A study of the effect of capsule composition on the viability of cultured alginate/poly-l-lysine--encapsulated rat islets.
Islets of Langerhans were isolated from WAGola rats and encapsulated in high mannuronic acid sodium alginate droplets. The capsules were completed in the following ways: (a) poly-l-lysine alone, (b) poly-l-lysine plus high guluronic acid alginate, (c) poly-l-lysine plus high mannuronic acid alginate. Islet viability was assessed every 3-4 days over a period of 4 weeks, by a microfluorometric assay using fluorescein diacetate and propidium iodide, and every 7 days by perifusion. The perifusion results were corrected for DNA content to take islet size differences into account. The results from the microfluorometric assay showed a generally high viability of the islets in all groups at each time interval. The perifusion experiments showed that the response time and stimulation indices of the islets was similar in all groups, but the absolute amount of insulin released was slightly lower from encapsulated islets relative to unencapsulated controls. It was concluded that the presence of a capsule, regardless of its composition, did not adversely affect the membrane integrity of the islets, their response time, nor their proportionate increase in insulin release following glucose stimulation. However, the absolute amount of insulin released from encapsulated islets was reduced during perifusion. This reduction was apparent after 1 week in culture, but remained stable thereafter.
Clayton
H A
HA
Department of Surgery, University of Leicester, UK.
London
N J
NJ
Colloby
P S
PS
Bell
P R
PR
James
R F
RF
D000464:Alginates; D000818:Animals; D001672:Biocompatible Materials; D002470:Cell Survival; D004247:DNA / Q000032:analysis; D005260:Female; D020723:Glucuronic Acid; D006603:Hexuronic Acids; D007515:Islets of Langerhans / Q000166:cytology*; D008297:Male; D008567:Membranes, Artificial; D011107:Polylysine; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors
D000464:Alginates; D001672:Biocompatible Materials; D006603:Hexuronic Acids; D008567:Membranes, Artificial; D011107:Polylysine; D020723:Glucuronic Acid; D004247:DNA