Islet Encapsulation: Strategies to Enhance Islet Cell Functions

Beck, Jonathan; Angus, Ryan; Madsen, Ben; Britt, David W.; Vernon, Brent L.; Nguyen, Kytai T.

doi:10.1089/ten.2006.0183

Cited by 164 publications

(74 citation statements)

References 112 publications

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“…A particular class of yield stress materials is the physical gel. Due to their large water content, the physical gels are compatible with biological tissues which makes them excellent candidates for various biomedical applications: targeted drug delivery 1,2 , contact lenses, noninvasive intervertebral disc repair 3 and tissue engineering 4 .…”

Section: Introductionmentioning

confidence: 99%

A microscopic Gibbs field model for the macroscopic yielding behaviour of a viscoplastic fluid

2015

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We present a Gibbs random field model for the microscopic interactions in a viscoplastic fluid. The model has only two parameters which are sufficient to describe the internal energy of the material in the absence of external stress and a third parameter for a constant externally applied stress. The energy function is derived from the Gibbs potential in terms of the external stress and internal energy. The resulting Gibbs distribution, over a configuration space of microscopic interactions, can mimic experimentally observed macroscopic behavioural phenomena that depend on the externally applied stress. A simulation algorithm that can be used to approximate samples from the Gibbs distribution is given and it is used to gain several insights about the model. Corresponding to weak interactions between the microscopic solid units, our model reveals a smooth solid-fluid transition which is fully reversible upon increasing/decreasing external stresses. If the interaction between neighbouring microscopic constituents exceeds a critical threshold the solid-fluid transition becomes abrupt and a hysteresis of the deformation states is observed even at the asymptotic limit of steady forcing. Quite remarkably, in spite of the limited number of parameters involved, the predictions of our model are in a good qualitative agreement with macro rheological experimental results on the solid-fluid transition in various yield stress materials subjected to an external stress.

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Section: Introductionmentioning

confidence: 99%

A microscopic Gibbs field model for the macroscopic yielding behaviour of a viscoplastic fluid

2015

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“…Moreover, in certain encapsulation systems, the gel material provides an additional barrier that affects the diffusion of important factors (e.g., oxygen, glucose, insulin) into and out of the aggregate (Hulst et al 1989;Lovett et al 2009;Li et al 1996;Khattak et al 2007;Beck et al 2007). More recently, microfabrication techniques have been applied to develop a number of systems that could be used to create cell aggregates in a more controlled and efficient manner, via passive (e.g., cell sedimentation) and/or active (e.g., vacuum, surface functionalization, dielectrophoretic forces) means (Karp et al 2007;Moeller et al 2008;Fukuda et al 2006;Mendelsohn et al 2010;Albrecht et al 2006;Ferrell et al 2010;Bernard et al 2012).…”

Section: Introductionmentioning

confidence: 99%

Micro/nanoscale technologies for the development of hormone-expressing islet-like cell clusters

Gallego‐Perez

Higuita‐Castro

Reen

et al. 2012

Biomed Microdevices

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Insulin-expressing islet-like cell clusters derived from precursor cells have significant potential in the treatment of type-I diabetes. Given that cluster size and uniformity are known to influence islet cell behavior, the ability to effectively control these parameters could find applications in the development of anti-diabetic therapies. In this work, we combined micro and nanofabrication techniques to build a biodegradable platform capable of supporting the formation of islet-like structures from pancreatic precursors. Soft lithography and electrospinning were used to create arrays of microwells (150-500 μm diameter) structurally interfaced with a porous sheet of micro/nanoscale polyblend fibers (~0.5-10 μm in cross-sectional size), upon which human pancreatic ductal epithelial cells anchored and assembled into insulin-expressing 3D clusters. The microwells effectively regulated the spatial distribution of the cells on the platform, as well as cluster size, shape and homogeneity. Average cluster cross-sectional area (~14000-17500 μm(2)) varied in proportion to the microwell dimensions, and mean circularity values remained above 0.7 for all microwell sizes. In comparison, clustering on control surfaces (fibers without microwells or tissue culture plastic) resulted in irregularly shaped/sized cell aggregates. Immunoreactivity for insulin, C-peptide and glucagon was detected on both the platform and control surfaces; however, intracellular levels of C-peptide/cell were ~60 % higher on the platform.

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“…One advantage of macrocapsules is that they can be implanted and removed with minimal risk. On the other hand, their major drawback is the limited oxygen diffusion and nutrient transport, which tends to result in impaired viability, dysfunction, or even central necrosis in islets (Beck et al, 2007;Weir, 2013). Current research on macroencapsulation systems focuses largely on the development of techniques and configurations, which can promote neovascularization and provide sufficient oxygen and nutrition for islet cells (Grundfest-Broniatowski et al, 2009;Dufrane et al, 2010;Barkai et al, 2013;Vér-iter et al, 2014;Scharp and Marchetti, 2014).…”

Section: Macrocapsulesmentioning

confidence: 99%

“…A number of considerations favor microcapsules over macrocapsules ( Table 2). The spherical geometry and low volume of microcapsules offer better oxygen and nutrient transport due to a higher surface area-to-volume ratio (van Schilfgaarde and de Vos, 1999;Beck et al, 2007). Furthermore, microcapsules require less complex or expensive manufacturing procedures, and can be simply injected without major surgery (Scharp and Marchetti, 2014).…”

Section: Microcapsulesmentioning

confidence: 99%

Treatment of diabetes with encapsulated pig islets: an update on current developments

Zhu

Liu

et al. 2015

J. Zhejiang Univ. Sci. B

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Abstract:The potential use of allogeneic islet transplantation in curing type 1 diabetes mellitus has been adequately demonstrated, but its large-scale application is limited by the short supply of donor islets and the need for sustained and heavy immunosuppressive therapy. Encapsulation of pig islets was therefore suggested with a view to providing a possible alternative source of islet grafts and avoiding chronic immunosuppression and associated adverse or toxic effects. Nevertheless, several vital elements should be taken into account before this therapy becomes a clinical reality, including cell sources, encapsulation approaches, and implantation sites. This paper provides a comprehensive review of xenotransplantation of encapsulated pig islets for the treatment of type 1 diabetes mellitus, including current research findings and suggestions for future studies.

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Islet Encapsulation: Strategies to Enhance Islet Cell Functions

Cited by 164 publications

References 112 publications

A microscopic Gibbs field model for the macroscopic yielding behaviour of a viscoplastic fluid

A microscopic Gibbs field model for the macroscopic yielding behaviour of a viscoplastic fluid

Micro/nanoscale technologies for the development of hormone-expressing islet-like cell clusters

Treatment of diabetes with encapsulated pig islets: an update on current developments

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