Method of containing core material in microcapsules
First Claim
1. A method of containing a core material within microcapsules having a semipermeable wall to prevent the core material from incorporation into the wall of the microcapsules which comprises:
- (a) suspending the core material in a solution containing between about 0.2% and about 0.5% of a polysaccharide gum containing acid groups capable of forming a gel to permit the polysaccharide gum to attach to the core material, wherein the solution of polysaccharide gum is physiologically compatible with the core material;
(b) removing the core material from the solution of polysaccharide gum in step (a) and washing the core material in a solution not containing the polysaccharide gum to remove from the core material all but a thin layer of polysaccharide gum attached to the core material;
(c) treating the washed core material having the attached thin layer of polysaccharide gum from step (b) under conditions to cause the polysaccharide gum attached to the core material to gel to form a pretreated core material;
(d) suspending the pretreated core material from step (c) in a solution containing a polysaccharide gum containing acid groups capable of forming a gel, wherein the solution of polysaccharide gum is physiologically compatible with the core material;
(e) forming the suspension from step (d) into droplets of a size sufficient to encapsulate the core material;
(f) treating the droplets from step (e) under conditions to cause the polysaccharide gum to gel to form temporary shape-retaining capsules; and
(g) treating the temporary shape-retaining capsules from step (f) under conditions with a polymeric material containing groups that react with and crosslink acid groups of the temporary shape-retaining capsules to cause the formation of a permanent semipermeable membrane around the capsules to form said microcapsules.
2 Assignments
0 Petitions
Accused Products
Abstract
A core material such as animal tissue or cells is contained within a semipermeable vessel which may be a microcapsule, hollow fiber or plastic membrane having a semipermeable wall by a method that prevents the core material from incorporation into the wall of the vessel. This is accomplished by suspending the core material in a solution of polysaccharide gum such as an alkali metal alginate in an amount between about 0.2% and about 0.5%, removing and washing the core material to remove all but a thin layer of polysaccharide gum, and gelling the polysaccharide gum with multivalent cations or other means to form a pretreated core material. The pretreated core material is contained within a semipermeable vessel such as by suspending the pretreated core material in a solution of alkali metal alginate, forming the suspension into droplets, gelling the droplets to form temporary shape-retaining capsules and treating the capsules with a polymeric material having groups that react with and crosslink acid groups of the capsules to form a permanent semipermeable membrane around the capsules. A second permanent semipermeable membrane may be formed around the capsules to form double-walled microcapsules by further treating the capsules with the polymeric material. The semipermeable vessel may be impermeable to immune factors. Cells or tissue can be transplanted from a donor to a subject such as by using pancreatic islet tissue or cells as the core material of the double-walled microcapsules and transplanting the microcapsules by intraperitoneal injection into a diabetic subject.
29 Citations
25 Claims
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1. A method of containing a core material within microcapsules having a semipermeable wall to prevent the core material from incorporation into the wall of the microcapsules which comprises:
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(a) suspending the core material in a solution containing between about 0.2% and about 0.5% of a polysaccharide gum containing acid groups capable of forming a gel to permit the polysaccharide gum to attach to the core material, wherein the solution of polysaccharide gum is physiologically compatible with the core material; (b) removing the core material from the solution of polysaccharide gum in step (a) and washing the core material in a solution not containing the polysaccharide gum to remove from the core material all but a thin layer of polysaccharide gum attached to the core material; (c) treating the washed core material having the attached thin layer of polysaccharide gum from step (b) under conditions to cause the polysaccharide gum attached to the core material to gel to form a pretreated core material; (d) suspending the pretreated core material from step (c) in a solution containing a polysaccharide gum containing acid groups capable of forming a gel, wherein the solution of polysaccharide gum is physiologically compatible with the core material; (e) forming the suspension from step (d) into droplets of a size sufficient to encapsulate the core material; (f) treating the droplets from step (e) under conditions to cause the polysaccharide gum to gel to form temporary shape-retaining capsules; and (g) treating the temporary shape-retaining capsules from step (f) under conditions with a polymeric material containing groups that react with and crosslink acid groups of the temporary shape-retaining capsules to cause the formation of a permanent semipermeable membrane around the capsules to form said microcapsules. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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Specification