title: Microencapsulation of living cells in semi-permeable membranes with covalently cross-linked layers.
abstract: Microencapsulation in semi-permeable membranes protects transplanted cells against immune destruction. Microcapsule strength is critical. We describe a method to microencapsulate living cells in alginate-poly-L-lysine (PLL)-alginate membranes with covalent links between adjacent layers of microcapsule membranes, while preserving the desired membrane molecular weight cut-off (MWCO) and microencapsulated cell viability. A heterobifunctional photoactivatable cross-linker, N-5-azido-2-nitrobenzoyloxysuccinimide (ANB-NOS) was used. The N-hydroxysuccinimide ester group of ANB-NOS was covalently linked to PLL. Islets of Langerhans were immobilized in alginate beads, incubated in PLL-ANB-NOS and again in alginate. Upon illumination with UVA, covalent links were created between the phenyl azide residue of ANB-NOS and alginate from both the core bead and the outer coating. Covalently linked microcapsules remained intact after 3 years in a strong alkaline buffer (pH 12), whereas standard microcapsules disappeared within 45 s in the same solution. A standardized mechanical stress broke 22-fold more standard than covalently linked microcapsules. The MWCO and microencapsulated cell viability were similar with standard and covalently linked microcapsules. These microcapsules, extremely resistant to chemical and mechanical stresses, will be useful in numerous applications.
authors.affiliation: Centre de Recherche Guy-Bernier, Hôpital Maisonneuve-Rosemont, 5415 Boul de l'Assomption, Montréal, Québec, Canada H1T 2M4.
authors.forename: Julie
authors.initials: J
authors.lastname: Dusseault
authors.forename: Francois A
authors.initials: FA
authors.lastname: Leblond
authors.forename: Robert
authors.initials: R
authors.lastname: Robitaille
authors.forename: Guillaume
authors.initials: G
authors.lastname: Jourdan
authors.forename: Josée
authors.initials: J
authors.lastname: Tessier
authors.forename: Martin
authors.initials: M
authors.lastname: Ménard
authors.forename: Nathalie
authors.initials: N
authors.lastname: Henley
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Hallé
mesh_terms: D000464:Alginates / Q000032:analysis / Q000737:chemistry*; D000818:Animals; D018929:Cell Culture Techniques / Q000379:methods*; D002470:Cell Survival / Q000502:physiology; D002478:Cells, Cultured; D020099:Coated Materials, Biocompatible / Q000032:analysis / Q000737:chemistry; D019245:Compressive Strength; D003432:Cross-Linking Reagents / Q000737:chemistry; D007515:Islets of Langerhans / Q000166:cytology* / Q000502:physiology*; D016381:Islets of Langerhans Transplantation / Q000379:methods*; D008422:Materials Testing; D008567:Membranes, Artificial; D008970:Molecular Weight; D019397:Pancreas, Artificial; D010539:Permeability; D011107:Polylysine / Q000032:analysis / Q000737:chemistry*; D051381:Rats; D017208:Rats, Wistar; D023822:Tissue Engineering / Q000379:methods
chemical_list: D000464:Alginates; D020099:Coated Materials, Biocompatible; D003432:Cross-Linking Reagents; D008567:Membranes, Artificial; D011107:Polylysine