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. Author manuscript; available in PMC: 2015 Jun 8.
Published in final edited form as: J Thorac Cardiovasc Surg. 2014 Oct 18;149(2):588–593. doi: 10.1016/j.jtcvs.2014.10.074

High Molecular Weight Polyethylene Glycol Inhibits Myocardial Ischemia-Reperfusion Injury In Vivo

Xianyao Xu 1, Jennifer L Philip 1, Md Abdur Razzaque 1, James W Lloyd 2, Charlie M Muller 2, Shahab A Akhter 1
PMCID: PMC4459731  NIHMSID: NIHMS690904  PMID: 25455467

Abstract

Objectives

Cardiac ischemia-reperfusion (I-R) injury remains a significant problem as there are no therapies available to minimize the cell death that can lead to impaired function and heart failure. We have shown that high-molecular-weight PEG (15–20kD) can protect cardiac myocytes in vitro from hypoxia-reoxygenation injury. In this study, we investigated the potential protective effects of PEG in vivo.

Methods

Adult rats underwent LAD occlusion for 60 minutes followed by 48 hrs or 4 weeks of reperfusion. One mL of 10% PEG solution or saline (PBS) control (n=10 per group) was administered intravenously (IV) immediately prior to reperfusion.

Results

Fluorescein-labeled PEG was robustly visualized in the myocardium 1 hr after IV delivery. The PEG group had significant recovery of LV ejection fraction at 4 wks vs. a 25% decline in the PBS group (p<0.01). There was 50% less LV fibrosis in the PEG group vs. PBS with smaller peri-infarct and remote territory fibrosis (p<0.01). Cell survival signaling was upregulated in the PEG group with increased Akt (3-fold, p<0.01) and ERK (4-fold, p<0.05) phosphorylation compared to PBS controls at 48 hrs. PEG also inhibited apoptosis as measured by TUNEL positive nuclei (56% decrease, p<0.02) and caspase-3 activity (55% decrease, p<0.05).

Conclusions

High-molecular-weight PEG appears to have a significant protective effect from I-R injury in the heart when administered IV immediately prior to reperfusion. This may have important clinical translation in the setting of acute coronary revascularization and myocardial protection in cardiac surgery.

Introduction

Ischemic heart disease continues to be the most significant etiology for the development of heart failure (HF) [1]. Despite acute revascularization, up to 30% of patients suffering an acute myocardial infarction will go on to develop HF within six years [2]. The loss of cardiac myocytes after ischemia-reperfusion injury is primarily due to necrosis and apoptosis [3]. Apoptosis occurs primarily after reperfusion following ischemia, whereas prolonged ischemia leads to necrosis. Cell death due to apoptosis can continue in the long-term as previous reports have demonstrated the presence of apoptotic cells in the border zone of the infarct and in remote myocardium during the early phase [4], as well as months after myocardial infarction [5], providing evidence that apoptosis plays an important role in maladaptive remodeling and the progression to HF following ischemic injury. Apoptosis represents a potential target for therapeutic intervention as there is a critical need to prevent cardiac myocyte loss and subsequent adverse remodeling following ischemia-reperfusion (I-R) injury.

We have previously investigated the efficacy of high molecular weight (15–20 kD) polyethylene glycol (PEG) as a therapeutic agent to inhibit apoptotic cell death in isolated cardiac myocytes subjected to hypoxia-reoxygenation (H-R) injury [6]. Pretreatment of neonatal rat ventricular myocytes with a 5% PEG solution led to three-fold decline apoptosis after H-R relative to untreated controls. This was associated with a significant decline in caspase-3 activity and reactive oxygen species (ROS) generation and led to upregulation of prosurvival signaling including Akt, ERK, and GSK-3β phosphorylation. Sarcolemmal membrane lipid-raft architecture was also preserved, consistent with membrane stabilization, a known protective effect of PEG 15–20 from previous studies in intestinal epithelial cells [7]. PEG has demonstrated membrane-protective effects in a variety of cells and organs against various insults. PEGs have been shown to decrease ROS generation and lipid peroxidation in these injury models. Since PEGs do not scavenge superoxide anion or inhibit xanthine oxidase [8], it is thought that these polymers inhibit or reduce oxidative stress through preservation or restoration of membrane integrity.

The primary goal of this study is to translate our previous in vitro findings of the protective effects of PEG in cardiac myocytes to a small animal in vivo model of acute ischemia-reperfusion injury. We used an adult rat model of left anterior descending coronary artery occlusion for one hour followed by reperfusion for 48 hours or 4 weeks. To provide more clinical relevance, the PEG solution was delivered intravenously just prior to reperfusion. The subsequent studies include measurement of left ventricular function and dimensions, myocardial fibrosis, apoptotic signaling, prosurvival signaling, and overall survival.

Materials and Methods

High-molecular-weight PEG (15,000–20,000 Da), referred to as PEG 15–20, was purchased from Sigma (St. Louis, MO).

Model of ischemia-reperfusion and delivery of PEG

All animal studies were approved by the Institutional Animal Care and Use Committee at the University of Wisconsin School of Medicine and Public Health and the University of Chicago Biological Sciences Division. Adult male Sprague-Dawley rats weighing 300–350g were purchased from Charles Rivers Laboratories (Wilmington, MA). The animals underwent left thoracotomy and left anterior descending artery (LAD) occlusion at the junction of the proximal and mid-third of the vessel for 60 minutes followed by either 48 hours or 4 weeks of reperfusion. LAD occlusion led to a significantly darker color change of the anterior left ventricle which returned to the baseline color after reperfusion. This was observed routinely in all experiments. One ml of 10% PEG solution or saline control was administered via the internal jugular vein just prior to reperfusion. For the 48 hour studies, n=5 in both the PEG and saline control (PBS) groups. For the 4 week studies, n=11 in the PEG group and n=14 in the PBS group.

TUNEL staining

Using the TUNEL (terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick-end labeling) method, cardiac sections were stained for the detection of fragmented DNA, which is indicative of apoptotic cells, according to the manufacturer’s protocol (Chemicon International, Temecula, CA). The number of TUNEL-positive cells was also counted in five different fields.

Histochemistry

Select heart tissues were perfused and fixed in 10% buffered formalin overnight at 4°C for paraffin embedding. Tissues were then sectioned at 5μm, placed on slides and heated at 60°C overnight, and deparaffinized in xylene. The sections were then rehydrated in an ethanol series and stained with Masson’s Trichrome kit (Sigma), or Picro-Sirius Red. For Sirius Red staining, nuclei were stained for 1 minute with Weigert’s hematoxylin, washed then stained for 1 hour in 0.1% Sirius Red stain (Direct Red 80, Sigma) in saturated picric acid. Slides were washed twice in acidified water (5% acetic acid), dehydrated in an ethanol series, and cleared with xylene. Sections were cover-slipped with Permount (Sigma). Images were collected using bright field microscopy at 40–100× magnification.

Protein Immunoblotting

Left ventricular tissues were lysed in buffer containing 25 mM HEPES, 1 mM EDTA, 125 mM NaCl, 0.5 mM NaF, 0.25% Nonidet P-40, 5% glycerol (pH 6.8), 10 μg/ml leupeptin, 20 μg/ml aprotinin and 1mM phenyl-methylsulfonyl fluoride. Equal amounts of protein for each sample were separated by SDS-PAGE, transferred onto a nitrocellulose membrane, and immunoblotted. Chemiluminescence detection was performed using the ECL reagent (Pierce). Antibodies against phospho Ser473 residues of Akt (1:1000), Ser9 residue of GSK-3β (1:1000), Ser1177 residue of eNOS (1:1000), Thr202/Tyr204 residues of ERK1/2 (1:1000) and cleaved Caspase 3 (1:1000) were used (Cell Signaling, Beverly, MA). Blots were stripped and reprobed with total Akt, GSK-3β, eNOS or ERK1/2 antibodies, respectively, to confirm equal protein loading. Band intensity was quantitated using NIH ImageJ software. α-tubulin was used as a loading control.

Statistical Analysis

All data are expressed as mean ± SEM and analyzed using Student’s t-test. Values of P<0.05 were considered significant.

Results

Effects of PEG on Myocardial Function and Mortality After Ischemia-Reperfusion Injury

Preliminary experiments were done to verify that the 10% PEG solution was being taken up in the myocardium after intravenous delivery via the right internal jugular vein. This was done using fluorescein-labeled PEG and it was robustly visualized in the myocardium (Figure 1). Following 60 minutes of ischemia induced by LAD occlusion and intravenous delivery of PBS (control) just prior to reperfusion, fractional shortening declined from a baseline of 50% to 35% at 1 week which did not improve by 4 weeks. In contrast, intravenous delivery of PEG just prior to reperfusion led to a significant recovery of fractional shortening by 4 weeks at 47% versus 51% at baseline (Figure 2A). Similarly, treatment with PEG led to a near normal recovery of left ventricular ejection fraction compared to PBS controls (Figure 2B). End-systolic diameter was increased by 1 week after ischemia-reperfusion in both groups and continued to increase by 4 weeks in the PBS group (Figure 2C). PEG treatment led to stabilization of end-systolic diameter by 2 weeks and was significantly smaller compared to the PBS group at 3 and 4 weeks post-reperfusion. Mortality after ischemia-reperfusion injury occurred within the first 24 hours and there were no immediate operative deaths or late deaths after 1 day. There was a 40% mortality rate in the PBS group compared to 10% in the PEG treated rats (Figure 2D).

Figure 1.

Figure 1

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PEG 15–20 is present in the myocardium following intracoronary or intravenous delivery. Fluorescein-labeled PEG or PBS (control) was delivered via direct injection into the left ventricular outflow tract following transient aortic crossclamping (intracoronary delivery) or by intravenous delivery via the right internal jugular vein. Both delivery techniques resulted in robust uptake of PEG in the heart as demonstrated by the green fluorescein labeling.

Figure 2.

Figure 2

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PEG treatment improves cardiac function following ischemia-reperfusion injury Cardiac function was studied by echocardiography in rats 4 weeks following ischemia-reperfusion (I/R) injury and treatment with either IV PBS or PEG. (A) Fractional shortening is significantly higher in PEG compared to PBS group at 2–4 weeks. n=6 in each group; *p<0.03 vs. PBS. (B) Ejection Fraction in PBS vs. PEG treated rats up to 4 weeks post I/R injury. n=6 in each group; *p<0.04 vs. PBS. (C) End-systolic diameter is significantly smaller in PEG vs. PBS groups at 3 and 4 weeks post I/R injury. n=6 in each group; *p<0.03 vs. PBS, #p=0.05 vs. PBS. (D) Mortality rate at 48 hours following 1 hour ischemia in PBS and PEG treated animals. n=14 for PBS and 11 for PEG. p=0.34 using Fischer exact test.

PEG Treatment Inhibits Ventricular Remodeling Following Ischemia-Reperfusion Injury

Left ventricular fibrosis was measured by picrosirius red and masson trichrome staining at 4 weeks post-ischemia-reperfusion injury induced by 60 minutes of LAD ligation. Baseline fibrotic area is approximately 1% and this was markedly increased to 7% by picrosirius red staining by 4 weeks in the PBS treated group (Figure 3A and 3B). PEG treatment significantly inhibited the development of ventricular fibrosis with a fibrotic area of 3%. Fibrosis as measured by trichrome staining showed an increase to nearly 14% by area in the PBS group versus only 4% in the PEG group (Figure 3C and 3D).

Figure 3.

Figure 3

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PEG treatment decreases fibrosis at 4 weeks following ischemia-reperfusion injury (A) Representative photomicrographs of picrosirusis red stained left ventricles of control rats and PBS or PEG treated rats harvested 4 weeks post I/R injury. (B) Quantitation of fibrotic area (red staining area) of left ventricle. n=5–6 per group; *p=0.001 vs. Control, #p<0.01 vs. PBS. (C) Representative photomicrographs of masson trichrome stained left ventricles from control, PBS, and PEG treated rats harvested 4 weeks post I/R injury. (D) Quantitation of left ventricular fibrotic area (purple/blue staining area). n=5–6 per group; *p<0.001 vs. Control, #p<0.001 vs. PBS.

PEG Inhibits Apoptotic Cell Death and Caspase-3 Activity

To investigate the potential effects of PEG treatment on myocardial apoptosis in vivo, we measured TUNEL positive nuclei in the left ventricle at 48 hours after ischemia-reperfusion. As seen in Figure 3A and B, the number of TUNEL positive cells was increased 3.4-fold in the PBS group. Treatment with PEG prior to reperfusion led to a significant decrease in apoptosis as there was only a 1.4-fold increase in TUNEL positive cells (Figure 4A and 4B). To further assess the effects of PEG on apoptotic signaling, caspase-3 activity was studied by measuring expression of cleaved caspase-3. Correlating with the TUNEL results, cleaved caspase-3 expression was more than 2-fold greater in the PBS group compared to the PEG treated group (Figure 4C and 4D).

Figure 4.

Figure 4

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PEG treatment decreases apoptosis following Ischemia-Reperfusion Injury (A) Representative photomicrographs of TUNEL staining in left ventricles of control rats and PBS or PEG treated rats harvested 48 hours post-I/R injury. Black arrows show examples of TUNEL positive cells in each image. (B) Quantitation of TUNEL positive cells per high powered field (hpf). n=3–5 per group; *p=0.01 vs. Control, #p<0.02 vs. PBS. (C) Representative immunoblot showing cleaved caspase-3 expression in left ventricles at 48 hours following ischemia-reperfusion in rats treated with PBS or PEG. α-tubulin was used as a loading control. (D) Densitometric analysis of cleaved caspase-3/a-tubulin expression. n=5 per group; *p<0.003 vs. PBS.

Treatment with PEG Upregulates Cell Survival Signaling In Vivo

PEG treatment led to a significant reduction in ischemia-perfusion-induced myocardial apoptosis and therefore, we went on to investigate cell survival signaling. Akt (protein kinase B) signaling was increased in the PEG treated hearts 2-fold versus the PBS controls as measured by Akt phosphorylation (Figure 5A). Extracellular signal regulated kinase (ERK) 1/2 signaling was upregulated greater than 2-fold (Figure 5B) and phosphorylation of the prosurvival signaling molecule, GSK-3β, was also increased nearly 4-fold in the PEG treated group versus controls (Figure 5C). Endothelial NO synthase (eNOS) activity was significantly upregulated in the PEG treated hearts by approximately 2.5-fold (Figure 5D) once again demonstrating PEG-mediated activation of cell survival signaling.

Figure 5.

Figure 5

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Increased left ventricular survival signaling with PEG treatment at 48 hours post-I/R injury. (A) Representative immunoblot showing phosphorylated Akt (p-Akt) and total Akt (t-Akt) expression in left ventricles at 48 hours following ischemia-reperfusion in rats treated with PBS or PEG and densitometric analysis of p-Akt/t-Akt expression. n=4–5 per group; *p<0.002 vs. PBS. (B) Representative immunoblot of phosphorylated ERK1/2 (p-ERK1/2) and total ERK1/2 (t-ERK1/2) expression and densitometric analysis of p-ERK1/2:t-ERK1/2 expression. n=4 per group; #p<0.05 vs. PBS. (C) Representative immunoblot showing phosphorylated GSK 3β (p-GSK 3β) and total GSK 3β (t-GSK 3β) expression and densitometric analysis of p-GSK 3β/t-GSK 3β expression. n=4–5 per group; *p<0.05 vs. PBS. (D) Representative immunoblot showing phosphorylated eNOS (p-eNOS) and total eNOS (t-eNOS) expression at 48 hours following ischemia-reperfusion in rats treated with PBS or PEG and densitometric analysis of p-eNOS / t-eNOS expression. n=5 per group; #p<0.02 vs. PBS.

Discussion

This is the first report describing the use of PEG to protect the heart from I-R injury in an in vivo model. In this study, we have shown that the protective effects of PEG 15–20 that were seen in cardiac myocytes subjected to hypoxia-reoxygenation injury in vitro [6] are translatable to an in vivo rat model of I-R injury. Intravenous delivery of 10% PEG 15–20 prior to reperfusion following 60 minutes of ischemia by LAD occlusion resulted in significant recovery of LV function, markedly less myocardial apoptosis as measured by TUNEL staining and caspase-3 activity, and inhibition of ventricular fibrosis and adverse remodeling. Similar to our studies using PEG in primary cultures of neonatal rat cardiac myocytes exposed to hypoxia and reoxygenation, PEG treatment again led to the upregulation of myocardial prosurvival signaling as measured by the phosphorylation of Akt, ERK1/2, GSK-3β, and eNOS indicative of increased activity of these signaling pathways.

Based on previous in vitro studies, PEG plays an important role in stabilization and preservation of lipid-raft domains leading to maintenance of sarcolemmal membrane integrity and upregulation in cell survival signaling [6, 7]. Lipid-raft coalescence in association with apoptosis is a known sequela of cell injury [9]. Lipid rafts are sphingolipid and cholesterol-rich domains of the plasma membrane which contain a variety of signaling and transport proteins. There are different subtypes of lipid rafts that can be distinguished based on their protein and lipid composition. Caveolae, a subset of lipid rafts, are flask-like invaginations of plasma membrane that contain proteins of the caveolin family such as caveolin-1, 2, and 3 [10]. The presence within lipid rafts of several membrane proteins involved in cell signaling has led to the consensus that these lipid domains play an important role in the process of signal transduction [11]. In some cases, preassembled signaling complexes are localized in lipid raft domains. The phosphatidylinositol-3-kinase/protein kinase B (PI3K/PKB, Akt) pathway is a protein kinase system that interacts with caveolin and this interaction may regulate cell survival [12]. Receptor tyrosine kinases have also been shown to be localized to caveolae, including EGF, NGF, IGF, and PDGF, and their downstream effector MAP kinases, which regulate numerous cellular processes, are also regulated by caveolin [13, 14]. eNOS activity is also regulated by binding to caveolin [15]. Therefore, the beneficial effects of PEG in the upregulation of prosurvival signaling may be mediated, in large part, by preservation of lipid-raft domains.

PEGs are multifunctional molecules that can target several pathological processes associated with organ injury following ischemia-reperfusion including tissue edema, cell membrane dysfunction, immune activation, and tight junction function [16]. Due to their large molecular size and hydrophilic properties, PEGs generate an oncotic sink to reduce cellular and tissue edema. PEG can attenuate lipid peroxidation and cellular membrane injury. Previous studies have demonstrated the efficacy of PEG 15–20 in protecting intestinal epithelial cells against various injurious stimuli including radiation injury [7] and bile acid exposure [17].

PEG has been used both experimentally and clinically for myocardial preservation in the transplantation setting. The only previously reported clinical study utilized standard cardioplegia solution with 5% PEG 20 during the donor heart procurement in 22 patients [18]. This was associated with a significant decline in acute rejection episodes during the first year after transplant compared with standard cardioplegia solution. Although there were no mechanistic studies performed, it was hypothesized that there may have been less preservation injury with the addition of PEG. PEG compounds have also been described to be used in early clinical trials for renal [19] and liver transplantation [20, 21].

In conclusion, our results suggest that PEG 15–20 can be safely delivered intravenously and is very effective in minimizing normothermic myocardial I-R injury through the inhibition of apoptotic signaling and upregulation of cell survival signaling leading to less ventricular remodeling and preservation of ventricular function. As there are currently no pharmacological strategies to inhibit or decrease acute I-R injury in the setting of acute coronary syndrome and emergent revascularization, PEG 15–20 appears to be an intriguing polymer-based therapeutic approach for this important clinical problem. In addition, PEG may prove to be beneficial in cardiac surgery, potentially by being added to cardioplegia solution for complex operations requiring long aortic cross clamp times and for patients with severe ventricular dysfunction or in the setting of cardiac transplantation as a component of the organ preservation solution.

Acknowledgments

Grants: This work was supported, in part, by a Howard Hughes Medical Institute Medical Research Fellowship (to JLP) and the National Institutes of Health (HL107949 to SAA).

Footnotes

Conflict of Interest

None of the authors has any conflicts of interest to disclose relevant to this work.

References

  • 1.Pagidipati NJ, Gaziano TA. Estimating Deaths from Cardiovascular Disease: A Review of Global Methodologies of Mortality Measurement. Circulation. 2013;127:749–756. doi: 10.1161/CIRCULATIONAHA.112.128413. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 2.Yancy CW, Jessup M, Bozkurt B, Butler J, Casey DE, Jr, Drazner MH, Fonarow GC, Geraci SA, Horwich T, Januzzi JL, Johnson MR, Kasper EK, Levy WC, Masoudi FA, McBride PE, McMurray JJV, Mitchell JE, Peterson PN, Riegel B, Sam F, Stevenson LW, Tang WHW, Tasi EJ, Wilkoff BL. 2013 ACCF/AHA Guideline for the Management of Heart Failure: A Report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. Circulation. 2013;128:e240–e327. doi: 10.1161/CIR.0b013e31829e8776. [DOI] [PubMed] [Google Scholar]
  • 3.Gottlieb RA, et al. Reperfusion injury induces apoptosis in rabbit cardiomyocytes. J Clin Invest. 1994;94:1621–1628. doi: 10.1172/JCI117504. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 4.Saraste A, et al. Apoptosis in human acute myocardial infarction. Circulation. 1997;95:320–323. doi: 10.1161/01.cir.95.2.320. [DOI] [PubMed] [Google Scholar]
  • 5.Takemura G, et al. Role of apoptosis in the disappearance of infiltrated and proliferated interstitial cells after myocardial infarction. Circ Res. 1998;82:1130–1138. doi: 10.1161/01.res.82.11.1130. [DOI] [PubMed] [Google Scholar]
  • 6.Malhotra R, Valuckaite V, Staron ML, Theccanat T, D’Souza KM, Alverdy JC, Akhter SA. High Molecular Weight Polyethylene Glycol Protects Cardiac Myocytes From Hypoxia and Reoxygenation-Induced Cell Death and Preserves Ventricular Function. Am J Physiol Heart Circ Physiol. 2011;300(5):H1733–42. doi: 10.1152/ajpheart.01054.2010. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 7.Valuckaite V, et al. Oral PEG 15–20 protects the intestine against radiation: role of lipid rafts. Am J Physiol Gastrointest Liver Physiol. 2009;297:G1041–G1052. doi: 10.1152/ajpgi.00328.2009. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 8.Rubio-Gayosso I, Platts SH, Duling BR. Reactive oxygen species mediate modification of glycocalyx during ischemia-reperfusion injury. Am J Physiol Heart Circ Physiol. doi: 10.1152/ajpheart.00796.2005. [DOI] [PubMed] [Google Scholar]
  • 9.Bionda C, et al. Radioresistance of human carcinoma cells is correlated to a defect in raft membrane clustering. Free Radic Biol Med. 2007;43:681–694. doi: 10.1016/j.freeradbiomed.2007.04.031. [DOI] [PubMed] [Google Scholar]
  • 10.Pike LJ, et al. Lipid Rafts: bringing order to chaos. J Lipid Res. 2003;44(4):655–67. doi: 10.1194/jlr.R200021-JLR200. [DOI] [PubMed] [Google Scholar]
  • 11.Michel V, Bakovic M. Lipid Rafts in health and disease. Biol Cell. 2007;99(3):129–40. doi: 10.1042/BC20060051. [DOI] [PubMed] [Google Scholar]
  • 12.Zhuang L, Lin J, Lu ML, Solomon KR, Freeman MR. Cholesterol-rich lipid rafts mediate akt-regulated survival in prostate cancer cells. Cancer Res. 2002;62(8):2227–31. [PubMed] [Google Scholar]
  • 13.Das M, Das DK. Lipid raft in cardiac health and disease. Curr Caridol Rev. 2009;5(2):105–11. doi: 10.2174/157340309788166660. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 14.Couet J, Sargiacomo M, Lisanti MP. Interaction of a receptor tyrosine kinase, EGF-R, with caveolins. Caveolin binding negatively regulates tyrosine and serine/threonine kinase activities. J Biol Chem. 1997;272(48):30429–38. doi: 10.1074/jbc.272.48.30429. [DOI] [PubMed] [Google Scholar]
  • 15.García-Cardeña G, Fan R, Stern DF, Liu J, Sessa WC. Endothelial nitric oxide synthase is regulated by tyrosine phosphorylation and interacts with caveolin-1. J Biol Chem. 1996;271(44):27237–40. doi: 10.1074/jbc.271.44.27237. [DOI] [PubMed] [Google Scholar]
  • 16.Valuckaite V, Seal J, Zaborina O, Tretiakova M, Testa G, Alverdy JC. High molecular weight polyethylene glycol (PEG 15–20) maintains mucosal microbial barrier function during intestinal graft preservation. J Surg Res. 2013;183:869–875. doi: 10.1016/j.jss.2013.02.035. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 17.Oltean M, Joshi M, Herlenius G, Olausson M. Improved intestinal preservation using an intraluminal macromolecular solution: evidence from a rat model. Transplantation. 2010;89:285. doi: 10.1097/TP.0b013e3181c9905a. [DOI] [PubMed] [Google Scholar]
  • 18.Collins GM, Wicomb WN, Levin BS, Verma S, Avery J, Hill JD. Heart preservation solution containing polyethylene glycol: an immunosuppressive effect? Lancet. 1991;338:890–891. doi: 10.1016/0140-6736(91)91550-e. [DOI] [PubMed] [Google Scholar]
  • 19.Hauet T, Goujon JM, Baumert H, et al. Polyethylene glycol reduces the inflammatory injury due to cold ischemia/reperfusion in autotransplanted piog kidneys. Kidney Int. 2002;62:654. doi: 10.1046/j.1523-1755.2002.00473.x. [DOI] [PubMed] [Google Scholar]
  • 20.Franco-Gou R, Mosbah IB, Serafin A, Abdennebi HB, Rosello-Catafau J, Peralta C. New preservation strategies for protecting liver grafts against cold ischemia reperfusion injury. J Gastroenterol Hepatol. 2007;(22):1120. doi: 10.1111/j.1440-1746.2006.04495.x. [DOI] [PubMed] [Google Scholar]
  • 21.Abbas R, Kombu RS, Dignam D, et al. Polyethylene glycol modified-albumin enhances the cold preservation properties of University of Wisconsin solution in rat liver and a hepatocyte cell line. J Surg Res. 2010;164:95. doi: 10.1016/j.jss.2009.03.030. [DOI] [PubMed] [Google Scholar]

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