Coronary Flow Reserve in the Remote Myocardium Predicts Left Ventricular Remodeling Following Acute Myocardial Infarction

Purpose

Coronary flow reserve (CFR) in the non-infarcted myocardium is often impaired following acute myocardial infarction (AMI). However, the clinical significance of CFR in the non-infarcted myocardium is not fully understood. The objective of the present study was to assess whether a relationship exists between CFR and left ventricular remodeling following AMI.

Materials and Methods

We enrolled 18 consecutive patients undergoing coronary intervention. Heart function was analyzed using real-time myocardial contrast echocardiography at one week and six months after coronary angioplasty. Ten subjects were enrolled as the control group and were examined using the same method at the same time to assess CFR. Cardiac troponin I (cTnI) levels were routinely analyzed to estimate peak concentration.

Results

CFR was 1.55±0.11 in the infarcted zone and 2.05±0.31 in the remote zone (p<0.01) at one week following AMI. According to CFR values in the remote zone, all patients were divided into two groups: Group I (CFR <2.05) and Group II (CFR >2.05). The levels of cTnI were higher in Group I compared to Group II on admission (36.40 vs. 21.38, p<0.05). Furthermore, left ventricular end diastolic volume was higher in Group I compared to Group II at six months following coronary angioplasty.

Conclusion

Microvascular dysfunction is commonly observed in the remote myocardium. The CFR value accurately predicts adverse ventricular remodeling following AMI.     

Tension cost correlates with mechanical and biochemical parameters in different myocardial contractility conditions

OBJECTIVES:

Tension cost, the ratio of myosin ATPase activity to tension, reflects the economy of tension development in the myocardium. To evaluate the mechanical advantage represented by the tension cost, we studied papillary muscle contractility and the activity of myosin ATPase in the left ventricles in normal and pathophysiological conditions.

METHODS:

Experimental protocols were performed using rat left ventricles from: (1) streptozotocin-induced diabetic and control Wistar rats; (2) N-nitro-L-arginine methyl ester (L-NAME) hypertensive and untreated Wistar rats; (3) deoxycorticosterone acetate (DOCA) salt-treated, nephrectomized and salt- and DOCA-treated rats; (4) spontaneous hypertensive rats (SHR) and Wistar Kyoto (WKY) rats; (5) rats with myocardial infarction and sham-operated rats. The isometric force, tetanic tension, and the activity of myosin ATPase were measured.

RESULTS:

The results obtained from infarcted, diabetic, and deoxycorticosterone acetate-salt-treated rats showed reductions in twitch and tetanic tension compared to the control and sham-operated groups. Twitch and tetanic tension increased in the N-nitro-L-arginine methyl ester-treated rats compared with the Wistar rats. Myosin ATPase activity was depressed in the infarcted, diabetic, and deoxycorticosterone acetate salt-treated rats compared with control and sham-operated rats and was increased in N-nitro-L-arginine methyl ester-treated rats. These parameters did not differ between SHR and WKY rats. In the studied conditions (e.g., post-myocardial infarction, deoxycorticosterone acetate salt-induced hypertension, chronic N-nitro-L-arginine methyl ester treatment, and streptozotocin-induced diabetes), a positive correlation between force or plateau tetanic tension and myosin ATPase activity was observed.

CONCLUSION:

Our results suggest that the myocardium adapts to force generation by increasing or reducing the tension cost to maintain myocardial contractility with a better mechanical advantage.     

High admission levels of γ-glutamyltransferase predict poor myocardial perfusion after primary percutaneous intervention

OBJECTIVE:

This retrospective study aimed to investigate the relationship between admission levels of serum γ-glutamyltransferase and poor myocardial perfusion after primary percutaneous coronary intervention in patients with acute myocardial infarction.

INTRODUCTION:

Reperfusion injury caused by free radical release and increased oxidative stress is responsible for the pathophysiology of the no-reflow phenomenon in patients with acute myocardial infarction undergoing primary percutaneous coronary intervention. Serum γ-glutamyltransferase is an established marker of increased oxidative stress.

METHODS:

The study population consisted of 80 patients (64 men and 16 women, mean age = 67.5±6.6 years) with thrombolysis in myocardial infarction 0/1 flow pre-procedurally. The patients were divided into two groups according to thrombolysis in myocardial perfusion grades that were assessed immediately following primary percutaneous coronary intervention. The two groups (group 1 and group 2) each consisted of 40 patients with thrombolysis in myocardial perfusion grades 0-1 and thrombolysis in myocardial perfusion grades 2-3, respectively.

RESULTS:

Admission pain to balloon time, γ-glutamyltransferase and creatine kinase-MB isoenzyme levels of group 1 patients were significantly higher than those of group 2 patients. Pain to balloon time, γ-glutamyltransferase, peak creatine kinase-MB isoenzyme, low left ventricular ejection fraction and poor pre-procedural thrombolysis in myocardial infarction grade were significantly associated with poor myocardial perfusion by univariate analysis. However, only pain to balloon time and γ-glutamyltransferase levels showed a significant independent association with poor myocardial perfusion by backward logistic regression analysis. Adjusted odds ratios were calculated as 4.92 for pain to balloon time and 1.13 for γ-glutamyltransferase.

CONCLUSION:

High admission γ-glutamyltransferase levels are associated with poor myocardial perfusion in patients with acute myocardial infarction undergoing primary percutaneous coronary intervention, particularly in patients with prolonged pain to balloon time.     

Cardioprotection conferred by exercise training is blunted by blockade of the opioid system

OBJECTIVES:

To investigate the effect of opioid receptor blockade on the myocardial protection conferred by chronic exercise and to compare exercise training with different strategies of myocardial protection (opioid infusion and brief periods of ischemia-reperfusion) preceding irreversible left anterior descending coronary ligation.

INTRODUCTION:

The acute cardioprotective effects of exercise training are at least partly mediated through opioid receptor-dependent mechanisms in ischemia-reperfusion models.

METHODS:

Male Wistar rats (n = 76) were randomly assigned to 7 groups: (1) control; (2) exercise training; (3) morphine; (4) intermittent ischemia-reperfusion (three alternating periods of left anterior descending coronary occlusion and reperfusion); (5) exercise training+morphine; (6) naloxone (a non-selective opioid receptor blocker) plus morphine; (7) naloxone before each exercise-training session. Myocardial infarction was established in all groups by left anterior descending coronary ligation. Exercise training was performed on a treadmill for 60 minutes, 5 times/week, for 12 weeks, at 60% peak oxygen (peak VO₂). Infarct size was histologically evaluated.

RESULTS:

Exercise training significantly increased exercise capacity and ΔVO₂ (VO₂ peak − VO₂ rest) (p<0.01 vs. sedentary groups). Compared with control, all treatment groups except morphine plus naloxone and exercise training plus naloxone showed a smaller infarcted area (p<0.05). No additional decrease in infarct size occurred in the exercise training plus morphine group. No difference in myocardial capillary density (p = 0.88) was observed in any group.

CONCLUSIONS:

Exercise training, morphine, exercise training plus morphine and ischemia-reperfusion groups had a smaller infarcted area than the control group. The effect of chronic exercise training in decreasing infarct size seems to occur, at least in part, through the opioid receptor stimulus and not by increasing myocardial perfusion.     

Short-term diabetes attenuates left ventricular dysfunction and mortality rates after myocardial infarction in rodents

OBJECTIVES:

To investigate the effects of hyperglycemia on left ventricular dysfunction, morphometry, myocardial infarction area, hemodynamic parameters, oxidative stress profile, and mortality rate in rats that had undergone seven days of myocardial infarction.

INTRODUCTION:

Previous research has demonstrated that hyperglycemia may protect the heart against ischemic injury.

METHODS:

Male Wistar rats were divided into four groups: control-sham, diabetes-sham, myocardial infarction, and diabetes + myocardial infarction. Myocardial infarction was induced 14 days after diabetes induction. Ventricular function and morphometry, as well as oxidative stress and hemodynamic parameters, were evaluated after seven days of myocardial infarction.

RESULTS:

The myocardial infarction area, which was similar in the infarcted groups at the initial evaluation, was reduced in the diabetes + myocardial infarction animals (23±3%) when compared with the myocardial infarction (42±7%, p<0.001) animals at the final evaluation. The ejection fraction (22%, p = 0.003), velocity of circumferential fiber shortening (30%, p = 0.001), and left ventricular isovolumetric relaxation time (26%, p = 0.002) were increased in the diabetes + myocardial infarction group compared with the myocardial infarction group. The diabetes-sham and diabetes + myocardial infarction groups displayed increased catalase concentrations compared to the control-sham and myocardial infarction groups (diabetes-sham: 32±3; diabetes + myocardial infarction: 35±0.7; control-sham: 12±2; myocardial infarction: 16±0.1 pmol min^-1 mg^-1 protein). The levels of thiobarbituric acid-reactive substances were reduced in the diabetes-sham rats compared to the control-sham rats. These positive adaptations were reflected in a reduced mortality rate in the diabetes + myocardial infarction animals (18.5%) compared with the myocardial infarction animals (40.7%, p = 0.001).

CONCLUSIONS:

These data suggest that short-term hyperglycemia initiates compensatory mechanisms, as demonstrated by increased catalase levels, which culminate in improvements in the ventricular response, infarcted area, and mortality rate in diabetic rats exposed to ischemic injury.     

Diagnosis of Myocardial Viability by Fluorodeoxyglucose Distribution at the Border Zone of a Low Uptake Region

Purpose

In cardiac 2-[F-18]fluoro-2-deoxy-D-glucose (FDG)-positron emission tomography (PET) examination, interpretation of myocardial viability in the low uptake region (LUR) has been difficult without additional perfusion imaging. We evaluated distribution patterns of FDG at the border zone of the LUR in the cardiac FDG-PET and established a novel parameter for diagnosing myocardial viability and for discriminating the LUR of normal variants.

Materials and Methods

Cardiac FDG-PET was performed in patients with a myocardial ischemic event (n = 22) and in healthy volunteers (n = 22). Whether the myocardium was not a viable myocardium (not-VM) or an ischemic but viable myocardium (isch-VM) was defined by an echocardiogram under a low dose of dobutamine infusion as the gold standard. FDG images were displayed as gray scaled-bull''s eye mappings. FDG-plot profiles for LUR (= true ischemic region in the patients or normal variant region in healthy subjects) were calculated. Maximal values of FDG change at the LUR border zone (a steepness index; S_max scale/pixel) were compared among not-VM, isch-VM, and normal myocardium.

Results

S_max was significantly higher for n-VM compared to those with isch-VM or normal myocardium (ANOVA). A cut-off value of 0.30 in Smax demonstrated 100% sensitivity and 83% specificity for diagnosing n-VM and isch-VM. S_max less than 0.23 discriminated LUR in normal myocardium from the LUR in patients with both n-VM and isch-VM with a 94% sensitivity and a 93% specificity.

Conclusion

S_max of the LUR in cardiac FDG-PET is a simple and useful parameter to diagnose n-VM and isch-VM, as well as to discriminate thr LUR of normal variants.     

Previous exercise training increases levels of PPAR-α in long-term post-myocardial infarction in rats,which is correlated with better inflammatory response

OBJECTIVE:

Exercise is a protective factor for cardiovascular morbidity and mortality, with unclear mechanisms. Changing the myocardial metabolism causes harmful consequences for heart function and exercise contributes to metabolic adjustment modulation. Peroxisome proliferator-activated receptors (PPARs) are also myocardium metabolism regulators capable of decreasing the inflammatory response. We hypothesized that PPAR-α is involved in the beneficial effects of previous exercise on myocardial infarction (MI) and cardiac function, changing the expression of metabolic and inflammatory response regulators and reducing myocardial apoptosis, which partially explains the better outcome.

METHODS AND RESULTS:

Exercised rats engaged in swimming sessions for 60 min/day, 5 days/week, for 8 weeks. Both the exercised rats and sedentary rats were randomized to MI surgery and followed for 1 week (EI1 or SI1) or 4 weeks (EI4 or SI4) of healing or to sham groups. Echocardiography was employed to detect left ventricular function and the infarct size. Additionally, the TUNEL technique was used to assess apoptosis and immunohistochemistry was used to quantitatively analyze the PPAR-α, TNF-α and NF-κB antigens in the infarcted and non-infarcted myocardium. MI-related mortality was higher in SI4 than in EI4 (25% vs 12%), without a difference in MI size. SI4 exhibited a lower shortening fraction than EI4 did (24% vs 35%) and a higher apoptosis/area rate (3.97±0.61 vs 1.90±1.82) in infarcted areas (both p=0.001). Immunohistochemistry also revealed higher TNF-α levels in SI1 than in EI1 (9.59 vs 4.09, p<0.001) in infarcted areas. In non-infarcted areas, EI4 showed higher levels of TNF-α and positive correlations between PPAR-α and NF-κB (r=0.75, p=0.02), in contrast to SI4 (r=0.05, p=0.87).

CONCLUSION:

Previously exercised animals had better long-term ventricular function post-MI, in addition to lower levels of local inflammatory markers and less myocardial apoptosis, which seemed to be related to the presence of PPAR-α.     

Effects of Intracoronary Administration of Autologous Adipose Tissue-Derived Stem Cells on Acute Myocardial Infarction in a Porcine Model

Purpose

Adipose-derived stem cells (ADSCs) are known to be potentially effective in regeneration of damaged tissue. We aimed to assess the effectiveness of intracoronary administration of ADSCs in reducing the infarction area and improving function after acute transmural myocardial infarction (MI) in a porcine model.

Materials and Methods

ADSCs were obtained from each pig''s abdominal subcutaneous fat tissue by simple liposuction. After 3 passages of 14-days culture, 2 million ADSCs were injected into the coronary artery 30 min after acute transmural MI. At baseline and 4 weeks after the ADSC injection, 99mTc methoxyisobutylisonitrile-single photon emission computed tomography (MIBI-SPECT) was performed to evaluate the left ventricular volume, left ventricular ejection fraction (LVEF; %), and perfusion defects as well as the myocardial salvage (%) and salvage index. At 4 weeks, each pig was sacrificed, and the heart was extracted and dissected. Gross and microscopic analyses with specific immunohistochemistry staining were then performed.

Results

Analysis showed improvement in the perfusion defect, but not in the LVEF in the ADSC group (n=14), compared with the control group (n=14) (perfusion defect, -13.0±10.0 vs. -2.6±12.0, p=0.019; LVEF, -8.0±15.4 vs. -15.9±14.8, p=0.181). There was a tendency of reducing left ventricular volume in ADSC group. The ADSCs identified by stromal cell-derived factor-1 (SDF-1) staining were well co-localized by von Willebrand factor and Troponin T staining.

Conclusion

Intracoronary injection of cultured ADSCs improved myocardial perfusion in this porcine acute transmural MI model.     

Correlations between serum inflammation factors and left ventricular remodeling in acute ST segment elevation myocardial infarction

Purpose

To investigate the changes and correlations of the serum inflammation factors levels and left ventricular (LV) structure and function in patients with acute ST segment elevation myocardial infarction (STEMI).

Materials and Methods

A prospective study was performed on 70 STEMI patients and 70 control subjects. Serum levels of interleukin-6 (IL-6), soluble CD40 ligand (sCD40L), metalloproteinase-9 (MMP-9) and tissue inhibitor of metalloproteinase-1 (TIMP-1) were measured by sandwich enzyme-linked immunosorbent assay (ELISA), and cardiac structure and function were assessed by echocardiography at admission and 3-year follow-up.

Results

We found that the levels of serum IL-6, sCD40L and MMP-9 increased steadily among control subjects, remote myocardial infarction and acute STEMI patients, and the level of TIMP-1 elevated remarkly at 3-year follow-up visit in STEMI. The admission level of serum MMP-9 positively correlated with LV end-diastolic and end-diastole volume (r=0.294, p=0.022; r=0.269, p=0.036, respectively), and TIMP-1 positively correlated with E/A ratio (r=0.278, p=0.044) at 3-year follow-up.

Conclusion

The study indicates that admission levels of serum MMP-9 and TIMP-1 closely correlated with left ventricular structure and function, which may be involved in the process of post-infarction remodeling of myocardium.     

S100B protein expression in the heart of deceased individuals by overdose: a new forensic marker?

OBJECTIVE:

The evaluation of S100B protein expression in the human heart and its correlation with drug-related death.

METHOD:

Left ventricular samples were collected from 74 serial forensic autopsies (15 overdose-related deaths; 59 non-overdose-related deaths) from 2007 to 2010. Tissue sections from each sample were immunostained for S100B protein by a commercial antibody.

RESULTS:

The S100B protein was detected in the heart samples of all 15 cases of drug-related deaths; S100B immunoreactivity was mainly observed in the cytoplasm of cardiomyocytes and as globular deposits in the interstitial spaces. No reactivity or weak reactivity was found in the cardiomyocytes of the 59 subjects who died of other causes.

CONCLUSION:

Our preliminary data show that the S100B protein accumulates in injured cardiomyocytes during drug-related sudden death. Given the near absence of S100B protein in the heart of subjects who died from causes other than drug overdose, S100B immunopositivity may be used as a new ancillary screening tool for the postmortem diagnosis of overdose-related cardiac death.     

Therapeutic Potential of Human Adipose Stem Cells in a Rat Myocardial Infarction Model

Purpose

Stem cell transplantation is expected to have good effects in the treatment of myocardial infarction (MI). We tested the effect of the transplantation of human adipose-derived cells (ASCs) in Sprague-Dawley (SD) rats with myocardial infarctions.

Materials and Methods

ASCs were isolated from the waste of elective abdominal surgery. The MI model was set up in SD rats by permanent ligation of the left anterior descending coronary artery. One week after MI, either 1 × 10⁶ ASCs or an equal volume of phosphate-buffered saline (PBS) was injected into the infarct zone. Cardiac function was assessed by echocardiography, 1 day, 1 week, 2 weeks, and 4 weeks after treatment. Four weeks after transplantation, immunohistochemistry was performed.

Results

Left ventricular function, including fractional shortening (FS), and ejection fraction (EF) showed a significant improvement in the ASCs transplantation group compared to the PBS group 4 weeks after treatment (p < 0.05). The anterior wall thickness of the left ventricle was significantly thicker in the ASCs transplantation group compared to the PBS group (p < 0.01). Multiple troponin T staining, and irregular, small amounts of connexin 43 expression also was observed in the ASCs transplantation group. Infarcted myocardium showed higher capillary density in the ASCs transplantation group than in the PBS injected group (p < 0.01).

Conclusion

This study provides encouraging evidence that transplantation of ASCs can improve cardiac function of infarct myocardium in rat models with a limitation of cardiac remodeling, improved wall thickness, and increased neovascularization.     

Use of long-term cultured embryoid bodies may enhance cardiomyocyte differentiation by BMP2

Purpose

Human embryonic stem cells (hESCs) can proliferate for a prolonged period and differentiate into cardiomyocytes in vitro. Recent studies used bone morphogenetic protein 2 (BMP2) to generate cardiomyocytes from hESCs, however, all those studies used early embryoid bodies (EBs) and did not retrieve cardiomyocytes with a high yield. In this study, we treated long-term cultured EBs with BMP2 in order to promote differentiation into cardiomyocytes from hESCs.

Materials and Methods

hESC lines, including SNUhES3 and SNUhES4, were used in this study. Undifferentiated hESC colonies were detached to form EBs and cultured for up to 30 days. These long-term cultured EBs were differentiated into cardiomyocytes in serum-containing media. In our protocol, BMP2 was applied for 5 days after attachment of EBs. Cardiac specific markers, beating of differentiated cells and electron microscopic (EM) ultrastructures were evaluated and analyzed.

Results

Compared to 10-day or 20-day EBs, 30-day EBs showed a higher expression level of cardiac specific markers, Nkx2.5 and α-myosin heavy chain (αMHC). Treatment of BMP2 increased expression of cardiac troponin (cTn) I and α-actinin when evaluated at 20 days after attachment of 30-day EBs. Beating of differentiated cells was observed from 7 to 20 days after attachment. Moreover, EM findings demonstrated fine structures such as Z bands in these differentiated cardiomyocytes. These long-term cultured EBs yielded cardiomyocytes with an efficiency of as high as 73.6% when assessed by FACS.

Conclusion

We demonstrated that the use of long-term cultured EBs may enhance differentiation into cardiomyocytes from hESCs when treated with BMP2.     

Overexpressions of Cyclin B1, cdc2, p16 and p53 in human breast cancer: the clinicopathologic correlations and prognostic implications

Purpose

The molecular mechanisms that are responsible for the initiation and progression of breast cancers are largely unknown. This study was to analyze the cyclin B1, cdc2, p53 and p16 tumor suppressor genes in human breast cancer.

Materials and Methods

To investigate the role of cyclin B1, cdc2, p53 and p16 in the pathogenesis and progression of breast carcinomas, 98 cases of breast cancers were examined by immunohistochemical method. The correlations of cyclin B1, cdc2, p53 and p16 expression with various clinico-pathologic findings were analysed.

Results

In the normal breast tissues, cyclin B1, cdc2 and p16 were weakly expressed, while p53 was not expressed. On the other hand, cyclin B1, cdc2, p53 and p16 were overexpressed in breast cancer, showing correlation between the expression of cyclin B1 and cdc2 and breast cancers (p=0.00). The overexpressions of cdc2 and p16 were correlated with an infiltrative tumor border pattern and this was statistically significant (p<0.05). In addition, the overexpression of cdc2 was correlated with histologic high grade carcinomas (p=0.00).

Conclusion

Cyclin B1 and cdc2 appeared to be involved in the genesis or progression of breast cancers. In addition, the overexpressions of p16 and p53 may play important roles in more aggressive tumor and the overexpression of cdc2 is associated with progression of tumor to a higher grade of breast carcinomas. The deranged overexpressions of cyclin B1, cdc2, p16 and p53 may play an important role in human breast carcinogenesis.     

Moderate exercise training promotes adaptations in coronary blood flow and adenosine production in normotensive rats

OBJECTIVES:

Aerobic exercise training prevents cardiovascular risks. Regular exercise promotes functional and structural adaptations that are associated with several cardiovascular benefits. The aim of this study is to investigate the effects of swimming training on coronary blood flow, adenosine production and cardiac capillaries in normotensive rats.

METHODS:

Wistar rats were randomly divided into two groups: control (C) and trained (T). An exercise protocol was performed for 10 weeks and 60 min/day with a tail overload of 5% bodyweight. Coronary blood flow was quantified with a color microsphere technique, and cardiac capillaries were quantified using light microscopy. Adenine nucleotide hydrolysis was evaluated by enzymatic activity, and protein expression was evaluated by western blot. The results are presented as the means ± SEMs (p<0.05).

RESULTS:

Exercise training increased the coronary blood flow and the myocardial capillary-to-fiber ratio. Moreover, the circulating and cardiac extracellular adenine nucleotide hydrolysis was higher in the trained rats than in the sedentary rats due to the increased activity and protein expression of enzymes, such as E-NTPDase and 5′-nucleotidase.

CONCLUSIONS:

Swimming training increases coronary blood flow, number of cardiac capillaries, and adenine nucleotide hydrolysis. Increased adenosine production may be an important contributor to the enhanced coronary blood flow and angiogenesis that were observed in the exercise-trained rats; collectively, these results suggest improved myocardial perfusion.     

Ethyl pyruvate has anti-inflammatory and delayed myocardial protective effects after regional ischemia/reperfusion injury

Purpose

Ethyl pyruvate has anti-inflammatory properties and protects organs from ischemia/reperfusion (I/R)-induced tissue injury. The aim of this study was to determine whether ethyl pyruvate decreases the inflammatory response after regional I/R injury and whether ethyl pyruvate protects against delayed regional I/R injury in an in vivo rat heart model after a 24 hours reperfusion.

Materials and Methods

Rats were randomized to receive lactated Ringer''s solution or ethyl pyruvate dissolved in Ringer''s solution, which was given by intraperitoneal injection 1 hour prior to ischemia. Rats were subjected to 30 min of ischemia followed by reperfusion of the left coronary artery territory. After a 2 hours reperfusion, nuclear factor κB, myocardial myeloperoxidase activity, and inflammatory cytokine levels were determined. After the 24 hours reperfusion, the hemodynamic function and myocardial infarct size were evaluated.

Results

At 2 hours after I/R injury, ethyl pyruvate attenuated I/R-induced nuclear factor κB translocation and reduced myeloperoxidase activity in myocardium. The plasma circulating levels of inflammatory cytokines decreased significantly in the ethyl pyruvate-treated group. At 24 hours after I/R injury, ethyl pyruvate significantly improved cardiac function and reduced infarct size after regional I/R injury.

Conclusion

Ethyl pyruvate has the ability to inhibit neutrophil activation, inflammatory cytokine release, and nuclear factor κB translocation. Ethyl pyruvate is associated with a delayed myocardial protective effect after regional I/R injury in an in vivo rat heart model.     

Effects of Transplantation with Marrow-Derived Mesenchymal Stem Cells Modified with Survivin on Renal Ischemia-Reperfusion Injury in Mice

Purpose

To determine whether renal injury induced by ischemia-reperfusion (I/R) could be further improved by mesenchymal stem cells (MSCs) modified with survivin.

Materials and Methods

Lentiviral vectors were used to introduce the survivin gene into MSCs and the MSCs modified with survivin were transplanted into established mice models of renal I/R injury. Seven days later, serum creatinine (Scr) and blood urea nitrogen (BUN) were measured and the survival of MSCs was determined. Hematoxylin and eosin staining was used to assess renal pathological change. The expressions of hepatocyte growth factor (HGF) and basic fibroblast growth factor (bFGF) in kidney tissue were detected by western blot.

Results

Mice transplanted with survivin-modified MSCs demonstrated good renal function recovery with Scr and BUN decline close to normal levels and improvement of renal I/R injury repair. Additionally, the survival of transplanted MSCs modified with survivin was enhanced and the expression of HGF and bFGF in kidney tissue was increased.

Conclusion

Our results demonstrated that MSCs engineered to over-express survivin could enhance their therapeutic effect on renal I/R injury in mice, probably via the improved survival ability of MSCs and increased production of protective cytokines in ischemic tissue.     

Cardioprotection Via Modulation of Calcium Homeostasis by Thiopental in Hypoxia-Reoxygenated Neonatal Rat Cardiomyocytes

Purpose

Ca²⁺ homeostasis plays an important role in myocardial cell injury induced by hypoxia-reoxygenation, and prevention of intracellular Ca²⁺ overload is key to cardioprotection. Even though thiopental is a frequently used anesthetic agent, little is known about its cardioprotective effects, particulary in association with Ca²⁺ homeostasis. We investigated whether thiopental protects cardiomyocytes against hypoxia-reoxygenation injury by regulating Ca²⁺ homeostasis.

Materials and Methods

Neonatal rat cardiomyocytes were isolated. Cardiomyocytes were exposed to different concentrations of thiopental and immediately replaced in the hypoxic chamber to maintain hypoxia. After 1 hour of exposure, a culture dish was transferred to the CO₂ incubator and cells were incubated at 37℃ for 5 hours. At the end of the experiments, the authors assessed cell protection using immunoblot analysis and caspase activity. The mRNA of genes involved in Ca²⁺ homeostasis, mitochondrial membrane potential, and cellular Ca²⁺ levels were examined.

Results

In thiopental-treated cardiomyocytes, there was a decrease in expression of the proapoptotic protein Bax, caspase-3 activation, and intracellular Ca²⁺ content. In addition, both enhancement of anti-apoptotic protein Bcl-2 and activation of Erk concerned with survival were shown. Furthermore, thiopental attenuated alterations of genes involving Ca²⁺ regulation and significantly modulated abnormal changes of NCX and SERCA2a genes in hypoxia-reoxygenated neonatal cardiomyocytes. Thiopental suppressed disruption of mitochondrial membrane potential (ΔΨ_m) induced by hypoxia-reoxygenation.

Conclusion

Thiopental is likely to modulate expression of genes that regulate Ca²⁺ homeostasis, which reduces apoptotic cell death and results in cardioprotection.