Change search
Refine search result
1 - 10 of 10
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    EL Andaloussi, Samir
    et al.
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Lehto, Taavi
    Mäger, Imre
    Rosenthal-Aizman, Katri
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Oprea, Iulian I.
    Simonson, Oscar E.
    Sork, Helena
    Ezzat, Kariem
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Copolovici, Dana M.
    Kurrikoff, Kaido
    Viola, Joana R.
    Zaghloul, Eman M.
    Sillard, Rannar
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Johansson, Henrik J.
    Said Hassane, Fatouma
    Guterstam, Peter
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Suhorutsenko, Julia
    Moreno, Pedro M. D.
    Oskolkov, Nikita
    Hälldin, Jonas
    Tedebark, Ulf
    Metspalu, Andres
    Lebleu, Bernard
    Lehtiö, Janne
    Smith, C. I. Edvard
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Design of a peptide-based vector, PepFect6, for efficient delivery of siRNA in cell culture and systemically in vivo2011In: Nucleic Acids Research, ISSN 0305-1048, E-ISSN 1362-4962, Vol. 39, no 9, p. 3972-3987Article in journal (Refereed)
    Abstract [en]

    While small interfering RNAs (siRNAs) have been rapidly appreciated to silence genes, efficient and non-toxic vectors for primary cells and for systemic in vivo delivery are lacking. Several siRNA-delivery vehicles, including cell-penetrating peptides (CPPs), have been developed but their utility is often restricted by entrapment following endocytosis. Hence, developing CPPs that promote endosomal escape is a prerequisite for successful siRNA implementation. We here present a novel CPP, PepFect 6 (PF6), comprising the previously reported stearyl-TP10 peptide, having pH titratable trifluoromethylquinoline moieties covalently incorporated to facilitate endosomal release. Stable PF6/siRNA nanoparticles enter entire cell populations and rapidly promote endosomal escape, resulting in robust RNAi responses in various cell types (including primary cells), with minimal associated transcriptomic or proteomic changes. Furthermore, PF6-mediated delivery is independent of cell confluence and, in most cases, not significantly hampered by serum proteins. Finally, these nanoparticles promote strong RNAi responses in different organs following systemic delivery in mice without any associated toxicity. Strikingly, similar knockdown in liver is achieved by PF6/siRNA nanoparticles and siRNA injected by hydrodynamic infusion, a golden standard technique for liver transfection. These results imply that the peptide, in addition to having utility for RNAi screens in vitro, displays therapeutic potential.

  • 2.
    Ezzat, Kariem
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    CELL PENETRATING PEPTIDES: CHEMICAL MODIFICATION AND FORMULATION DEVELOPMENT2011Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Cell penetrating peptides (CPPs) have been extensively studied and exploited as drug delivery vectors for a wide variety of therapeu-tic cargos. However, several issues remain to be addressed regarding the enhancement of their efficiency and stability. In addition, to be available for patients, CPP-based therapeutics have to be formulated into suitable pharmaceutical forms that can be readily manufactured, transported, stored and conveniently used.In this thesis, three chemically modified CPPs are developed having superior delivery properties for several nucleic acid-based the-rapeutic cargoes including: plasmids, small interfering RNA (siRNA) and splice switching oligonucleutides (SSOs), in different in-vitro and in-vivo models. In Paper I, we show that an N-terminally stearic acid-modified version of transportan-10 (TP10) can form stable nanopar-ticles with plasmids that efficiently transfect different cell types and can mediate efficient gene delivery in-vivo when administrated intra muscularly (i.m.) or intradermaly (i.d.). In paper II, stearyl-TP10 is further modified with pH titratable trifluoromethylquinoline moieties to facilitate endosomal release. The new peptide, denoted PepFect 6 (PF6), elicited robust RNAi responses when complexed with siRNA in several cell models and promoted strong RNAi responses in differ-ent organs following systemic delivery in mice without any associated toxicity. In paper III , a new peptide with ornithine modification, PF14, is shown to efficiently deliver SSOs in different cell models including HeLa pLuc705 and mdx mouse myotubes; a cell culture model of Duchenne‟s muscular dystrophy (DMD). Additionally, we have developed a method for incorporating this delivery system into solid formulation that could be suitable for several therapeutic appli-cations. Solid dispersion technique is utilized and the formed solid formulations are as active as the freshly prepared nanocparticles in solution even when stored at elevated temperatures for several weeks.Taken together, these results demonstrate that certain chemical modifications could drastically enhance the activity and stability of CPPs in-vitro and in-vivo. Moreover, we show that CPP-based thera-peutics could be formulated into convenient and manufacturable do-sage forms.

  • 3.
    Ezzat, Kariem
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Cell-penetrating peptides; chemical modification, mechanism of uptake and formulation development2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Gene therapy holds the promise of revolutionizing the way we treat diseases. By using recombinant DNA and oligonucleotides (ONs), gene functions can be restored, altered or silenced according to the therapeutic need. However, gene therapy approaches require the delivery of large and charged nucleic acid-based molecules to their intracellular targets across the plasma membrane, which is inherently impermeable to such molecules. In this thesis, two chemically modified cell-penetrating peptides (CPPs) that have superior delivery properties for several nucleic acid-based therapeutics are developed. These CPPs can spontaneously form nanoparticles upon non-covalent complexation with the nucleic acid cargo, and the formed nanoparticles mediate efficient cellular transfection. In paper I, we show that an N-terminally stearic acid-modified version of transportan-10 (PF3) can efficiently transfect different cell types with plasmid DNA and mediates efficient gene delivery in-vivo when administrated intra muscularly (i.m.) or intradermaly (i.d.). In paper II, a new peptide with ornithine modification, PF14, is shown to efficiently deliver splice-switching oligonucleotides (SSOs) in different cell models including mdx mouse myotubes; a cell culture model of Duchenne’s muscular dystrophy (DMD). Additionally, we describe a method for incorporating the PF14-SSO nanoparticles into a solid formulation that is active and stable even when stored at elevated temperatures for several weeks. In paper III, we demonstrate the involvement of class-A scavenger receptor subtypes (SCARA3 & SCARA5) in the uptake of PF14-SSO nanoparticles, which possess negative surface charge, and suggest for the first time that some CPP-based systems function through scavenger receptors. In paper IV, the ability of PF14 to deliver siRNA to different cell lines is shown and their stability in simulated gastric acidic conditions is highlighted.

    Taken together, these results demonstrate that certain chemical modifications can drastically enhance the activity and stability of CPPs for delivering nucleic acids after spontaneous nanoparticle formation upon non-covalent complexation. Moreover, we show that CPP-based nanoparticles can be formulated into convenient and stable solid formulations that can be suitable for several therapeutic applications. Importantly, the involvement of scavenger receptors in the uptake of such nanoparticles is presented, which could yield novel possibilities to understand and improve the transfection by CPPs and other gene therapy nanoparticles.

  • 4.
    Ezzat, Kariem
    et al.
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    EL Andaloussi, Samir
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Abdo, Rania
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Peptide-based matrices as drug delivery vehicles2010In: Current pharmaceutical design, ISSN 1381-6128, E-ISSN 1873-4286, Vol. 16, no 9, p. 1167-1178Article, review/survey (Refereed)
    Abstract [en]

    Peptides, polypeptides and proteins have been extensively studied for their various structural and functional roles in living organisms. However, breakthrough discoveries in the last decades identified some peptide-based matrices that posses the ability to traverse biological membranes, and many peptides, polypeptides and even complete proteins have been shown to have such properties. Hence, these matrices have been successfully used for the intracellular delivery of many therapeutic cargos including small molecules, proteins, peptides, oligonucleutides, plasmids and nanoparticles both in vitro and in vivo. Being neither toxic nor carcinogenic and meanwhile efficient in delivery, they are recognized as very promising vectors to overcome the shortcomings of the available technologies. The characteristics of these peptide-based matrices and their applications in drug delivery are here briefly illustrated together with current challenges and future prospects.

  • 5.
    Ezzat, Kariem
    et al.
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    EL Andaloussi, Samir
    Zaghloul, Eman M.
    Lehto, Taavi
    Lindberg, Staffan
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Moreno, Pedro M. D.
    Viola, Joana R.
    Magdy, Tarek
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Abdo, Rania
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Guterstam, Peter
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Sillard, Rannar
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Hammond, Suzan M.
    Wood, Matthew J. A.
    Arzumanov, Andrey A.
    Gait, Michael J.
    Smith, C. I. Edvard
    Hällbrink, Mattias
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Neurochemistry. University of Tartu, Estonia.
    PepFect 14, a novel cell-penetrating peptide for oligonucleotide delivery in solution and as solid formulation2011In: Nucleic Acids Research, ISSN 0305-1048, E-ISSN 1362-4962, Vol. 39, no 12, p. 5284-5298Article in journal (Refereed)
    Abstract [en]

    Numerous human genetic diseases are caused by mutations that give rise to aberrant alternative splicing. Recently, several of these debilitating disorders have been shown to be amenable for splice-correcting oligonucleotides (SCOs) that modify splicing patterns and restore the phenotype in experimental models. However, translational approaches are required to transform SCOs into usable drug products. In this study, we present a new cell-penetrating peptide, PepFect14 (PF14), which efficiently delivers SCOs to different cell models including HeLa pLuc705 and mdx mouse myotubes; a cell culture model of Duchenne's muscular dystrophy (DMD). Non-covalent PF14-SCO nanocomplexes induce splice-correction at rates higher than the commercially available lipid-based vector Lipofectamine™ 2000 (LF2000) and remain active in the presence of serum. Furthermore, we demonstrate the feasibility of incorporating this delivery system into solid formulations that could be suitable for several therapeutic applications. Solid dispersion technique is utilized and the formed solid formulations are as active as the freshly prepared nanocomplexes in solution even when stored at an elevated temperatures for several weeks. In contrast, LF2000 drastically loses activity after being subjected to same procedure. This shows that using PF14 is a very promising translational approach for the delivery of SCOs in different pharmaceutical forms.

  • 6.
    Ezzat, Kariem
    et al.
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Helmfors, Henrik
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Tudoran, Oana
    Juks, Carmen
    Lindberg, Staffan
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Padari, Kärt
    EL Andaloussi, Samir
    Pooga, Margus
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Neurochemistry. University of Tartu, Estonia.
    Scavenger receptor-mediated uptake of cell-penetrating peptide nanoparticles with oligonucleotides2012In: The FASEB Journal, ISSN 0892-6638, E-ISSN 1530-6860, Vol. 26, no 3, p. 1172-1180Article in journal (Refereed)
    Abstract [en]

    Cell-penetrating peptides (CPPs) are shortcationic peptides that penetrate cells by interacting withthe negatively charged plasma membrane; however, thedetailed uptake mechanism is not clear. In contrary to theconventional mode of action of CPPs, we show here thata CPP, PepFect14 (PF14), forms negatively charged nanocomplexeswith oligonucleotides and their uptake is mediatedby class-A scavenger receptors (SCARAs). Specificinhibitory ligands of SCARAs, such as fucoidin, polyinosinicacid, and dextran sulfate, totally inhibit the activityof PF14-oligonucleotide nanocomplexes in the HeLapLuc705 splice-correction cell model, while nonspecific,chemically related molecules do not. Furthermore, RNAinterference (RNAi) knockdown of SCARA subtypes(SCARA3 and SCARA5) that are expressed in this cell lineled to a significant reduction of the activity to <50%. Inline with this, immunostaining shows prevalent colocalizationof the nanocomplexes with the receptors, and electronmicroscopy images show no binding or internalizationof the nanocomplexes in the presence of theinhibitory ligands. Interestingly, naked oligonucleotidesalso colocalize with SCARAs when used at high concentrations.These results demonstrate the involvement ofSCARA3 and SCARA5 in the uptake of PF14-oligonucleotidenanocomplexes and suggest for the first time thatsome CPP-based systems function through scavenger receptors,which could yield novel possibilities to understandand improve the transfection by CPPs.

  • 7.
    Ezzat, Kariem
    et al.
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Zaghloul, Eman M.
    EL Andaloussi, Samir
    Lehto, Taavi
    Hilal, Ramy
    Magdy, Tarek
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Smith, Edvard C. I.
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Solid formulation of cell-penetrating peptide nanoparticles with siRNA and their stability in simulated gastric conditions2012In: Journal of Controlled Release, ISSN 0168-3659, E-ISSN 1873-4995, Vol. 162, no 1, p. 1-8Article in journal (Refereed)
    Abstract [en]

    Cell-penetrating peptides (CPPs) are short cationic peptides that have been extensively studied as drug delivery vehicles for proteins, nucleic acids and nanoparticles. However, the formulation of CPP-based therapeutics into different pharmaceutical formulations and their stability in relevant biological environments have not been given the same attention. Here, we show that a newly developed CPP, PepFect 14 (PF14), forms non-covalent nanocomplexes with short interfering RNA (siRNA), which are able to elicit efficient RNA-interference (RNAi) response in different cell-lines. RNAi effect was obtained at low siRNA doses with a unique kinetic profile. Furthermore, we utilized the solid dispersion technique to formulate PF14/siRNA nanocomplexes into solid formulations that were as active as the freshly prepared nanocomplexes in solution. Importantly, the freshly prepared nanocomplexes and solid formulations were stable after incubation with simulated gastric fluid having a pH of 1.2 and containing proteolytic enzymes. These results demonstrate the activity of PF14 in delivering and protecting siRNA in different pharmaceutical forms and biological environments.

  • 8.
    Lehto, Taavi
    et al.
    Stockholm University, Faculty of Science, Department of Neurochemistry. University of Tartu, Estonia.
    Abes, Rachida
    Oskolkov, Nikita
    Suhorutšenko, Julia
    Copolovici, Dana-Maria
    Mäger, Imre
    Stockholm University, Faculty of Science, Department of Neurochemistry. University of Tartu, Estonia.
    Viola, Joana R.
    Simonson, Oscar E.
    Ezzat, Kariem
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Guterstam, Peter
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Eriste, Elo
    Smith, Edvard
    Lebleu, Bernard
    EL Andaloussi, Samir
    Stockholm University, Faculty of Science, Department of Neurochemistry. University of Tartu, Estonia.
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Neurochemistry. University of Tartu, Estonia.
    Delivery of nucleic acids with a stearylated (RxR)4 peptide using a non-covalent co-incubation strategy2010In: Journal of Controlled Release, ISSN 0168-3659, E-ISSN 1873-4995, Vol. 141, no 1, p. 42-51Article in journal (Refereed)
    Abstract [en]

    In recent years, oligonucleotide-based molecules have been intensely used to modulate gene expression. All these molecules share the common feature of being essentially impermeable over cellular membranes and they therefore require efficient delivery vectors. Cell-penetrating peptides are a group of delivery peptides that has been readily used for nucleic acid delivery. In particular, polyarginine and derivates thereof, i.e. the (RxR)4 peptide, have been applied with success both in vitro and in vivo. A major problem, however, with these arginine-rich peptides is that they frequently remain trapped in endosomal compartments following internalization. The activity of polyarginine has previously been improved by conjugation to a stearyl moiety. Therefore, we sought to investigate what impact such modification would have on the pre-clinically used (RxR)4 peptide for non-covalent delivery of plasmids and splice-correcting oligonucleotides (SCOs) and compare it with stearylated Arg9 and Lipofectamine™ 2000. We show that stearyl-(RxR)4 mediates efficient plasmid transfections in several cell lines and the expression levels are significantly higher than when using unmodified (RxR)4 or stearylated Arg9. Although the transfection efficiency is lower than with Lipofectamine™ 2000, we show that stearyl-(RxR)4 is substantially less toxic. Furthermore, using a functional splice-correction assay, we show that stearyl-(RxR)4 complexed with 2′-OMe SCOs promotes significant splice correction whereas stearyl-Arg9 fails to do so. Moreover, stearyl-(RxR)4 promotes dose-dependent splice correction in parity with (RxR)4-PMO covalent conjugates, but at least 10-times lower concentration. These features make this stearic acid modified analog of (RxR)4 an intriguing vector for future in vivo experiments.

  • 9.
    Lehto, Taavi
    et al.
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Simonson, Oscar E.
    Mäger, Imre
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Ezzat, Kariem
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Sork, Helena
    Copolovici, Dana-Maria
    Viola, Joana R.
    Zaghloul, Eman M.
    Lundin, Per
    Moreno, Pedro M. D.
    Mäe, Maarja
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Oskolkov, Nikita
    Suhorutšenko, Julia
    Smith, C. I. Edvard
    EL Andaloussi, Samir
    A Peptide-based Vector for Efficient Gene Transfer In Vitro and In Vivo2011In: Molecular Therapy, ISSN 1525-0016, E-ISSN 1525-0024, Vol. 19, no 8, p. 1457-1467Article in journal (Refereed)
    Abstract [en]

    Finding suitable nonviral delivery vehicles for nucleic acid-based therapeutics is a landmark goal in gene therapy. Cell-penetrating peptides (CPPs) are one class of delivery vectors that has been exploited for this purpose. However, since CPPs use endocytosis to enter cells, a large fraction of peptides remain trapped in endosomes. We have previously reported that stearylation of amphipathic CPPs, such as transportan 10 (TP10), dramatically increases transfection of oligonucleotides in vitro partially by promoting endosomal escape. Therefore, we aimed to evaluate whether stearyl-TP10 could be used for the delivery of plasmids as well. Our results demonstrate that stearyl-TP10 forms stable nanoparticles with plasmids that efficiently enter different cell-types in a ubiquitous manner, including primary cells, resulting in significantly higher gene expression levels than when using stearyl-Arg9 or unmodified CPPs. In fact, the transfection efficacy of stearyl-TP10 almost reached the levels of Lipofectamine 2000 (LF2000), however, without any of the observed lipofection-associated toxicities. Most importantly, stearyl-TP10/plasmid nanoparticles are nonimmunogenic, mediate efficient gene delivery in vivo, when administrated intramuscularly (i.m.) or intradermally (i.d.) without any associated toxicity in mice.

  • 10.
    Lindberg, Staffan
    et al.
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Regberg, Jakob
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Eriksson, Jonas
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Helmfors, Henrik
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Muñoz-Alarcón, Andrés
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Srimanee, Artita
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Figueroa, Ricardo
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Hallberg, Einar
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Ezzat, Kariem
    Stockholm University, Faculty of Science, Department of Neurochemistry.
    Langel, Ülo
    Stockholm University, Faculty of Science, Department of Neurochemistry. University of Tartu, Estonia.
    A convergent uptake route for peptide- and polymer-based nucleotide delivery systems2015In: Journal of Controlled Release, ISSN 0168-3659, E-ISSN 1873-4995, Vol. 206, p. 58-66Article in journal (Refereed)
    Abstract [en]

    Cell-penetrating peptides (CPPs) have been used as vehicles to deliver various cargos into cells and are promising as tools to deliver therapeutic biomolecules such as oligonucleotides both in vitro and in vivo. CPPs are positively charged and it is believed that CPPs deliver their cargo in a receptor-independent manner by interactingwith the negatively charged plasmamembrane and thereby inducing endocytosis. In this study we examine the mechanism of uptake of several different, well known, CPPs that form complexes with oligonucleotides.We show that these CPP:oligonucleotide complexes are negatively charged in transfection-media and their uptake is mediated by class A scavenger receptors (SCARA). These receptors are known to promiscuously bind to, and mediate uptake of poly-anionic macromolecules. Uptake of CPP:oligonucleotide complexes was abolished using pharmacological SCARA inhibitors as well as siRNA-mediated knockdown of SCARA. Additionally, uptake of CPP:oligonucleotide was significantly increased by transiently overexpressing SCARA. Furthermore, SCARA inhibitors also blocked internalization of cationic polymer:oligonucleotide complexes.Our results demonstrate that the previous held belief that CPPs act receptor independently does not hold true for CPP:oligonucleotide complexes, as scavenger receptor class A (SCARA) mediates the uptake of all the examined CPP:oligonucleotide complexes in this study.

1 - 10 of 10
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf