: A 1.5-mg/kg bolus administration of adenosine through an arterial catheter immediately after the aorta cross-clamp is removed is feasible and well tolerated in patients undergoing heart valve replacement. An adenosine postconditioning adjunct to high potassium cold blood myocardial protection is related to less troponin I release, less inotropic drug use, and shorter ICU stay.

Histological/biological characterization of decellularized bovine jugular vein.

Several deficiencies in currently available right ventricular valved conduits make them problematic for use in infants and children. A solution would be to develop a tissue-engineered valved conduit containing autologous cells. A method was devised to produce a decellularized bovine matrix scaffold for developing a tissue-engineered right ventricular valved conduit. Fresh bovine jugular veins were treated with sodium deoxycholate and Triton X-100. The major structural proteins of the fresh and decellularized jugular venous valves and vessel walls were detected by histological methods. Thickness, water absorption rate, water maintenance rate, disruption strength, and extensibility were determined. Circumferential and radial specimens of valves and vessel walls were subjected to tensile testing. Histological analysis showed that no cell fragments were retained within the decellularized matrix scaffold and the major structural proteins had been retained intact. There were no significant differences in thickness, rates of absorption and maintenance of water, disruption strength, and extensibility between the decellularized and fresh veins. It was concluded that this treatment can successfully remove cellular components while maintaining the major structural components and the histological and biological properties of bovine jugular veins.

Role of reverse mode Na+/Ca2+ exchanger in the cardioprotection of metabolic inhibition preconditioning in rat ventricular myocytes.

This study determined the role of the reverse mode Na(+)/Ca(2+) exchanger (NCX) in cardioprotection of metabolic inhibition preconditioning in isolated ventricular myocyctes. Activity of the reverse mode NCX was assessed by changes of [Ca(2+)](i) upon withdrawal of extracellular Na(+). [Ca(2+)](i) was measured by spectrofluorometry, using Fura-2 as Ca(2+) indicator. The amplitude of contraction and exclusion of trypan blue by myocytes served as indices of contractile function and viability, respectively. Firstly, NCX activity significantly decreased during simulated reperfusion after severe metabolic inhibition (index ischaemia) in myocytes subjected to metabolic inhibition preconditioning. This inhibitory effect on NCX activity correlated with the enhancing effect of metabolic inhibition preconditioning on cell viability following ischaemic insult. Treatment myocytes with E4031, an activator of reverse mode NCX, during index ischaemia and reperfusion attenuated the enhancing effects of metabolic inhibition preconditioning on cell contraction and viability. Secondly, NCX activity was significantly higher at the end of metabolic inhibition preconditioning. More importantly, E4031 pretreatment mimicked the beneficial effects of metabolic inhibition preconditioning in myocytes and ischaemic preconditioning in the isolated perfused heart, respectively, and these effects were abolished by KB-R7943, an inhibitor of reverse mode NCX. The results indicate that increased reverse mode NCX activity during preconditioning triggered cardioprotection, and reduced reverse mode NCX activity during reperfusion after index ischaemia conferred cardioprotection.

[Construction of a tissue-engineered valve with decellular porcine aortic valve scaffold in the abdominal aorta of canine].

OBJECTIVE: To explore an experimental method for construction of tissue-engineered heart valve (TEHV) in canine abdominal aorta. METHODS: The decellular porcine aortic valve (PAV) leaflets seeded with canine vessel interstitial cells and endothelial cells (ECs) were implanted into 6 canine abdominal aortas. Valve specimens were obtained respectively at the end of 4, 6, 8 and 10 weeks after implantation were studied for morphology, histology and immunohistochemistry. RESULTS: (1) After 4 weeks implantation, multiple layers of cells grew into peripheral portion of valve scaffold, while new extracellular matrix appeared, and original scaffold tissue was partially absorbed. (2) At the end of 10th week after implantation, the decellular PAV scaffold disappeared completely and was substituted by recipient cells and new extracellular matrix. The interstitial cells in matrix was mainly consisted of fibroblasts and myofibroblast. The matrix was mainly composed by type I, III collagen, some elastic fibers with neutral and acid mucopolysaccharide. (3) Surface of valve leaflets were covered with endothelial cells. CONCLUSIONS: (1) TEHV is primarily constructed with recellularized PAV after implantation into canine abdominal aorta for 10 weeks. (2) Heterotopic implantation into the abdominal aorta is an alternative experimental procedure to study the TEHV.

[Construction and evaluation of the property of decellular porcine aortic valve].

OBJECTIVE: To construct decellular porcine aortic valve (PAV) and to observe the existence of porcine endogenous retrovirus (PERV) and valve scaffold structure before and after implantation. METHODS: (1) Porcine aortic valve was obtained. The cellular components of PAV were completely removed by using detergent and nucleotidase solution combined with alteration of osmosis. (2) The decellular underwent HE staining and light microscopy and detection of its physical and chemical properties. (3) 20 pieces of decellular PAV were implanted into dogs. On e month later blood samples of the dogs were collected. PCR and RT-PCR were used to detect the PERV expression in 20 samples of pig's peripheral blood, 20 fresh PAVs, cultured pig kidney cells of the PK15 line (as positive control), decellular PAVs implanted into the dogs, and 10 samples of dogs' peripheral blood. (4) Small pieces of decellular PAVs were implanted into the subcutaneous tissues of 6 rabbits at the back, 6 pieces for one rabbit, and then extracted by the ends of the 4th, 6th, 8th and 10th week respectively after implantation to undergo HE staining and light microscopy. RESULTS: (1) Almost all cellular components in the PAVs had been removed after decellularization; the soluble protein contents lost markedly [(0.238 +/- 0.038)% vs. (0.484 +/- 0.116)%]; the water content of the decellular tissues increased significantly [(92.16 +/- 1.48)% vs. (89.2 +/- 1.55)%]; however, the decellular PAVs still maintained their excellent fibrous scaffold structure, and their shrinkage temperature and tension at fracture were not significantly changed [(72.0 +/- 0.7) degrees C vs. (71.2 +/- 0.8) degrees C, and (448.7 +/- 18.65)g/mm2 vs. (540.7 +/- 19.46)g/mm2 respectively]. (2) Agarose gel electrophoresis of all fresh PAVs and porcine peripheral blood samples showed a 219 bp band, which was 90% to 97% homologous with PERV-C gene, and the sequence of which is published in Medline. No 219 bp amplified band was found in all decellular PAVs and the peripheral blood samples of the dogs implanted with decellular PAV one month after the implantation. (3) The PAVs implanted in rabbit body showed very slight tissue reaction. Neutrophil, lymphocyte and plasmacyte infiltration were seen 4 weeks after; such inflammatory cell infiltration decreased markedly and the peripheral portions of the decellular PAVs began to be absorbed by the end of the 6th week after implantation. The decellular PAVs were completely absorbed without fibrosis or scar formation in the implantation area by the end of the 10th week. CONCLUSION: (1) The cellular components of PAV can be completely removed, the excellent fibrous scaffold structure and mechanical strength of aorta valve can be maintained, and the antigenicity is very weak. Subcutaneous implantation investigation shows that decellular PAV is an absorbable and degradable biological material. (2) There is PERV-C in PAV that can be removed after decellularization. PERV-C reaction is negative in the peripheral blood samples of the recipients implanted with decellular PAV.