title: Effect of poly-L-lysine coating on macrophage activation by alginate-based microcapsules: assessment using a new in vitro method.
abstract: The characteristics of the microcapsule surface, which interacts directly with the host macrophages, may have a role in the biocompatibility of alginate-poly-L-lysine (PLL)-alginate (APA) microcapsule. The objectives of the study were: 1) to develop and validate a simple, rapid, and sensitive in vitro method for assessing microcapsule biocompatibility, based on microcapsule coincubation with macrophages and measurement, by reverse transcriptase-polymerase chain reaction, of cytokine mRNA expression, and 2) to evaluate the effect of alginate purification and PLL coating on macrophage activation. The mRNA expression of tumor necrosis factor-alpha and interleukin-1beta was significantly higher when macrophages were coincubated with beads made with nonpurified compared with purified alginate (p<0.01, p<0.05, respectively) and negative control (p<0.001) or with APA microcapsules compared with non-PLL-coated alginate beads and negative control (p<0.001). The mRNA expression of interleukin-6 differed significantly only when APA microcapsules were compared with a negative control (p<0.05). These results confirm that alginate purification improves microcapsule biocompatibility, and suggest that PLL is not completely covered and/or neutralized by the second alginate incubation and thus has a role in the host macrophage activation. The assay is sensitive to both alginate contaminants and microcapsule surface characteristics and may be a useful tool for the development of biocompatible microcapsules.
authors.affiliation: Centre de Recherche Guy-Bernier, Hôpital Maisonneuve-Rosemont, 5415, boulevard de l'Assomption, Montréal, Québec, H1T 2M4, Canada.
authors.forename: Sandy
authors.initials: S
authors.lastname: Juste
authors.forename: Mélanie
authors.initials: M
authors.lastname: Lessard
authors.forename: Nathalie
authors.initials: N
authors.lastname: Henley
authors.forename: Martin
authors.initials: M
authors.lastname: Ménard
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Hallé
mesh_terms: D000464:Alginates; D000818:Animals; D002214:Capsules / Q000737:chemistry* / Q000494:pharmacology; D002460:Cell Line; D020099:Coated Materials, Biocompatible / Q000494:pharmacology; D016207:Cytokines / Q000235:genetics; D020723:Glucuronic Acid; D006603:Hexuronic Acids; D008262:Macrophage Activation / Q000187:drug effects* / Q000276:immunology; D016676:Macrophages, Alveolar / Q000166:cytology / Q000187:drug effects; D011107:Polylysine / Q000494:pharmacology*; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods
chemical_list: D000464:Alginates; D002214:Capsules; D020099:Coated Materials, Biocompatible; D016207:Cytokines; D006603:Hexuronic Acids; D012333:RNA, Messenger; D011107:Polylysine; D020723:Glucuronic Acid