Publications by authors named "Roberta Napolitano"

19 Publications

  • Page 1 of 1

Kevetrin induces apoptosis in TP53 wild‑type and mutant acute myeloid leukemia cells.

Oncol Rep 2020 Oct 11;44(4):1561-1573. Epub 2020 Aug 11.

Biosciences Laboratory, Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori (IRST) IRCCS, I‑47014 Meldola, Italy.

Tumor protein p53 is a key regulator of several cellular pathways, including DNA repair, cell cycle and angiogenesis. Kevetrin exhibits p53‑dependent as well as‑independent activity in solid tumors, while its effects on leukemic cells remain unknown. The aim of the present study was to analyze the response of acute myeloid leukemia (AML) cell lines (TP53 wild‑type: OCI‑AML3 and MOLM‑13; and TP53‑mutant: KASUMI‑1 and NOMO‑1) to kevetrin at a concentration range of 85‑340 µM. The cellular and molecular effects of the treatment were analyzed in terms of cell growth, viability [Annexin V‑propidium iodide (PI) staining] and cell cycle alterations (PI staining). Gene expression profiling, western blotting and immunofluorescence were performed to elucidate the pathways underlying kevetrin activity. Pulsed exposure exerted no effect on the wild‑type cells, but was effective on mutant cells. After continuous treatment, significant cell growth arrest and apoptosis were observed in all cell lines, with TP53‑mutant models displaying a higher sensitivity and p53 induction. Kevetrin also displayed efficacy against TP53 wild‑type and mutant primary AML, with a preferential cytotoxic activity against blast cells. Gene expression profiling revealed a common core transcriptional program altered by drug exposure and the downregulation of glycolysis, DNA repair and unfolded protein response signatures. These findings suggest that kevetrin may be a promising therapeutic option for patients with both wild‑type and TP53‑mutant AML.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3892/or.2020.7730DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7448420PMC
October 2020

Unexpected low expression of platelet fibrinogen receptor in patients with chronic myeloproliferative neoplasms: how does it change with aspirin?

Br J Haematol 2020 04 2;189(2):335-338. Epub 2019 Dec 2.

Biosciences Laboratory, Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori (IRST) IRCCS, Meldola, Italy.

This study was conducted to evaluate the expression of fibrinogen receptors on platelets of Philadelphia-negative chronic myeloproliferative neoplasm (MPN) patients. We collected blood samples from 40 consecutive MPN patients and healthy volunteers. We performed flow cytometry analysis of P-selectin expression and integrin beta-3, activation of glycoprotein (GP) IIb/IIIa and fibrinogen receptor exposure (PAC-1 binding). Surprisingly, we found a very low PAC-1 binding capacity in MPN patients; however, the expression of PAC-1 was almost completely recovered with aspirin intake. We hypothesize that the hypercoagulable states observed in MPN patients could depend on a primarily plasma-driven impairment of fibrin turnover and thrombin generation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/bjh.16335DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7187459PMC
April 2020

Synergism Through WEE1 and CHK1 Inhibition in Acute Lymphoblastic Leukemia.

Cancers (Basel) 2019 Oct 25;11(11). Epub 2019 Oct 25.

Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori (IRST) IRCCS, 47014 Meldola, Italy.

Introduction: Screening for synthetic lethality markers has demonstrated that the inhibition of the cell cycle checkpoint kinases WEE1 together with CHK1 drastically affects stability of the cell cycle and induces cell death in rapidly proliferating cells. Exploiting this finding for a possible therapeutic approach has showed efficacy in various solid and hematologic tumors, though not specifically tested in acute lymphoblastic leukemia.

Methods: The efficacy of the combination between WEE1 and CHK1 inhibitors in B and T cell precursor acute lymphoblastic leukemia (B/T-ALL) was evaluated in vitro and ex vivo studies. The efficacy of the therapeutic strategy was tested in terms of cytotoxicity, induction of apoptosis, and changes in cell cycle profile and protein expression using B/T-ALL cell lines. In addition, the efficacy of the drug combination was studied in primary B-ALL blasts using clonogenic assays.

Results: This study reports, for the first time, the efficacy of the concomitant inhibition of CHK1/CHK2 and WEE1 in ALL cell lines and primary leukemic B-ALL cells using two selective inhibitors: PF-0047736 (CHK1/CHK2 inhibitor) and AZD-1775 (WEE1 inhibitor). We showed strong synergism in the reduction of cell viability, proliferation and induction of apoptosis. The efficacy of the combination was related to the induction of early S-phase arrest and to the induction of DNA damage, ultimately triggering cell death. We reported evidence that the efficacy of the combination treatment is independent from the activation of the p53-p21 pathway. Moreover, gene expression analysis on B-ALL primary samples showed that Chek1 and Wee1 are significantly co-expressed in samples at diagnosis (Pearson = 0.5770, = 0.0001) and relapse (Pearson = 0.8919; = 0.0001). Finally, the efficacy of the combination was confirmed by the reduction in clonogenic survival of primary leukemic B-ALL cells.

Conclusion: Our findings suggest that the combination of CHK1 and WEE1 inhibitors may be a promising therapeutic strategy to be tested in clinical trials for adult ALL.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/cancers11111654DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6895917PMC
October 2019

Exploring the intramolecular catalysis of the proton exchange process to modulate the relaxivity of Gd(iii)-complexes of HP-DO3A-like ligands.

Chem Commun (Camb) 2018 Sep;54(72):10056-10059

Department of Drug Science and Technology, University of Torino, Via. P. Giuria 7, 10125 Torino, Italy.

The Gd(iii)-complexes of three novel HP-DO3A-like ligands have been investigated to assess the relationship between relaxometry and intramolecular catalysis of the proton exchange. The structures of these ligands differ from the parent HP-DO3A because the methyl group of the hydroxy-propyl arm has been replaced by -Ph-OH, -Ph-NH2 and -Ph-COOH, respectively. The phenol, amine and carboxylate functionalities display an intramolecular H-bonding with the coordinated hydroxyl moiety that affects either the pK values of the involved functionalities and the rate of the proton exchange process.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/c8cc05284kDOI Listing
September 2018

Immunosuppressive Treg cells acquire the phenotype of effector-T cells in chronic lymphocytic leukemia patients.

J Transl Med 2018 06 20;16(1):172. Epub 2018 Jun 20.

Scientific Directorate, Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori (IRST) IRCCS, Meldola, Italy.

Background: In chronic lymphocytic leukemia (CLL) disease onset and progression are influenced by the behavior of specific CD4 T cell subsets, such as T regulatory cells (Tregs). Here, we focused on the phenotypic and functional characterization of Tregs in CLL patients to improve our understanding of the putative mechanism by which these cells combine immunosuppressive and effector-like properties.

Methods: Peripheral blood mononuclear cells were isolated from newly diagnosed CLL patients (n = 25) and healthy volunteers (n = 25). The phenotypic and functional characterization of Tregs and their subsets was assessed by flow cytometry. In vitro analysis of TH1, TH2, TH17 and Tregs cytokines was evaluated by IFN-γ, IL-4, IL-17A and IL-10 secretion assays. The transcriptional profiling of 84 genes panel was evaluated by RT Profiler PCR Array. Statistical analysis was carried out using exact non parametric Mann-Whitney U test.

Results: In all CLL samples, we found a significant increase in the frequency of IL-10-secreting Tregs and Tregs subsets, a significant rise of TH2 IL-4 and TH17 IL-17A cells, and a higher percentage of IFN-γ/IL-10 and IL-4/IL-10 double-releasing CD4 T cells. In addition, we also observed the up-regulation of innate immunity genes and the down-regulation of adaptive immunity ones.

Conclusions: Our data show that Tregs switch towards an effector-like phenotype in CLL patients. This multifaceted behavior is accompanied by an altered cytokine profiling and transcriptional program of immune genes, leading to a dysfunction in immune response in the peripheral blood environment of CLL patients.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/s12967-018-1545-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6011245PMC
June 2018

Exploiting the Proton Exchange as an Additional Route to Enhance the Relaxivity of Paramagnetic MRI Contrast Agents.

Inorg Chem 2018 May 24;57(9):5567-5574. Epub 2018 Apr 24.

Bracco Imaging Spa , Bracco Research Centre , Via Ribes 5 , 10010 Colleretto Giacosa ( TO ), Italy.

The relaxivity of Gd(HP-DO3A) was studied as a function of pH and buffer composition in order to identify the main factors of the observed relaxation enhancement due to the exchange of the coordinated hydroxyl proton. It was established that the paramagnetic relaxation time, T, of the coordinated hydroxyl proton is about 50% shorter than that of the protons in the coordinated water molecule. The control of the p K of the coordinated alcoholic -OH moiety in the ligand is fundamental to utilize the proton exchange enhanced relaxivity under physio/pathologic conditions. A new derivative of Gd(HP-DO3A) was synthesized by replacing the -CH group with a -CF moiety. In this complex, the -OH group becomes more acidic. Consequently, the maximum contribution of the proton exchange to the relaxivity is shifted to a lower pH region with the fluorinated ligand.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/acs.inorgchem.8b00521DOI Listing
May 2018

Pentoxifylline-Induced Apoptosis in Chronic Lymphocytic Leukemia: New Insights into Molecular Mechanism.

Mini Rev Med Chem 2018 ;18(3):287-294

Hematology Unit, Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori (IRST) IRCCS, Meldola (FC). Italy.

Background: Chronic lymphocytic leukemia (CLL) is an indolent B-lineage neoplasm, characterized by clonal expansion of CD5 positive B cells with constitutive activation of survival pathways including NF-kB. Pentoxifylline, a xanthine-derivative compound indicated for the treatment of microvascular disturbancies, has been suggested to have anti-proliferative and anti-metastatic activities in various types of cancer. In the present study we extend these data showing one of the potential molecular mechanisms through which Pentoxifylline may promote apoptosis in CLL clonal lymphocytes.

Methods: Peripheral blood mononuclear cells were isolated from 15 CLL patients 0 RAI stage and 15 healthy volunteers and treated for 24 and 48 hours with Pentoxifylline. Apoptosis induction was evaluated through Annexin V and TUNEL assays. Mitochondrial membrane potential depolarization analysis, active Caspase-3 assay, reactive oxygen species generation and Western Blot were assessed to further investigate the alterations induced by Pentoxifylline.

Results: We observed a statistically significant occurrence of apoptosis, DNA fragmentation and active Caspase-3 in lymphocytes from CLL patients compared to healthy volunteers after 48 hours of Pentoxifylline treatment. To clarify the molecular mechanism of the drug, we also evaluated the expression levels of NF-kB/p65 and its related proteins. In treated CLL cells, NF-kB/p65 was significantly decreased in comparison to normal cells, whereas we observed a less marked reduction of Bcl-2 expression. The treatment also induced a decrease of Mcl-1 in CLL cells with a greater down-regulation of the anti-apoptotic alternatively spliced isoform.

Conclusion: These findings showed that Pentoxifylline induced apoptosis in leukemic cells through a molecular mechanism that involves the NF-kB signaling.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.2174/1389557517666171002162258DOI Listing
February 2018

Interplay Between SIRT-3, Metabolism and Its Tumor Suppressor Role in Hepatocellular Carcinoma.

Dig Dis Sci 2017 08 19;62(8):1872-1880. Epub 2017 May 19.

Department of Medical Oncology, IRST IRCCS, Via Maroncelli, 40, 47014, Meldola, Italy.

Sirtuins (SIRT), first described as nicotinamide adenine dinucleotide (NAD)-dependent type III histone deacetylases, are produced by cells to support in the defense against chronic stress conditions such as metabolic syndromes, neurodegeneration, and cancer. SIRT-3 is one of the most studied members of the mitochondrial sirtuins family. In particular, its involvement in metabolic diseases and its dual role in cancer have been described. In the present review, based on the evidence of SIRT-3 involvement in metabolic dysfunctions, we aimed to provide an insight into the multifaceted role of SIRT-3 in many solid and hematological tumors with a particular focus on hepatocellular carcinoma (HCC). SIRT-3 regulatory effect and involvement in metabolism dysfunctions may have strong implications in HCC development and treatment. Research literature widely reports the relationship between metabolic disorders and HCC development. This evidence suggests a putative bridge role of SIRT-3 between metabolic diseases and HCC. However, further studies are necessary to demonstrate such interconnection.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s10620-017-4615-xDOI Listing
August 2017

The emerging role of GSK-3β in the pathobiology of classical Hodgkin lymphoma.

Histopathology 2017 Jul 11;71(1):72-80. Epub 2017 Apr 11.

Biosciences Laboratory, Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori IRCCS, Meldola, Italy.

Aims: Glycogen synthase kinase-3 beta (GSK-3β) is a serine/threonine kinase involved in glycogen metabolism, cell cycle progression, differentiation, embryogenesis, migration, metabolism, survival and cellular senescence. Its main biological function is to inhibit β-catenin by sequestration and promotion of its proteasomal degradation in the Wnt canonical pathway; however, GSK-3β interacts with multiple signalling pathways, and aberrant expression of the enzyme was reported in many solid neoplasms. This study aimed to investigate the biological relevance of GSK-3β in classical Hodgkin lymphomas (cHL).

Methods And Results: We analysed the functional status of GSK-3β enzyme in cHL by using antibodies raised against fixation-resistant epitopes of phospho Y216 GSK-3β (active form), phospho S9 GSK-3β (inactive form) and β-catenin protein. We first detected the pY216 GSK-3β active form of the enzyme in 100 of 100 (100%) of the cases, and in line with the latter expression profile, the β-catenin protein was found in only 12 of 100 (12%) of the samples. As reported previously in bladder cancer, pancreatic adenocarcinoma and chronic lymphocytic leukaemia, we showed an aberrant nuclear localization in the neoplastic clone of active pY216 GSK-3β in 78 of 100 (78%) of cHL cases.

Conclusions: We demonstrated the activation of GSK-3β in cHL resulting in inhibition of the Wnt/β-catenin signal cascade and the aberrant accumulation of its activated form in nuclei of Hodgkin Reed-Sternberg and Hodgkin cells. These findings may be relevant for future clinical studies, identifying GSK-3β as a potential therapeutic target for cHL.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/his.13189DOI Listing
July 2017

Macrocyclic paramagnetic agents for MRI: Determinants of relaxivity and strategies for their improvement.

Magn Reson Med 2017 10 28;78(4):1523-1532. Epub 2016 Oct 28.

Dipartimento di Chimica I.F.M, Università degli Studi di Torino, Via Pietro Giuria 7, 10125, Torino (TO), Italy.

Purpose: To dissect the contributions to the longitudinal relaxivity (r ) of two commercial contrast agents (CAs), Gd-DOTA and Gd-HP-DO3A, and to synthesize/characterize a novel macrocyclic agent (Gd-Phen-DO3A) having superior r .

Methods: Longitudinal relaxation rates R of the CAs in saline with/without human serum albumin (HSA), ionized simulated body fluid (i-SBF), viscous simulated body fluid (v-SBF), and human plasma were measured. Results have been interpreted to evince the main determinants to the observed r values.

Results: In v-SBF or in the presence of HSA, r is enhanced for all complexes, reflecting the viscosity increase and a weak interaction with proteins. The CAs further differentiate in plasma, with a relaxivity increase (versus saline) of approximately 1, 1.5, and 2.5 mM s for Gd-DOTA, Gd-HPDO3A, and Gd-Phen-DO3A, respectively. R versus pH curves in i-SBF indicates that prototropic exchange sizably contributes to the relaxivity of Gd-HP-DO3A and Gd-Phen-DO3A.

Conclusion: The major contributions to r in the physiological environment have been highlighted, namely, increased viscosity, complex-protein interaction, and prototropic exchange. The control of these terms allows the design of novel macrocyclic structures with enhanced r as a result of an improved interaction with plasma's macromolecules and the shift of the prototropic exchange to physiological pH. Magn Reson Med 78:1523-1532, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/mrm.26519DOI Listing
October 2017

IL-17/IL-10 double-producing T cells: new link between infections, immunosuppression and acute myeloid leukemia.

J Transl Med 2015 Jul 15;13:229. Epub 2015 Jul 15.

Biosciences Laboratory, Istituto Scientifico Romagnolo per lo Studio e la Cura dei Tumori (IRST) IRCCS, Meldola, Italy.

Background: Acute myeloid leukemia (AML) is an incurable disease with fatal infections or relapse being the main causes of death in most cases. In particular, the severe infections occurring in these patients before or during any treatment suggest an intrinsic alteration of the immune system. In this respect, IL-17-producing T helper (Th17) besides playing a key role in regulating inflammatory response, tumor growth and autoimmune diseases, have been shown to protect against bacterial and fungal pathogens. However, the role of Th17 cells in AML has not yet been clarified.

Methods: T cell frequencies were assessed by flow cytometry in the peripheral blood of 30 newly diagnosed AML patients and 30 age-matched healthy volunteers. Cytokine production was determined before and after culture of T cells with either Candida Albicans or AML blasts. Statistical analyses were carried out using the paired and unpaired two-tailed Student's t tests and confirmed with the non parametric Wilcoxon signed-rank test.

Results: A strong increase of Th17 cells producing immunosuppressive IL-10 was observed in AML patients compared with healthy donors. In addition, stimulation of AML-derived T cells with a Candida albicans antigen induced significantly lower IFN-γ production than that observed in healthy donors; intriguingly, depletion of patient Th17 cells restored IFN-γ production after stimulation. To address the role of AML blasts in inducing Th17 alterations, CD4+ cells from healthy donors were co-cultured with CD33+ blasts: data obtained showed that AML blasts induce in healthy donors levels of IL-10-producing Th17 cells similar to those observed in patients.

Conclusions: In AML patients altered Th17 cells actively cause an immunosuppressive state that may promote infections and probably tumor escape. Th17 cells could thus represent a new target to improve AML immunotherapy.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/s12967-015-0590-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4502949PMC
July 2015

Solution structures, stabilities, kinetics, and dynamics of DO3A and DO3A-sulphonamide complexes.

Inorg Chem 2014 Mar 24;53(6):2858-72. Epub 2014 Feb 24.

Department of Inorganic and Analytical Chemistry, ‡MTA-DE Homogeneous Catalysis and Reaction Mechanisms Research Group, §Department of Physical Chemistry, University of Debrecen , H-4032 Debrecen, Egyetem tér 1, Hungary.

The Gd(3+)-DO3A-arylsulphonamide (DO3A-SA) complex is a promising pH-sensitive MRI agent. The stability constants of the DO3A-SA and DO3A complexes formed with Mg(2+), Ca(2+), Mn(2+), Zn(2+), and Cu(2+) ions are similar, whereas the logKLnL values of Ln(DO3A-SA) complexes are 2 orders of magnitude higher than those of the Ln(DO3A) complexes. The protonation constant (log KMHL) of the sulphonamide nitrogen in the Mg(2+), Ca(2+), Mn(2+), Zn(2+), and Cu(2+) complexes is very similar to that of the free ligand, whereas the logKLnHL values of the Ln(DO3A-SA) complexes are lower by about 4 logK units, indicating a strong interaction between the Ln(3+) ions and the sulphonamide N atom. The Ln(HDO3A-SA) complexes are formed via triprotonated *Ln(H3DO3A-SA) intermediates which rearrange to the final complex in an OH(-)-assisted deprotonation process. The transmetalation reaction of Gd(HDO3A-SA) with Cu(2+) is very slow (t1/2 = 5.6 × 10(3) h at pH = 7.4), and it mainly occurs through proton-assisted dissociation of the complex. The (1)H and (13)C NMR spectra of the La-, Eu-, Y-, and Lu(DO3A-SA) complexes have been assigned using 2D correlation spectroscopy (COSY, EXSY, HSQC). Two sets of signals are observed for Eu-, Y-, and Lu(DO3A-SA), showing two coordination isomers in solution, that is, square antiprismatic (SAP) and twisted square antiprismatic (TSAP) geometries with ratios of 86-14, 93-7, and 94-6%, respectively. Line shape analysis of the (13)C NMR spectra of La-, Y- , and Lu(DO3A-SA) gives higher rates and lower activation entropy values compared to Ln(DOTA) for the arm rotation, which indicates that the Ln(DO3A-SA) complexes are less rigid due to the larger flexibility of the ethylene group in the sulphonamide pendant arm. The fast isomerization and the lower activation parameters of Ln(DO3A-SA) have been confirmed by theoretical calculations in vacuo and by using the polarizable continuum model. The solid state X-ray structure of Cu(H2DO3A-SA) shows distorted octahedral coordination. The coordination sites of Cu(2+) are occupied by two ring N- and two carboxylate O-atoms in equatorial position. The other two ring N-atoms complete the coordination sphere in axial positions. The solid state structure also indicates that a carboxylate O atom and the sulphonamide nitrogen are protonated and noncoordinated.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/ic4025958DOI Listing
March 2014

Synthesis and relaxometric characterization of a MRI Gd-based probe responsive to glutamic acid decarboxylase enzymatic activity.

J Med Chem 2013 Mar 15;56(6):2466-77. Epub 2013 Mar 15.

Department of Molecular Biotechnologies and Health Sciences and Molecular Imaging Center, University of Torino, Turin, Italy.

Novel contrast agent based systems, which selectively visualize specific cells, e.g., neurons in the brain, would be of substantial importance for the fast developing field of molecular magnetic resonance imaging (MRI). We report here the synthesis and in vitro validation of a Gd(III)-based contrast agent designed to act as an MRI responsive probe for imaging the activity of the enzyme glutamic acid decarboxylase (GAD) present in neurons. Upon the action of the enzyme, the Gd(III) complex increases its hydration sphere and takes on a residual positive charge that promotes its binding to endogenous macromolecules. Both effects contribute in a synergic way to generate a marked relaxation enhancement, which directly reports enzyme activity and will allow activity detection of GAD positive cells in vitro and in vivo selectively.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/jm301831fDOI Listing
March 2013

In vivo imaging of inhibitory, GABAergic neurons by MRI.

Neuroimage 2012 Sep 18;62(3):1685-93. Epub 2012 May 18.

In-vivo-NMR Laboratory, Max Planck Institute for Neurological Research, Cologne, Germany.

The unambiguous detection of specific neuronal subtypes is up to now only possible with invasive techniques or optical imaging after genetic modification. High field magnetic resonance imaging (MRI) has the ability to visualize the brain structure and anatomy noninvasively, with high resolution--but missing the cell specific and functional information. Here we present a new tool for neuroimaging with MRI, enabling the selective detection of GABAergic neurons under in vivo conditions. The specific imaging contrast is achieved by a novel paramagnetic contrast agent, which responds to the activity of the enzyme glutamic acid decarboxylase--expressed solely by inhibitory neurons. The relaxivity of the complex is increased upon decarboxylation of two glutamic acid moieties, thus allowing increased water access to the inner and outer coordination spheres of the paramagnetic ion. The mechanism and specificity of activation were proven with tissue lysates and further applied to a differentiation protocol for murine embryonic stem cells. The relaxation enhancement was studied quantitatively and revealed decreased longitudinal relaxation times in the inhibitory neuron samples compared to the naïve stem cells in vitro and in vivo. Furthermore, this approach offers not only the discrimination of inhibitory, GABAergic neurons in the brain but also may expand the usefulness of MRI for functional imaging on a cellular level.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.neuroimage.2012.05.029DOI Listing
September 2012

On-bead combinatorial synthesis and imaging of chemical exchange saturation transfer magnetic resonance imaging agents to identify factors that influence water exchange.

J Am Chem Soc 2011 Aug 27;133(33):13023-30. Epub 2011 Jul 27.

Advanced Imaging Research Center, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas 75390-8568, USA.

The sensitivity of magnetic resonance imaging (MRI) contrast agents is highly dependent on the rate of water exchange between the inner sphere of a paramagnetic ion and bulk water. Normally, identifying a paramagnetic complex that has optimal water exchange kinetics is done by synthesizing and testing one compound at a time. We report here a rapid, economical on-bead combinatorial synthesis of a library of imaging agents. Eighty different 1,4,7,10-tetraazacyclododecan-1,4,7,10-tetraacetic acid (DOTA)-tetraamide peptoid derivatives were prepared on beads using a variety of charged, uncharged but polar, hydrophobic, and variably sized primary amines. A single chemical exchange saturation transfer image of the on-bead library easily distinguished those compounds having the most favorable water exchange kinetics. This combinatorial approach will allow rapid screening of libraries of imaging agents to identify the chemical characteristics of a ligand that yield the most sensitive imaging agents. This technique could be automated and readily adapted to other types of MRI or magnetic resonance/positron emission tomography agents as well.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/ja201123fDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3180893PMC
August 2011

Improved paramagnetic liposomes for MRI visualization of pH triggered release.

J Control Release 2011 Sep 20;154(2):196-202. Epub 2011 May 20.

Department of Chemistry IFM and Molecular & Preclinical Imaging Centers, University of Torino, Via Nizza 52, 10126, Torino, Italy.

This work aims at assessing the in vitro potential of paramagnetic pH sensitive liposomes as imaging tools for visualizing drug-delivery and release processes by Magnetic Resonance Imaging (MRI). pH sensitive liposomes (pSLs) were formulated using the fusogenic phospholipid 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE), the membrane stabilizer D-α-tocopherol-hemisuccinate (THS), and were loaded with several paramagnetic complexes including the clinically approved Gadoteridol (marketed as ProHance™). The proposed formulation allows the fast and full release of Gadoteridol at pH 5.5. The leakage of the imaging reporter from the vesicles was associated with a relaxivity enhancement that allowed its visualization by MRI. It was observed that the release mechanism implies the protonation of the THS basic sites that leads to vesicle aggregation, thus enabling the expression of the fusogenic property of POPE. Attempts for improving the MRI properties of pSLs were pursued through the encapsulation of imaging agents with higher relaxivity than Gadoteridol, but it was observed that the release kinetic can be significantly affected by the probe size. Aiming at preparing stealth pSLs, PEG chains were conjugated to the external surface of the vesicles via cleavable disulphide bridges. Such nanomedicines do not release their content at acidic pH as long as the coating polymer is not removed from the surface. The results obtained suggest that the liposomal formulation investigated in this work has the potential for visualizing drug-delivery and release processes by in vivo MRI preclinical studies.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jconrel.2011.05.017DOI Listing
September 2011

Exofacial protein thiols as a route for the internalization of Gd(III)-based complexes for magnetic resonance imaging cell labeling.

J Med Chem 2010 Jul;53(13):4877-90

Department of Environmental and Life Sciences, University of Eastern Piedmont "A. Avogadro", Viale T. Michel 11, I-15121 Alessandria, Italy.

Four novel MRI Gd(III)-based probes have been synthesized and evaluated for their labeling properties on cultured cell lines K562, C6, and B16. The labeling strategy relies upon the fact that cells display a large number of reactive exofacial protein thiols (EPTs) that can be exploited as anchorage points for suitably activated MRI probes. The probes are composed of a Gd(III) chelate (based on either DO3A or DTPA) connected through a flexible linker to the 2-pyridyldithio chemical function for binding to EPTs. GdDO3A-based chelates could efficiently label cells (up to a level of 1.2 x 10(10) Gd(III) atoms/cell), whereas GdDTPA-based chelates showed poor or no cell labeling ability at all. Among the GdDO3A based compounds, that having the longest spacer (compound GdL1A) showed the best labeling efficacy. The mechanism of EPT mediated cell labeling by GdL1A involves probe internalization without sequestration of the Gd(III) chelate within subcellular structures such as endosomes.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/jm901876rDOI Listing
July 2010

Poly-beta-cyclodextrin based platform for pH mapping via a ratiometric 19F/1H MRI method.

Chem Commun (Camb) 2009 Oct 21(40):6044-6. Epub 2009 Sep 21.

Dept. of Chemistry IFM and Molecular Imaging Center, Via Nizza 52, Torino, Italy.

The in vitro validation of a new pH mapping MRI method based on a supramolecular poly-beta-cyclodextrin-19F-Gd adduct is reported.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/b914540kDOI Listing
October 2009

Targeting exofacial protein thiols with Gd(III) complexes. An efficient procedure for MRI cell labelling.

Chem Commun (Camb) 2009 Feb 26(8):893-5. Epub 2009 Jan 26.

Department of Environmental and Life Sciences, University of Eastern Piedmont "A. Avogadro", Via Bellni 25G, 15100 Alessandria, Italy.

Cells display on the outer surface of the plasma membrane a large number of protein thiols that can be reversibly labelled with suitably designed Gd(III)-based contrast agents for cell tracking by MRI.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1039/b820593kDOI Listing
February 2009