scholarly journals L-Arginine Modulates Neonatal Leukocyte Recruitment in a Gestational Age-Dependent Manner

2020 ◽  
Vol 9 (9) ◽  
pp. 2772
Author(s):  
Raphaela Fitterer ◽  
Trim Lajqi ◽  
Simon Alexander Kranig ◽  
Maylis Braun ◽  
Nicole Theissig ◽  
...  
Keyword(s):  
Premature Infants ◽  
Gestational Age ◽  
Ex Vivo ◽  
Age Groups ◽  
Leukocyte Recruitment ◽  
Leukocyte Rolling ◽  
Dependent Manner ◽  
Immune Functions ◽  
Arginase 1

(1) Background: L-arginine is a complex modulator of immune functions, and its levels are known to decrease under septic conditions. L-arginine may suppress leukocyte recruitment in vivo; however, little is known about the gestational age-specific effects of L-arginine on leukocyte recruitment in preterm infants. We now asked whether L-arginine alters leukocyte recruitment in preterm and term neonates. (2) Methods: Leukocytes were isolated from preterm (28 + 0 to 32 + 6 weeks of gestation) and term (>37 weeks of gestation) newborns as well as from healthy adults. After incubation with 10 µg/mL L-arginine, we assessed leukocyte rolling and adhesion in dynamic microflow chamber experiments and leukocyte transmigration in fluorescence assays. In addition, we measured the expression of inducible nitric oxide synthase (iNOS) and Arginase 1 (Arg-1) in neutrophils by flow cytometry. (3) Results: Leukocyte rolling, adhesion, and transmigration increased with gestational age. Leukocyte rolling, adhesion, and transmigration were decreased by L-arginine in term-born infants and adults. Preterm leukocytes showed no change in recruitment upon L-arginine exposure. Leukocyte adhesion after L-arginine exposure reached similar levels among all groups. In line, the expression of iNOS and Arg-1 was similar in all three age groups. (4) Conclusion: L-arginine dampens the ex vivo recruitment capacity of leukocytes from term-born infants, whereas no effect was seen in premature infants. As levels of iNOS and Arg-1 in neutrophils remain ontogenetically unchanged, the anti-inflammatory effect of L-arginine on the leukocyte recruitment cascade needs further investigation. These results add to the controversial debate of L-arginine supplementation in premature infants in sepsis.

Ethanol Extract of Achillea fragrantissima Enhances Angiogenesis through Stimulation of VEGF Production

2020 ◽  
Vol 21 ◽  
Author(s):  
Hana M. Hammad ◽  
Amer Imraish ◽  
Maysa Al-Hussaini ◽  
Malek Zihlif ◽  
Amani A. Harb ◽  
...  
Keyword(s):  
Wound Healing ◽  
Rural Communities ◽  
Ex Vivo ◽  
Ethanol Extract ◽  
Aortic Ring ◽  
Treated Group ◽  
Control Group ◽  
Dependent Manner ◽  
Achillea Fragrantissima

Objective: Achillea fragrantissima L. (Asteraceae) is a traditionally used medicinal herb in the rural communities of Jordan. Methods: The present study evaluated the efficacy of the ethanol extract of this species on angiogenesis in both, ex vivo using rat aortic ring assay and in vivo using rat excision wound model. Results: In concentrations of 50 and 100 µg/ml, the ethanol extract showed angiogenic stimulatory effect and significantly increased length of capillary protrusions around aorta rings of about 60% in comparison to those of untreated aorta rings. In MCF-7 cells, the ethanol extract of A. fragrantissima stimulates the production of VEGF in a dose-dependent manner. 1% and 5% of ethanol extract of A. fragrantissima containing vaseline based ointment was applied on rat excision wounds for six days and was found to be effective in wound healing and maturation of the scar. Both preparations resulted in better wound healing when compared to the untreated control group and vaseline-treated group. This effect was comparable to that induced by MEBO, the positive control. Conclusion: The results indicate that A. fragrantissima has a pro-angiogenic effect, which may act through the VEGF signaling pathway.

scholarly journals Uptake and Distribution of Administered Bone Marrow Mesenchymal Stem Cell Extracellular Vesicles in Retina

Cells ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 730
Author(s):  
Biji Mathew ◽  
Leianne A. Torres ◽  
Lorea Gamboa Gamboa Acha ◽  
Sophie Tran ◽  
Alice Liu ◽  
...  
Keyword(s):  
Stem Cell ◽  
Mesenchymal Stem Cell ◽  
Extracellular Vesicles ◽  
Time Course ◽  
Ganglion Cells ◽  
Ex Vivo ◽  
Dependent Manner ◽  
Paracrine Effects

Cell replacement therapy using mesenchymal (MSC) and other stem cells has been evaluated for diabetic retinopathy and glaucoma. This approach has significant limitations, including few cells integrated, aberrant growth, and surgical complications. Mesenchymal Stem Cell Exosomes/Extracellular Vesicles (MSC EVs), which include exosomes and microvesicles, are an emerging alternative, promoting immunomodulation, repair, and regeneration by mediating MSC’s paracrine effects. For the clinical translation of EV therapy, it is important to determine the cellular destination and time course of EV uptake in the retina following administration. Here, we tested the cellular fate of EVs using in vivo rat retinas, ex vivo retinal explant, and primary retinal cells. Intravitreally administered fluorescent EVs were rapidly cleared from the vitreous. Retinal ganglion cells (RGCs) had maximal EV fluorescence at 14 days post administration, and microglia at 7 days. Both in vivo and in the explant model, most EVs were no deeper than the inner nuclear layer. Retinal astrocytes, microglia, and mixed neurons in vitro endocytosed EVs in a dose-dependent manner. Thus, our results indicate that intravitreal EVs are suited for the treatment of retinal diseases affecting the inner retina. Modification of the EV surface should be considered for maintaining EVs in the vitreous for prolonged delivery.

Skeletal muscle phenotype signaling with ex vivo endurance-type dynamic contractions in rat muscle

2021 ◽  
Author(s):  
Jesper Emil Jakobsgaard ◽  
Jacob Andresen ◽  
Frank V. de Paoli ◽  
Kristian Vissing
Keyword(s):  
Skeletal Muscle ◽  
Translation Initiation ◽  
Ex Vivo ◽  
Contractile Activity ◽  
Specific Protein ◽  
Signaling Proteins ◽  
Dependent Manner ◽  
Metabolic Signaling ◽  
Dynamic Endurance

Skeletal muscle phenotype may influence the response sensitivity of myocellular regulatory mechanisms to contractile activity. To examine this, we employed an ex vivo endurance-type dynamic contraction model to evaluate skeletal muscle phenotype-specific protein signaling responses in rat skeletal muscle. Preparations of slow-twitch soleus and fast-twitch extensor digitorum longus skeletal muscle from 4-wk old female Wistar rats were exposed to an identical ex vivo dynamic endurance-type contraction paradigm consisting of 40 minutes of stretch-shortening contractions under simultaneous low-frequency electrostimulation delivered in an intermittent pattern. Phosphorylation of proteins involved in metabolic signaling and signaling for translation initiation was evaluated at 0, 1, and 4 hours after stimulation by immunoblotting. For both muscle phenotypes, signaling related to metabolic events was upregulated immediately after stimulation, with concomitant absence of signaling for translation-initiation. Signaling for translation-initiation was then activated in both muscle phenotypes at 1-4 hours after stimulation, coinciding with attenuated metabolic signaling. The recognizable pattern of signaling responses support how our ex vivo dynamic muscle contraction model can be utilized to infer a stretch-shortening contraction pattern resembling stretch-shortening contraction of in vivo endurance exercise. Moreover, using this model, we observed that some specific signaling proteins adhering to metabolic events or to translation initation exhibited phosphorylation changes in a phenotype-dependent manner, whereas other signaling proteins exhibited phenotype-independent changes. These findings may aid the interpretation of myocellular signaling outcomes adhering to mixed muscle samples collected during human experimental trials.

scholarly journals The NADPH Oxidase Nox4 Controls Macrophage Polarization in an NFκB-Dependent Manner

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
V. Helfinger ◽  
K. Palfi ◽  
A. Weigert ◽  
K. Schröder
Keyword(s):  
Ex Vivo ◽  
Macrophage Polarization ◽  
Dependent Manner ◽  
Oxygen Species ◽  
Superoxide Anions ◽  
Wild Type ◽  
Macrophage Population ◽  
The Family ◽  
High Level

The family of NADPH oxidases represents an important source of reactive oxygen species (ROS) within the cell. Nox4 is a special member of this family as it constitutively produces H2O2 and its loss promotes inflammation. A major cellular component of inflammation is the macrophage population, which can be divided into several subpopulations depending on their phenotype, with proinflammatory M(LPS+IFNγ) and wound-healing M(IL4+IL13) macrophages being extremes of the functional spectrum. Whether Nox4 is expressed in macrophages is discussed controversially. Here, we show that macrophages besides a high level of Nox2 indeed express Nox4. As Nox4 contributes to differentiation of many cells, we hypothesize that Nox4 plays a role in determining the polarization and the phenotype of macrophages. In bone marrow-derived monocytes, ex vivo treatment with LPS/IFNγ or IL4/IL13 results in polarization of the cells into M(LPS+IFNγ) or M(IL4+IL13) macrophages, respectively. In this ex vivo setting, Nox4 deficiency reduces M(IL4+IL13) polarization and forces M(LPS+IFNγ). Nox4-/- M(LPS+IFNγ)-polarized macrophages express more Nox2 and produce more superoxide anions than wild type M(LPS+IFNγ)-polarized macrophages. Mechanistically, Nox4 deficiency reduces STAT6 activation and promotes NFκB activity, with the latter being responsible for the higher level of Nox2 in Nox4-deficient M(LPS+IFNγ)-polarized macrophages. According to those findings, in vivo, in a murine inflammation-driven fibrosarcoma model, Nox4 deficiency forces the expression of proinflammatory genes and cytokines, accompanied by an increase in the number of proinflammatory Ly6C+ macrophages in the tumors. Collectively, the data obtained in this study suggest an anti-inflammatory role for Nox4 in macrophages. Nox4 deficiency results in less M(IL4+IL13) polarization and suppression of NFκB activity in monocytes.

scholarly journals Peptidic degron for IMiD-induced degradation of heterologous proteins

2019 ◽  
Vol 116 (7) ◽  
pp. 2539-2544 ◽  
Author(s):  
Vidyasagar Koduri ◽  
Samuel K. McBrayer ◽  
Ella Liberzon ◽  
Adam C. Wang ◽  
Kimberly J. Briggs ◽  
...  
Keyword(s):  
Protein Function ◽  
Cultured Cells ◽  
Ex Vivo ◽  
Ease Of Use ◽  
Dependent Manner ◽  
Heterologous Proteins ◽  
Ubiquitin Ligase Complex ◽  
Dose Dependent ◽  
Current Systems

Current systems for modulating the abundance of proteins of interest in living cells are powerful tools for studying protein function but differ in terms of their complexity and ease of use. Moreover, no one system is ideal for all applications, and the best system for a given protein of interest must often be determined empirically. The thalidomide-like molecules (collectively called the IMiDs) bind to the ubiquitously expressed cereblon ubiquitin ligase complex and alter its substrate specificity such that it targets the IKZF1 and IKZF3 lymphocyte transcription factors for destruction. Here, we mapped the minimal IMiD-responsive IKZF3 degron and show that this peptidic degron can be used to target heterologous proteins for destruction with IMiDs in a time- and dose-dependent manner in cultured cells grown ex vivo or in vivo.

Sialic acid in sickle cell disease.

1988 ◽  
Vol 34 (7) ◽  
pp. 1443-1446 ◽  
Author(s):  
G I Ekeke ◽  
G O Ibeh
Keyword(s):  
Sialic Acid ◽  
Sickle Cell Disease ◽  
Sickle Cell ◽  
Age Groups ◽  
Dependent Manner ◽  
Cell Disease ◽  
Concentration Dependent Manner ◽  
Sialic Acid Content ◽  
Age Range

Abstract Neuraminic (sialic) acid concentrations in serum from normal and sickle cell (HbSS) subjects were determined for discrete age groups from childhood through adolescence. Values in sickle cell disease were consistently lower over the entire age range. We further investigated the effect of exogenous sialic acid on the rate of sickling reversion of HbSS erythrocytes and demonstrated that this compound in millimole per liter concentrations could revert pre-sickled erythrocytes to their normal morphology in a concentration-dependent manner. When subjected to partial de-sialation with sialidase (EC 3.2.1.18), the HbSS erythrocytes not only sickled faster upon deoxygenation, they also reverted more slowly on treatment with phenylalanine (a more efficient anti-sickling agent than sialic acid) than did untreated cells. We conclude that, in sickle cell disease, erythrocyte sialic acid content could play a significant role, not only in the control of the sickling rate in vivo, but also, after sickling has occurred, in the rate of recovery from a sickling crisis.

scholarly journals Opposing effects of nitric oxide and prostaglandin inhibition on muscle mitochondrial V̇o2 during exercise

2012 ◽  
Vol 303 (1) ◽  
pp. R94-R100 ◽  
Author(s):  
Robert Boushel ◽  
Teresa Fuentes ◽  
Ylva Hellsten ◽  
Bengt Saltin
Keyword(s):  
Nitric Oxide ◽  
Blood Flow ◽  
Mitochondrial Respiration ◽  
Complex I ◽  
Ex Vivo ◽  
Knee Extension ◽  
Physiological Effect ◽  
Dependent Manner ◽  
Concentration Dependent Manner

Nitric oxide (NO) and prostaglandins (PG) together play a role in regulating blood flow during exercise. NO also regulates mitochondrial oxygen consumption through competitive binding to cytochrome- c oxidase. Indomethacin uncouples and inhibits the electron transport chain in a concentration-dependent manner, and thus, inhibition of NO and PG synthesis may regulate both muscle oxygen delivery and utilization. The purpose of this study was to examine the independent and combined effects of NO and PG synthesis blockade (l-NMMA and indomethacin, respectively) on mitochondrial respiration in human muscle following knee extension exercise (KEE). Specifically, this study examined the physiological effect of NO, and the pharmacological effect of indomethacin, on muscle mitochondrial function. Consistent with their mechanism of action, we hypothesized that inhibition of nitric oxide synthase (NOS) and PG synthesis would have opposite effects on muscle mitochondrial respiration. Mitochondrial respiration was measured ex vivo by high-resolution respirometry in saponin-permeabilized fibers following 6 min KEE in control (CON; n = 8), arterial infusion of NG-monomethyl-l-arginine (l-NMMA; n = 4) and Indo ( n = 4) followed by combined inhibition of NOS and PG synthesis (l-NMMA + Indo, n = 8). ADP-stimulated state 3 respiration (OXPHOS) with substrates for complex I (glutamate, malate) was reduced 50% by Indo. State 3 O2 flux with complex I and II substrates was reduced less with both Indo (20%) and l-NMMA + Indo (15%) compared with CON. The results indicate that indomethacin reduces state 3 mitochondrial respiration primarily at complex I of the respiratory chain, while blockade of NOS by l-NMMA counteracts the inhibition by Indo. This effect on muscle mitochondria, in concert with a reduction of blood flow accounts for in vivo changes in muscle O2 consumption during combined blockade of NOS and PG synthesis.

Nicotinamide Enhances the Polyploidization of Primary Megakaryocytes.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 1366-1366
Author(s):  
Lisa M. Giammona ◽  
Eleftherios Papoutsakis ◽  
William M. Miller
Keyword(s):  
Dna Content ◽  
Molecular Mechanisms ◽  
Ex Vivo ◽  
Annexin V ◽  
Dependent Manner ◽  
Vitamin B3 ◽  
Ploidy Levels ◽  
High Ploidy

Abstract Megakaryocyte (Mk) maturation includes the development of polyploid cells via endomitosis. In vitro models of Mk differentiation can be used to gain a better understanding of the molecular mechanisms controlling this process. However, it is challenging to achieve ploidy levels in cultured human cells that are as high as those observed in vivo. Others have recently reported the use of chemical inhibitors to increase Mk ploidy (Lannutti et al., Blood 105:3875, 2005). Here, we show that nicotinamide (NIC), a form of vitamin B3, enhances the normal process of Mk polyploidization and leads to both a greater fraction of high ploidy cells and a greater degree of polyploidization. Human mobilized peripheral blood CD34+ cells were cultured in serum-free medium supplemented with thrombopoietin (TPO) to induce Mk differentiation. Beginning on day 5 of culture, cells were treated with nicotinamide (3 and 6.25 mM) and monitored for DNA content, growth, apoptosis, and surface marker expression. NIC treatment resulted in a greater fraction of Mks with high ploidy (DNA content greater than or equal to 8N). The ploidy of NIC treated cells continued to increase over the duration of the 13-day culture, whereas the ploidy of untreated cells peaked at day 9. On day 13 (8 days of NIC exposure), the percentages of high ploidy Mks for the untreated, 3 mM NIC, and 6.25 mM NIC conditions were 23%, 48%, and 63%, respectively. Furthermore, cells treated with NIC reached ploidy levels of 64N and 32N for 6.25 and 3 mM NIC, respectively, compared to 16N for untreated cells. NIC-treated cells also displayed dramatic differences in morphology - characterized by an increase in cell size, the presence of a more highly lobated nucleus, and an increased frequency of proplatelet-forming cells. Nicotinamide is known to inhibit poly(ADP-ribose) polymerase (PARP) and Sir2, which are both NAD+ dependent enzymes. Preliminary experiments show that PARP activity is low in cultured Mks and is not affected by addition of 6.25 mM NIC. Continued exposure (beginning at day 5) to the PARP inhibitors (and nicotinamide analogs) 3-aminobenzamide (3-AB) and benzamide at concentrations of 1, 3, and 6.25 mM was toxic to cells in a dose dependent manner. Interestingly, high doses of NIC (25 and 50 mM) were also toxic to cells. Remarkably, while Mk polyploidization and apoptosis are typically correlated, the increase in DNA content observed for NIC-treated cells occurred without significantly affecting the percentage of apoptotic Mks (assessed by Annexin V staining). These data suggest that it may be possible to partially decouple Mk apoptosis and polyploidization. Furthermore, while 6.25 mM NIC inhibited cell proliferation by ~35%, total expansion of cells cultured with 3 mM NIC was similar to that of untreated cells. This, combined with similar Mk commitment, as defined by a similar percentage of CD41+ cells, resulted in a greater overall number of high ploidy Mks in cultures treated with NIC. Since there is a direct correlation between Mk DNA content and platelet production (Mattia et al., Blood 99:888, 2002), these results suggest a possible therapeutic benefit of NIC for the management of thrombocytopenia. Similarly, NIC could also be used as an additive to ex vivo Mk cultures destined for transplantation. Figure Figure

Phenotypic and Functional Effects of Perifosine on Dendritic Cells.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 4803-4803
Author(s):  
Weihua Song ◽  
Teru Hideshima ◽  
Yu-Tzu Tai ◽  
Kenneth C. Anderson ◽  
Nikhil C. Munshi
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
Annexin V ◽  
Antitumor Agent ◽  
Dependent Manner ◽  
Immune Functions ◽  
Akt Inhibitor ◽  
Antitumor Effects

Abstract Perifosine is a synthetic novel alkylphospholipid, a new class of antitumor agent which targets cell membranes and inhibits Akt activation. Perifosine inhibits multiple myeloma (MM) cell growth in vitro and in vivo mouse model. Currently perifosine is under the evaluation of phase II clinical trail in MM. Although perifosine has shown significant direct antitumor effects, its effect on immune system has not yet been clarified. The objective of this study is to evaluate the effects of perifosine on the activity of antigen presenting cells (APCs). Monocyte-derived dendritic cells (DCs) from normal human donors were used as the APCs, and mature DCs were obtained by the treatment of TNF-α and IL-1β. Perifosine was used at the concentrations of 2.5 uM, 5 uM and 10 uM for the treatment with DCs. We first evaluated the effect of perifosine on the survival of DCs. We observed that the perifosine treatment up to 48 hours had no effect on viability (>90%) of DCs, assessed by annexin V and PI staining. Alteration of phenotype by perifosine on DCs was further examined by flow cytometry. Our results demonstrated that with dose-dependent manner, perifosine led to a significant down-regulation of surface antigens on immature DCs at 24 and 48 hours, which associated to costimulation (CD40, CD80 and CD86), antigen presentation (HLA-ABC, HLA-DPQR) and maturation (CD83). However, we did not observed significant effect of perifosine on above surface markers on mature DCs. Since DCs play a crucial role on the regulation of Th1/Th2 immune responses by the production of IL-12, we next evaluated IL-12 secretion by DCs with and without perifosine treatment. Importantly, treatment with perifosine significantly decreased LPS-induced-IL-12 production, compared to untreated DCs (untrt vs. trt = 192.29 vs. 166.23 pg/ml (2.5uM), 111.19 pg/ml (5uM) and 44.886 pg/ml (10uM)) at 24 hours. To assess the effect of perifosine on DCs function on the regulation of T cell responses, we stimulated allogenic T cells with mature DCs with or without the pre-treatment of perifosine. The proliferation assay by 3H-TdR incorporation and IFN-γ production by ELISA indicated perifosine-treated DCs had no significant effect on the regulation of T cells function. Taken together, these results showed that DCs function are influenced by the treatment of perifosine. Our pre-clinical data therefore indicates the need to monitor immune functions in patients under the Akt inhibitor treatment.

Further Preclinical Studies with APR-246, a Novel Anticancer Compound Currently in Clinical Trials for Hematological Malignancies and Prostate Cancer.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 3773-3773
Author(s):  
Nina Mohell ◽  
Charlotta Liljebris ◽  
Jessica Alfredsson ◽  
Ylva Lindman ◽  
Maria Uustalu ◽  
...  
Keyword(s):  
Clinical Trials ◽  
Cancer Cells ◽  
Cell Lines ◽  
Cancer Cell ◽  
Ex Vivo ◽  
Cancer Cell Lines ◽  
Solid Cancer ◽  
Dependent Manner

Abstract Abstract 3773 Poster Board III-709 Introduction The tumor suppressor protein p53 induces cell cycle arrest and/or apoptosis in response to various forms of cellular stress, through transcriptional regulation of a large number of down stream target genes. p53 is frequently mutated in cancer, and cancer cells carrying defects in the p53 protein are often more resistant to conventional chemotherapy. Thus, restoration of the wild type function to mutant p53 appears to be a new attractive strategy for cancer therapy. APR-246 is a novel small molecule quinuclidinone compound that has been shown to reactivate non-functional p53 and induce apoptosis. Although the exact molecular mechanism remains to be determined, recent results suggest that an active metabolite of APR-246 alkylates thiol groups in the core domain of p53, which promotes correct folding of p53 and induces apoptosis (Lambert et al., Cancer Cell 15, 2009). Currently, APR-246 is in Phase I/IIa clinical trials for hematological malignancies and prostate cancer. In the present abstract results from in vitro, ex vivo and in vivo preclinical studies with APR-246 are presented. Results The lead compound of APR-246, PRIMA-1 (p53 reactivation and induction of massive apoptosis), was originally identified by a cellular screening of the NCI library for low molecular weight compounds (Bykov et al., Nat. Med., 8, 2002). Further development and optimization of PRIMA-1 led to the discovery of the structural analog APR-246 (PRIMA-1MET), with improved drug like and preclinical characteristics. In in vitro experiments APR-246 reduced cell viability (WST-1 assay) in a large number of human cancer cell lines with various p53 status, including several leukemia (CCRF-CEM, CEM/VM-1, KBM3), lymphoma (U-937 GTP, U-937-vcr), and myeloma (RPMI 8226/S, 8226/dox40, 8226/LR5) cell lines, as well as many solid cancer cell lines, including osteosarcoma (SaOS-2, SaOS-2-His273,U-2OS), prostate (PC3, PC3-His175, 22Rv1), breast (BT474, MCF-7, MDA-MB-231), lung (H1299, H1299-His175) and colon cancer (HT-29). In human osteosarcoma cell lines APR-246 reduced cell viability and induced apoptosis (FLICA caspase assay) in a concentration dependent manner being more potent in the p53 mutant (SaOS-2-His273) than in the parental p53 null (SaOS-2) cells. The IC50 values (WST-1 assay) were 14 ± 3 and 27 ± 5 μM, respectively (n=35). In in vivo subcutaneous xenograft studies in SCID (severe combined immunodeficiency) mice APR-246 reduced growth of p53 mutant SaOS-2-His273 cells in a dose-dependent manner, when injected i.v. twice daily with 20 -100 mg/kg (64 – 76% inhibition). An in vivo anticancer effect of APR-246 was also observed in hollow-fiber test with NMRI mice using the acute myeloid leukemia (AML) cell line MV-4-11. An ex vivo cytotoxic effect of APR-246 and/or its lead compound PRIMA-1 has also been shown in primary cells from AML and CLL (chronic lymphocytic leukemia) patients, harbouring both hemizygously deleted p53 as well as normal karyotype (Nahi et al., Br. J. Haematol., 127, 2004; Nahi et al., Br. J. Haematol., 132, 2005; Jonsson-Videsater et al., abstract at this meeting). APR-246 was also tested in a FMCA (fluorometric microculture assay) test using normal healthy lymphocytes (PBMC) and cancer lymphocytes (CLL). It was 4-8 fold more potent in killing cancer cells than normal cells, indicating a favorable therapeutic index. This is in contrast to conventional cytostatics that often show negative ratio in this test. Furthermore, when tested in a well-defined panel of 10 human cancer cell lines consisting of both hematological and solid cancer cell lines, the cytotoxicity profile/activity pattern of APR-246 differed from common chemotherapeutic drugs (correlation coefficient less than 0.4), suggesting a different mechanism of action. Conclusion In relevant in vitro, in vivo and ex vivo cancer models, APR-246 showed unique pharmacological properties in comparison with conventional cytostatics, by being effective also in cancer cells with p53 mutations and by demonstrating tumor specificity. Moreover, in experimental safety/toxicology models required to start clinical trials, APR-246 was non toxic at the predicted therapeutic plasma concentrations. Thus, APR-246 appears to be a promising novel anticancer compound that may specifically target cancer cells in patients with genetic abnormality associated with poor prognosis. Disclosures: Mohell: Aprea AB: Employment. Liljebris:Aprea AB: Employment. Alfredsson:Aprea AB: Employment. Lindman:Aprea AB: Employment. Uustalu:Aprea AB: Employment. Wiman:Aprea AB: Co-founder, shareholder, and member of the board. Uhlin:Aprea AB: Employment.

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