title: Effect of polyethylene glycol grafted onto islet capsules on prevention of splenocyte and cytokine attacks.
abstract: In the graft rejection of transplanted islets, the host's immune cells recognize the islets as antigens, which then stimulate the immune cells to begin the cytokine secretion and also the proliferation of immune cells. To prevent the recognition of islets by the immune cells, we grafted biocompatible polyethylene glycol (PEG) onto the collagen capsule of islets without incurring any changes in the morphology and function of islets. To evaluate the efficiency of PEG grafting, PEG-grafted islets were cultured with splenocytes consisting mainly of lymphocytes and macrophages. A splenocyte proliferation assessment using a BrdU incorporation assay showed that the PEG-grafted islets did not stimulate the splenocytes. In addition, the viability and microorganisms in islet cells of co-cultured PEG-grafted islets were not altered. However, in the co-culture of free islets (control) splenocytes were stimulated; they mainly secreted TNF-alpha and strongly affected the viability and structure of free islets. Furthermore, when islets were treated with the rat recombinant TNF-alpha for 7 days, the viabilities of PEG-grafted and free islets were significantly damaged, although the viability of PEG-grafted islets was higher than that of free islets by nearly three times. These results demonstrate that PEG grafted on the surface of islets could prevent the recognition of islets by splenocytes, but could not completely protect islets from cytokines.
authors.affiliation: Department of Materials Science and Engineering, Kwangju Institute of Science and Technology, 1 Oryong-dong, Buk-gu, Gwangju 500-712, South Korea.
authors.forename: Dong Yun
authors.initials: DY
authors.lastname: Lee
authors.forename: Jong Hee
authors.initials: JH
authors.lastname: Nam
authors.forename: Youngro
authors.initials: Y
authors.lastname: Byun
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry*; D001973:Bromodeoxyuridine / Q000494:pharmacology; D049109:Cell Proliferation; D002470:Cell Survival; D018920:Coculture Techniques; D004396:Coloring Agents / Q000494:pharmacology; D016207:Cytokines / Q000096:biosynthesis* / Q000378:metabolism; D006084:Graft Rejection / Q000517:prevention & control; D007371:Interferon-gamma / Q000378:metabolism; D007515:Islets of Langerhans / Q000276:immunology / Q000378:metabolism*; D008214:Lymphocytes / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism; D008297:Male; D046529:Microscopy, Electron, Transmission; D011092:Polyethylene Glycols / Q000737:chemistry* / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D011994:Recombinant Proteins / Q000737:chemistry; D013154:Spleen / Q000166:cytology* / Q000648:ultrastructure; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D001672:Biocompatible Materials; D004396:Coloring Agents; D016207:Cytokines; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; D011092:Polyethylene Glycols; D007371:Interferon-gamma; D001973:Bromodeoxyuridine