Pancreatic cell immobilization in alginate beads produced by emulsion and internal gelation
ABSTRACT Alginate has been used to protect transplanted pancreatic islets from immune rejection and as a matrix to increase the insulin content of islet progenitor cells. The throughput of alginate bead generation by the standard extrusion and external gelation method is limited by the rate of droplet formation from nozzles. Alginate bead generation by emulsion and internal gelation is a scaleable alternative that has been used with biological molecules and microbial cells, but not mammalian cells. We describe the novel adaptation of this process to mammalian cell immobilization. After optimization, the emulsion process yielded 90 ± 2% mouse insulinoma 6 (MIN6) cell survival, similar to the extrusion process. The MIN6 cells expanded at the same rate in both bead types to form pseudo-islets with increased glucose stimulation index compared to cells in suspension. The emulsion process was suitable for primary pancreatic exocrine cell immobilization, leading to 67 ± 32 fold increased insulin expression after 10 days of immobilized culture. Due to the scaleability and broad availability of stirred mixers, the emulsion process represents an attractive option for laboratories that are not equipped with extrusion-based cell encapsulators, as well as for the production of immobilized or encapsulated cellular therapeutics on a clinical scale.
SourceAvailable from: Tohid Pirbodaghi[Show abstract] [Hide abstract]
ABSTRACT: An improved internal gelation approach is developed to encapsulate single mammalian cells in monodisperse alginate microbeads as small as 26 μm in diameter and at rates of up to 1 kHz with high cell viability. The cell damage resulting from contact with calcium carbonate nanoparticles as gelation reagents is eliminated by employing a co-flow microfluidic device, and the cell exposure to low pH is minimized by a chemically balanced off-chip gelation step. These modifications significantly improve the viability of cells encapsulated in gelled alginate particles. Two different mammalian cell types are encapsulated with viability of over 84 %. The cells are functional and continue to grow inside the microparticles.Microfluidics and Nanofluidics 04/2014; 16(4). DOI:10.1007/s10404-013-1264-z · 2.67 Impact Factor
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ABSTRACT: The adjustable microfluidic droplet generator (ADG) described herein successfully uses a micro-mixer and a flow-focusing device to produce water droplets with eleven different trypan blue concentrations under various flow rate ratios of the trypan blue solution (sample phase 1, w1) and D.I. water (sample phase 2, w2) and uses these chitosan microparticles to encapsulate the magnetic nanoparticles. These eleven trypan blue/water droplet variations are uniform in size, with a coefficient of variation less than 10%, and can be precisely controlled by adjusting the sum of the sample phase flow rates (w1+w2) and the oil phase flow rate. Chitosan emulsions with eleven different Fe3O4 nanoparticle concentrations are used for magnetic targets, with the chitosan microparticles ranging from 44 to 83 µm in diameter. The ADG has the advantages of active droplet diameter control, the generation of droplets of uniform and specific size with different concentrations and the simplicity of the process. This preparation approach for chitosan microparticles with eleven different concentrations has many potential applications in drug delivery and pharmaceuticals.Journal of Micromechanics and Microengineering 12/2013; 23(12):5025-. DOI:10.1088/0960-1317/23/12/125025 · 1.73 Impact Factor
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ABSTRACT: In this study, we present an ionotropic gelation route for obtaining porous alumina/silica microbeads (MBs) with tailorable morphology, specific surface area (S BET), and pore size, which can directly be sintered into porous, monolithic adsorbents (MAds). After sintering, S BETs from 20 m2/g up to 70 m2/g with open porosities up to 90% could be achieved depending on the silica nanoparticle addition. Due to the significantly increased S BET, a more than 100‐fold faster uptake of model dye molecules was obtained. Pore sizes ranged between 13 and 184 nm with adjustable mono‐ and bimodal size distributions. Depending on silica content and sintering temperature, the MBs were also found to be chemically stable in technologically relevant solvents such as water, acetone, acetonitrile, hydrochloric acid, and methanol for at least 1 week except for sodium hydroxide. By adjusting the processing parameters, spherical, fibrous or irregular microbead morphologies could be obtained. The same route was also successfully applied for obtaining calcium phosphate, titania, and zirconia microbeads. The presented straight‐forward ionotropic gelation route is basically applicable to any other ceramic material and therefore extremely versatile. The obtained MBs and MAds can be further adapted to any type of environmental or biotechnological purification process by additional functionalization steps.Journal of the American Ceramic Society 03/2012; 95(3). DOI:10.1111/j.1551-2916.2011.04982.x · 2.43 Impact Factor