title: Durability of sodium sulfate-treated polylysine-alginate microcapsules.
abstract: Chelated hollow microcapsules are unstable under in vitro conditions because of their hygroscopic nature. Nongel inducing cations, such as Na+, stabilize the outer membrane of the alginate-polylysine-alginate microcapsules leading to more stable beads. We made different batches of empty capsules with a mean +/- SEM diameter of 607+/-11 microns, and found that within 1 week of incubating these capsules in normal saline at 37 degrees C, they increased to 718+/-10 microns (p < 0.05, n = 5). In initial experiments, we made different batches of capsules and divided them into two groups. One group was left untreated (control) whereas the other was treated with 6 mM Na2SO4 for 30 min, before incubation in saline at 37 degrees C. Control capsules increased in weight and size, before beginning to melt in less than 1 week. In contrast, treated capsules rapidly lost weight and remained intact during 1 month of follow-up. In perifusion experiments, we found no deleterious effect of sodium sulfate treatment on the function of islets enclosed in the capsules.
authors.affiliation: Department of Surgery, Duke University Medical Center, Durham, North Carolina 27710, USA.
authors.forename: M
authors.initials: M
authors.lastname: Darrabie
authors.forename: B K
authors.initials: BK
authors.lastname: Freeman
authors.forename: W F
authors.initials: WF
authors.lastname: Kendall
authors.forename: H A
authors.initials: HA
authors.lastname: Hobbs
authors.forename: E C
authors.initials: EC
authors.lastname: Opara
mesh_terms: D020341:Absorbable Implants; D000464:Alginates / Q000737:chemistry*; D000818:Animals; D002214:Capsules / Q000737:chemistry*; D004339:Drug Compounding; D005947:Glucose / Q000494:pharmacology; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism; D016381:Islets of Langerhans Transplantation / Q000502:physiology*; D008297:Male; D010316:Particle Size; D011107:Polylysine / Q000737:chemistry*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013431:Sulfates / Q000737:chemistry*
chemical_list: D000464:Alginates; D002214:Capsules; D013431:Sulfates; C012036:sodium sulfate; D011107:Polylysine; D005947:Glucose