Bioactive cells immobilized in alginate beads containing voids formed with polyethylene glycol
AssigneeLehigh University
InventorDouglas B. Seifert
Life of this patent
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Abstract
Bioactive cells are immobilized by suspending bioactive cells in an aqueous solution of a salt-free osmolarity adjuster, alginate and polyethylene glycol, dividing the suspension into bead-sized globules, contacting the globules with a solution of divalent cations to gel the alginate to form beads containing polyethylene glycol-filled areas and removing the polyethylene glycol to form voids in the beads entrapping the bioactive cells. By perfusing the beads with a nutrient medium, the cells can proliferate in the voids to produce high cell densities and produce a product which can be separated from the medium.
Claims19
Method of immobilizing bioactive cells comprising forming a suspension of said cells in a solution of a salt-free osmolarity adjuster which prevents precipitation of alginate in said solution, between 0.25 wt % and 5 wt % alginate and between 10 wt T and 30 wt % polyethylene glycol in water, dividing said suspension into bead-sized globules, between 20 .mu. and 5 mm in diameter, contacting said globules with a solution of divalent cations to cause said alginate to gel into gelled alginate beads, and removing said polyethylene glycol from said gelled alginate beads, to produce alginate gel beads of between 20 .mu. and 5 mm in diameter containing said cells, said beads containing a multiplicity of enclosed void spaces projecting radially from the center of the beads, and said cells being entrapped in said void spaces.
A method for continuously producing and removing the product of bioactive cells comprising first immobilizing said bioactive cells by forming a suspension of said cells in an aqueous solution of a salt-free osmolarity adjuster which prevents precipitation of alginate in said solution, between 0.25 wt % and 5 wt % alginate and between 10 wt % and 30 wt T polyethylene glycol, dividing said suspension into bead-sized globules of 20 .mu. to 5 mm in diameter and contacting said globules with a solution of divalent cations to cause said alginate to form gel beads, removing said polyethylene glycol from said gel beads to produce alginate gel beads of between 20 .mu. and 5 mm in diameter containing said cells, said beads containing a multiplicity of enclosed void spaces projecting radially from the center of the beads, and said cells being entrapped in said void spaces and thereafter perfusing a bed of said beads containing said cells with a medium and removing products produced by said cells from the medium.
A method for obtaining the products of bioactive cells comprising:
- mixing said bioactive cells with an aqueous solution of a salt-free osmolarity adjuster which prevents precipitation of alginate in said solution, between 0.25 wt % and 5 wt % alginate and between 10 wt % and 30 wt % polyethylene glycol;
- forming porous beads of said mixture by adding bead size globules of said mixture to a divalent ion-containing solution;
- removing said polyethylene glycol from said beads to produce alginate gel beads of between 20 .mu. and 5 mm in diameter containing said cells, said beads containing a multiplicity of enclosed void spaces projecting radially from the center of the beads, and said cells being entrapped in said void spaces;
- placing said beads in a medium including a nutrient for said cells;
- allowing said cells to grow and produce cell products in said medium;
- and
- draining at least part of said medium, and separating therefrom cell products.
Dependencies are inferred from the claim text.