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Abdel Fattah AR, Ranga A. Nanoparticles as Versatile Tools for Mechanotransduction in Tissues and Organoids. Front Bioeng Biotechnol 2020; 8:240. [PMID: 32363177 PMCID: PMC7180186 DOI: 10.3389/fbioe.2020.00240] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 03/09/2020] [Indexed: 12/28/2022] Open
Abstract
Organoids are 3D multicellular constructs that rely on self-organized cell differentiation, patterning and morphogenesis to recapitulate key features of the form and function of tissues and organs of interest. Dynamic changes in these systems are orchestrated by biochemical and mechanical microenvironments, which can be engineered and manipulated to probe their role in developmental and disease mechanisms. In particular, the in vitro investigation of mechanical cues has been the focus of recent research, where mechanical manipulations imparting local as well as large-scale mechanical stresses aim to mimic in vivo tissue deformations which occur through proliferation, folding, invagination, and elongation. However, current in vitro approaches largely impose homogeneous mechanical changes via a host matrix and lack the required positional and directional specificity to mimic the diversity of in vivo scenarios. Thus, while organoids exhibit limited aspects of in vivo morphogenetic events, how local forces are coordinated to enable large-scale changes in tissue architecture remains a difficult question to address using current techniques. Nanoparticles, through their efficient internalization by cells and dispersion through extracellular matrices, have the ability to provide local or global, as well as passive or active modulation of mechanical stresses on organoids and tissues. In this review, we explore how nanoparticles can be used to manipulate matrix and tissue mechanics, and highlight their potential as tools for fate regulation through mechanotransduction in multicellular model systems.
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Affiliation(s)
- Abdel Rahman Abdel Fattah
- Laboratory of Bioengineering and Morphogenesis, Department of Mechanical Engineering, KU Leuven, Leuven, Belgium
| | - Adrian Ranga
- Laboratory of Bioengineering and Morphogenesis, Department of Mechanical Engineering, KU Leuven, Leuven, Belgium
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Sharma M, Sharma R. Implications of designing a bromelain loaded enteric nanoformulation on its stability and anti-inflammatory potential upon oral administration. RSC Adv 2018; 8:2541-2551. [PMID: 35541457 PMCID: PMC9077456 DOI: 10.1039/c7ra13555f] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Accepted: 01/03/2018] [Indexed: 12/31/2022] Open
Abstract
The objective of the present investigation was to develop an enteric nano-formulation of bromelain to improve its stability and anti-inflammatory potential. Bromelain loaded nanoparticles (Br-NPs) were developed using a Eudragit L 100 polymer by a double emulsion solvent evaporation method to obtain gastro-resistant properties. Br-NPs were characterized for particle size (248.89 ± 22.76 nm), zeta potential (-27.34 ± 2.17 mV), entrapment efficiency (85.42 ± 5.34%), surface morphology (spherical) and in vitro release profile. Infrared spectroscopy confirmed the entrapment of bromelain while thermal and pXRD analysis concomitantly corroborated the reduced crystallinity of bromelain in nanoparticles. Formulations showed gastro-resistant behavior at gastric pH and sustained bromelain release up to 10 h in phosphate buffer at pH 6.8 and followed Higuchi square root release kinetics. The optimized lyophilized formulation ensured 2 year shelf-life at room temperature. In vivo studies revealed significantly improved performance of entrapped bromelain in inhibiting carrageenan induced paw edema by mitigating leucocyte migration and release of nitric oxide, TNFα and IL-1β in paw compared to bromelain solution. In conclusion, enteric Br-NPs could be a viable drug delivery system for effective oral bromelain delivery in inflammatory conditions.
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Affiliation(s)
- Manu Sharma
- Department of Pharmacy, Banasthali Vidyapith Banasthali Rajasthan India-304022 +91-9694881221
| | - Rishu Sharma
- Department of Pharmacy, Banasthali Vidyapith Banasthali Rajasthan India-304022 +91-9694881221
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Bone Regeneration from PLGA Micro-Nanoparticles. BIOMED RESEARCH INTERNATIONAL 2015; 2015:415289. [PMID: 26509156 PMCID: PMC4609778 DOI: 10.1155/2015/415289] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Accepted: 06/04/2015] [Indexed: 12/19/2022]
Abstract
Poly-lactic-co-glycolic acid (PLGA) is one of the most widely used synthetic polymers for development of delivery systems for drugs and therapeutic biomolecules and as component of tissue engineering applications. Its properties and versatility allow it to be a reference polymer in manufacturing of nano- and microparticles to encapsulate and deliver a wide variety of hydrophobic and hydrophilic molecules. It additionally facilitates and extends its use to encapsulate biomolecules such as proteins or nucleic acids that can be released in a controlled way. This review focuses on the use of nano/microparticles of PLGA as a delivery system of one of the most commonly used growth factors in bone tissue engineering, the bone morphogenetic protein 2 (BMP2). Thus, all the needed requirements to reach a controlled delivery of BMP2 using PLGA particles as a main component have been examined. The problems and solutions for the adequate development of this system with a great potential in cell differentiation and proliferation processes under a bone regenerative point of view are discussed.
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Elsaid Ali AA, Taher M, Mohamed F. Microencapsulation of alpha-mangostin into PLGA microspheres and optimization using response surface methodology intended for pulmonary delivery. J Microencapsul 2013; 30:728-40. [PMID: 23631380 DOI: 10.3109/02652048.2013.788081] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Documented to exhibit cytotoxicity and poor oral bioavailability, alpha-mangostin was encapsulated into PLGA microspheres with optimization of formulation using response surface methodology. Mixed levels of four factors Face central composite design was employed to evaluate critical formulation variables. With 30 runs, optimized formula was 1% w/v polyvinyl alcohol, 1:10 ratio of oil to aqueous and sonicated at 2 and 5 min time for primary and secondary emulsion, respectively. Optimized responses for encapsulation efficiency, particle size and polydispersity index were found to be 39.12 ± 0.01%, 2.06 ± 0.017 µm and 0.95 ± 0.009, respectively, which matched values predicted by mathematical models. About 44.4% of the encapsulated alpha-mangostin was released over 4 weeks. Thermal analysis of the microspheres showed physical conversion of alpha-mangostin from crystallinity to amorphous with encapsulated one had lower in vitro cytotoxicity than free alpha-mangostin. Aerodynamic diameter (784.3 ± 7.5 nm) of this alpha-mangostin microsphere suggests suitability for peripheral pulmonary delivery.
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Affiliation(s)
- Aimen Abdo Elsaid Ali
- Department of Pharmaceutical Technology, Kulliyyah of Pharmacy, International Islamic University Malaysia , Kuantan, Pahang , Malaysia
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Li X, Guo Y, Zhang J, Zhang L. Preparation of polysulfone microspheres with a hollow core/porous shell structure and their application for oil spill cleanup. J Appl Polym Sci 2012. [DOI: 10.1002/app.38355] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Taha MA, Singh SR, Dennis VA. Biodegradable PLGA85/15 nanoparticles as a delivery vehicle for Chlamydia trachomatis recombinant MOMP-187 peptide. NANOTECHNOLOGY 2012; 23:325101. [PMID: 22824940 DOI: 10.1088/0957-4484/23/32/325101] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Development of a Chlamydia trachomatis vaccine has been a formidable task partly because of an ineffective delivery system. Our laboratory has generated a recombinant peptide of C. trachomatis major outer membrane protein (MOMP) (rMOMP-187) and demonstrated that it induced at 20 μg ml(-1) maximal interleukin (IL)-6 and IL-12p40 Th1 cytokines in mouse J774 macrophages. In a continuous pursuit of a C. trachomatis effective vaccine-delivery system, we encapsulated rMOMP-187 in poly(d,l-lactic-co-glycolic acid) (PLGA, 85:15 PLA/PGA ratio) to serve as a nanovaccine candidate. Physiochemical characterizations were assessed by Fourier transform-infrared spectroscopy, atomic force microscopy, Zetasizer, Zeta potential, transmission electron microcopy and differential scanning calorimetry. The encapsulated rMOMP-187 was small (∼200 nm) with an apparently smooth uniform oval structure, thermally stable (54 °C), negatively charged ( - 27.00 mV) and exhibited minimal toxicity at concentrations <250 μg ml (-1) to eukaryotic cells (>95% viable cells) over a 24-72 h period. We achieved a high encapsulation efficiency of rMOMP-187 (∼98%) in PLGA, a loading peptide capacity of 2.7% and a slow release of the encapsulated peptide. Stimulation of J774 macrophages with a concentration as low as 1 μg ml (-1) of encapsulated rMOMP-187 evoked high production levels of the Th1 cytokines IL-6 (874 pg ml(-1)) and IL-12p40 (674 pg ml(-1)) as well as nitric oxide (8 μM) at 24 h post-stimulation, and in a dose-response and time-kinetics manner. Our data indicate the successful encapsulation and characterization of rMOMP-187 in PLGA and, more importantly, that PLGA enhanced the capacity of the peptide to induce Th1 cytokines and NO in vitro. These findings make this nanovaccine an attractive candidate in pursuit of an efficacious vaccine against C. trachomatis.
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Affiliation(s)
- Murtada A Taha
- Center for NanoBiotechnology and Life Science Research (CNBR), Alabama State University, Montgomery, AL 36104, USA
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Yu Q, Tao Y, Huang Y, Lin Z, Zhuang Y, Ge L, Shen Y, Hong M, Xie A. Preparation of Porous Polysulfone Microspheres and Their Application in Removal of Oil from Water. Ind Eng Chem Res 2012. [DOI: 10.1021/ie203028h] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Qingbo Yu
- Department of Materials Science
and Engineering, Anhui University of Science and Technology, Huainan 232001, PR China
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Meng B, Li L, Hua S, Wang Q, Liu C, Xu X, Yin X. Effect of medium-chain triglycerides on the release behavior of Endostar® encapsulated PLGA microspheres. Int J Pharm 2010; 397:136-43. [DOI: 10.1016/j.ijpharm.2010.07.018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2010] [Revised: 07/07/2010] [Accepted: 07/14/2010] [Indexed: 11/17/2022]
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Chaisri W, Hennink WE, Ampasavate C, Okonogi S. Cephalexin microspheres for dairy mastitis: effect of preparation method and surfactant type on physicochemical properties of the microspheres. AAPS PharmSciTech 2010; 11:945-51. [PMID: 20509056 DOI: 10.1208/s12249-010-9453-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2010] [Accepted: 04/27/2010] [Indexed: 11/30/2022] Open
Abstract
The aim of this study was to evaluate the effects of preparation method and the type of surfactant on the properties of cephalexin (CPX) microspheres in order to obtain delivery systems suitable for the treatment of dairy mastitis. Microspheres were obtained using various preparation conditions and their physicochemical characteristics such as size, loading efficiency, morphology, and drug crystallinity were investigated. Antibacterial activity of microspheres from the optimum preparation condition was also studied. CPX microspheres were prepared by two different W/O/W emulsion solvent evaporation methods using PLGA as a matrix forming polymer. Several types of surfactants including nonionic, cationic, and anionic at different concentrations were used for preparation of the particles. The type and concentration of surfactant did neither affect the size nor morphology of the microspheres but showed a pronounced effect on the CPX encapsulation efficiency. It was found that Tween 80 showed the highest drug encapsulation efficiency (66.5%). Results from X-ray diffraction diffractograms and differential scanning calorimetry thermograms indicated that CPX entrapped in these microparticles was amorphous. Assessment of antibacterial activity showed that the obtained CPX microspheres exhibited good inhibition with minimum inhibitory concentration and minimum bactericidal concentration values of 128 microg/mL and 2,048 mg/mL against Staphylococcus aureus ATCC 25923, 512 microg/mL and 4,096 mg/mL against Escherichia coli ATCC 25922, respectively.
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Moore BD, Deere J, Edrada-Ebel R, Ingram A, van der Walle CF. Isolation of recombinant proteins from culture broth by co-precipitation with an amino acid carrier to form stable dry powders. Biotechnol Bioeng 2010; 106:764-73. [DOI: 10.1002/bit.22730] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Xu Q, Crossley A, Czernuszka J. Preparation and characterization of negatively charged poly(lactic-co-glycolic acid) microspheres. J Pharm Sci 2009; 98:2377-89. [DOI: 10.1002/jps.21612] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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van der Walle CF, Sharma G, Ravi Kumar MNV. Current approaches to stabilising and analysing proteins during microencapsulation in PLGA. Expert Opin Drug Deliv 2009; 6:177-86. [DOI: 10.1517/17425240802680169] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Puapermpoonsiri U, Spencer J, van der Walle CF. A freeze-dried formulation of bacteriophage encapsulated in biodegradable microspheres. Eur J Pharm Biopharm 2008; 72:26-33. [PMID: 19118627 DOI: 10.1016/j.ejpb.2008.12.001] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2008] [Revised: 11/24/2008] [Accepted: 12/02/2008] [Indexed: 11/24/2022]
Abstract
With the emergence of widespread antibiotic resistance, there has been renewed interest in the use of bacteriophages. While their potency, safety and specificity have underpinned their clinical potential, to date, little work has been focussed on their formulation with respect to controlled release and/or passive targeting. Here, we show that bacteriophages selective for Staphylococcus aureus or Pseudomonas aeruginosa can be encapsulated into biodegradable polyester microspheres via a modified w/o/w double emulsion-solvent extraction protocol with only a partial loss of lytic activity. Loss of lytic activity could be attributed to the exposure of the bacteriophages to the water-dichloromethane interface, with the lyophilization process itself having little effect. The microspheres were engineered to have an appropriate size and density to facilitate inhalation via a dry-powder inhaler and fluorescently labeled bacteriophages were distributed entirely within the internal porous matrix. The release profile showed a burst release phase (55-63% release within 30 min), followed by a sustained release till around 6h, as appropriate for pulmonary delivery. Despite the poor shelf-life of the formulation, the work is proof-of-concept for the formulation and controlled delivery of bacteriophages, as suitable for the treatment of bacterial lung infections.
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Affiliation(s)
- U Puapermpoonsiri
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, UK
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Mohamed F, van der Walle CF. Engineering biodegradable polyester particles with specific drug targeting and drug release properties. J Pharm Sci 2008; 97:71-87. [PMID: 17722085 DOI: 10.1002/jps.21082] [Citation(s) in RCA: 228] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Poly(lactic acid) (PLA) and poly(lactic-co-glycolic acid) (PLGA) microspheres and nanoparticles remain the focus of intensive research effort directed to the controlled release and in vivo localization of drugs. In recent years engineering approaches have been devised to create novel micro- and nano-particles which provide greater control over the drug release profile and present opportunities for drug targeting at the tissue and cellular levels. This has been possible with better understanding and manipulation of the fabrication and degradation processes, particularly emulsion-solvent extraction, and conjugation of polyesters with ligands or other polymers before or after particle formation. As a result, particle surface and internal porosity have been designed to meet criteria-facilitating passive targeting (e.g., for pulmonary delivery), modification of the drug release profile (e.g., attenuation of the burst release) and active targeting via ligand binding to specific cell receptors. It is now possible to envisage adventurous applications for polyester microparticles beyond their inherent role as biodegradable, controlled drug delivery vehicles. These may include drug delivery vehicles for the treatment of cerebral disease and tumor targeting, and co-delivery of drugs in a pulsatile and/or time-delayed fashion.
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Affiliation(s)
- Farahidah Mohamed
- Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, 27 Taylor Street, Glasgow, UK
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Liu F, Liu L, Li X, Zhang Q. Preparation of chitosan-hyaluronate double-walled microspheres by emulsification-coacervation method. JOURNAL OF MATERIALS SCIENCE. MATERIALS IN MEDICINE 2007; 18:2215-24. [PMID: 17701294 DOI: 10.1007/s10856-007-3228-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2006] [Accepted: 06/19/2007] [Indexed: 05/16/2023]
Abstract
Chitosan (CHS)-hyaluronate (HA) double-walled microspheres were prepared by emulsification-coacervation method. Tripolyphosphate (TPP) acted as ion crosslinker. The effects of oil/water volume ratio, surfactant, solution pH, TPP concentration, HA concentration, and emulsification time on microspheres fabrication and morphology were examined by Zeta (zeta) potential, Scanning electron microscopy (SEM) and Fourier-transform infrared spectrometry (FT-IR). It was found that TPP concentration, solution pH, surfactant and emulsification time were crucial factors for microspheres fabrication. Spherical microspheres with smooth surface were formed when TPP concentration was 8% or higher. The optimal pH for microspheres formation ranged from 6.0 to 7.0. As for surfactant, the microspheres obtained when span80 was applied alone were shapelier compared with those obtained when both span80 and tween80 were applied. With insufficient emulsification time, vacuous microcapsules, but not compact microspheres were formed. In addition, oil/water volume ratio and HA concentration also affected the microspheres morphology, but less importantly.
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Affiliation(s)
- Fengxia Liu
- Institute of Biomedical Engineering, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin 300192, PR China
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Rouse JJ, Mohamed F, van der Walle CF. Physical ageing and thermal analysis of PLGA microspheres encapsulating protein or DNA. Int J Pharm 2007; 339:112-20. [PMID: 17395410 DOI: 10.1016/j.ijpharm.2007.02.026] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2006] [Revised: 02/19/2007] [Accepted: 02/23/2007] [Indexed: 11/21/2022]
Abstract
PLGA microspheres undergo physical ageing but their ageing kinetics have not been reported, nor the effect of encapsulated protein or plasmid DNA on any associated changes to the glass transition. Differential scanning calorimetry (DSC) was used to measure the rate of ageing of various PLGA microsphere formulations, with temperature-modulated DSC used to accurately measure the associated glass transition. The Cowie-Ferguson model was applied to determine the parameters describing the enthalpy relaxation kinetics. We show that encapsulated proteins had no significant effect on the glass transition of the microspheres, whereas DNA and PVA were mild antiplasticising agents, particularly with high Mw PLGA. Physical ageing occurred through a range of enthalpy relaxation times (or modes) and was independent of both encapsulated protein and surfactant used during microsphere preparation. Analysis of accelerated ageing at 35 degrees C gave calculated enthalpy relaxation times to thermal equilibrium of 280-400 h. No ageing was observed < or = 10 degrees C and at 25 degrees C estimated relaxation times were at least one order of magnitude greater than at 35 degrees C. Ageing of PLGA microspheres therefore occurs at temperatures >10 degrees C, but relaxation will be far from equilibrium unless storage times and/or temperatures are prolonged or nearing the glass transition, respectively.
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Affiliation(s)
- J J Rouse
- Strathclyde Institute of Pharmacy & Biomedical Sciences, University of Strathclyde, 27 Taylor Street, Glasgow, UK
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Yoshida M, Babensee JE. Differential effects of agarose and poly(lactic-co-glycolic acid) on dendritic cell maturation. J Biomed Mater Res A 2006; 79:393-408. [PMID: 16886225 DOI: 10.1002/jbm.a.30798] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Application of biomaterials in combination products in which the biomaterial is presented to the host with a biological component prompts the need for understanding the biomaterial-associated adjuvant effect in the immune response against antigens associated with such a product. We have previously demonstrated that a polymer commonly used in tissue engineering and vaccine delivery, poly(lactic-co-glycolic acid) (PLGA), exerts an adjuvant effect in vivo, which was supported by PLGA-induced dendritic cell (DC) maturation in vitro. In this study, the effects of agarose and PLGA on DC maturation were compared in vitro to establish differential biomaterial effects. Human monocyte-derived DCs were treated with agarose or PLGA microparticles or films, and their maturation effect was measured as expression of costimulatory and MHC class II molecules, allostimulatory capacity, and proinflammatory cytokine secretion. Direct comparison of DC maturation phenotype indicated that PLGA was a stronger stimulus of DC maturation than agarose, and this maturation was not affected by microparticle phagocytosis. However, agarose-treated DCs showed higher activation of nuclear factor kappaB (NFkappaB) 24 h after the initial stimulation of DCs. Taken together, these results demonstrate differential biomaterial effects on DC maturation, substantiating the maturation effect of PLGA, and provide screening methods for biomaterial adjuvant effect for applications in combination products.
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Affiliation(s)
- Mutsumi Yoshida
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technologyand Emory University, 313 Ferst Drive Atlanta, 30332, USA
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Bouissou C, Rouse JJ, Price R, van der Walle CF. The Influence of Surfactant on PLGA Microsphere Glass Transition and Water Sorption: Remodeling the Surface Morphology to Attenuate the Burst Release. Pharm Res 2006; 23:1295-305. [PMID: 16715359 DOI: 10.1007/s11095-006-0180-2] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2005] [Accepted: 02/06/2006] [Indexed: 10/24/2022]
Abstract
PURPOSE The stability of protein unloaded and loaded poly(lactic-co-glycolic acid) (PLGA) microspheres fabricated with surfactant was challenged through exposure to environmental conditions of different relative humidity. METHODS Polyvinyl alcohol (PVA) or Triton X-100 was added to the primary emulsion of the double-emulsion solvent evaporation technique. After storage at ambient humidity and 75% relative humidity, the mechanical stability of the polymer was tested to reveal PLGA chain mobility using differential scanning calorimetry. Subsequent surface modifications were examined by atomic force microscopy (AFM), and protein release profiles were collected. RESULTS Residual amounts of PVA and particularly Triton X-100 raised the hydrophilicity of the microspheres. When exposed to ambient humidity or 75% relative humidity, PVA and Triton X-100 had, respectively, an antiplasticizing and a plasticizing effect upon PLGA, and both led to physical aging. The high-resolution AFM imaging of microspheres containing model protein and Triton X-100 showed that the depth of the surface pores was reduced when exposed to 75% relative humidity, and the initial burst release subsequently decreased. CONCLUSION These studies suggested that the mechanical stability of PLGA was influenced by the addition of surfactants, which, depending on the formulation, led to surface pore remodeling under high humidity, reducing the initial burst release while maintaining the spherical integrity of the microsphere.
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Affiliation(s)
- C Bouissou
- Department of Pharmacy, University of Bath, Bath, BA2 7AY, UK
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Mohamed F, van der Walle CF. PLGA microcapsules with novel dimpled surfaces for pulmonary delivery of DNA. Int J Pharm 2006; 311:97-107. [PMID: 16414217 DOI: 10.1016/j.ijpharm.2005.12.016] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2005] [Revised: 11/28/2005] [Accepted: 12/11/2005] [Indexed: 11/15/2022]
Abstract
We describe the fabrication of DNA-loaded poly(lactic-co-glycolic acid) (PLGA) microcapsules with novel surface morphologies that will be of use in pulmonary delivery. Our approach was to examine surface morphology and DNA encapsulation efficiency as a function of primary emulsion stability; using two surfactant series based on hydrophile-lipophile balance and hydrophobe molecular weight. Hydrophilic non-ionic surfactants yielded the most stable water-in-dichloromethane emulsions (HLB values >8). These surfactants normally favor convex (o/w) interfacial curvatures and therefore this atypical behavior suggested a relatively high surfactant solvation in the dichloromethane 'oil' phase. This was consistent with the large fall in the glass transition temperature for microspheres prepared with Tween 20, which therefore efficiently penetrated the PLGA matrix and acted as a plasiticizer. Blends of Pluronic triblock copolymers performed poorly as water-in-dichloromethane emulsifiers, and were therefore used to generate hollow microspheres ('microcapsules') with low densities (0.24 g/cm(3)). Although the Pluronic-stabilized emulsions resulted in lower DNA loading (15-28%), microspheres (approximately 8 microm) with novel dimpled surfaces were fabricated. The depth and definition of the dimples was greatest for triblock copolymers with high MW hydrophobe blocks. By cascade impaction, the geometric mean weight diameter of the microcapsules was 3.43 microm, suggesting that they will be of interest as biodegradable pulmonary delivery vehicles.
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Affiliation(s)
- Farahidah Mohamed
- Pharmaceutical Sciences, University of Strathclyde, 27 Taylor St., Glasgow, UK
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Messaritaki A, Black SJ, van der Walle CF, Rigby SP. NMR and confocal microscopy studies of the mechanisms of burst drug release from PLGA microspheres. J Control Release 2005; 108:271-81. [PMID: 16169112 DOI: 10.1016/j.jconrel.2005.08.010] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2005] [Revised: 08/15/2005] [Accepted: 08/16/2005] [Indexed: 11/25/2022]
Abstract
Pulsed-field gradient (PFG) NMR and confocal microscopy techniques have been used to study the structural evolution and drug release profile of poly(d,l-lactide-co-glycolide) (PLGA) microspheres over time during immersion in an aqueous phase. Variation of the drying process used in the synthesis of the PLGA microspheres has been found to significantly influence the degree of permeability of the spheres to water. PFG NMR has been used to study the change in the cavity sizes within the pore structure of the microspheres over time following initial immersion. In these studies, the temperature of the secondary emulsion, used in the sphere synthesis, has been found to significantly change the temporal evolution of the pore structure. Confocal microscopy studies of the release of a model drug from within the microspheres suggest that the rate-limiting step in drug release is the swelling rate of the polymer matrix, and that the mechanism may be a percolation process. These studies also showed that the local rate of drug release is heterogeneously distributed across a microsphere, and thus, strictly, cannot be modelled as purely a simple diffusive release process from a sphere.
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Affiliation(s)
- Antigoni Messaritaki
- Department of Chemical Engineering, University of Bath, Claverton Down, Bath BA2 7AY, United Kingdom
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Duncan G, Jess TJ, Mohamed F, Price NC, Kelly SM, van der Walle CF. The influence of protein solubilisation, conformation and size on the burst release from poly(lactide-co-glycolide) microspheres. J Control Release 2005; 110:34-48. [PMID: 16225952 DOI: 10.1016/j.jconrel.2005.09.007] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2005] [Revised: 09/08/2005] [Accepted: 09/15/2005] [Indexed: 10/25/2022]
Abstract
Encapsulation of proteins in poly(lactide-co-glycolide) microspheres via emulsion is known to cause insoluble protein aggregates. Following protein emulsification and encapsulation in PLGA microspheres, we used circular dichroism to show that the recoverable soluble protein fraction also suffers subtle conformational changes. For a panel of proteins selected on the basis of molecular size and structural class, conformational stability measured by chemical denaturation was not indicative of stability during emulsion-encapsulation. Partial loss of structure was observed for alpha-helical proteins released from freeze-dried microspheres in aqueous buffer, with dramatic loss of structure for a beta-sandwich protein. The addition of sucrose (a lyoprotectant) did not prevent the loss of protein conformation upon encapsulation. Therefore, the conformational changes seen for the released soluble protein fraction originates during emulsification rather than microsphere freeze-drying. Analysis of the burst release for all proteins in buffer containing denaturant or surfactant showed that the degree of protein solubilisation was the dominant factor in determining the initial rate and extent of release. Our data for protein release into increasing concentrations of denaturing buffer suggest that the emulsion-denatured protein fraction remains insoluble; this fraction may represent the protein loss encountered upon comparison of protein encapsulated versus protein released.
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Affiliation(s)
- Gayle Duncan
- University of Strathclyde, Pharmaceutical Sciences, Glasgow, Scotland
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Literature alerts. J Microencapsul 2005; 21:687-94. [PMID: 15762324 DOI: 10.1080/02652040412331343791] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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