Evaluation of asymmetric poly(vinyl alcohol) membranes for use in artificial islets

Center for Biomedical Engineering, College of Medicine, National Taiwan University, Taipei, Taiwan, R.O.C.
Biomaterials (Impact Factor: 8.56). 12/1996; 17(22):2139-2145. DOI: 10.1016/0142-9612(96)00043-9
Source: PubMed


Islets of Langerhans surrounded by a semipermeable membrane to prevent the host immunosystem is a potential way to treat type I diabetes mellitus. In this study, a series of poly (vinyl alcohol) membranes were formed by adding polyethylene glycols to create pores in the skin layer. The permeability study showed the skin layer structure had an influence on the diffusion of low molecular weight glucose, vitamin B12 and insulin. The mass transfer coefficient was improved from 1.04 × 10−4 to 2.16 × 10−4cm/ sec for glucose, from 2.84 × 10−5 to 8.36 × 10−5 cm/sec for vitamin B12 and from 1.45 × 10−6 to 4.15 × 10−6 cm/sec for insulin, whereas the passage of immunoglobulin G was completely prevented, indicating that these membranes could be effective in protecting islets from immunorejection. Thus such a membrane is an alternative potential material for artificial islets. In addition, we examined the insulin secretory response of islets separated by a poly(vinyl alcohol) membrane. We found that the insulinsecretion rate is relatively rapid compared to the permeation rate of insulin; thus, the process of the artificial islets is insulin-diffusion-controlled.

    • "The use of synthetic membranes is therefore restricted to cases where the cells are encapsulated after membrane formation (Youngsukkasem et al. 2012). Synthetic membranes can also be constructed into larger devices, with a planar or cylindrical arrangement (Young et al. 1996; Cheryan and Mehaia 1983). In this approach, a large amount of cells is enveloped in large flat-sheet, hollow-fiber, or encased membranes. "
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    ABSTRACT: This paper reviews the latest developments in microbial products by encapsulated microorganisms in a liquid core surrounded by natural or synthetic membranes. Cells can be encapsulated in one or several steps using liquid droplet formation, pregel dissolving, coacervation, and interfacial polymerization. The use of encapsulated yeast and bacteria for fermentative production of ethanol, lactic acid, biogas, L-phenylacetylcarbinol, 1,3-propanediol, and riboflavin has been investigated. Encapsulated cells have furthermore been used for the biocatalytic conversion of chemicals. Fermentation, using encapsulated cells, offers various advantages compared to traditional cultivations, e.g., higher cell density, faster fermentation, improved tolerance of the cells to toxic media and high temperatures, and selective exclusion of toxic hydrophobic substances. However, mass transfer through the capsule membrane as well as the robustness of the capsules still challenge the utilization of encapsulated cells. The history and the current state of applying microbial encapsulation for production processes, along with the benefits and drawbacks concerning productivity and general physiology of the encapsulated cells, are discussed.
    No preview · Article · Oct 2012 · Applied Microbiology and Biotechnology
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    • "Poly(vinyl alcohol) (PVA) has been developed for vari- 41 ous biomedical applications such as artificial pancreas [8], 42 hemodialysis [9] and implantable medical materials [10] "
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    ABSTRACT: The purpose of this study was to evaluate the behaviors of rat tooth germ (TG) cells cultured on poly(vinyl alcohol) (PVA). It was found that TG cells suspended and aggregated to form three-dimensional spheroids on PVA. Compared with traditional monolayered cells on tissue culture polystyrene, TG cell spheroids on PVA obviously increased the alkaline phosphatase activity, the degree of mineralization, and upregulated both osteopontin and dentin matrix protein 1 genes, regardless of the seeding density. Surprisingly, PVA appears to activate the alkaline phosphatase activity and mineralization effects on TG cell spheroids in the absence of a differentiation medium. Furthermore, the present study indicates that integrins may play an important role in the mineralization on TG cell spheroids by adding Arg-Gly-Asp (RGD) peptides. Therefore, the information presented here should help to clarify the role of PVA in the regulation of the mineralization, differentiation and integrin-mediation of TG cells.
    Preview · Article · May 2009 · Acta biomaterialia
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    • "Transplantation of the cells encapsulated in polymer vehicles with semi-permeable membranes is an attractive method for in vivo delivery of proteins without the need for immunosuppressant drugs [1]. A number of polymer vehicles with various configurations have been reported [2] [3] [4] [5], and of these, spherical-and fiber-shaped vehicles were the most frequently investigated. The fibershaped vehicles have an important advantage over spherical-shaped vehicles in that they are easily removed from patients when either adverse effects are observed or after the cessation of function [4]. "
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