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Santi MD, Hune TLK, Rodriguez GG, Fries LM, Mei R, Sternkopf S, Elsaßer J, Glöggler S. Parahydrogen-enhanced pH measurements using [1- 13C]bicarbonate derived from non-enzymatic decarboxylation of [1- 13C]pyruvate-d 3. Analyst 2024. [PMID: 39230365 PMCID: PMC11373534 DOI: 10.1039/d4an00832d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/05/2024]
Abstract
Alterations in pH are a hallmark in several pathologies including cancer, ischemia, and inflammation. Non-invasive magnetic resonance methods to measure pH offer a new approach for early diagnosis of diseases characterized by acid-base imbalances. The hyperpolarization with parahydrogen-induced polarization (PHIP) enhances inherently low signals in magnetic resonance experiments by several orders of magnitude and offers a suitable platform to obtain biocompatible markers in less than one minute. Here, we present an optimized preparation of an hyperpolarized H13CO3-/13CO2 pH sensor via non-enzymatic decarboxylation with H2O2 of [1-13C]pyruvate-d3 obtained by PHIP at 7 T. An improved 13C polarization of purified [1-13C]pyruvate-d3 in water with 36.65 ± 0.06% polarization was obtained starting from 50 mM precursor. Subsequent decarboxylation, H13CO3-/13CO2 exhibited 12.46 ± 0.01% of polarization at physiological pH, 45 seconds after the reaction start. Considering the dilution factor that [1-13C]pyruvate-d3 exhibits in vivo, we optimized our methodology to test the accuracy of the pH sensor at single digit millimolar concentration. In vitro pH estimations on phantoms and cell culture media demonstrated accurate pH calculations with uncertainties of less than 0.08 units. These promising results highlight the efficiency of a pH sensor generated via PHIP in less than one minute, with remarkable polarization, and biocompatibility suitable for future in vivo studies.
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Affiliation(s)
- Maria Daniela Santi
- NMR Signal Enhancement Group, Max Planck Institute for Multidisciplinary Sciences, Am Fassberg 11, 37077 Göttingen, Germany.
- Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Von-Siebold-Str. 3A, 37075 Göttigen, German
| | - Theresa Luca Katrin Hune
- NMR Signal Enhancement Group, Max Planck Institute for Multidisciplinary Sciences, Am Fassberg 11, 37077 Göttingen, Germany.
- Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Von-Siebold-Str. 3A, 37075 Göttigen, German
| | - Gonzalo Gabriel Rodriguez
- NMR Signal Enhancement Group, Max Planck Institute for Multidisciplinary Sciences, Am Fassberg 11, 37077 Göttingen, Germany.
- Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Von-Siebold-Str. 3A, 37075 Göttigen, German
| | - Lisa M Fries
- NMR Signal Enhancement Group, Max Planck Institute for Multidisciplinary Sciences, Am Fassberg 11, 37077 Göttingen, Germany.
- Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Von-Siebold-Str. 3A, 37075 Göttigen, German
| | - Ruhuai Mei
- NMR Signal Enhancement Group, Max Planck Institute for Multidisciplinary Sciences, Am Fassberg 11, 37077 Göttingen, Germany.
- Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Von-Siebold-Str. 3A, 37075 Göttigen, German
| | - Sonja Sternkopf
- NMR Signal Enhancement Group, Max Planck Institute for Multidisciplinary Sciences, Am Fassberg 11, 37077 Göttingen, Germany.
- Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Von-Siebold-Str. 3A, 37075 Göttigen, German
| | - Josef Elsaßer
- NMR Signal Enhancement Group, Max Planck Institute for Multidisciplinary Sciences, Am Fassberg 11, 37077 Göttingen, Germany.
- Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Von-Siebold-Str. 3A, 37075 Göttigen, German
| | - Stefan Glöggler
- NMR Signal Enhancement Group, Max Planck Institute for Multidisciplinary Sciences, Am Fassberg 11, 37077 Göttingen, Germany.
- Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Von-Siebold-Str. 3A, 37075 Göttigen, German
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Wang XF, Duan YF, Zhu YQ, Liu ZJ, Wu YC, Liu TH, Zhang L, Wei JF, Liu GC. An Insulin-Modified pH-Responsive Nanopipette Based on Ion Current Rectification. SENSORS (BASEL, SWITZERLAND) 2024; 24:4264. [PMID: 39001043 PMCID: PMC11244478 DOI: 10.3390/s24134264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/23/2024] [Revised: 06/17/2024] [Accepted: 06/21/2024] [Indexed: 07/16/2024]
Abstract
The properties of nanopipettes largely rely on the materials introduced onto their inner walls, which allow for a vast extension of their sensing capabilities. The challenge of simultaneously enhancing the sensitivity and selectivity of nanopipettes for pH sensing remains, hindering their practical applications. Herein, we report insulin-modified nanopipettes with excellent pH response performances, which were prepared by introducing insulin onto their inner walls via a two-step reaction involving silanization and amidation. The pH response intensity based on ion current rectification was significantly enhanced by approximately 4.29 times when utilizing insulin-modified nanopipettes compared with bare ones, demonstrating a linear response within the pH range of 2.50 to 7.80. In addition, insulin-modified nanopipettes featured good reversibility and selectivity. The modification processes were monitored using the I-V curves, and the relevant mechanisms were discussed. The effects of solution pH and insulin concentration on the modification results were investigated to achieve optimal insulin introduction. This study showed that the pH response behavior of nanopipettes can be greatly improved by introducing versatile molecules onto the inner walls, thereby contributing to the development and utilization of pH-responsive nanopipettes.
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Affiliation(s)
- Xu-Fan Wang
- Department of Histology and Embryology, School of Basic Medical Sciences, Xuzhou Medical University, Xuzhou 221004, China; (X.-F.W.); (Y.-F.D.); (Y.-Q.Z.); (Z.-J.L.); (T.-H.L.); (L.Z.)
- The Second Clinical Medical College, Xuzhou Medical University, Xuzhou 221004, China;
- National Demonstration Center for Experimental Basic Medical Science Education, Xuzhou Medical University, Xuzhou 221004, China
| | - Yi-Fan Duan
- Department of Histology and Embryology, School of Basic Medical Sciences, Xuzhou Medical University, Xuzhou 221004, China; (X.-F.W.); (Y.-F.D.); (Y.-Q.Z.); (Z.-J.L.); (T.-H.L.); (L.Z.)
- The Second Clinical Medical College, Xuzhou Medical University, Xuzhou 221004, China;
| | - Yue-Qian Zhu
- Department of Histology and Embryology, School of Basic Medical Sciences, Xuzhou Medical University, Xuzhou 221004, China; (X.-F.W.); (Y.-F.D.); (Y.-Q.Z.); (Z.-J.L.); (T.-H.L.); (L.Z.)
- The Second Clinical Medical College, Xuzhou Medical University, Xuzhou 221004, China;
- National Demonstration Center for Experimental Basic Medical Science Education, Xuzhou Medical University, Xuzhou 221004, China
| | - Zi-Jing Liu
- Department of Histology and Embryology, School of Basic Medical Sciences, Xuzhou Medical University, Xuzhou 221004, China; (X.-F.W.); (Y.-F.D.); (Y.-Q.Z.); (Z.-J.L.); (T.-H.L.); (L.Z.)
- National Demonstration Center for Experimental Basic Medical Science Education, Xuzhou Medical University, Xuzhou 221004, China
| | - Yu-Chen Wu
- The Second Clinical Medical College, Xuzhou Medical University, Xuzhou 221004, China;
- National Demonstration Center for Experimental Basic Medical Science Education, Xuzhou Medical University, Xuzhou 221004, China
| | - Tian-Hao Liu
- Department of Histology and Embryology, School of Basic Medical Sciences, Xuzhou Medical University, Xuzhou 221004, China; (X.-F.W.); (Y.-F.D.); (Y.-Q.Z.); (Z.-J.L.); (T.-H.L.); (L.Z.)
- The Second Clinical Medical College, Xuzhou Medical University, Xuzhou 221004, China;
| | - Ling Zhang
- Department of Histology and Embryology, School of Basic Medical Sciences, Xuzhou Medical University, Xuzhou 221004, China; (X.-F.W.); (Y.-F.D.); (Y.-Q.Z.); (Z.-J.L.); (T.-H.L.); (L.Z.)
| | - Jian-Feng Wei
- Department of Histology and Embryology, School of Basic Medical Sciences, Xuzhou Medical University, Xuzhou 221004, China; (X.-F.W.); (Y.-F.D.); (Y.-Q.Z.); (Z.-J.L.); (T.-H.L.); (L.Z.)
- Jiangsu Key Laboratory of Brain Disease Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou 221004, China
| | - Guo-Chang Liu
- Department of Histology and Embryology, School of Basic Medical Sciences, Xuzhou Medical University, Xuzhou 221004, China; (X.-F.W.); (Y.-F.D.); (Y.-Q.Z.); (Z.-J.L.); (T.-H.L.); (L.Z.)
- National Demonstration Center for Experimental Basic Medical Science Education, Xuzhou Medical University, Xuzhou 221004, China
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3
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Sadeqi Nezhad M. Poly (beta-amino ester) as an in vivo nanocarrier for therapeutic nucleic acids. Biotechnol Bioeng 2023; 120:95-113. [PMID: 36266918 DOI: 10.1002/bit.28269] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 10/12/2022] [Accepted: 10/19/2022] [Indexed: 11/11/2022]
Abstract
Therapeutic nucleic acids are an emerging class of therapy for treating various diseases through immunomodulation, protein replacement, gene editing, and genetic engineering. However, they need a vector to effectively and safely reach the target cells. Most gene and cell therapies rely on ex vivo gene delivery, which is laborious, time-consuming, and costly; therefore, devising a systematic vector for effective and safe in vivo delivery of therapeutic nucleic acids is required to target the cells of interest in an efficient manner. Synthetic nanoparticle vector poly beta amino ester (PBAE), a class of degradable polymer, is a promising candidate for in vivo gene delivery. PBAE is considered the most potent in vivo vector due to its excellent transfection performance and biodegradability. PBAE nanoparticles showed tunable charge density, diverse structural characteristics, excellent encapsulation capacity, high stability, stimuli-responsive release, site-specific delivery, potent binding to nucleic acids, flexible binding ability to various conjugates, and effective endosomal escape. These unique properties of PBAE are an essential contribution to in vivo gene delivery. The current review discusses each of the components used for PBAE synthesis and the impact of various environmental and physicochemical factors of the body on PBAE nanocarrier.
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Affiliation(s)
- Muhammad Sadeqi Nezhad
- Clinical and Translational Science Institute, Translational Biomedical Science Department, University of Rochester Medical Center, Rochester, New York, USA.,Wilmot Cancer Institute, University of Rochester Medical Center, Rochester, New York, USA.,Department of Immunology, University of Rochester Medical Center, Rochester, New York, USA
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Theillet FX, Luchinat E. In-cell NMR: Why and how? PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2022; 132-133:1-112. [PMID: 36496255 DOI: 10.1016/j.pnmrs.2022.04.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 04/19/2022] [Accepted: 04/27/2022] [Indexed: 06/17/2023]
Abstract
NMR spectroscopy has been applied to cells and tissues analysis since its beginnings, as early as 1950. We have attempted to gather here in a didactic fashion the broad diversity of data and ideas that emerged from NMR investigations on living cells. Covering a large proportion of the periodic table, NMR spectroscopy permits scrutiny of a great variety of atomic nuclei in all living organisms non-invasively. It has thus provided quantitative information on cellular atoms and their chemical environment, dynamics, or interactions. We will show that NMR studies have generated valuable knowledge on a vast array of cellular molecules and events, from water, salts, metabolites, cell walls, proteins, nucleic acids, drugs and drug targets, to pH, redox equilibria and chemical reactions. The characterization of such a multitude of objects at the atomic scale has thus shaped our mental representation of cellular life at multiple levels, together with major techniques like mass-spectrometry or microscopies. NMR studies on cells has accompanied the developments of MRI and metabolomics, and various subfields have flourished, coined with appealing names: fluxomics, foodomics, MRI and MRS (i.e. imaging and localized spectroscopy of living tissues, respectively), whole-cell NMR, on-cell ligand-based NMR, systems NMR, cellular structural biology, in-cell NMR… All these have not grown separately, but rather by reinforcing each other like a braided trunk. Hence, we try here to provide an analytical account of a large ensemble of intricately linked approaches, whose integration has been and will be key to their success. We present extensive overviews, firstly on the various types of information provided by NMR in a cellular environment (the "why", oriented towards a broad readership), and secondly on the employed NMR techniques and setups (the "how", where we discuss the past, current and future methods). Each subsection is constructed as a historical anthology, showing how the intrinsic properties of NMR spectroscopy and its developments structured the accessible knowledge on cellular phenomena. Using this systematic approach, we sought i) to make this review accessible to the broadest audience and ii) to highlight some early techniques that may find renewed interest. Finally, we present a brief discussion on what may be potential and desirable developments in the context of integrative studies in biology.
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Affiliation(s)
- Francois-Xavier Theillet
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France.
| | - Enrico Luchinat
- Dipartimento di Scienze e Tecnologie Agro-Alimentari, Alma Mater Studiorum - Università di Bologna, Piazza Goidanich 60, 47521 Cesena, Italy; CERM - Magnetic Resonance Center, and Neurofarba Department, Università degli Studi di Firenze, 50019 Sesto Fiorentino, Italy
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5
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Delehedde C, Culcasi M, Ricquebourg E, Cassien M, Siri D, Blaive B, Pietri S, Thétiot-Laurent S. Novel Sterically Crowded and Conformationally Constrained α-Aminophosphonates with a Near-Neutral p Ka as Highly Accurate 31P NMR pH Probes. Application to Subtle pH Gradients Determination in Dictyostelium discoideum Cells. Molecules 2022; 27:molecules27144506. [PMID: 35889385 PMCID: PMC9320275 DOI: 10.3390/molecules27144506] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2022] [Revised: 07/10/2022] [Accepted: 07/12/2022] [Indexed: 11/16/2022] Open
Abstract
In order to discover new 31P NMR markers for probing subtle pH changes (<0.2 pH unit) in biological environments, fifteen new conformationally constrained or sterically hindered α-aminophosphonates derived from diethyl(2-methylpyrrolidin-2-yl)phosphonate were synthesized and tested for their pH reporting and cytotoxic properties in vitro. All compounds showed near-neutral pKas (ranging 6.28−6.97), chemical shifts not overlapping those of phosphorus metabolites, and spectroscopic sensitivities (i.e., chemical shifts variation Δδab between the acidic and basic forms) ranging from 9.2−10.7 ppm, being fourfold larger than conventional endogenous markers such as inorganic phosphate. X-ray crystallographic studies combined with predictive empirical relationships and ab initio calculations addressed the inductive and stereochemical effects of substituents linked to the protonated amine function. Satisfactory correlations were established between pKas and both the 2D structure and pyramidalization at phosphorus, showing that steric crowding around the phosphorus is crucial for modulating Δδab. Finally, the hit 31P NMR pH probe 1b bearing an unsubstituted 1,3,2-dioxaphosphorinane ring, which is moderately lipophilic, nontoxic on A549 and NHLF cells, and showing pKa = 6.45 with Δδab = 10.64 ppm, allowed the first clear-cut evidence of trans-sarcolemmal pH gradients in normoxic Dictyostelium discoideum cells with an accuracy of <0.05 pH units.
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Affiliation(s)
- Caroline Delehedde
- Aix Marseille Univ, CNRS, ICR, UMR 7273, SMBSO, 13397 Marseille, France; (C.D.); (M.C.); (E.R.); (B.B.); (S.P.)
| | - Marcel Culcasi
- Aix Marseille Univ, CNRS, ICR, UMR 7273, SMBSO, 13397 Marseille, France; (C.D.); (M.C.); (E.R.); (B.B.); (S.P.)
| | - Emilie Ricquebourg
- Aix Marseille Univ, CNRS, ICR, UMR 7273, SMBSO, 13397 Marseille, France; (C.D.); (M.C.); (E.R.); (B.B.); (S.P.)
| | - Mathieu Cassien
- Yelen Analytics, 10 Boulevard Tempête, 13820 Ensuès-la-Redonne, France;
| | - Didier Siri
- Aix Marseille Univ, CNRS, ICR, UMR 7273, CT, 13397 Marseille, France;
| | - Bruno Blaive
- Aix Marseille Univ, CNRS, ICR, UMR 7273, SMBSO, 13397 Marseille, France; (C.D.); (M.C.); (E.R.); (B.B.); (S.P.)
| | - Sylvia Pietri
- Aix Marseille Univ, CNRS, ICR, UMR 7273, SMBSO, 13397 Marseille, France; (C.D.); (M.C.); (E.R.); (B.B.); (S.P.)
| | - Sophie Thétiot-Laurent
- Aix Marseille Univ, CNRS, ICR, UMR 7273, SMBSO, 13397 Marseille, France; (C.D.); (M.C.); (E.R.); (B.B.); (S.P.)
- Correspondence: ; Tel.: +33-(0)4-13-94-58-07
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Lyu Y, Timofeyev V, Overton J, Thai PN, Yamoah EN, Chiamvimonvat N, Zhang XD. Protocol to record and quantify the intracellular pH in contracting cardiomyocytes. STAR Protoc 2022; 3:101301. [PMID: 35463464 PMCID: PMC9026584 DOI: 10.1016/j.xpro.2022.101301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Intracellular pH (pHi) plays critical roles in the regulation of cardiac function. Methods and techniques for cardiac pHi measurement have continued to evolve since early 1960s. Fluorescent microscopy is the most recently developed technique with several advantages over other techniques including higher spatial and temporal resolutions, and feasibility for contracting cell measurement. Here, we describe detailed methods for mouse cardiomyocyte isolation, and simultaneous measurement and quantification of pHi and sarcomere length in contracting cardiomyocytes. For complete details on the use and execution of this protocol, please refer to Lyu et al. (2022).
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Affiliation(s)
- Yankun Lyu
- Department of Internal Medicine, University of California, Davis, Davis, CA 95616, USA
| | - Valeriy Timofeyev
- Department of Internal Medicine, University of California, Davis, Davis, CA 95616, USA
| | - James Overton
- Department of Internal Medicine, University of California, Davis, Davis, CA 95616, USA
| | - Phung N. Thai
- Department of Internal Medicine, University of California, Davis, Davis, CA 95616, USA
| | - Ebenezer N. Yamoah
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV 89557, USA
| | - Nipavan Chiamvimonvat
- Department of Internal Medicine, University of California, Davis, Davis, CA 95616, USA
- Department of Veterans Affairs, Northern California Health Care System, Mather, CA 95655, USA
| | - Xiao-Dong Zhang
- Department of Internal Medicine, University of California, Davis, Davis, CA 95616, USA
- Department of Veterans Affairs, Northern California Health Care System, Mather, CA 95655, USA
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7
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Lyu Y, Thai PN, Ren L, Timofeyev V, Jian Z, Park S, Ginsburg KS, Overton J, Bossuyt J, Bers DM, Yamoah EN, Chen-Izu Y, Chiamvimonvat N, Zhang XD. Beat-to-beat dynamic regulation of intracellular pH in cardiomyocytes. iScience 2022; 25:103624. [PMID: 35005560 PMCID: PMC8718820 DOI: 10.1016/j.isci.2021.103624] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 11/10/2021] [Accepted: 12/10/2021] [Indexed: 11/20/2022] Open
Abstract
The mammalian heart beats incessantly with rhythmic mechanical activities generating acids that need to be buffered to maintain a stable intracellular pH (pHi) for normal cardiac function. Even though spatial pHi non-uniformity in cardiomyocytes has been documented, it remains unknown how pHi is regulated to match the dynamic cardiac contractions. Here, we demonstrated beat-to-beat intracellular acidification, termed pHi transients, in synchrony with cardiomyocyte contractions. The pHi transients are regulated by pacing rate, Cl-/HCO3 - transporters, pHi buffering capacity, and β-adrenergic signaling. Mitochondrial electron-transport chain inhibition attenuates the pHi transients, implicating mitochondrial activity in sculpting the pHi regulation. The pHi transients provide dynamic alterations of H+ transport required for ATP synthesis, and a decrease in pHi may serve as a negative feedback to cardiac contractions. Current findings dovetail with the prevailing three known dynamic systems, namely electrical, Ca2+, and mechanical systems, and may reveal broader features of pHi handling in excitable cells.
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Affiliation(s)
- Yankun Lyu
- Department of Internal Medicine, University of California, Davis, Davis, CA 95616, USA
| | - Phung N. Thai
- Department of Internal Medicine, University of California, Davis, Davis, CA 95616, USA
| | - Lu Ren
- Department of Internal Medicine, University of California, Davis, Davis, CA 95616, USA
| | - Valeriy Timofeyev
- Department of Internal Medicine, University of California, Davis, Davis, CA 95616, USA
| | - Zhong Jian
- Department of Pharmacology, University of California, Davis, Davis, CA 95616, USA
| | - Seojin Park
- Department of Physiology and Cell Biology, University of Nevada, Reno, Reno, NV 89557, USA
| | - Kenneth S. Ginsburg
- Department of Pharmacology, University of California, Davis, Davis, CA 95616, USA
| | - James Overton
- Department of Internal Medicine, University of California, Davis, Davis, CA 95616, USA
| | - Julie Bossuyt
- Department of Pharmacology, University of California, Davis, Davis, CA 95616, USA
| | - Donald M. Bers
- Department of Pharmacology, University of California, Davis, Davis, CA 95616, USA
| | - Ebenezer N. Yamoah
- Department of Physiology and Cell Biology, University of Nevada, Reno, Reno, NV 89557, USA
| | - Ye Chen-Izu
- Department of Internal Medicine, University of California, Davis, Davis, CA 95616, USA
- Department of Pharmacology, University of California, Davis, Davis, CA 95616, USA
- Department of Biomedical Engineering, University of California, Davis, Davis, CA 95616, USA
| | - Nipavan Chiamvimonvat
- Department of Internal Medicine, University of California, Davis, Davis, CA 95616, USA
- Department of Pharmacology, University of California, Davis, Davis, CA 95616, USA
- Department of Veterans Affairs, Northern California Health Care System, Mather, CA 95655, USA
| | - Xiao-Dong Zhang
- Department of Internal Medicine, University of California, Davis, Davis, CA 95616, USA
- Department of Veterans Affairs, Northern California Health Care System, Mather, CA 95655, USA
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8
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Tumor Microenvironment Biosensors for Hyperpolarized Carbon-13 Magnetic Resonance Spectroscopy. Mol Imaging Biol 2021; 23:323-334. [PMID: 33415679 DOI: 10.1007/s11307-020-01570-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 11/12/2020] [Accepted: 12/01/2020] [Indexed: 02/07/2023]
Abstract
Hyperpolarization (HP) of a carbon-13 molecule via dynamic nuclear polarization (DNP) involves polarization at low temperature, followed by a dissolution procedure producing a solution with highly polarized spins at room temperature. This dissolution DNP method significantly increases the signal-to-noise ratio (SNR) of nuclear magnetic resonance (NMR) over 10,000-fold and facilitates the use of magnetic resonance spectroscopy (MRS) to image not only metabolism but also the extracellular microenvironment. The extracellular tumor microenvironment (TME) closely interacts with tumor cells and stimulates their growth and metastasis. Thus, the ability to detect pathological changes in the TME is pivotal for the detection and study of cancers. This review highlights the potential use of MRS to study features of the TME-elevated export of lactate, reduced interstitial pH, imbalanced redox equilibrium, and altered metal homeostasis. The promising outcomes of both in vitro and in vivo assays suggest that DNP-MRS may be a useful technique to study aspects of the TME. With continued improvements, this tool has the potential to study the TME and provide guidance for accurate patient stratification and precise personal therapy. Graphical Abstract.
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9
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Ren L, Chen S, Jiang W, Zeng Q, Zhang X, Xiao L, McMahon MT, Xin L, Zhou X. Efficient temperature-feedback liposome for 19F MRI signal enhancement. Chem Commun (Camb) 2020; 56:14427-14430. [PMID: 33146184 DOI: 10.1039/d0cc05809b] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
A new non-encapsulated fluorinated liposome (TSL) was developed, which showed instantaneous temperature-induced 19F MR signal enhancement and excellent stability under reversible signal transition at different conditions.
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Affiliation(s)
- Lili Ren
- Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan National Laboratory for Optoelectronics, 430071, Wuhan, China.
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10
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Hyperpolarized Amino Acid Derivatives as Multivalent Magnetic Resonance pH Sensor Molecules. SENSORS 2018; 18:s18020600. [PMID: 29462891 PMCID: PMC5856118 DOI: 10.3390/s18020600] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Revised: 02/07/2018] [Accepted: 02/08/2018] [Indexed: 11/17/2022]
Abstract
pH is a tightly regulated physiological parameter that is often altered in diseased states like cancer. The development of biosensors that can be used to non-invasively image pH with hyperpolarized (HP) magnetic resonance spectroscopic imaging has therefore recently gained tremendous interest. However, most of the known HP-sensors have only individually and not comprehensively been analyzed for their biocompatibility, their pH sensitivity under physiological conditions, and the effects of chemical derivatization on their logarithmic acid dissociation constant (pKa). Proteinogenic amino acids are biocompatible, can be hyperpolarized and have at least two pH sensitive moieties. However, they do not exhibit a pH sensitivity in the physiologically relevant pH range. Here, we developed a systematic approach to tailor the pKa of molecules using modifications of carbon chain length and derivatization rendering these molecules interesting for pH biosensing. Notably, we identified several derivatives such as [1-13C]serine amide and [1-13C]-2,3-diaminopropionic acid as novel pH sensors. They bear several spin-1/2 nuclei (13C, 15N, 31P) with high sensitivity up to 4.8 ppm/pH and we show that 13C spins can be hyperpolarized with dissolution dynamic polarization (DNP). Our findings elucidate the molecular mechanisms of chemical shift pH sensors that might help to design tailored probes for specific pH in vivo imaging applications.
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11
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Optimization of Polyplex Formation between DNA Oligonucleotide and Poly(ʟ-Lysine): Experimental Study and Modeling Approach. Int J Mol Sci 2017. [PMID: 28629130 PMCID: PMC5486112 DOI: 10.3390/ijms18061291] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The polyplexes formed by nucleic acids and polycations have received a great attention owing to their potential application in gene therapy. In our study, we report experimental results and modeling outcomes regarding the optimization of polyplex formation between the double-stranded DNA (dsDNA) and poly(l-Lysine) (PLL). The quantification of the binding efficiency during polyplex formation was performed by processing of the images captured from the gel electrophoresis assays. The design of experiments (DoE) and response surface methodology (RSM) were employed to investigate the coupling effect of key factors (pH and N/P ratio) affecting the binding efficiency. According to the experimental observations and response surface analysis, the N/P ratio showed a major influence on binding efficiency compared to pH. Model-based optimization calculations along with the experimental confirmation runs unveiled the maximal binding efficiency (99.4%) achieved at pH 5.4 and N/P ratio 125. To support the experimental data and reveal insights of molecular mechanism responsible for the polyplex formation between dsDNA and PLL, molecular dynamics simulations were performed at pH 5.4 and 7.4.
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12
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Hundshammer C, Düwel S, Schilling F. Imaging of Extracellular pH Using Hyperpolarized Molecules. Isr J Chem 2017. [DOI: 10.1002/ijch.201700017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Christian Hundshammer
- Department of Nuclear Medicine, Klinikum rechts der Isar; Technical University of Munich; Ismaninger Str. 22 81675 München Germany
- Department of Chemistry; Technical University of Munich; Lichtenbergstr. 2 85748 Garching Germany
| | - Stephan Düwel
- Department of Nuclear Medicine, Klinikum rechts der Isar; Technical University of Munich; Ismaninger Str. 22 81675 München Germany
- Department of Chemistry; Technical University of Munich; Lichtenbergstr. 2 85748 Garching Germany
- Institute of Medical Engineering; Technical University of Munich; Boltzmannstr. 11 85748 Garching Germany
| | - Franz Schilling
- Department of Nuclear Medicine, Klinikum rechts der Isar; Technical University of Munich; Ismaninger Str. 22 81675 München Germany
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Flavell RR, von Morze C, Blecha JE, Korenchan DE, Van Criekinge M, Sriram R, Gordon JW, Chen HY, Subramaniam S, Bok RA, Wang ZJ, Vigneron DB, Larson PE, Kurhanewicz J, Wilson DM. Application of Good's buffers to pH imaging using hyperpolarized (13)C MRI. Chem Commun (Camb) 2016; 51:14119-22. [PMID: 26257040 DOI: 10.1039/c5cc05348j] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
N-(2-Acetamido)-2-aminoethanesulfonic acid (ACES), one of Good's buffers, was applied to pH imaging using hyperpolarized (13)C magnetic resonance spectroscopy. Rapid NMR- and MRI-based pH measurements were obtained by exploiting the sensitive pH-dependence of its (13)C chemical shift within the physiologic range.
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Affiliation(s)
- Robert R Flavell
- Department of Radiology and Biomedical Imaging, University of California, San Francisco, California 94158, USA.
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Abouelmagd SA, Hyun H, Yeo Y. Extracellularly activatable nanocarriers for drug delivery to tumors. Expert Opin Drug Deliv 2014; 11:1601-1618. [PMID: 24950343 DOI: 10.1517/17425247.2014.930434] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
INTRODUCTION Nanoparticles (NPs) for drug delivery to tumors need to satisfy two seemingly conflicting requirements: they should maintain physical and chemical stability during circulation and be able to interact with target cells and release the drug at desired locations with no substantial delay. The unique microenvironment of tumors and externally applied stimuli provide a useful means to maintain a balance between the two requirements. AREAS COVERED We discuss nanoparticulate drug carriers that maintain stable structures in normal conditions but respond to stimuli for the spatiotemporal control of drug delivery. We first define the desired effects of extracellular activation of NPs and frequently used stimuli and then review the examples of extracellularly activated NPs. EXPERT OPINION Several challenges remain in developing extracellularly activatable NPs. First, some of the stimuli-responsive NPs undergo incremental changes in response to stimuli, losing circulation stability. Second, the applicability of stimuli in clinical settings is limited due to the occasional occurrence of the activating conditions in normal tissues. Third, the construction of stimuli-responsive NPs involves increasing complexity in NP structure and production methods. Future efforts are needed to identify new targeting conditions and increase the contrast between activated and nonactivated NPs while keeping the production methods simple and scalable.
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Affiliation(s)
- Sara A Abouelmagd
- Department of Industrial and Physical Pharmacy, Purdue University, 575 Stadium Mall Drive, West Lafayette, IN 47907, USA
| | - Hyesun Hyun
- Department of Industrial and Physical Pharmacy, Purdue University, 575 Stadium Mall Drive, West Lafayette, IN 47907, USA
| | - Yoon Yeo
- Department of Industrial and Physical Pharmacy, Purdue University, 575 Stadium Mall Drive, West Lafayette, IN 47907, USA.,Weldon School of Biomedical Engineering, Purdue University, 206 South Martin Jischke Drive, West Lafayette, IN 47907, USA
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Pilot study of Iopamidol-based quantitative pH imaging on a clinical 3T MR scanner. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2014; 27:477-85. [DOI: 10.1007/s10334-014-0433-8] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Revised: 01/24/2014] [Accepted: 01/27/2014] [Indexed: 12/22/2022]
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16
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Yu JX, Hallac RR, Chiguru S, Mason RP. New frontiers and developing applications in 19F NMR. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2013; 70:25-49. [PMID: 23540575 PMCID: PMC3613763 DOI: 10.1016/j.pnmrs.2012.10.001] [Citation(s) in RCA: 142] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Accepted: 10/23/2012] [Indexed: 05/06/2023]
Affiliation(s)
- Jian-Xin Yu
- Laboratory of Prognostic Radiology, Division of Advanced Radiological Sciences, Department of Radiology, UT Southwestern Medical Center, Dallas, Texas
| | - Rami R. Hallac
- Laboratory of Prognostic Radiology, Division of Advanced Radiological Sciences, Department of Radiology, UT Southwestern Medical Center, Dallas, Texas
| | - Srinivas Chiguru
- Laboratory of Prognostic Radiology, Division of Advanced Radiological Sciences, Department of Radiology, UT Southwestern Medical Center, Dallas, Texas
| | - Ralph P. Mason
- Laboratory of Prognostic Radiology, Division of Advanced Radiological Sciences, Department of Radiology, UT Southwestern Medical Center, Dallas, Texas
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Yu JX, Cui W, Bourke VA, Mason RP. 6-Trifluoromethylpyridoxine: novel (19)F NMR pH indicator for in vivo detection. J Med Chem 2012; 55:6814-21. [PMID: 22775397 PMCID: PMC3430128 DOI: 10.1021/jm300520q] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
pH plays an important role in tumor proliferation, angiogenesis, metabolic control, and the efficacy of cytotoxic therapy, and accurate noninvasive assessment of tumor pH promises to provide insight into developmental processes and prognostic information. In this paper, we report the design, synthesis, and characterization of two novel pH indicators 6-trifluoromethylpyridoxine 8 and α(4),α(5)-di-O-[3'-O-(β-d-glucopyranosyl)propyl]-6-trifluoromethylpyridoxine 17 and demonstrate 8 as an extracellular (19)F NMR pH probe to assess pH(e) of various tumors in vivo.
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Affiliation(s)
- Jian-Xin Yu
- Advanced Radiological Sciences, Department of Radiology, The University of Texas Southwestern Medical Center at Dallas , 5323 Harry Hines Boulevard, Dallas, Texas 75390-9058, United States.
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18
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Kang HC, Huh KM, Bae YH. Polymeric nucleic acid carriers: current issues and novel design approaches. J Control Release 2012; 164:256-64. [PMID: 22771981 DOI: 10.1016/j.jconrel.2012.06.036] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2012] [Revised: 06/25/2012] [Accepted: 06/27/2012] [Indexed: 11/26/2022]
Abstract
To deliver nucleic acids including plasmid DNA (pDNA) and short interfering RNA (siRNA), polymeric gene carriers equipped with various functionalities have been extensively investigated. The functionalities of these polymeric vectors have been designed to overcome various extracellular and intracellular hurdles that nucleic acids and their carriers encounter during their journey from injection site to intracellular target site. This review briefly introduces known extracellular and intracellular issues of nucleic acid delivery and their solution strategies. We examine significant yet overlooked factors affecting nucleic acid delivery (e.g., microenvironmental pH, polymer/siRNA complexation, and pharmaceutical formulation) and highlight our reported approaches to solve these problems.
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Affiliation(s)
- 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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19
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20
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Kang HC, Samsonova O, Kang SW, Bae YH. The effect of environmental pH on polymeric transfection efficiency. Biomaterials 2011; 33:1651-62. [PMID: 22130563 DOI: 10.1016/j.biomaterials.2011.11.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2011] [Accepted: 11/07/2011] [Indexed: 11/15/2022]
Abstract
Although polymers, polyplexes, and cells are exposed to various extracellular and intracellular pH environments during polyplex preparation and polymeric transfection, the impact of environmental pH on polymeric transfection has not yet been investigated. This study aims to understand the influence of environmental pH on polymeric transfection by modulating the pH of the transfection medium or the culture medium. Changes in the extracellular pH affected polymeric transfection by way of complex factors such as pH-induced changes in polymer characteristics (e.g., proton buffering capacity and ionization), polyplex characteristics (e.g., size, surface charge, and decomplexation), and cellular characteristics (e.g., cellular uptake, cell cycle phases, and intracellular pH environment). Notably, acidic medium delayed endocytosis, endosomal acidification, cytosolic release, and decomplexation of polyplexes, thereby negatively affecting gene expression. However, acidic medium inhibited mitosis and reduced dilution of gene expression, resulting in increased transfection efficiency. Compared to pH 7.4 medium, acidic transfection medium reduced gene expression 1.6-7.7-fold whereas acidic culture medium enhanced transfection efficiency 2.1-2.6-fold. Polymeric transfection was affected more by the culture medium than by the transfection medium. Understanding the effects of extracellular pH during polymeric transfection may stimulate new strategies for determining effective and safe polymeric gene carriers.
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Affiliation(s)
- Han Chang Kang
- Department of Pharmaceutics and Pharmaceutical Chemistry, The University of Utah, Salt Lake City, UT 84108, USA
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21
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Hashim AI, Zhang X, Wojtkowiak JW, Martinez GV, Gillies RJ. Imaging pH and metastasis. NMR IN BIOMEDICINE 2011; 24:582-91. [PMID: 21387439 PMCID: PMC3740268 DOI: 10.1002/nbm.1644] [Citation(s) in RCA: 202] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2010] [Revised: 09/30/2010] [Accepted: 10/19/2010] [Indexed: 05/05/2023]
Abstract
Metastasis is a multistep process that culminates in the spread of cells from a primary tumor to a distant site or organs. For tumor cells to be able to metastasize, they have to locally invade through basement membrane into the lymphatic and the blood vasculatures. Eventually they extravasate from the blood and colonize in the secondary organ. This process involves multiple interactions between the tumor cells and their microenvironments. The microenvironment surrounding tumors has a significant impact on tumor development and progression. A key factor in the microenvironment is an acidic pH. The extracellular pH of solid tumors is more acidic in comparison to normal tissue as a consequence of high glycolysis and poor perfusion. It plays an important role in almost all steps of metastasis. The past decades have seen development of technologies to non-invasively measure intra- and/or extracellular pH. Most successful measurements are MR-based, and sensitivity and accuracy have dramatically improved. Quantitatively imaging the distribution of acidity helps us understand the role of the tumor microenvironment in cancer progression. The present review discusses different MR methods in measuring tumor pH along with emphasizing the importance of extracelluar tumor low pH on different steps of metastasis; more specifically focusing on epithelial-to-mesenchymal transition (EMT), and anti cancer immunity.
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Affiliation(s)
- Arig Ibrahim Hashim
- Department of Imaging research, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, USA
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Kapur S, Wasserstrom JA, Kelly JE, Kadish AH, Aistrup GL. Acidosis and ischemia increase cellular Ca2+ transient alternans and repolarization alternans susceptibility in the intact rat heart. Am J Physiol Heart Circ Physiol 2009; 296:H1491-512. [PMID: 19286955 DOI: 10.1152/ajpheart.00539.2008] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Cardiac cellular Ca(2+) transient (CaT) alternans and electrocardiographic T-wave alternans (TWA) often develop in myocardial ischemia, but the mechanisms for this relationship have not been elucidated. Acidosis is a major component of ischemia, but there is no direct evidence linking acidosis-induced cellular CaT alternans to ischemia-induced CaT alternans and TWA in whole heart. We used laser-scanning confocal microscopy to measure intracellular Ca(2+) (Ca(i)(2+)) cycling in individual myocytes of fluo-4 AM-loaded rat hearts and simultaneously recorded pseudo-ECGs to investigate changes in CaTs and late-phase repolarization, respectively, during baseline and rapid pacing under control and either globally acidic or globally ischemic conditions. Acidosis (hypercapnia; pH 6.6) increased diastolic Ca(i)(2+) levels, prolonged CaT duration, and shifted to slower heart rates both the development of pacing-induced acidosis-induced CaT alternans (both concordant and discordant) and of repolarization alternans (RPA, a measure of TWA in rat ECGs). The magnitudes of these shifts were equivalent for both CaT alternans and RPA, suggesting a close association between them. Nearly identical results were found in low-flow global ischemia. Additionally, ischemic preconditioning reduced the increased propensity for CaT alternans and RPA development and was mimicked by preconditioning by acidosis alone. Our results demonstrate that global acidosis or ischemia modifies Ca(i)(2+) cycling in myocytes such that the diastolic Ca(i)(2+) rises and the cellular CaT duration is prolonged, causing spatially concordant as well as spatially discordant cellular CaT alternans to develop at slower heart rates than in controls. Since RPA also developed at slower heart rates, our results suggest that acidosis is a major contributor to CaT alternans, which underlies the proarrhythmic state induced by myocardial ischemia and therefore may play a role in its modulation and prevention.
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Affiliation(s)
- Sunil Kapur
- Department of Medicine, Div. of Cardiology, Northwestern University Feinberg School of Medicine, 310 E. Superior St., Morton 7-607, Chicago, IL 60611, USA
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Løkling KE, Skurtveit R, Bjørnerud A, Fossheim SL. Novel pH-sensitive paramagnetic liposomes with improved MR properties. Magn Reson Med 2004; 51:688-96. [PMID: 15065240 DOI: 10.1002/mrm.20009] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The use of paramagnetic pH-sensitive liposomes was recently suggested as a new approach for monitoring pathologic changes in pH by MRI. Such liposomes must be stable in blood and selectively release the encapsulated paramagnetic agent when exposed to lower pH in the target tissue. In the present study, different liposomal systems were formulated and characterized by relaxometry, cryo-transmission electron microscopy (cryo-TEM), and MRI. The pH-sensitive system dipalmitoylphosphatidylethanolamine/palmitic acid (DPPE/PA) liposomal GdDTPA-BMA, which was previously shown to be unstable in blood, was modified to improve its stability. The incorporation of cholesterol into the DPPE/PA liposomes significantly increased their stability in blood, but the pH sensitivity was diminished. Polyethylene glycol (PEG)-modified DPPE/PA liposomes were pH-insensitive in buffer, and unstable in blood. However, exchanging PA with the double-chained amphiphile dipalmitoylglycerosuccinate (DPSG) yielded liposomes with improved properties. DPPE/DPSG liposomal GdDTPA-BMA was stable in blood at physiological pH, and displayed a marked pH sensitivity. The pH sensitivity was not diminished after preincubation in blood, contrary to what has been reported for analogues containing unsaturated lipids. The potential of this system for monitoring pH was demonstrated in an in vitro MRI phantom study.
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Affiliation(s)
- Knut-Egil Løkling
- Department of Medicinal Chemistry, School of Pharmacy, University of Oslo, Oslo, Norway.
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Løkling KE, Fossheim SL, Klaveness J, Skurtveit R. Biodistribution of pH-responsive liposomes for MRI and a novel approach to improve the pH-responsiveness. J Control Release 2004; 98:87-95. [PMID: 15245892 DOI: 10.1016/j.jconrel.2004.04.015] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2004] [Accepted: 04/27/2004] [Indexed: 11/21/2022]
Abstract
The potential of pH-sensitive paramagnetic liposomes as a probe for monitoring acidic pH in tumours with magnetic resonance imaging has recently been demonstrated. If the blood retention time is prolonged, such liposomes can accumulate in tumour interstitium due to increased vascular permeability and interstitial retention. In the present study, biodistribution studies in healthy rats showed rapid clearance of the pH-sensitive system dipalmitoylphosphatidylethanolamine (DPPE)/dipalmitoylglycerosuccinate (DPSG) liposomal GdDTPA-BMA from the blood circulation with most of the Gd dose in the liver at 15 min post intravenous injection. Incorporation of 1.5 mol% polyethylene glycol (PEG) grafted DPPE (DPPE-PEG) in the above-mentioned formulation resulted in a significantly prolonged blood circulation time. However, the relaxometric pH-response of the DPPE/DPSG/DPPE-PEG system decreased as a function of mol% DPPE-PEG. Therefore, a compromise would be necessary between long blood residence time and a suitable pH-sensitivity of the liposomes. A possible approach to compensate for the reduced pH-sensitivity was investigated. Gadofosveset, a low-molecular weight Gd-chelate with high affinity for albumin, was encapsulated within DPPE/DPSG liposomes. This promising system showed in blood a markedly higher relaxometric response than the corresponding system with GdDTPA-BMA, due to release of gadofosveset at low pH and subsequent binding to albumin.
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Affiliation(s)
- Knut-Egil Løkling
- Department of Medicinal Chemistry, School of Pharmacy, University of Oslo, P.O. Box 1155 Blindern, N-0318, Norway.
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Løkling KE, Skurtveit R, Fossheim SL, Smistad G, Henriksen I, Klaveness J. pH-sensitive paramagnetic liposomes for MRI: assessment of stability in blood. Magn Reson Imaging 2003; 21:531-40. [PMID: 12878263 DOI: 10.1016/s0730-725x(03)00076-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The pH-dependent stability of dipalmitoyl phosphatidyl ethanolamine/palmitic acid (DPPE/PA) liposomal GdDTPA-BMA was investigated in human blood and after exposure to selected blood components. Relaxometry, visual observations and cryo-transmission electron microscopy (cryo-TEM) were employed for the assessment of stability. The liposomes were stable in buffer at physiological pH and the T(1)-relaxivity (r(1)) of the system was significantly lowered compared to that of non-liposomal GdDTPA-BMA, which could be explained by an exchange limited relaxation process. Lowering the pH, however, gave a marked increase in r(1), due to liposome aggregation and subsequent leakage of GdDTPA-BMA. After a few minutes incubation in human blood the liposomes were destabilised and leaky at both high and low pH, and blood components likely to cause the instability were studied. Physiological level of Na(+) (150 mM) did not affect the relaxometric behavior of the liposomes at pH 7.4, but shifted the pH-r(1) profile laterally to higher pH-values compared to a level of 50 mM Na(+). Increased screening of the surface charges and, concomitantly, a lowering of the energy-barrier against aggregation is a plausible explanation for this phenomenon. In contrast, both Ca(2+) and Mg(2+) (physiological level, both 2 mM) caused massive aggregation of the liposomes and leakage of contents, and were therefore much more detrimental to the stability of the liposomes than a physiological level of Na(+). This could be due to the higher screening ability of divalent cations, but aggregation could also be induced through an inter-liposomal "bridging" effect. Physiological level of both Na(+) and Ca(2+) caused less leakage than for lower Na(+) concentration (50 mM Na(+) and 2 mM Ca(2+)), probably due to competition for the negative surface charges. Albumin also destabilised the liposomes, and it was shown to be due to an interaction between albumin and PA in the liposomal membrane.
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Affiliation(s)
- Knut-Egil Løkling
- Department of Medicinal Chemistry, School of Pharmacy, University of Oslo, Norway.
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Gillies RJ, Raghunand N, Karczmar GS, Bhujwalla ZM. MRI of the tumor microenvironment. J Magn Reson Imaging 2002; 16:430-50. [PMID: 12353258 DOI: 10.1002/jmri.10181] [Citation(s) in RCA: 418] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The microenvironment within tumors is significantly different from that in normal tissues. A major difference is seen in the chaotic vasculature of tumors, which results in unbalanced blood supply and significant perfusion heterogeneities. As a consequence, many regions within tumors are transiently or chronically hypoxic. This exacerbates tumor cells' natural tendency to overproduce acids, resulting in very acidic pH values. The hypoxia and acidity of tumors have important consequences for antitumor therapy and can contribute to the progression of tumors to a more aggressive metastatic phenotype. Over the past decade, techniques have emerged that allow the interrogation of the tumor microenvironment with high resolution and molecularly specific probes. Techniques are available to interrogate perfusion, vascular distribution, pH, and pO(2) nondestructively in living tissues with relatively high precision. Studies employing these methods have provided new insights into the causes and consequences of the hostile tumor microenvironment. Furthermore, it is quite exciting that there are emerging techniques that generate tumor image contrast via ill-defined mechanisms. Elucidation of these mechanisms will yield further insights into the tumor microenvironment. This review attempts to identify techniques and their application to tumor biology, with an emphasis on nuclear magnetic resonance (NMR) approaches. Examples are also discussed using electron MR, optical, and radionuclear imaging techniques.
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Affiliation(s)
- Robert J Gillies
- Department of Biochemistry, Arizona Cancer Center, University of Arizona HSC, Tucson, Arizona 85724-5024, USA.
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Løkling KE, Fossheim SL, Skurtveit R, Bjørnerud A, Klaveness J. pH-sensitive paramagnetic liposomes as MRI contrast agents: in vitro feasibility studies. Magn Reson Imaging 2001; 19:731-8. [PMID: 11672632 DOI: 10.1016/s0730-725x(01)00380-0] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
A novel type of pH-sensitive paramagnetic contrast agent is introduced; a low molecular weight gadolinium (Gd) chelate (GdDTPA-BMA) encapsulated within pH-sensitive liposomes. The in vitro relaxometric properties of the liposomal Gd chelate were shown to be a function of the pH in the liposomal dispersion and the membrane composition. Only a minor pH-dependency of the T1 relaxivity (r1) was observed for liposomal GdDTPA-BMA composed of the unsaturated lipids dioleoyl phosphatidyl ethanolamine (DOPE) and oleic acid (OA). On the other hand, the r1 of GdDTPA-BMA encapsulated within saturated dipalmitoyl phosphatidyl ethanolamine/palmitic acid (DPPE/PA) liposomes demonstrated a strong pH-dependency. At physiological pH and above, the r1 of this system was significantly lowered compared to that of non-liposomal Gd chelate, which was explained by an exchange limited relaxation process. Lowering the pH below physiological value, however, gave a sharp and 6-7 fold increase in r1, due to liposome destabilisation and subsequent leakage of entrapped GdDTPA-BMA. The pH-sensitivity of the DPPE/PA liposome system was confirmed in an in vitro magnetic resonance imaging (MRI) phantom study.
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Affiliation(s)
- K E Løkling
- Department of Medicinal Chemistry, School of Pharmacy, University of Oslo, Oslo, Norway.
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Cherton JC, Hamm S, Hallé JC, Menguy L, Beaufour M. Potential proinsecticides of fluorinated carboxylic acids and β-ethanolamines. J Fluor Chem 2001. [DOI: 10.1016/s0022-1139(00)00382-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Ojugo AS, McSheehy PM, McIntyre DJ, McCoy C, Stubbs M, Leach MO, Judson IR, Griffiths JR. Measurement of the extracellular pH of solid tumours in mice by magnetic resonance spectroscopy: a comparison of exogenous (19)F and (31)P probes. NMR IN BIOMEDICINE 1999; 12:495-504. [PMID: 10668042 DOI: 10.1002/(sici)1099-1492(199912)12:8<495::aid-nbm594>3.0.co;2-k] [Citation(s) in RCA: 155] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Precise measurement of pH(e) in vivo may be of clinical value for both diagnosis and selection of therapy. pH(e) measurements made by the (31)P probe 3-aminopropylphosphonate (3-APP) were compared with those made by the (19)F probe, 3-[N-(4-fluor-2-trifluoromethylphenyl)-sulphamoyl]-propionic acid (ZK-150471) in three solid tumour types, human HT29 xenografts, murine RIF-1 fibrosarcomas and Lettre tumours grown subcutaneously in mice. No significant differences were observed when probe measurements of pH(e) were compared at 20-60 min post-administration, although very low pH(e) values (ca. 6.0) were recorded in two out of eight Lettre tumours by ZK-150471. The more rapid pH(e) measurements possible using ZK-150471 showed that during the first 20 min post-administration significant increases occurred in pH(e) which were greatest in the more necrotic tumours. Since isolated cell experiments showed that ZK-150471 was non-toxic and did not enter the cells, this early increase in pH(e) may reflect gradual penetration by ZK-150471 of the reportedly alkaline necrotic space in the tumours. The wide chemical shift range, improved signal-to-noise and absence of signal overlap allowed a more rapid and precise measurement of pH(e) by ZK-150471 compared to 3-APP. These characteristics suggest that ZK-150471 is currently the preferred pH(e) probe for non-invasive MRS.
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Affiliation(s)
- A S Ojugo
- CRC Biomedical Magnetic Resonance Research Group, Department of Biochemistry, St George's Hospital Medical School, Cranmer Terrace, London SW17 0RE, UK
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He S, Mason RP, Hunjan S, Mehta VD, Arora V, Katipally R, Kulkarni PV, Antich PP. Development of novel 19F NMR pH indicators: synthesis and evaluation of a series of fluorinated vitamin B6 analogues. Bioorg Med Chem 1998; 6:1631-9. [PMID: 9801834 DOI: 10.1016/s0968-0896(98)00104-7] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We have synthesized a series of novel fluorinated vitamin B6 analogues (6-fluoropyridoxol derivatives) as potential 19F NMR pH indicators for use in vivo. Modifications included addition of aldehyde, carboxyl or aminomethyl groups at the 4- or 5-ring position, and examination of a trifluoromethyl moiety as an internal chemical shift standard. The variation in chemical shift with respect to acid-base titration showed pKa values in the range 7.05-9.5 with a chemical shift sensitivity in the range 7.4-12 ppm. Several of the molecules readily cross cell membranes providing estimates of both intra- and extra-cellular pH in whole blood. 6-Fluoropyridoxamine (6-FPAM) exhibits a pKa = 7.05, which is closer to normal physiological pH than the parent molecule 6-fluoropyridoxol (6-FPOL) (pKa = 8.2), and should thus, be useful for precise and accurate measurements of pH in vivo. Enhanced spectral resolution for 6-FPAM over 6-FPOL is demonstrated in whole blood and the perfused rat heart.
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Affiliation(s)
- S He
- University of Texas-Southwestern Medical Center, Dallas 75235, USA
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