Studies on small (<350 microm) alginate-poly-L-lysine microcapsules. V. Determination of carbohydrate and protein permeation through microcapsules by reverse-size exclusion chromatography.
Membrane molecular weight (MW) cut-off is a critical factor for immunoprotection of transplanted microencapsulated cells as well as for graft survival. Our goal was to study dextran and protein permeation through small (<350 microm in diameter) alginate-poly-L-lysine microcapsules made with an electrostatic system. Microcapsules were packed into a column, and gel-sieving chromatography was performed with proteins and dextrans of known MW. The objectives of this study were (1) to validate this approach for the assessment of the MW cut-off of <350 microm-in-diameter microcapsules and (2) to evaluate the effect on MW cut-off of changes in experimental conditions. Elution profiles of proteins suggest that the MW cut-off of our small microcapsules lies between 14,500 and 44,000 Da whereas dextrans > or =19,000 Da were excluded. The increase in poly-L-lysine (PLL) concentration from 0.02 to 0.08% reduced the MW cut-off. Increasing the PLL MW from 11.6 to 69.6 kDa induced no change in the MW cut-off. The results also show that the method can be used to discriminate between adsorption and absorption and that insulin diffuses freely across the microcapsule membrane. This method will be useful in establishing the ideal MW cut-off, in optimizing microcapsule characteristics, and in performing routine quality controls.
Robitaille
R
R
Centre de Recherche Guy-Bernier, Hôpital Maisonneuve-Rosemont, 5415 boulevard de l'Assomption, Montréal, Québec, H1T 2M4, Canada.
Leblond
F A
FA
Bourgeois
Y
Y
Henley
N
N
Loignon
M
M
Hallé
J P
JP
D000464:Alginates; D000818:Animals; D001672:Biocompatible Materials; D002214:Capsules; D002241:Carbohydrates; D006801:Humans; D016381:Islets of Langerhans Transplantation; D008567:Membranes, Artificial; D010316:Particle Size; D011107:Polylysine / Q000031:analogs & derivatives*; D011506:Proteins
D000464:Alginates; D001672:Biocompatible Materials; D002214:Capsules; D002241:Carbohydrates; D008567:Membranes, Artificial; D011506:Proteins; C051546:alginate-polylysine-alginate; D011107:Polylysine