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Mitochondrial Consequences of Organ Preservation Techniques during Liver Transplantation. Int J Mol Sci 2021; 22:ijms22062816. [PMID: 33802177 PMCID: PMC7998211 DOI: 10.3390/ijms22062816] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 02/26/2021] [Accepted: 03/03/2021] [Indexed: 02/08/2023] Open
Abstract
Allograft ischemia during liver transplantation (LT) adversely affects the function of mitochondria, resulting in impairment of oxidative phosphorylation and compromised post-transplant recovery of the affected organ. Several preservation methods have been developed to improve donor organ quality; however, their effects on mitochondrial functions have not yet been compared. This study aimed to summarize the available data on mitochondrial effects of graft preservation methods in preclinical models of LT. Furthermore, a network meta-analysis was conducted to determine if any of these treatments provide a superior benefit, suggesting that they might be used on humans. A systematic search was conducted using electronic databases (EMBASE, MEDLINE (via PubMed), the Cochrane Central Register of Controlled Trials (CENTRAL) and Web of Science) for controlled animal studies using preservation methods for LT. The ATP content of the graft was the primary outcome, as this is an indicator overall mitochondrial function. Secondary outcomes were the respiratory activity of mitochondrial complexes, cytochrome c and aspartate aminotransferase (ALT) release. Both a random-effects model and the SYRCLE risk of bias analysis for animal studies were used. After a comprehensive search of the databases, 25 studies were enrolled in the analysis. Treatments that had the most significant protective effect on ATP content included hypothermic and subnormothermic machine perfusion (HMP and SNMP) (MD = −1.0, 95% CI: (−2.3, 0.3) and MD = −1.1, 95% CI: (−3.2, 1.02)), while the effects of warm ischemia (WI) without cold storage (WI) and normothermic machine perfusion (NMP) were less pronounced (MD = −1.8, 95% CI: (−2.9, −0.7) and MD = −2.1 MD; CI: (−4.6; 0.4)). The subgroup of static cold storage (SCS) with shorter preservation time (< 12 h) yielded better results than SCS ≥ 12 h, NMP and WI, in terms of ATP preservation and the respiratory capacity of complexes. HMP and SNMP stand out in terms of mitochondrial protection when compared to other treatments for LT in animals. The shorter storage time at lower temperatures, together with the dynamic preservation, provided superior protection for the grafts in terms of mitochondrial function. Additional clinical studies on human patients including marginal donors and longer ischemia times are needed to confirm any superiority of preservation methods with respect to mitochondrial function.
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Rouquette M, Lepetre-Mouelhi S, Couvreur P. Adenosine and lipids: A forced marriage or a love match? Adv Drug Deliv Rev 2019; 151-152:233-244. [PMID: 30797954 DOI: 10.1016/j.addr.2019.02.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Revised: 02/12/2019] [Accepted: 02/13/2019] [Indexed: 12/21/2022]
Abstract
Adenosine is a fascinating compound, crucial in many biochemical processes: this ubiquitous nucleoside serves as an essential building block of RNA, is also a component of ATP and regulates numerous pathophysiological mechanisms via binding to four extracellular receptors. Due to its hydrophilic nature, it belongs to a different world than lipids, and has no affinity for them. Since the 1970's, however, new discoveries have emerged and prompted the scientific community to associate adenosine with the lipid family, especially via liposomal preparations and bioconjugation. This seems to be an arranged marriage, but could it turn into a true love match? This review considered all types of unions established between adenosine and lipids. Even though exciting supramolecular structures were observed with adenosine-lipid conjugates, as well as with liposomal preparations which resulted in promising pre-clinical results, the translation of these technologies to the clinic is still limited.
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Choi YS, Cho DY, Lee HK, Cho JK, Lee DH, Bae YH, Lee JK, Kang HC. Enhanced cell survival of pH-sensitive bioenergetic nucleotide nanoparticles in energy/oxygen-depleted cells and their intranasal delivery for reduced brain infarction. Acta Biomater 2016; 41:147-60. [PMID: 27245429 DOI: 10.1016/j.actbio.2016.05.037] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2015] [Revised: 05/07/2016] [Accepted: 05/27/2016] [Indexed: 01/23/2023]
Abstract
UNLABELLED Nucleotides (NTs) (e.g., adenosine triphosphate) are very important molecules in the body. They generate bioenergy through phosphate group release, are involved in various biological processes, and are used to treat various diseases that involve energy depletion. However, their highly anionic characteristics might limit delivery of exogenous NTs into the cell, which is required to realize their functions as bioenergy sources. In this study, ionic complexation between Ca(2+) and NT phosphates was used to form Ca(2+)/NT nanocomplexes (NCs), and branched polyethyleneimine (bPEI1.8kDa) was coated on the surface of Ca(2+)/NT NCs via a simple electrostatic coating. The resultant Ca(2+)/NT/bPEI1.8kDa NCs were approximately 10-25nm in size and had positive zeta-potentials, and their NT loading efficiency and content were approximately 60-75% and 10-20 wt%, respectively. Faster NT release from Ca(2+)/NT/bPEI1.8kDa NCs was induced by lower pH and by NTs with fewer phosphates. Reductions in cell viability in response to low temperature, serum deprivation, or hypoxia were recovered by NT delivery in Ca(2+)/NT/bPEI1.8kDa NCs. In a middle cerebral artery occlusion (MCAO)-induced post-ischemic rat model, the BBB (blood brain barrier)-detoured intranasal administration of Ca(2+)/ATP/bPEI1.8kDa NCs induced a better reduction in infarct volume and neurological deficits than did free ATP. In conclusion, intracellular NT delivery using Ca(2+)/NT/bPEI1.8kDa NCs might potentially enhance cell survival and reduce infarction in energy-/oxygen-depleted environments. STATEMENT OF SIGNIFICANCE This study describes bioenergetic nucleotide delivery systems and their preparation, physicochemical characterization, and biological characterization both in vitro and in vivo. Nucleotides, such as adenosine triphosphate (ATP) and guanosine triphosphate (GTP), are very important signaling and energy molecules in the body. However, research on these nucleotides using nanosized carriers has been very limited. Liposomal ATP delivery has been reported in heart and renal ischemia studies. Notably, although this delivery system has potential in energy-depleted environments (e.g., low temperature, serum deprivation, and hypoxia) and in brain ischemia, studies are lacking regarding these systems. Thus, we designed polycation-shielded Ca(2+)/nucleotide nanocomplexes using simple mixing, which produced 10- to 25-nm-sized particles. The nanocomplexes released nucleotides in response to acidic pH, and they enhanced cell survival rates under conditions of low temperature, serum deprivation, or hypoxia. Importantly, the nanocomplexes reduced cerebral infarct volumes in a post-ischemic rat model. Thus, our study demonstrates that a novel nucleotide nanocomplex could have potential for preventing or treating diseases that involve energy depletion, such as cardiac, cerebral, and retinal ischemia, and liver failure.
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Affiliation(s)
- Yeon Su Choi
- Department of Pharmacy, The Catholic University of Korea, 43 Jibong-ro, Wonmi-gu, Bucheon, Gyeonggi-do 14662, Republic of Korea
| | - Dong Youl Cho
- Department of Pharmacy, The Catholic University of Korea, 43 Jibong-ro, Wonmi-gu, Bucheon, Gyeonggi-do 14662, Republic of Korea
| | - Hye-Kyung Lee
- Department of Anatomy and Inha Research Institute of Medical Sciences, Inha University School of Medicine, 100 Inha-ro, Nam-gu, Incheon 22212, Republic of Korea
| | - Jung-Kyo Cho
- Department of Pharmacy, The Catholic University of Korea, 43 Jibong-ro, Wonmi-gu, Bucheon, Gyeonggi-do 14662, Republic of Korea
| | - Don Haeng Lee
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, Inha University Hospital, 27 Inhang-ro, Jung-gu, Incheon 22332, Republic of Korea; Utah-Inha Drug Delivery Systems and Advanced Therapeutics Research Center, 9 Songdomirae-ro, Yeonsu-gu, Incheon 21988, Republic of Korea
| | - You Han Bae
- Utah-Inha Drug Delivery Systems and Advanced Therapeutics Research Center, 9 Songdomirae-ro, Yeonsu-gu, Incheon 21988, Republic of Korea; Department of Pharmaceutics and Pharmaceutical Chemistry, The University of Utah, 30 S 2000 E, Rm 2972, Salt Lake City, UT 84112, USA
| | - Ja-Kyeong Lee
- Department of Anatomy and Inha Research Institute of Medical Sciences, Inha University School of Medicine, 100 Inha-ro, Nam-gu, Incheon 22212, Republic of Korea.
| | - Han Chang Kang
- Department of Pharmacy, The Catholic University of Korea, 43 Jibong-ro, Wonmi-gu, Bucheon, Gyeonggi-do 14662, Republic of Korea.
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Cho H, Lee YJ, Bae YH, Kang HC. Synthetic polynucleotides as endosomolytic agents and bioenergy sources. J Control Release 2015; 216:30-6. [PMID: 26271546 DOI: 10.1016/j.jconrel.2015.08.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2015] [Revised: 06/17/2015] [Accepted: 08/05/2015] [Indexed: 11/28/2022]
Abstract
Nucleotides (NTs), such as adenosine triphosphate (ATP) and guanosine triphosphate (GTP), are signaling and bioenergy molecules to mediate a range of cellular pathways. We recently reported their significant endosomolytic activity. To evaluate whether polymeric NTs keep endosomolytic and bioenergetic functions of NTs in drug delivery and cell survival, NTs were polymerized by a coupling reaction to form polynucleotides (pNTs: pATP and pGTP) with their molecular weights around 500kDa. The cellular toxicity, indicated by IC50, of pNT was as low as that of corresponding monomeric NT. pNTs were degraded by an intracellular enzyme, alkaline phosphatase. Introduction of pNTs in a polycation-gene complex (polyplex) enhanced the extent of gene expression in cancerous, non-cancerous, and stem cells, up to 1500-fold higher than that of pNT-free polyplex. In addition, cells stored in a pATP solution resulted in a significantly higher survival rate (e.g., up to 20% increase) when exposed to low temperatures than pATP-free solution. The presence of pNT in polyplexes prevented the reduction of transfection efficiency induced by a low temperature. The findings in this study suggest that endosomolytic and bioenergetic pNTs serve as a non-toxic gene carrier component and protect cells from a cold shock or energy depletion.
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Affiliation(s)
- Hana Cho
- Department of Pharmacy and Integrated Research Institute of Pharmaceutical Sciences, College of Pharmacy, The Catholic University of Korea, 43 Jibong-ro, Wonmi-gu, Bucheon-si, Gyeonggi-do 420-743, Republic of Korea
| | - Young Ju Lee
- Gwangju Center, Korean Basic Science Institute, 77 Yongbong-ro, Buk-gu, Gwangju 500-757, Republic of Korea
| | - You Han Bae
- Department of Pharmaceutics and Pharmaceutical Chemistry, The University of Utah, 30S 2000 E, Rm 2972, Salt Lake City, UT 84112, USA; Utah-Inha Drug Delivery Systems (DDS) and Advanced Therapeutics Research Center, 7-50 Songdo-dong, Yeonsu-gu, Incheon 406-840, Republic of Korea.
| | - Han Chang Kang
- Department of Pharmacy and Integrated Research Institute of Pharmaceutical Sciences, College of Pharmacy, The Catholic University of Korea, 43 Jibong-ro, Wonmi-gu, Bucheon-si, Gyeonggi-do 420-743, Republic of Korea.
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Maléth J, Hegyi P, Rakonczay Z, Venglovecz V. Breakdown of bioenergetics evoked by mitochondrial damage in acute pancreatitis: Mechanisms and consequences. Pancreatology 2015; 15:S18-22. [PMID: 26162756 DOI: 10.1016/j.pan.2015.06.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Revised: 06/11/2015] [Accepted: 06/12/2015] [Indexed: 02/07/2023]
Abstract
Acute pancreatitis is a severe inflammatory disease with unacceptably high mortality and without specific therapy. Clinical studies revealed that energy supplementation of patients via enteral feeding decreases systemic infections, multi-organ failure and mortality. These clinical observations have been supported by in vitro and in vivo experimental studies which showed that the most common pancreatitis inducing factors, such as bile acids, ethanol and non-oxidative ethanol metabolites induce intracellular ATP depletion and mitochondrial damage both in pancreatic acinar and ductal cells. Notably, the in vitro supplementation of ATP prevented the cellular damage and restored cell functions in both cell types. These observations suggest that either prevention of mitochondrial damage or restoration of intracellular ATP level might provide therapeutical benefits.
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Affiliation(s)
- József Maléth
- First Department of Medicine, University of Szeged, Szeged, Hungary
| | - Péter Hegyi
- First Department of Medicine, University of Szeged, Szeged, Hungary; MTA-SZTE Lendulet Translational Gastroenterology Research Group, Szeged, Hungary
| | - Zoltán Rakonczay
- First Department of Medicine, University of Szeged, Szeged, Hungary
| | - Viktória Venglovecz
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary.
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Cho H, Cho YY, Bae YH, Kang HC. Nucleotides as nontoxic endogenous endosomolytic agents in drug delivery. Adv Healthc Mater 2014; 3:1007-14. [PMID: 24535942 DOI: 10.1002/adhm.201400008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Revised: 01/27/2014] [Indexed: 11/07/2022]
Abstract
Nontoxic endogenous nucleotides such as adenosine triphosphate and guanosine triphosphate have secondary phosphate groups, causing proton-buffering capacity and/or hemolytic activity in endolysosomal pH ranges. Nucleotides co-delivered in single polymeric pDNA nanocarrier induce highly enhanced transfection efficiency with negligible cytotoxicity due to their endosomolytic functions.
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Affiliation(s)
- Hana Cho
- Department of Pharmacy and Integrated Research; Institute of Pharmaceutical Sciences; College of Pharmacy; The Catholic University of Korea; 43 Jibong-ro Wonmi-gu, Bucheon-si Gyeonggi-do 420-743 Republic of Korea
| | - Yong-Yeon Cho
- Department of Pharmacy and Integrated Research; Institute of Pharmaceutical Sciences; College of Pharmacy; The Catholic University of Korea; 43 Jibong-ro Wonmi-gu, Bucheon-si Gyeonggi-do 420-743 Republic of Korea
| | - You Han Bae
- Department of Pharmaceutics and Pharmaceutical Chemistry; The University of Utah; 30 S 2000 E, Rm 2972 Salt Lake City UT 84112 USA
- Utah-Inha Drug Delivery Systems (DDS) and Advanced Therapeutics Research Center; 7-50 Songdo-dong Yeonsu-gu Incheon 406-840 Republic of Korea
| | - Han Chang Kang
- Department of Pharmacy and Integrated Research; Institute of Pharmaceutical Sciences; College of Pharmacy; The Catholic University of Korea; 43 Jibong-ro Wonmi-gu, Bucheon-si Gyeonggi-do 420-743 Republic of Korea
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Charrueau C, Neveux N, Chaumeil JC, Hannoun L, Cynober L, Savier E. Best temperature for static liver graft storage is 1°C. J Surg Res 2013; 180:322-9. [DOI: 10.1016/j.jss.2012.04.046] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Revised: 04/16/2012] [Accepted: 04/20/2012] [Indexed: 12/17/2022]
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Giacalone G, Bochot A, Fattal E, Hillaireau H. Drug-induced nanocarrier assembly as a strategy for the cellular delivery of nucleotides and nucleotide analogues. Biomacromolecules 2013; 14:737-42. [PMID: 23351139 DOI: 10.1021/bm301832v] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The natural nucleotide adenosine triphosphate (ATP) and nucleotide analogues such as azidothymidine triphosphate (AZT-TP) display important pharmacological activities for the treatment of ischemia and HIV infections, respectively. Their clinical use is, however, limited mostly due to their hydrophilicity, which highly restricts their diffusion into the target cells. Few nanocarriers have been proposed to address the challenge of ATP/AZT-TP cellular delivery, but the loading efficiency, preparation complexity, and efficient cellular delivery remain important barriers to their development. In this study, we propose an original, straightforward and versatile design of nucleotide and nucleotide analogue nanocarriers based on the natural polysaccharide chitosan (CS). We show that the drugs ATP and AZT-TP can induce ionotropic gelation of CS, leading to CS/ATP and CS/AZT-TP nanoparticles with high drug entrapment efficiency and loading rate-up to 44%. Such nanocarriers release ATP and AZT-TP in physiological media and allow an efficient in vitro cellular delivery of these molecules down to the cell cytoplasm.
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Affiliation(s)
- Giovanna Giacalone
- Institut Galien Paris-Sud, Université Paris-Sud, Châtenay-Malabry, France
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Maléth J, Rakonczay Z, Venglovecz V, Dolman NJ, Hegyi P. Central role of mitochondrial injury in the pathogenesis of acute pancreatitis. Acta Physiol (Oxf) 2013; 207:226-35. [PMID: 23167280 DOI: 10.1111/apha.12037] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Revised: 10/26/2012] [Accepted: 10/30/2012] [Indexed: 12/11/2022]
Abstract
Acute pancreatitis is an inflammatory disease with no specific treatment. One of the main reasons behind the lack of specific therapy is that the pathogenesis of acute pancreatitis is poorly understood. During the development of acute pancreatitis, the disease-inducing factors can damage both cell types of the exocrine pancreas, namely the acinar and ductal cells. Because damage of either of the cell types can contribute to the inflammation, it is crucial to find common intracellular mechanisms that can be targeted by pharmacological therapies. Despite the many differences, recent studies revealed that the most common factors that induce pancreatitis cause mitochondrial damage with the consequent breakdown of bioenergetics, that is, ATP depletion in both cell types. In this review, we summarize our knowledge of mitochondrial function and damage within both pancreatic acinar and ductal cells. We also suggest that colloidal ATP delivery systems for pancreatic energy supply may be able to protect acinar and ductal cells from cellular damage in the early phase of the disease. An effective energy delivery system combined with the prevention of further mitochondrial damage may, for the first time, open up the possibility of pharmacological therapy for acute pancreatitis, leading to reduced disease severity and mortality.
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Affiliation(s)
- J. Maléth
- First Department of Medicine; University of Szeged; Szeged; Hungary
| | - Z. Rakonczay
- First Department of Medicine; University of Szeged; Szeged; Hungary
| | - V. Venglovecz
- Department of Pharmacology and Pharmacotherapy; University of Szeged; Szeged; Hungary
| | - N. J. Dolman
- Molecular Probes Labelling and Detection Technologies; Life Technologies Corporation; Eugene; OR; USA
| | - P. Hegyi
- First Department of Medicine; University of Szeged; Szeged; Hungary
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Maldonado C, Pushpakumar SB, Perez-Abadia G, Arumugam S, Lane AN. Administration of exogenous adenosine triphosphate to ischemic skeletal muscle induces an energy-sparing effect: role of adenosine receptors. J Surg Res 2012; 181:e15-22. [PMID: 22795271 DOI: 10.1016/j.jss.2012.06.033] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2012] [Revised: 06/12/2012] [Accepted: 06/15/2012] [Indexed: 10/28/2022]
Abstract
BACKGROUND Ischemia-reperfusion injury is a devastating complication that occurs in allotransplantation and replantation of limbs. Over the years, several preservation strategies have been used to conserve the critical levels of intracellular adenosine triphosphate (ATP) during ischemia to sustain the ion gradients across the membranes and thus the tissue viability. The administration of exogenous ATP to ischemic tissues is known to provide beneficial effects during reperfusion, but it is unclear whether it provides protection during ischemia. The purpose of the present study was to determine the effect of ATP administration on high-energy phosphate levels in ischemic skeletal muscle and to examine the role of purinergic and adenosine receptors in mediating the response to exogenous ATP. METHODS The extensor digitorum longus muscles of Fischer rats were subjected to ischemia and treated with different concentrations of ATP with or without purinergic and adenosine receptor blockers. Phosphorus-31 nuclear magnetic resonance spectroscopy was used to measure the rate of decay of ATP, phosphocreatine (PCr), and the formation of adenosine monophosphate and acidification. Phosphorylated compounds were analyzed using a simple model of energy metabolism, and the PCr half-life was used as an index of internal depletion of ATP to distinguish between intracellular and extracellular ATP. RESULTS PCr decay was rapid in all muscle groups and was followed by gradual ATP decay. The half-life of PCr was significantly longer in the ATP-treated muscles than in the vehicle controls and was maximally prolonged by treating with slow hydrolyzing adenosine 5'-O-(3-thio)triphosphate. Purinoceptor (P2X) blockade with ATP treatment significantly increased the half-life of PCr, and adenosine receptor blockers blunted the response. Administration of adenosine to ischemic muscles significantly increased the half-life of PCr compared with that in the vehicle controls. CONCLUSIONS Exogenous ATP administration to ischemic skeletal muscles appears to spare intracellular energy by acting primarily through adenosine receptors.
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Affiliation(s)
- Claudio Maldonado
- Department of Physiology and Biophysics, University of Louisville, Louisville, Kentucky.
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Wang L, MacDonald RC. Cationic phospholiposomes: efficient delivery vehicles of anticancer derivatives of ATP to multiple myeloma cells. J Liposome Res 2011; 21:306-14. [PMID: 21457078 DOI: 10.3109/08982104.2011.565476] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Analogs of adenosine triphosphate (ATP) with substitutions at the 8-position have been shown to be cytotoxic to multiple myeloma, one of the most prevalent and serious blood cancers. However, these drugs do not readily cross biological membranes and are very sensitive to phosphatases present in body fluids. To circumvent these disadvantages, 8-substituted ATPs were encapsulated into cationic phospholiposomes generated from cationic phosphatidylcholines (EDOPC; 1,2-dioleoyl-sn-glycero-3-ethylphosphocholine, and EDPPC, the corresponding dipalmitoyl homolog), compounds with low toxicity that readily form liposomes. Vortexing was an efficient encapsulation procedure, more so than freeze-thawing. At the lipid:drug ratio of 5:1 (mol/mol), 20% of 8-Br-ATP was encapsulated within EDOPC liposomes. Efficient encapsulation and retention of 8-NH₂-ATP required the inclusion of cholesterol. Liposomes of EDOPC:cholesterol (55:45 mole/mole), at a lipid:drug mole ratio of 10:1, captured ~40% of the drug presented. Cytotoxicity assays of this formulation on multiple myeloma cells in culture showed encapsulated drug to be up to 10-fold more effective than free drug, depending upon dose. Intracellular distribution studies (based on fluorescent derivatives of lipids and of ATP) revealed that both liposomes and drug were taken up by multiple myeloma cells, and that uptake of a fluorescent ATP derivative was significantly greater when encapsulated than when free. Liposomes prepared from EDPPC, having a higher phase-transition temperature than EDOPC, captured 8-NH₂-ATP satisfactorily and released it more slowly than the unsaturated formulations, but were also less cytotoxic. The superior encapsulation efficiencies of the positively charged liposomes can be understood in terms of the electrostatic double layer due to a very high positive charge density on their inner surface. Electrostatic augmentation of encapsulation for small vesicles can be dramatic, easily exceeding an order of magnitude.
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Affiliation(s)
- Li Wang
- Department of Biochemistry, Molecular Biology and Cell Biology, Northwestern University, Evanston, Illinois 60208, USA
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Abstract
ATP cannot be effectively delivered to most tissues including the ischemic myocardium without protection from degradation by plasma endonucleotidases. However, it has been established that ATP can be delivered to various tissues by its encapsulation within liposomal preparations. We describe here, the materials needed and methods used to optimize the encapsulation of ATP in liposomes, enhance their effectiveness by increasing their circulation time and target injured myocardial cells with liposomal surface anti-myosin antibody. Additionally, we outline methods for ex vivo studies of these ATP liposomal preparations in an isolated ischemic rat heart model and for in vivo studies of rabbits with an induced myocardial infarction. The expectation is that these methods will provide a basis for continued studies of effective ways to deliver energy substrates to the ischemic myocardium.
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Hartner WC, Verma DD, Levchenko TS, Bernstein EA, Torchilin VP. ATP-loaded liposomes for treatment of myocardial ischemia. WILEY INTERDISCIPLINARY REVIEWS-NANOMEDICINE AND NANOBIOTECHNOLOGY 2010; 1:530-9. [PMID: 20049815 DOI: 10.1002/wnan.46] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
A major obstacle to drug therapy for treatment of potential myocardial infarction is the limited access to the ischemic myocardium by drugs in an active form. Encouraging results have been reported with liposomes loaded with ATP in a variety of in vitro and in vivo models. We describe methods for optimized encapsulation of ATP in liposomes, enhancement of their effectiveness by increasing circulation time, and targeting of injured myocardial cells with surface attached antimyosin. In isolated ischemic rat hearts, ATP-loaded liposomes and ATP-loaded immunoliposomes effectively protected myocardium from ischemia/reperfusion damage as measured by systolic and diastolic functional improvements. In vivo, in rabbits with induced localized myocardial ischemia, liposomal encapsulation of ATP significantly diminished the proportion of ventricular muscle at risk that was irreversibly damaged during reperfusion. Therefore, ATP encapsulated in liposomes can provide an effective exogenous source for in vivo application which can protect ischemically damaged hearts.
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Affiliation(s)
- William C Hartner
- Departmentof Pharmaceutical Sciences, Northeastern University, Boston, MA 02115, USA
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Tep K, Korb V, Richard C, Escriou V, Largeau C, Vincourt V, Bessodes M, Guellier A, Scherman D, Cynober L, Chaumeil JC, Dumortier G. Formulation and evaluation of ATP-containing liposomes including lactosylated ASGPr ligand. J Liposome Res 2010; 19:287-300. [PMID: 19863164 DOI: 10.3109/08982100902838682] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
An original ligand (Lac-10-Chol) designed to interact with asialoglycoprotein receptors to potentially target hepatocyte was synthesised by grafting a lactose head to a cholesteryl structure, which was then included in liposomes. Preliminary formulation tests led to the selection of conventional formulations based on soybean phosphatidylcholine/cholesterol/DOTAP (+/- DOPE) (+/- Lac-10-Chol) that present reproducible absolute entrapment value (1.45 +/- 0.10%), with a size of 109 +/- 7 nm and a slight positive charge (3.77 +/- 1.59 mV). Cell viability (via the MTT test), expressed as the percentage of nontreated cells in HepG2 cells, was very close to the control. Internalization tests evidenced an intracellular penetration of fluorescent liposomes, but no specific ligand effect was demonstrated (P > 0.05). Nevertheless, regarding the adenosine triphosphate (ATP) assay, a slight increase was obtained with liposome loaded with ATP incorporating Lac-10-chol after 24 hours (P < 0.05).
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Affiliation(s)
- Karona Tep
- Laboratoire de Pharmacie Galénique, Université Paris Descartes, Faculté des Sciences Pharmaceutiques et Biologiques, Paris Cedex, France
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El Kateb N, Cynober L, Chaumeil JC, Dumortier G. L-cysteine encapsulation in liposomes: effect of phospholipids nature on entrapment efficiency and stability. J Microencapsul 2008; 25:399-413. [PMID: 18608804 DOI: 10.1080/02652040802012453] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Liposomal entrapment of L-cysteine (L-CySH) could be a solution to enhance its oxidative stability and its intracellular bioavailability for glutathione (GSH) synthesis. This study addresses the influence of different factors (i.e. pH value (6.3 vs 7.4), antioxidant agents (EDTA or tocopherol (TO and nature of phosphatidylcholine (PC) (Soybean PC (SPC) vs hydrogenated SPC (HSPC)) to formulate and optimize Large Unilamellar Vesicles (LUVs) of L-CySH composed of PC/Cholesterol/ Phosphatidylglycerol (6:3:1). pH decrease (p = 0.0002) and substitution of SPC by HSPC (p < 0.001) reduced L-CySH oxidation. EE% (entrapment efficiency) varied from 0.98% +/- 0.54 (SPC, pH 7.4) to 6.46% +/- 1.37 (HSPC, pH 6.3) and was improved by decreasing pH (p = 0.011) and using HSPC (p < 0.0001). An immediate release of L-CySH was observed with SPC. On the contrary, with HSPC at pH 6.3, 42.0% +/- 1.2 and 73.0% +/- 1.7 remained encapsulated after 24h at 25 degrees C and 4 degrees C, respectively. In conclusion, HSPC offering both stronger rigidity and lesser propensity for peroxidation led to optimize L-CySH liposomal stability.
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Affiliation(s)
- Nabil El Kateb
- Faculté des Sciences Pharmaceutiques et Biologiques, Laboratoire de Pharmacie Galénique, Paris, France.
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Jourdan M, Cynober L, Moinard C, Blanc MC, Neveux N, De Bandt JP, Aussel C. Splanchnic sequestration of amino acids in aged rats: in vivo and ex vivo experiments using a model of isolated perfused liver. Am J Physiol Regul Integr Comp Physiol 2007; 294:R748-55. [PMID: 18056986 DOI: 10.1152/ajpregu.00291.2007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Splanchnic sequestration of amino acids (SSAA) is a process observed during aging that leads to decreased peripheral amino acid (AA) availability. The mechanisms underlying SSAA remain unknown. The aim of the present study was to determine whether a high-protein diet could increase nitrogen retention in aged rats by saturating SSAA and whether SSAA could be explained by dysregulation of hepatic nitrogen metabolism. Adult and aged male Sprague-Dawley rats were housed in individual metabolic cages and fed a normal-protein (17% protein) or high-protein diet (27%) for 2 wk. Nitrogen balance (NB) was calculated daily. On day 14, livers were isolated and perfused for 90 min to study AA and urea fluxes. NB was lower in aged rats fed a normal-protein diet than in adults, but a high-protein diet restored NB to adult levels. Isolated perfused livers from aged rats showed decreased urea production and arginine uptake, together with a release of alanine (vs. uptake in adult rats) and a hepatic accumulation of alanine. The in vivo data suggest that SSAA is a saturable process that responds to an increase in dietary protein content. The hepatic metabolism of AA in aged rats is greatly modified, and urea production decreases. This result refutes the hypothesis that SSAA is associated with an increase in AA disposal via urea production.
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Affiliation(s)
- M Jourdan
- Laboratory of Biological Nutrition, René Descartes Paris 5 University, Paris, France
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17
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Schuster H, Blanc MC, Neveux N, Bonnefont-Rousselot D, Le Tourneau A, De Bandt JP, Cynober L. Protective effects of regulatory amino acids on ischemia-reperfusion injury in the isolated perfused rat liver. Scand J Gastroenterol 2006; 41:1342-9. [PMID: 17060129 DOI: 10.1080/00365520600682039] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
OBJECTIVE Some amino acids (AAs) display potent regulatory activities on cell metabolism, including via anti-oxidative defences. The aim of this study was to evaluate the protective effect of these AAs on warm ischaemia-reperfusion (I/R) injury in the isolated perfused rat liver. MATERIAL AND METHODS Livers from fasted male Sprague-Dawley rats were isolated and perfused without (control group) or with (AP group) a mixture of regulatory AAs (glutamine, histidine, leucine, methionine, proline, phenylalanine, tryptophan and alanine). After 45 min of perfusion, warm ischaemia was induced for 45 min by clamping the portal vein catheter; thereafter, reperfusion was performed for 30 min. RESULTS TNF-alpha production was significantly lower in the AP group during reperfusion ( CONTROL 39+/-7 versus AP: 16+/-2 pg min-1 g-1, p<0.05), and lactate dehydrogenase (LDH) release decreased significantly during the last 15 min of reperfusion ( CONTROL 0.13+/-0.03 versus AP: 0.04+/-0.02 IU min-1 g-1, p<0.05), despite similar levels of oxidative stress. The addition of regulatory AAs was not associated with variations in portal flow, bile flow, hepatic glucose or urea metabolism. However, significant changes in intrahepatic glutamine ( CONTROL 1.4+/-0.2 versus AP: 2.6+/-0.5 micromol g-1, p < 0.05) together with higher glutamate release in the AP group ( CONTROL 10.2+/-5.4 versus AP: 42.6+/-10.9 nmol min-1 g-1, p < 0.05) indicated modifications in nitrogen metabolism. CONCLUSIONS Taken together, the lower TNF-alpha production, suggesting decreased inflammatory response, the decrease in LDH release in the AP group, demonstrating a better preservation of liver viability, and the increase in hepatic glutamine indicate that AAs play an important role in the liver's response to I/R.
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Affiliation(s)
- Heidi Schuster
- Laboratoire de Biologie de la Nutrition, EA2498, Faculté de Pharmacie, Université Paris 5, Paris, France
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Verma DD, Levchenko TS, Bernstein EA, Torchilin VP. ATP-loaded liposomes effectively protect mechanical functions of the myocardium from global ischemia in an isolated rat heart model. J Control Release 2005; 108:460-71. [PMID: 16233928 PMCID: PMC1634739 DOI: 10.1016/j.jconrel.2005.08.029] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2005] [Revised: 08/19/2005] [Accepted: 08/26/2005] [Indexed: 11/23/2022]
Abstract
ATP-loaded liposomes (ATP-L) infused into Langendorff-instrumented isolated rat hearts protect the mechanical functions of the myocardium during ischemia/reperfusion. The left ventricular developed pressure (LVDP) at the end of the reperfusion in the ATP-L group recovered to 72% of the baseline (preservation of the systolic function) compared to 26%, 40%, and 51% in the groups treated with Krebs-Henseleit (KH) buffer, empty liposomes (EL), and free ATP (F-ATP), respectively. The ATP-L-treated group also showed a significantly lower left ventricular end diastolic pressure (LVEDP; better preservation of the diastolic function) after ischemia/reperfusion than controls. After incubating the F-ATP and ATP-L with ATPase, the protective effect of the F-ATP was completely eliminated because of ATP degradation, while the protective effect of the ATP-L remained unchanged. Fluorescence microscopy confirmed the accumulation of liposomes in ischemic areas, and the net ATP in the ischemic heart increased with ATP-L. Our results suggest that ATP-L can effectively protect myocardium from ischemic/reperfusion damage.
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Affiliation(s)
- D D Verma
- Department of Pharmaceutical Sciences, Northeastern University, 360 Huntington Avenue, Boston, MA 02115, USA
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Mamprin ME, Vega F, Rodriguez JV. Adenosine 5'triphosphate transport and accumulation during the cold preservation of rat hepatocytes in University of Wisconsin solution. World J Gastroenterol 2005; 11:1957-64. [PMID: 15800986 PMCID: PMC4305717 DOI: 10.3748/wjg.v11.i13.1957] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: We used isolated hepatocytes to investigate how different concentrations of ATP in the University of Wisconsin (UW) solution affected both cellular ATP content and cell viability during the cold storage and the rewarming step. The mechanism involved in ATP transport and accumulation in hypothermia was also determined.
METHODS: The cells were preserved up to 72 h in different conditions: UW solution without ATP (a-group), UW+5 mmol/L ATP (b-group), and UW+10 mmol/L ATP (c-group). The ATP content and the cell viability (LDH release) were determined during the cold storage and the rewarming step. In the groups a and c, the respiratory function of the cells at rewarming was studied. In addition, the cell volume of hepatocytes and the mechanism involved in ATP transport and accumulation were assessed. The extracellular degradation of exogenous nucleotides during transport experiments was investigated by a HPLC technique.
RESULTS: After three days of cold storage a loss of cellular ATP content was observed in hepatocytes preserved either without nucleotides (a-group) or with 5 mmol/L ATP (b-group). In contrast, 10 mmol/L ATP (c-group) was able to maintain a normal ATP cellular content, with only a 6% diminution after 72 h of cold storage. The respiratory function was significantly different in hepatocytes preserved with 10 mmol/L ATP than without ATP. No significant change was detected for the three groups in cellular volume during the cold storage. We also report that the time course accumulation of [3H]-ATP by cold stored hepatocytes is a rapid process that is completed after 180 s with linear dependence on the extracellular ATP concentration (linear fitting results in a slope of 0.5624±0.1179 mmol/L ATP intracell/mmol/L ATP extracell).
CONCLUSION: Our results show that, during hypothermic storage in UW solution, hepatocytes are permeable to ATP by a diffusive mechanism. Also, we found that it is ATP the main extracellular nucleotide available for transport and it is not the breakdown products.
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Affiliation(s)
- Maria E Mamprin
- Farmacologia, Departamento Ciencias Fisiologicas, Facultad de Ciencias Bioquimicas y Farmaceuticas, Universidad Nacional de Rosario, Suipacha 531, Rosario, Argentina
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Jourdan M, Vaubourdolle M, Cynober L, Aussel C. Effect of aging on liver functions—an experimental study in a perfused rat liver model. Exp Gerontol 2004; 39:1341-6. [PMID: 15489057 DOI: 10.1016/j.exger.2004.07.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2004] [Revised: 06/23/2004] [Accepted: 07/01/2004] [Indexed: 01/10/2023]
Abstract
BACKGROUND Aging is associated with marked changes in the physiology of many organs. Aging of the liver has been little studied and findings are inconclusive. The purpose of this work was to determine the effect of aging on transport and metabolic functions of the liver as assessed by extraction ratio of indocyanine green (ICG) and urea flux respectively. Bile flow was also recorded. As ICG is removed exclusively by the liver without bioconversion, its clearance reflects hepatic functional mass. METHODS Livers from adult (3-month old) or old (24-month old) rats were perfused in a recirculating system for 90 min. At time 30 min, a bolus of 0.125 mg of indocyanine green was introduced in the perfusion buffer. At least every 10 minutes, the perfusion buffer was sampled for the measurements of ICG and urea. Bile flow was closely monitored throughout the experiment. RESULTS Extraction ratio of ICG was increased in livers from old rats (9.49 +/- 2.84 vs 3.70 +/- 1.56% of ICG extracted), whereas urea flux was diminished (0.33 +/- 0.06 vs 1.33 +/- 0.65 micromol/min/% of ICG extracted) and bile flow was unchanged (4.03 +/- 1.02 vs 3.57 +/- 1.34 microl/min). CONCLUSIONS Aging does not affect the different functions of the liver in the same way. It increases hepatocellular uptake function, but decreases the metabolic function of hepatocytes and does not change excretion function. These discrepancies are likely to be of some importance in the study of drug metabolism and action, and so we suggest that results should be corrected for ICG extraction.
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Affiliation(s)
- Marion Jourdan
- Laboratory of Biological Nutrition EA 2498, 4 avenue de l'Observatoire; 75270 Paris cedex 06, France.
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Wang F, Cheng L, Zhao G, Zhou HY, Yao WX. Effects of berberine on potassium and calcium currents in isolated rat hepatocytes. Shijie Huaren Xiaohua Zazhi 2004; 12:1600-1603. [DOI: 10.11569/wcjd.v12.i7.1600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To study the effects of berberine on ion channels in isolated rat hepatocytes.
METHODS: Tight-seal whole-cell patch-clamp techniques were performed to investigate the effects of berberine on the delayed outward potassium currents (IK) and Ca2+ release-activated Ca2+ current (ICRAC) in enzymatically isolated rat hepatocytes.
RESULTS: Berberine 1-300 moL/L reduced IK in a concentration-dependent manner with EC50 of 39±5 moL/L and nH of 0.82±0.05 (n = 8). When the bath solution was changed to tetraethylammonium (TEA) 8 mmol/L, IK was inhibited. Berberine 30 mol/L reduced IK at all membrane potentials examined, especially at potentials positive to +60 mV (n = 8, P < 0.05 or P < 0.01 vs control). Berberine 1-300 moL/L also inhibited ICRAC in a concentration-dependent manner. The fitting parameters were as follows: EC50 = 47±11 moL/L, nH = 0.71±0.09 (n = 8). The peak value of ICRAC in the I-V relationship was decreased by berberine 30 mol/L at potential negative to -80 mV (n = 8, P < 0.05 vs control). But the reverse potential of ICRAC occurred at voltage = 0 mV in all cells.
CONCLUSION: Berberine has inhibitory effects on potassium and calcium currents in isolated rat hepatocytes, which may be involved in the hepatoprotective effect.
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Chaïb S, Charrueau C, Neveux N, Coudray-Lucas C, Cynober L, De Bandt JP. Isolated perfused liver model: the rat and guinea pig compared. Nutrition 2004; 20:458-64. [PMID: 15105034 DOI: 10.1016/j.nut.2004.01.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
OBJECTIVE Although the rat is the most commonly used species for the study of hepatic metabolism, the physiology of the guinea pig is closer to human physiology. We compared the model of isolated perfused guinea pig liver with the classic model of isolated perfused rat liver, especially with respect to amino acid metabolism. METHODS After validation of an anesthetic mixture of ketamine, diazepam, and xylazine for the guinea pig, isolated perfused livers were harvested for both species. Three groups of animals were compared for the study of liver metabolic fluxes: 6-wk-old male Sprague-Dawley rats (R; 230 +/- 10 g, n = 5), young male Hartley guinea pigs (YG; 223 +/- 8 g, n = 6) matched to rats by liver weight, and adult male Hartley guinea pigs (AG; 389 +/- 5 g, n = 6) matched to rats by age. Results (mean +/- standard error of the mean) were compared by analysis of variance and Newman-Keuls tests. RESULTS Both models displayed a satisfactory hepatic viability, but differences were noted, with higher portal flows (R: 3.1 +/- 0.3 versus YG: 4.5 +/- 0.3 and AG: 4.2 +/- 0.3 mL. min(-1). g(-1); P < 0.05, YG and AG versus R) and bile flows (R: 0.34 +/- 0.01 versus YG: 2.38 +/- 0.22 versus AG: 3.17 +/- 0.28 microL. min(-1). g(-1); P < 0.05, YG and AG versus R, and YG versus AG) and higher amino acid fluxes (P < 0.05) leading to greater nitrogen uptake (P < 0.05) in guinea pigs. We performed a second set of experiments to evaluate the influence of anesthesia and portal flow on this last parameter. In these experiments, rats were anesthetized with ketamine, diazepam, and xylazine and guinea pig livers were perfused at rat blood flow. Apart from a 50% anesthesia-related mortality for rats, bile flow and metabolic parameters were only slightly modified. However, some amino acid fluxes were statistically different (aspartate, serine, and histidine; P < 0.05), as confirmed by a higher transfer constant. CONCLUSION Our results indicate that the isolated perfused guinea pig liver is a suitable model for the study of hepatic metabolism.
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Affiliation(s)
- Samira Chaïb
- Laboratoire de Biologie de la Nutrition EA 2498, Faculté de Pharmacie, Laboratoire de Biochimie A, Hôpital Hôtel-Dieu AP-HP, Paris, France
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Tan XD, Egami H, Wang FS, Ogawa M. Protective effect of exogenous adenosine triphosphate on hypothermically preserved rat liver. World J Gastroenterol 2004; 10:871-4. [PMID: 15040035 PMCID: PMC4727024 DOI: 10.3748/wjg.v10.i6.871] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
AIM: To clarify the protective effect of exogenous adenosine triphosphate (ATP) on hypothermically preserved rat livers.
METHODS: Establishment of continuous hypothermic machine perfusion model, detection of nucleotides in hepatocytes with HPLC, measurement of activities of LDH and AST in the perfusate, observation of histopathological changes in different experiment groups, and autoradiography were carried out to reveal the underlying mechanism of the protective effect of ATP.
RESULTS: The intracellular levels of ATP and EC decreased rapidly after hypothermic preservation in control group, while a higher ATP and EC level, and a slower decreasing rate were observed when ATP-MgCl2 was added to the perfusate (P < 0.01). As compared with the control group, the activities of LDH and AST in the ATP-MgCl2 group were lower (P < 0.05). Furthermore, more severe hepatocyte damage and neutrophil infiltration were observed in the control group. Radioactive [α-32P] ATP entered the hypothermically preserved rat hepatocytes.
CONCLUSION: Exogenous ATP has a protective effect on rat livers during hypothermical preservation. However, Mg2+ is indispensable, addition of ATP alone produces no protective effect. The underlying mechanism may be that exogenous ATP enters the hypothermically preserved rat liver cells.
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Affiliation(s)
- Xiao-Dong Tan
- Department of Surgery II, Kumamoto University Medical School. Honjo 1-1-1, Kumamoto 860-8556, Japan.
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Abstract
Amino acids are not only important precursors for the synthesis of proteins and other N-containing compounds, but also participate in the regulation of major metabolic pathways. Glutamate and aspartate, for example, are components of the malate/aspartate shuttle and their concentrations control the rate of mitochondrial oxidation of glycolytic NADH. Glutamate also controls the rate of urea synthesis, not only as the precursor of ammonia and aspartate, but as substrate for synthesis of N-acetylglutamate, the essential activator of carbamoyl-phosphate synthase. This mechanism allows large variations in urea synthesis at relatively constant ammonia concentrations. Increases in intracellular amino acid concentration increase cell volume. Cell swelling per se has anabolic effects on protein, carbohydrate and lipid metabolism: enhanced synthesis of macromolecules compensates for increases in intracellular osmolarity. Mechanisms responsible for cell swelling-induced changes in pathway fluxes include changes in intracellular ion concentrations and in signal transduction. Specific amino acids (e.g., leucine) stimulate protein synthesis and inhibit (autophagic) protein degradation independent of changes in cell volume because they stimulate mTOR (mammalian target of rapamycin), a protein kinase, which is one of the components of a signal transduction pathway used by insulin. When the cellular energy state is low, stimulation of mTOR by amino acids is prevented by activation of AMP-dependent protein kinase. Amino acid-dependent signaling also promotes insulin production by beta-cells. This further adds to the anabolic properties of amino acids. It is concluded that amino acids are important regulators of major metabolic pathways.
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Affiliation(s)
- Alfred J Meijer
- Department of Biochemistry, Academic Medical Center, University of Amsterdam, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands.
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Yard BA, Yedgar S, Scheele M, van der Woude D, Beck G, Heidrich B, Krimsky M, van der Woude FJ, Post S. Modulation of IFN-gamma-induced immunogenicity by phosphatidylethanolamine-linked hyaluronic acid. Transplantation 2002; 73:984-92. [PMID: 11923705 DOI: 10.1097/00007890-200203270-00028] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND The present study was conducted to examine the possibility of modulating interferon (IFN-gamma)-induced immunogenicity by a novel compound that is composed of a PLA2 inhibitor linked to hyaluronic acid (HYPE). METHODS HYPE was tested for its effect on IFN-gamma-induced expression of MHC class I, class II, and intercellular adhesion molecule (ICAM-1) in cultured endothelial and renal proximal tubular cells by flow cytometric analysis (FACS) as well as its ability to influence T cell activation in mixed lymphocyte reaction (MLR) or after mitogen stimulation. RESULTS In FACS, a profound inhibition in MHC class I and ICAM-1 staining was observed in stimulated or unstimulated cells that were incubated with HYPE. This was not due to down-regulation of antigen expression and only occurred when monoclonal antibodies, but not when polyclonal antibodies, were used. HYPE inhibited the induction of MHC class II in both cell types after IFN-gamma stimulation in a dose-dependent manner. Moreover, the induction of class II transactivator (CIITA) was completely inhibited under these conditions, most likely because it blocked the binding of IFN-gamma to the cell membrane. Addition of HYPE to MLR inhibited the proliferation of T cells and the secretion of interleukin (IL)-2, IFN-gamma, and IL-10. This was not observed when HYPE was added together with anti-CD3 or phytohemagglutinin (PHA). CONCLUSION Our study provides experimental evidence that HYPE has immunosuppressive features. This makes the compound an interesting candidate as an immunosuppressive drug, not only in organ transplantation, but also in diseases where IFN-gamma is overexpressed.
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Affiliation(s)
- Benito A Yard
- V. Medizinische Klinik, Klinikum Mannheim, University of Heidelberg, Germany
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Mamprin ME, Guibert EE, Rodriguez JV. Glutathione synthesis during the rewarming of rat hepatocytes preserved in the University of Wisconsin solution. Cryobiology 2001; 43:310-5. [PMID: 12009728 DOI: 10.1006/cryo.2001.2364] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In this study, we used isolated rat hepatocytes to investigate the effect of nucleoside content of the preserved cells on the ability to synthesize glutathione (GSH) during the rewarming process. We cold-stored hepatocytes in University of Wisconsin (UW) solution (72 h, 0 degrees C, N(2)) without nucleosides and with the addition of 5 mM adenosine or 10 mM ATP. After 72 h of cold storage, we determined the GSH synthesis rate and the ATP content of the cells. We found a GSH synthesis rate similar to that of freshly isolated hepatocytes only in the group of cells cold-stored with 10 mM ATP. When we tested the cellular ATP concentrations, we found that controls and preserved cells with 10 mM ATP showed a similar value of ATP during the rewarming step. Our results suggested that the incorporation of ATP in the UW solution increased the ATP content and the rate of GSH synthesis of cold-stored hepatocytes during rewarming.
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Affiliation(s)
- M E Mamprin
- Farmacología, Departamento de Ciencias Fisiológicas, Universidad Nacional de Rosario, Suipacha 531, S2002LRK Rosario, Argentina
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Abstract
OBJECTIVE We describe the effect of the metabolic and nutritional modifications caused by severe illness or injury in brain-dead organ donors on transplant organ function. Malnutrition is frequently found in brain-dead organ donors and nutrients may interfere with different organ functions. METHODS Literature was obtained from MEDLINE using the key words organ donation, brain death, transplantation, nutrition, fish oil, amino acids. RESULTS In the liver, infusion of large quantities of dextrose can restore glycogen reserves but may induce hyperglycemia and a hyperosmolar hepatic state. Feeding improves protein synthesis in hepatocytes, and fat (fish oil) administration in particular increases the hepatic energy and adenosine triphosphate content. Amino acids have a significant effect on regenerating hepatic tissue when given with fat and glucose. In the heart, free fatty acids administered during reperfusion improve cardiac functional recovery, and administration of propofol, a general anesthetic agent enriched with fatty acids, have protective effects on ischemia-and-reperfusion injury. Glutamine also can induce graft protection during ischemia-and-reperfusion injury. Renal function is improved by fish oil supplementation. In addition, effective renal plasma flow, glomerular filtration rate, and renal blood flow are increased, apparently by a reduction in thromboxane B2 production. Glycine or alanine can protect renal tubules from stress injury. CONCLUSION Nutrition plays an important role in the modulation of organ function after transplantation.
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Affiliation(s)
- P Singer
- Department of General Intensive Care, Rabin Medical Center, Beilinson Campus, Petah Tiqva, Israel.
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