16 results on '"Maas-Bakker, Roel F."'
Search Results
2. Quality Comparison of Biosimilar and Copy Filgrastim Products with the Innovator Product
- Author
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Halim, Liem Andhyk, Márquez, Maripaz, Maas-Bakker, Roel F., Castañeda-Hernández, Gilberto, Jiskoot, Wim, and Schellekens, Huub
- Published
- 2018
- Full Text
- View/download PDF
3. 3,4-Methylenedioxymethamphetamine (MDMA) interacts with therapeutic drugs on CYP3A by inhibition of pregnane X receptor (PXR) activation and catalytic enzyme inhibition
- Author
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Antolino-Lobo, Irene, Meulenbelt, Jan, Nijmeijer, Sandra M., Maas-Bakker, Roel F., Meijerman, Irma, van den Berg, Martin, and van Duursen, Majorie B.M.
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- 2011
- Full Text
- View/download PDF
4. Hyaluronic Acid-PEG-Based Diels-Alder In Situ Forming Hydrogels for Sustained Intraocular Delivery of Bevacizumab
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Ilochonwu, Blessing C, Mihajlovic, Marko, Maas-Bakker, Roel F, Rousou, Charis, Tang, Miao, Chen, Mei, Hennink, Wim E, Vermonden, Tina, Afd Pharmaceutics, Pharmaceutics, Afd Pharmaceutics, and Pharmaceutics
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Biomaterials ,Hyaluronic Acid/chemistry ,Retinal Diseases ,Polymers and Plastics ,Delayed-Action Preparations/chemistry ,Materials Chemistry ,Humans ,Bioengineering ,Bevacizumab/chemistry ,Hydrogels/chemistry - Abstract
Retinal diseases are the leading cause of visual impairment worldwide. The effectiveness of antibodies for the treatment of retinal diseases has been demonstrated. Despite the clinical success, achieving sufficiently high concentrations of these protein therapeutics at the target tissue for an extended period is challenging. Patients suffering from macular degeneration often receive injections once per month. Therefore, there is a growing need for suitable systems that can help reduce the number of injections and adverse effects while improving patient complacency. This study systematically characterized degradable “in situ” forming hydrogels that can be easily injected into the vitreous cavity using a small needle (29G). After intravitreal injection, the formulation is designed to undergo a sol–gel phase transition at the administration site to obtain an intraocular depot system for long-term sustained release of bioactives. A Diels–Alder reaction was exploited to crosslink hyaluronic acid-bearing furan groups (HAFU) with 4 arm-PEG10K-maleimide (4APM), yielding stable hydrogels. Here, a systematic investigation of the effects of polymer composition and the ratio between functional groups on the physicochemical properties of hydrogels was performed to select the most suitable formulation for protein delivery. Rheological analysis showed rapid hydrogel formation, with the fastest gel formation within 5 min after mixing the hydrogel precursors. In this study, the mechanical properties of an ex vivo intravitreally formed hydrogel were investigated and compared to the in vitro fabricated samples. Swelling and degradation studies showed that the hydrogels are biodegradable by the retro-Diels–Alder reaction under physiological conditions. The 4APM-HAFU (ratio 1:5) hydrogel formulation showed sustained release of bevacizumab > 400 days by a combination of diffusion, swelling, and degradation. A bioassay showed that the released bevacizumab remained bioactive. The hydrogel platform described in this study offers high potential for the sustained release of therapeutic antibodies to treat ocular diseases.
- Published
- 2022
5. Post-loading of proangiogenic growth factors in PLGA microspheres
- Author
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Scheiner, Karina C, Maas-Bakker, Roel F, van Steenbergen, Mies J, Schwendeman, Steven P, Hennink, Wim E, Kok, Robbert J, Afd Pharmaceutics, Pharmaceutics, Afd Pharmaceutics, and Pharmaceutics
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medicine.medical_treatment ,Drug Compounding ,Therapeutic angiogenesis ,Neovascularization, Physiologic ,Pharmaceutical Science ,Biocompatible Materials ,02 engineering and technology ,Fibroblast growth factor ,030226 pharmacology & pharmacy ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,Polylactic Acid-Polyglycolic Acid Copolymer ,Somatomedins ,medicine ,Humans ,Controlled release ,Implants ,Post-loading ,Drug Carriers ,Vascular Endothelial Growth Factors ,Growth factor ,Biomaterial ,PLGA ,General Medicine ,021001 nanoscience & nanotechnology ,In vitro ,Microspheres ,Recombinant Proteins ,Endothelial stem cell ,Vascular endothelial growth factor ,Fibroblast Growth Factors ,Drug Liberation ,chemistry ,Delayed-Action Preparations ,Biophysics ,Angiogenesis Inducing Agents ,0210 nano-technology ,Growth factors ,Biotechnology - Abstract
Active self-encapsulation (ASE) is a recently developed post-loading method based on absorption of (positively charged) proteins in microporous PLGA microspheres loaded with negatively charged polysaccharides (trapping agents). The aim of this study was to investigate ASE for simultaneous loading and controlled release of multiple growth factors. For this purpose, vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF) and insulin-like growth factor (IGF) were loaded in microspheres containing high molecular weight dextran sulfate (HDS) as trapping agent; loading was performed in a concentrated growth factor solution of low ionic strength and of pH 5 under conditions at which the proteins are positively charged. Subsequent pore closure was induced by incubation of the growth factor-loaded microspheres at 42.5 °C, i.e. above the Tg of (hydrated) PLGA (~30 °C). A 1:1:1 combination of VEGF, FGF and IGF was loaded with high loading (4.3%) and loading efficiency (91%). The in vitro release kinetics and bioactivity of loaded growth factors were studied for 4 weeks using ELISA and an endothelial cell proliferation assay, respectively. While IGF was released quickly, VEGF and FGF were continuously released for 4 weeks in their bioactive form, whereby a growth factor combination had a synergistic angiogenic effect. Therefore, ASE is a suitable method for co-loading growth factors which can provide sustained release profiles of bioactive growth factors, which is attractive for vascularization of biomaterial implants.
- Published
- 2021
6. The in-vitro effect of complementary and alternative medicines on cytochrome P450 2C9 activity
- Author
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Mooiman, Kim D., Goey, Andrew K.L., Huijbregts, Tomy J., Maas-Bakker, Roel F., Beijnen, Jos H., Schellens, Jan H.M., and Meijerman, Irma
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- 2014
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- View/download PDF
7. The effect of complementary and alternative medicines on CYP3A4-mediated metabolism of three different substrates: 7-benzyloxy-4-trifluoromethyl-coumarin, midazolam and docetaxel
- Author
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Mooiman, Kim D., Maas-Bakker, Roel F., Hendrikx, Jeroen J. M. A., Bank, Paul C. D., Rosing, Hilde, Beijnen, Jos H., Schellens, Jan H. M., and Meijerman, Irma
- Published
- 2014
- Full Text
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8. π-π-Stacked Poly(ε-caprolactone)-b-poly(ethylene glycol) Micelles Loaded with a Photosensitizer for Photodynamic Therapy
- Author
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Liu, Yanna, Fens, Marcel H A M, Lou, Bo, van Kronenburg, Nicky C H, Maas-Bakker, Roel F M, Kok, Robbert J, Oliveira, Sabrina, Hennink, Wim E, van Nostrum, Cornelus F, Pharmaceutics, Afd Pharmaceutics, Sub Cell Biology, Celbiologie, Pharmaceutics, Afd Pharmaceutics, Sub Cell Biology, and Celbiologie
- Subjects
Biodistribution ,in vitro release ,lcsh:RS1-441 ,Pharmaceutical Science ,02 engineering and technology ,macromolecular substances ,010402 general chemistry ,01 natural sciences ,Micelle ,lcsh:Pharmacy and materia medica ,chemistry.chemical_compound ,Polymer chemistry ,Copolymer ,polymer micelles ,photodynamic therapy ,circulation kinetics ,biodistribution ,Photosensitizer ,technology, industry, and agriculture ,Aromaticity ,021001 nanoscience & nanotechnology ,musculoskeletal system ,0104 chemical sciences ,chemistry ,Chlorin ,0210 nano-technology ,Ethylene glycol ,Caprolactone - Abstract
To improve the in vivo stability of poly(ε-caprolactone)-b-poly(ethylene glycol) (PCL-PEG)-based micelles and cargo retention by π-π stacking interactions, pendant aromatic rings were introduced by copolymerization of ε-caprolactone with benzyl 5-methyl-2-oxo-1,3-dioxane-5-carboxylate (TMC-Bz). It was shown that the incorporation of aromatic rings yielded smaller micelles (18–30 nm) with better colloidal stability in PBS than micelles without aromatic groups. The circulation time of i.v. injected micelles containing multiple pendant aromatic groups was longer (t½-α: ~0.7 h; t½-β: 2.9 h) than that of micelles with a single terminal aromatic group (t½ < 0.3 h). In addition, the in vitro partitioning of the encapsulated photosensitizer (meta-tetra(hydroxyphenyl)chlorin, mTHPC) between micelles and human plasma was favored towards micelles for those that contained the pendant aromatic groups. However, this was not sufficient to fully retain mTHPC in the micelles in vivo, as indicated by similar biodistribution patterns of micellar mTHPC compared to free mTHPC, and unequal biodistribution patterns of mTHPC and the host micelles. Our study points out that more detailed in vitro methods are necessary to more reliably predict in vivo outcomes. Furthermore, additional measures beyond π-π stacking are needed to stably incorporate mTHPC in micelles in order to benefit from the use of micelles as targeted delivery systems.
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- 2020
- Full Text
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9. Structure and Dynamics of Thermosensitive pDNA Polyplexes Studied by Time-Resolved Fluorescence Spectroscopy
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Fliervoet, Lies A L, Lisitsyna, Ekaterina S, Durandin, Nikita A, Kotsis, Ilias, Maas-Bakker, Roel F M, Yliperttula, Marjo, Hennink, Wim E, Vuorimaa-Laukkanen, Elina, Vermonden, Tina, Afd Pharmaceutics, Pharmaceutics, Division of Pharmaceutical Biosciences, Drug Research Program, Biopharmaceutics Group, Tampere University, Materials Science and Environmental Engineering, Research group: Chemistry & Advanced Materials, Afd Pharmaceutics, and Pharmaceutics
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Magnetic Resonance Spectroscopy ,Polymers and Plastics ,HYDROGELS ,116 Chemical sciences ,Acrylic Resins ,Bioengineering ,02 engineering and technology ,010402 general chemistry ,Methacrylate ,RESONANCE ENERGY-TRANSFER ,01 natural sciences ,Article ,Polyethylene Glycols ,Biomaterials ,chemistry.chemical_compound ,POLYETHYLENIMINE ,PLASMID DNA ,Fluorescence Resonance Energy Transfer ,Materials Chemistry ,Copolymer ,POLY(N-ISOPROPYLACRYLAMIDE) ,TEMPERATURE ,chemistry.chemical_classification ,Polyethylenimine ,STABILITY ,Atom-transfer radical-polymerization ,Cationic polymerization ,DNA ,Polymer ,Carbocyanines ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Nylons ,POLYMERIZATION ,Spectrometry, Fluorescence ,chemistry ,Chemical engineering ,Polymerization ,Poly(N-isopropylacrylamide) ,Methacrylates ,1182 Biochemistry, cell and molecular biology ,Spectrophotometry, Ultraviolet ,POLYMERS ,0210 nano-technology ,Plasmids - Abstract
Combining multiple stimuli-responsive functionalities into the polymer design is an attractive approach to improve nucleic acid delivery. However, more in-depth fundamental understanding how the multiple functionalities in the polymer structures are influencing polyplex formation and stability is essential for the rational development of such delivery systems. Therefore, in this study the structure and dynamics of thermosensitive polyplexes were investigated by tracking the behavior of labeled plasmid DNA (pDNA) and polymer with time-resolved fluorescence spectroscopy using fluorescence resonance energy transfer (FRET). The successful synthesis of a heterofunctional poly(ethylene glycol) (PEG) macroinitiator containing both an atom transfer radical polymerization (ATRP) and reversible addition-fragmentation chain-transfer (RAFT) initiator is reported. The use of this novel PEG macroinitiator allows for the controlled polymerization of cationic and thermosensitive linear triblock copolymers and labeling of the chain-end with a fluorescent dye by maleimide-thiol chemistry. The polymers consisted of a thermosensitive poly(N-isopropylacrylamide) (PNIPAM, N), hydrophilic PEG (P), and cationic poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA, D) block, further referred to as NPD. Polymer block D chain-ends were labeled with Cy3, while pDNA was labeled with FITC. The thermosensitive NPD polymers were used to prepare pDNA polyplexes, and the effect of the N/P charge ratio, temperature, and composition of the triblock copolymer on the polyplex properties were investigated, taking nonthermosensitive PD polymers as the control. FRET was observed both at 4 and 37 °C, indicating that the introduction of the thermosensitive PNIPAM block did not compromise the polyplex structure even above the polymer's cloud point. Furthermore, FRET results showed that the NPD- and PD-based polyplexes have a less dense core compared to polyplexes based on cationic homopolymers (such as PEI) as reported before. The polyplexes showed to have a dynamic character meaning that the polymer chains can exchange between the polyplex core and shell. Mobility of the polymers allow their uniform redistribution within the polyplex and this feature has been reported to be favorable in the context of pDNA release and subsequent improved transfection efficiency, compared to nondynamic formulations. publishedVersion
- Published
- 2020
10. Sustained Release of Vascular Endothelial Growth Factor from Poly(ε-caprolactone-PEG-ε-caprolactone)‑b‑Poly(L‑lactide) Multiblock Copolymer Microspheres
- Author
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Scheiner, Karina C., Maas-Bakker, Roel F., Nguyen, Thanh T., Duarte, Ana M., Hendriks, Gert, Sequeira, Lídia, Duffy, Garry P., Steendam, Rob, Hennink, Wim E., Kok, Robbert J., Afd Pharmaceutics, Pharmaceutics, Afd Pharmaceutics, and Pharmaceutics
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chemistry.chemical_classification ,0303 health sciences ,Chemistry(all) ,Chemistry ,Angiogenesis ,General Chemical Engineering ,General Chemistry ,Polymer ,030226 pharmacology & pharmacy ,Umbilical vein ,Vascular endothelial growth factor ,lcsh:Chemistry ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,lcsh:QD1-999 ,PEG ratio ,Biophysics ,Chemical Engineering(all) ,Membrane emulsification ,Ethylene glycol ,Caprolactone ,030304 developmental biology - Abstract
Vascular endothelial growth factor (VEGF) is the major regulating factor for the formation of new blood vessels, also known as angiogenesis. VEGF is often incorporated in synthetic scaffolds to promote vascularization and to enhance the survival of cells that have been seeded in these devices. Such applications require sustained local delivery of VEGF of around 4 weeks for stable blood vessel formation. Most delivery systems for VEGF only provide short-term release for a couple of days, followed by a release phase with very low VEGF release. We now have developed VEGF-loaded polymeric microspheres that provide sustained release of bioactive VEGF for 4 weeks. Blends of two swellable poly(ε-caprolactone)−poly(ethylene glycol)−poly(ε-caprolactone)-b-poly(L-lactide) ([PCL−PEG−PCL]-b-[PLLA])-based multiblock copolymers with different PEG content and PEG molecular weight were used to prepare the microspheres. Loading of the microspheres was established by a solvent evaporation-based membrane emulsification method. The resulting VEGF-loaded microspheres had average sizes of 40−50 μm and a narrow size distribution. Optimized formulations of a 50:50 blend of the two multiblock copolymers had an average VEGF loading of 0.79 ± 0.09%, representing a high average VEGF loading efficiency of 78 ± 16%. These microspheres released VEGF continuously over 4 weeks in phosphate-buffered saline pH 7.4 at 37 °C. This release profile was preserved after repeated and long-term storage at −20 °C for up to 9 months, thereby demonstrating excellent storage stability. VEGF release was governed by diffusion through the water-filled polymer matrix, depending on PEG molecular weight and PEG content of the polymers. The bioactivity of the released VEGF was retained within the experimental error in the 4-week release window, as demonstrated using a human umbilical vein endothelial cells proliferation assay. Thus, the microspheres prepared in this study are suitable for embedment in polymeric scaffolds with the aim of promoting their functional vascularization.
- Published
- 2019
11. The in-vitro effect of complementary and alternative medicines on cytochrome P450 2C9 activity
- Author
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Mooiman, Kim D, Goey, Andrew K L, Huijbregts, Tomy J, Maas-Bakker, Roel F, Beijnen, Jos H, Schellens, Jan H M, Meijerman, Irma, Sub Clinical Pharmacology, Sub Drug delivery, Sub Immunopharmacology, and Pharmacoepidemiology and Clinical Pharmacology
- Subjects
cytochrome P450 2C9 ,tolbutamide ,7-benzyloxy-4-trifluoromethyl coumarin ,pharmacokinetic interactions ,complementary and alternative medicine - Abstract
OBJECTIVES: The aim of this study is to establish the inhibitory effects of 14 commonly used complementary and alternative medicines (CAM) on the metabolism of cytochrome P450 2C9 (CYP2C9) substrates 7-methoxy-4-trifluoromethyl coumarine (MFC) and tolbutamide. CYP2C9 is important for the metabolism of numerous drugs and inhibition of this enzyme by CAM could result in elevated plasma levels of drugs that are CYP2C9 substrates. Especially for anticancer drugs, which have a narrow therapeutic window, small changes in their plasma levels could easily result in clinically relevant toxicities. METHODS: The effects of CAM on CYP2C9-mediated metabolism of MFC were assessed in Supersomes, using the fluorometric CYP2C9 inhibition assay. In human liver microsomes (HLM) the inhibition of CYP2C9-mediated metabolism of tolbutamide was determined, using liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). KEY FINDINGS: The results indicated milk thistle as the most potent CYP2C9 inhibitor. For milk thistle, silybin (main constituent of milk thistle) was mainly responsible for the inhibition of CY2C9. CONCLUSIONS: Milk thistle and green tea were confirmed as potent inhibitors of CYP2C9-mediated metabolism of multiple substrates in vitro. Clinical studies with milk thistle are recommended to establish the clinical relevance of the demonstrated CYP2C9 inhibition.
- Published
- 2014
12. The effect of complementary and alternative medicines on CYP3A4-mediated metabolism of three different substrates: 7-benzyloxy-4-trifluoromethyl-coumarin, midazolam and docetaxel
- Author
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Mooiman, Kim D, Maas-Bakker, Roel F, Hendrikx, Jeroen J M A, Bank, Paul C D, Rosing, Hilde, Beijnen, Jos H, Schellens, Jan H M, Meijerman, Irma, Sub Clinical Pharmacology, Sub Drug delivery, Sub Immunopharmacology, and Pharmacoepidemiology and Clinical Pharmacology
- Subjects
Complementary Therapies ,Grape Seed Extract ,Tea ,Coumarins ,Midazolam ,Microsomes, Liver ,Cytochrome P-450 CYP3A ,Ginkgo biloba ,Humans ,Milk Thistle ,Taxoids - Abstract
OBJECTIVE: Concomitant use of complementary and alternative medicine (CAM) and anticancer drugs can affect the pharmacokinetics of anticancer drugs by inhibiting the metabolizing enzyme cytochrome P450 3A4 (CYP3A4) (EC 1.14.13.157). Several in vitro studies determined whether CAM can inhibit CYP3A4, but these studies revealed contradictory results. A plausible explanation for these conflicting results is the use only of a single model CYP3A4 substrate in each study. Therefore, the objective was to determine the potential of selected CAM (β-carotene, Echinacea, garlic, Ginkgo biloba, ginseng, grape seed extract, green tea extract, milk thistle, saw palmetto, valerian, vitamin B6, B12 and C) to inhibit CYP3A4-mediated metabolism of different substrates: 7-benzyloxy-4-trifluoromethyl-coumarin (BFC), midazolam and docetaxel. The effect of CAM on CYP3A4-mediated metabolism of an anticancer drug has never been determined before in vitro, which makes this study unique. The oncolytic CYP3A4 substrate docetaxel was used to establish the predictive value of the model substrates for pharmacokinetic interactions between CAM and anticancer drugs in vitro, and to more closely predict these interactions in vivo. METHODS: The inhibition of CYP3A4-mediated metabolism of 7-benzyloxy-4-trifluoromethyl-coumarin (BFC) by CAM was assessed in Supersomes, using the fluorometric CYP3A4 inhibition assay. In human liver microsomes (HLM) the inhibition of CYP3A4-mediated metabolism of midazolam and docetaxel was determined, using liquid-chromatography coupled to tandem mass spectrometry (LC-MS/MS). KEY FINDINGS: The results confirmed grape seed and green tea as potent inhibitors and milk thistle as moderate inhibitor of CYP3A4-mediated metabolism of BFC, midazolam and docetaxel. CONCLUSION: Clinical studies are required to determine the clinical relevance of the determined CYP3A4 inhibition by grape seed, green tea and milk thistle.
- Published
- 2014
13. Post-loading of proangiogenic growth factors in PLGA microspheres.
- Author
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Scheiner KC, Maas-Bakker RF, van Steenbergen MJ, Schwendeman SP, Hennink WE, and Kok RJ
- Subjects
- Angiogenesis Inducing Agents pharmacokinetics, Biocompatible Materials pharmacokinetics, Delayed-Action Preparations administration & dosage, Delayed-Action Preparations pharmacokinetics, Drug Compounding methods, Drug Liberation, Fibroblast Growth Factors administration & dosage, Fibroblast Growth Factors pharmacokinetics, Humans, Neovascularization, Physiologic drug effects, Recombinant Proteins administration & dosage, Recombinant Proteins pharmacokinetics, Somatomedins administration & dosage, Somatomedins pharmacokinetics, Vascular Endothelial Growth Factors administration & dosage, Vascular Endothelial Growth Factors pharmacokinetics, Angiogenesis Inducing Agents administration & dosage, Biocompatible Materials administration & dosage, Drug Carriers chemistry, Microspheres, Polylactic Acid-Polyglycolic Acid Copolymer chemistry
- Abstract
Active self-encapsulation (ASE) is a recently developed post-loading method based on absorption of (positively charged) proteins in microporous PLGA microspheres loaded with negatively charged polysaccharides (trapping agents). The aim of this study was to investigate ASE for simultaneous loading and controlled release of multiple growth factors. For this purpose, vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF) and insulin-like growth factor (IGF) were loaded in microspheres containing high molecular weight dextran sulfate (HDS) as trapping agent; loading was performed in a concentrated growth factor solution of low ionic strength and of pH 5 under conditions at which the proteins are positively charged. Subsequent pore closure was induced by incubation of the growth factor-loaded microspheres at 42.5 °C, i.e. above the T
g of (hydrated) PLGA (~30 °C). A 1:1:1 combination of VEGF, FGF and IGF was loaded with high loading (4.3%) and loading efficiency (91%). The in vitro release kinetics and bioactivity of loaded growth factors were studied for 4 weeks using ELISA and an endothelial cell proliferation assay, respectively. While IGF was released quickly, VEGF and FGF were continuously released for 4 weeks in their bioactive form, whereby a growth factor combination had a synergistic angiogenic effect. Therefore, ASE is a suitable method for co-loading growth factors which can provide sustained release profiles of bioactive growth factors, which is attractive for vascularization of biomaterial implants., (Copyright © 2020 The Authors. Published by Elsevier B.V. All rights reserved.)- Published
- 2021
- Full Text
- View/download PDF
14. Structure and Dynamics of Thermosensitive pDNA Polyplexes Studied by Time-Resolved Fluorescence Spectroscopy.
- Author
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Fliervoet LAL, Lisitsyna ES, Durandin NA, Kotsis I, Maas-Bakker RFM, Yliperttula M, Hennink WE, Vuorimaa-Laukkanen E, and Vermonden T
- Subjects
- Acrylic Resins chemistry, Carbocyanines chemistry, Fluorescence Resonance Energy Transfer, Magnetic Resonance Spectroscopy, Methacrylates chemistry, Nylons chemistry, Polyethylene Glycols chemistry, Polymerization, Polymers chemistry, Spectrometry, Fluorescence, Spectrophotometry, Ultraviolet, Temperature, DNA chemistry, Plasmids genetics, Polymers chemical synthesis
- Abstract
Combining multiple stimuli-responsive functionalities into the polymer design is an attractive approach to improve nucleic acid delivery. However, more in-depth fundamental understanding how the multiple functionalities in the polymer structures are influencing polyplex formation and stability is essential for the rational development of such delivery systems. Therefore, in this study the structure and dynamics of thermosensitive polyplexes were investigated by tracking the behavior of labeled plasmid DNA (pDNA) and polymer with time-resolved fluorescence spectroscopy using fluorescence resonance energy transfer (FRET). The successful synthesis of a heterofunctional poly(ethylene glycol) (PEG) macroinitiator containing both an atom transfer radical polymerization (ATRP) and reversible addition-fragmentation chain-transfer (RAFT) initiator is reported. The use of this novel PEG macroinitiator allows for the controlled polymerization of cationic and thermosensitive linear triblock copolymers and labeling of the chain-end with a fluorescent dye by maleimide-thiol chemistry. The polymers consisted of a thermosensitive poly( N -isopropylacrylamide) (PNIPAM, N), hydrophilic PEG (P), and cationic poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA, D) block, further referred to as NPD. Polymer block D chain-ends were labeled with Cy3, while pDNA was labeled with FITC. The thermosensitive NPD polymers were used to prepare pDNA polyplexes, and the effect of the N/P charge ratio, temperature, and composition of the triblock copolymer on the polyplex properties were investigated, taking nonthermosensitive PD polymers as the control. FRET was observed both at 4 and 37 °C, indicating that the introduction of the thermosensitive PNIPAM block did not compromise the polyplex structure even above the polymer's cloud point. Furthermore, FRET results showed that the NPD- and PD-based polyplexes have a less dense core compared to polyplexes based on cationic homopolymers (such as PEI) as reported before. The polyplexes showed to have a dynamic character meaning that the polymer chains can exchange between the polyplex core and shell. Mobility of the polymers allow their uniform redistribution within the polyplex and this feature has been reported to be favorable in the context of pDNA release and subsequent improved transfection efficiency, compared to nondynamic formulations.
- Published
- 2020
- Full Text
- View/download PDF
15. Influence of PEGylation of Vitamin-K-Loaded Mixed Micelles on the Uptake by and Transport through Caco-2 Cells.
- Author
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Sun F, Adrian M, Beztsinna N, van den Dikkenberg JB, Maas-Bakker RF, van Hasselt PM, van Steenbergen MJ, Su X, Kapitein LC, Hennink WE, and van Nostrum CF
- Subjects
- Biological Transport drug effects, Caco-2 Cells, Humans, Scavenger Receptors, Class B metabolism, Micelles, Phosphatidylethanolamines chemistry, Polyethylene Glycols chemistry, Vitamin K chemistry, Vitamin K pharmacology
- Abstract
The aim of the study is to investigate the uptake by and transport through Caco-2 cells of two mixed micelle formulations (based on egg phosphatidylcholine and glycocholic acid) of vitamin K, i.e., with and without DSPE-PEG2000. The uptake of vitamin K and fluorescently labeled mixed micelles with and without PEG coating showed similar kinetics and their uptake ratio remained constant over time. Together with the fact that an inhibitor of scavenger receptor B1 (BLT-1) decreased cellular uptake of vitamin K by ∼80% compared to the uptake in the absence of this inhibitor, we conclude that both types of micelles loaded with vitamin K can be taken up intactly by Caco-2 cells via this scavenger receptor. The amount of vitamin K in chylomicrons fraction from Caco-2 cell monolayers further indicates that mixed micelles (with or without PEGylation) are likely packed into chylomicrons after internalization by Caco-2 cells. Uptake of vitamin K from PEGylated mixed micelles increased four- to five-fold at simulated gastrointestinal conditions. In conclusion, PEGylated mixed micelles are stable upon exposure to simulated gastric conditions, and as a result, they do show overall a higher cellular uptake efficiency of vitamin K as compared to mixed micelles without PEG coating.
- Published
- 2018
- Full Text
- View/download PDF
16. Milk thistle's active components silybin and isosilybin: novel inhibitors of PXR-mediated CYP3A4 induction.
- Author
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Mooiman KD, Maas-Bakker RF, Moret EE, Beijnen JH, Schellens JH, and Meijerman I
- Subjects
- Binding, Competitive, Cell Line, Tumor, Complementary Therapies, Cytochrome P-450 CYP3A biosynthesis, Enzyme Induction, Humans, Silybum marianum chemistry, Molecular Docking Simulation, Pregnane X Receptor, Silybin, Silymarin pharmacology, Cytochrome P-450 CYP3A Inhibitors, Receptors, Steroid antagonists & inhibitors, Silymarin analogs & derivatives
- Abstract
Because cancer is often treated with combination therapy, unexpected pharmacological effects can occur because of drug-drug interactions. Several drugs are able to cause upregulation or downregulation of drug transporters or cytochrome P450 enzymes, particularly CYP3A4. Induction of CYP3A4 may result in decreased plasma levels and therapeutic efficacy of anticancer drugs. Since the pregnane X receptor (PXR) is one of the major transcriptional regulators of CYP3A4, PXR antagonists can possibly prevent CYP3A4 induction. Currently, a limited number of PXR antagonists are available. Some of these antagonists, such as sulphoraphane and coumestrol, belong to the so-called complementary and alternative medicines (CAM). Therefore, the aim was to determine the potential of selected CAM (β-carotene, Echinacea purpurea, garlic, Ginkgo biloba, ginseng, grape seed, green tea, milk thistle, saw palmetto, valerian, St. John's Wort, and vitamins B6, B12, and C) to inhibit PXR-mediated CYP3A4 induction at the transcriptional level, using a reporter gene assay and a real-time polymerase chain reaction assay in LS180 colon adenocarcinoma cells. Furthermore, computational molecular docking and a LanthaScreen time-resolved fluorescence resonance energy transfer (TR-FRET) PXR competitive binding assay were performed to explore whether the inhibiting CAM components interact with PXR. The results demonstrated that milk thistle is a strong inhibitor of PXR-mediated CYP3A4 induction. The components of milk thistle responsible for this effect were identified as silybin and isosilybin. Furthermore, computational molecular docking revealed a strong interaction between both silybin and isosilybin and PXR, which was confirmed in the TR-FRET PXR assay. In conclusion, silybin and isosilybin might be suitable candidates to design potent PXR antagonists to prevent drug-drug interactions via CYP3A4 in cancer patients.
- Published
- 2013
- Full Text
- View/download PDF
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