The demands placed on a material to be used for microencapsulation are stringent. The material should (1) be stable in the physiological environment over several years, (2) not engender any cytotoxicity, (3) be permselective so as to be immunoprotective and yet allow nutrient and metabolite access, and (4) be biocompatible so as not to elicit an inflammatory or fibrotic response from the host. Of the wide range of materials used, ionically coacervated microcapsules of alginate and poly(1-lysine) (PLL) have shown promise. O’Shea and Sun (1986) demonstrated rat islet survival times of 2 to 3 months, and occasionally of 1 year, in mice, using alginate/PLL/alginate trilayered microcapsules. The xenografts apparently failed as a result of over-growth with fibroblast-like and macrophage-like cells upon the microcapsules. This cellular overg-rowth is due to a nonspecific foreign body reaction elicited by the microcapsules and is by no means restricted to alginate/PLL/alginate microcapsules. Roberts et al, using HEMA-MMA copolymers for microencapsulation, also reported seeing up to a 10 μJim thick layer of cellular overgrowth after 4 weeks in vivo (Roberts et al 1991).
KeywordsGraft Copolymer Acryloyl Chloride Free Radical Propa Encapsulate Islet Reduce Protein Adsorption
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- Kam TI. 1990. Effects of visible radiation on cultured cells. Photochem and Photobiology 53(6): 1089.Google Scholar
- McMahon J, Schmid S, Weislow O, Stinson S, Camalier R, Gulakowski R, Shoemaker R, Kiser R, Dykes D, Harrison S, Mayo J, Boyd MJ. 1990. Feasibility of cellular microencapsulation technology for evaluation of anti-human immunodeficiency virus drugs in vivo. J Natl Cancer Inst 82:1761.PubMedCrossRefGoogle Scholar
- Roberts T, deBoni T, Sefton MV. 1991. Microencapsulation of dopamine secreting cells (PC 12) in a HEMAMMA copolymer. Trans Soc Biomater 14:157.Google Scholar
- Sawhney AS. 1992. Biocompatible microspheres and microcapsules for animal tissue encapsulation and transplantation. Dissertation. University of Texas at Austin, Austin, Texas.Google Scholar
- Yashon D, Jane JA, Gordon MC. 1966. Effects of methyl-2-cyanoacrylate adhesives on the somatic vessels and the central nervous system of animals. J Neurosurg 25:883–888.Google Scholar