Weiyong Liu

Cardioprotection of salidroside from ischemia/reperfusion injury by increasing N-acetylglucosamine linkage to cellular proteins

The modification of proteins with O-linked N-acetylglucosamine (O-GlcNAc) is increasingly recognized as an important posttranslational modification that modulates cellular function. Recent studies suggested that augmentation of O-GlcNAc levels increase cell survival following stress. Salidroside, one of the active components of Rhodiola rosea, shows potent anti-hypoxia property. In the present study, we reported the cardioprotection of salidroside from ischemia and reperfusion. Cardiomyocytes were exposed to 4 h of ischemia and 16 h of reperfusion, and then cell viability, apoptosis, glucose uptake, ATP levels and cytosolic Ca(2+) concentration were determined, and O-GlcNAc levels were assessed by Western blotting. Salidroside (80 uM) was added 24 h before ischemia/reperfusion was induced. Treatment with salidroside markedly improved cell viability from 64.7+/-4.5% to 85.8+/-3.1%, decreased lactate dehydrogenase (LDH) release from 38.5+/-2.1% to 21.2+/-1.7%, reduced cell apoptosis from 27.2+/-3.2% to 12.2+/-1.9%, significantly improved cardiomyocytes glucose uptake by 1.7-fold and increased O-GlcNAc levels by 1.6-fold, as well as reducing cytosolic Ca(2+) concentration compared to untreated cells following ischemia/reperfusion. Furthermore, the improved cell survival and the increase in O-GlcNAc with salidroside were attenuated by alloxan, an inhibitor of O-GlcNAc transferase. These results suggested that salidroside significantly enhances glucose uptake and increases protein O-GlcNAc levels and this is associated with decreased cardiomyocytes injury following ischemia/reperfusion.

Tissue-engineered heart valve on acellular aortic valve scaffold: in-vivo study.

The feasibility of constructing a tissue-engineered heart valve on an acellular porcine aortic valve leaflet was evaluated. A detergent and enzymatic extraction process was developed to remove the cellular components from porcine aortic valves. The acellular valve leaflets were seeded for 7 days in vitro with cells from canine arterial wall and endothelial cells. The constructs were implanted into the lumens of 6 canine abdominal aortas to assess the reconstruction of the valve leaflets. It was found that all cellular components had been removed from the porcine aortic valves. The valve leaflets were completely reconstructed at the end of the 10th week in vivo. Scanning electron microscopy showed that the valve leaflets were partially covered with endothelial cells. It was concluded that porcine aortic valves can be decellularized by the detergent and enzymatic extraction process and it is feasible to construct a tissue-engineered heart valve in vivo on an acellular valve scaffold.

TRANSPLANTATION OF EMBRYONIC SMALL HEPATOCYTES INDUCES REGENERATION OF INJURED LIVER IN ADULT RAT

Small hepatocytes as hepatic stem cells or progenitors may be transplanted to treat several end-stage liver diseases. To identify the characteristics of epithelial cells enriched from fetal liver, we used immunocytochemistry and electron micrography. All cells in the colonies were immunocytochemically positive for alpha fetoprotein and cytokeratins (CK) 7, CK8, and CK18, which are markers of hepatic progenitor. Under transmission electron microscopy, we observed the cultured cells to show naive characteristics of stem cells and to be significantly distinct from mature hepatocytes. To identity whether these small hepatocytes were able to proliferate and differentiate into mature hepatocytes, we cultured them in vitro, and, through the portal vein, and transplanted elements whose membrane were stained with red fluorescence using PKH26 linker dye, into the livers of CCl(4)-treated rats that had been subjected to two-thirds partial hepatectomy. Significant liver regeneration was observed 30 days later in rats that did or did not receive the cells. The livers of hepatocytes recipients showed sharper edges and smoother surfaces than the control group. Diffused cells labeled with red fluorescence were observed in the portal area, with branch-like red fluorescence in regions near portal areas of some lobules, suggesting that these elements were involved in the repair of liver lobules and differentiation into mature hepatocytes. Our results revealed that small hepatocytes not only have characteristics of hepatic stem cells, but also may be a source of cellular transplantation to treat liver diseases.

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.

Emergent cardiopulmonary bypass in canines with penetrating cardiac wounds caused by gunshot

Background: Most patients with penetrating cardiac wounds die within minutes of injury from uncontrolled haemorrhage and acute cardiac dysfunction. Thus, sustaining sufficient circulation rapidly is crucial to saving lives. Emergent cardiopulmonary bypass (CPB) is a potential intervention to maintain circulation after penetrating cardiac wounds from a gunshot. Methods: Canines were wounded with a bullet and randomly split into one of three treatment groups. Animals in group 1 (Gp1) were treated with conventional methods. Animals in group 2 (Gp2) received emergent CPB for 180 min and autologous blood transfusion. Animals in group 3 (Gp3) received emergent CPB for 30 min followed by surgical repair. Animal survival, haemodynamics and blood chemistry were measured, and lung water content was evaluated at the end of the experiment. Results: The right ventricle was the most severely wounded cardiac chamber. In Gp1, mean arterial pressure and central venous pressure were dramatically decreased 8 min after injury, and all animals died within 18 min. In Gp2 and Gp3, mean arterial pressure ranged from 60–90 mm Hg during CPB. 60 min after terminating CPB in Gp2, mean arterial pressure and heart rate were decreased compared to Gp3. In Gp3, most animals maintained haemodynamic stability. 60 min after CPB, free haemoglobin in circulating blood was elevated compared to pre-trauma levels. Pulmonary water content was significantly higher in Gp2 and Gp3 than in Gp1. Conclusions: Emergent CPB in the field can maintain haemodynamic stability and supply vital organs with sufficient blood flow, but surgery following CPB is essential to rescue patients with penetrating cardiac wounds.

Calcification Resistance of Procyanidin-Treated Decellularized Porcine Aortic Valves In Vivo

OBJECTIVES Conventional glutaraldehyde fixation is conducive to calcification of bioprosthetic tissues. The aim of this study was to test calcification resistance of procyanidin-treated decellularized porcine aortic valve in a rat model. MATERIALS AND METHODS We performed cross-linking of the decellularized porcine aortic heart valves by procyanidins and observed morphologic performance and examined the tensile strength and cross-linking index. Then we implanted subcutaneous samples of procyanidin cross-linking decellularized valves, glutaraldehyde cross-linking decellularized valves, and decellularized valves in rats. The retrieved grafts were stained with hematoxylin-eosin and von Kossa and were analyzed with scanning electron microscopy and x-ray energy dispersive spectroscopy (EDS) after 21 and 63 days. RESULTS After decellularized and cross-linking pretreatment, the procyanidin cross-linked leaflets were soft and stretchable. In addition, the cellular components of the porcine aortic heart valve leaflets were completely removed, and the extracelluar matrix was maintained completely. Examination of tensile strength revealed a significantly higher tissue resistance to tension in procyanidin cross-linked tissue than in other tissues, including the glutaraldehyde group (P< .05), even though the extents of cross-linking of each group were roughly the same at approximately 90%. Histopathologic examination showed that the procyanidin cross-linked valve matrix had no significant calcification, and there were no calcium peaks in the EDS profile of procyanidin cross-linked samples in the 21-day and 63-day rat studies. CONCLUSION This study demonstrated that procyanidin cross-linked decellularized heart valves can resist calcification to some extent.

Myocardial Protective Effect of Urethane on Isolated Rat Hearts in Prolonged Hypothermic Preservation

BACKGROUND One of the most important factors restricting heart transplantation is the limited myocardial ischemia time. This study investigated the effects of urethane on the hypothermic preservation of donor rat hearts. MATERIALS AND METHODS Hearts isolated from rats were divided into 2 groups (n = 8), a control group with histidine-tryptophan-ketoglutarate (HTK) solution alone and an experimental group with HTK solution plus 30 mM urethane. Hearts were mounted on a Langendorff apparatus to estimate the baseline cardiac function; the hearts were then arrested and stored in one of the 2 solutions for 6 hours and 18 hours at 4 degrees C. After preservation, the hearts were reperfused, and cardiac function was evaluated. Lactate dehydrogenase (LDH) release, adenosine triphosphate (ATP) content, cardiomyocyte apoptosis, and myocardial ultrastructure were examined. RESULTS Compared with the control group, the experimental group showed a significantly higher recovery of cardiac function for both 6 hours and 18 hours of preservation and demonstrated a lower rate of cardiomyocyte apoptosis (8.5% + or - 1.2% versus 12.2% + or - 1.8% for 6 hours; 14.1% + or - 2.1% versus 31.4% + or - 2.7% for 18 hours). ATP content was significantly higher in the experimental group than in the control group after 18 hours of preservation (229.4 + or - 29.7 microg/g versus 153.2 + or - 21.1 microg/g). The experimental group also showed lower levels of LDH release after 18 hours of preservation. Electron microscopy studies demonstrated better cardiomyocyte structure in the experimental group for both 6 hours and 18 hours of preservation. CONCLUSIONS Use of urethane improved cardiac functional recovery and led to significant protective effects on rat hearts placed in a hypothermic preservation solution for a prolonged period.