Principles of Bioreactor Design for Encapsulated Cells

Bugarski, Branko; Goosen, Mattheus F. A.; Vunjak‐Novakovic, Gordana

doi:10.1007/978-1-4612-1586-8_30

Cited by 7 publications

(5 citation statements)

References 34 publications

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“…Success of these applications depends on achieving the suitable microenvironmental conditions for cell growth inside the microbead (Bugarski et al 1999;Nedovic et al 2001;Nedovic and Willaert 2005;Pajic-Lijakovic et al 2007a, 2007b. Significant attempts have been made to examine the rheological response of hydrogel matrix to stresses generated by compression, shear and tension (Lee et al 2000;Stokke et al 2000;Drury et al 2004).…”

Section: Introductionmentioning

confidence: 99%

Investigation of Ca-alginate hydrogel rheological behaviour in conjunction with immobilized yeast cell growth dynamics

Pajić‐Lijaković

Plavšić

Nedović³

et al. 2007

Journal of Microencapsulation

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The rheological model is developed to elucidate the mechanism of Ca-alginate microbead deformation in the course of cell growth within. It is a complex process influenced by relaxation of the expanded polymer network inside a bead, and forces generated by cell growth inside the bead and interactions between solvent, network parts and cells as well. The resulting effects are measured experimentally by estimating isotropic volumetric deformations of beads with yeast cells as function of time and cell concentration per bead. The mathematical model of the process is developed based on a modified general Zener model with fractional derivatives. It is particularly suitable for incorporating effects of different nature also during different stages of such complex process development. The results of theoretical analyses using the model developed and comparison with experimental values obtained, indicate a high impact of partial decomposition, i.e. plastic response of polymer network inside a bead due to cell growth, on bead deformation. For comparison, corresponding deformation measurements and modelling were performed on the same network system exposed to swelling in the solvent, but without the cells. In this case elastic forces are dominant, indicating different mechanism of relaxation without the influence of cells, in agreement with previous conclusions.

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Section: Introductionmentioning

confidence: 99%

Investigation of Ca-alginate hydrogel rheological behaviour in conjunction with immobilized yeast cell growth dynamics

Pajić‐Lijaković

Plavšić

Nedović³

et al. 2007

Journal of Microencapsulation

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“…Different techniques for immunoisolation and immobilization of viable cells within microcapsules have been developed. Here we used a sophisticated droplet generator system based on the use of electrostatic field, which has proven to be applicable for the immobilization of higher-organism cells, such as hybridomas (Goosen et al 1997; Bugarski et al 1999), islets of Langerhans (Bugarski et al 1994, 1997), and parathyroid cells (Rosinski et al 2002). Besides the geometry of a designed electric field, rheological behavior (behavior of cells and polymer in an extrusion process) should be well understood, since it influences the formation of uniform capsules.…”

Section: Introductionmentioning

confidence: 99%

Immobilization of cells by electrostatic droplet generation: a model system for potential application in medicine

Manojlović¹,

Djonlagić²,

Obradović³

et al. 2006

International Journal of Nanomedicine

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Abstract:The process of electrostatic extrusion as a method for cell immobilization was investigated that could be used for potential applications in medicine. An attempt was made to assess the effects of cell addition and polymer concentration on the overall entrapment procedure, ie, on each stage of immobilization: polymer-cell suspension rheological characteristics, electrostatic extrusion process, and the process of gelation. The findings should contribute to a better understanding of polymer-cell interactions, which could be crucial in possible medical treatments. Alginate-yeast was used as a model system for carrier-cells. The electrostatic extrusion was considered as a complex two-phase flow system and the effects of cell and alginate concentrations on the resulting microbead size and uniformity were assessed. Under investigated conditions, microbeads 50-600 µm in diameter were produced and the increase in both alginate and cell concentrations resulted in larger microbeads with higher standard deviations in size. We attempted to rationalize the findings by rheological characterization of the cell-alginate suspensions. Rheological characterization revealed non-Newtonian, pseudoplastic behavior of cell-alginate suspensions with higher viscosities at higher alginate concentrations. However, the presence of cells even at high concentrations (5x10 8 and 1x10 9 cells/mL) did not significantly affect the rheological properties of Na-alginate solution. Lastly, we investigated the kinetics of alginate gelation with respect to the quantity of Ca 2+ ions and cell presence. The gelation kinetics were examined under conditions of limited supply with Ca 2+ ions, which can be essential for immobilization of highly sensitive mammalian cells that require minimal exposure to CaCl 2 solution. The molar ratio of G units to Ca 2+ ions of 3.8:1 provided complete crosslinking, while the increase in alginate concentration resulted in prolonged gelation times but higher strength of the resulting gel. The cell presence decreased the rate of network formation as well as the strength of the obtained Ca-alginate hydrogel.

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“…High-density cell cultures are often limited by inadequate supply of nutrients [1]. More specifically, the supply of oxygen already becomes limiting for the culture of tissues thicker than 100-200 mm [2,3].…”

Section: Introductionmentioning

confidence: 99%

The effect of PEGT/PBT scaffold architecture on oxygen gradients in tissue engineered cartilaginous constructs

et al. 2004

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Principles of Bioreactor Design for Encapsulated Cells

Cited by 7 publications

References 34 publications

Investigation of Ca-alginate hydrogel rheological behaviour in conjunction with immobilized yeast cell growth dynamics

Investigation of Ca-alginate hydrogel rheological behaviour in conjunction with immobilized yeast cell growth dynamics

Immobilization of cells by electrostatic droplet generation: a model system for potential application in medicine

The effect of PEGT/PBT scaffold architecture on oxygen gradients in tissue engineered cartilaginous constructs

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