title: Microencapsulation of islets within alginate/poly(ethylene glycol) gels cross-linked via Staudinger ligation.
abstract: Functionalized alginate and poly(ethylene glycol) (PEG) polymers were used to generate covalently linked alginate-PEG (XAlgPEG) microbeads of high stability. The cell-compatible Staudinger ligation scheme was used to cross-link phosphine-terminated PEG chemoselectively to azide-functionalized alginate, resulting in XAlgPEG hydrogels. XAlgPEG microbeads were formed by co-incubation of the two polymers, followed by ionic cross-linking of the alginate using barium ions. The enhanced stability and gel properties of the resulting XAlgPEG microbeads, as well as the compatibility of these polymers for the encapsulation of islets and beta cells lines, were investigated. The data show that XAlgPEG microbeads exhibit superior resistance to osmotic swelling compared with traditional barium cross-linked alginate (Ba-Alg) beads, with a five-fold reduction in observed swelling, as well as resistance to dissolution via chelation solution. Diffusion and porosity studies found XAlgPEG beads to exhibit properties comparable with standard Ba-Alg. XAlgPEG microbeads were found to be highly cell compatible with insulinoma cell lines, as well as rat and human pancreatic islets, where the viability and functional assessment of cells within XAlgPEG are comparable with Ba-Alg controls. The remarkable improved stability, as well as demonstrated cellular compatibility, of XAlgPEG hydrogels makes them an appealing option for a wide variety of tissue engineering applications.
authors.affiliation: Department of Biomedical Engineering, College of Engineering, University of Miami, 1450 NW 10th Avenue, Miami, FL 33136, USA.
authors.forename: K K
authors.initials: KK
authors.lastname: Hall
authors.forename: K M
authors.initials: KM
authors.lastname: Gattás-Asfura
authors.forename: C L
authors.initials: CL
authors.lastname: Stabler
mesh_terms: D000464:Alginates / Q000494:pharmacology*; D000818:Animals; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D003432:Cross-Linking Reagents / Q000494:pharmacology*; D004058:Diffusion; D004339:Drug Compounding / Q000379:methods*; D005782:Gels / Q000494:pharmacology*; D020723:Glucuronic Acid / Q000494:pharmacology; D006603:Hexuronic Acids / Q000494:pharmacology; D006801:Humans; D007515:Islets of Langerhans / Q000166:cytology / Q000187:drug effects*; D008297:Male; D051379:Mice; D018613:Microscopy, Confocal; D008863:Microspheres; D009995:Osmosis / Q000187:drug effects; D010539:Permeability / Q000187:drug effects; D011092:Polyethylene Glycols / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D000464:Alginates; D003432:Cross-Linking Reagents; D005782:Gels; D006603:Hexuronic Acids; D011092:Polyethylene Glycols; D020723:Glucuronic Acid