| 摘要 |
PCT No. PCT/GB92/01511 Sec. 371 Date Jun. 22, 1994 Sec. 102(e) Date Jun. 22, 1994 PCT Filed Aug. 14, 1992 PCT Pub. No. WO93/03710 PCT Pub. Date Mar. 4, 1993.Contaminating protein is removed from a water soluble gum such as alginate by dialyzing a solution of the gum against a solution of a disulphide bond reducing agent. Purifying the gum by removing antigenic protein improves biocompatability of the gum for making biocompatible capsules containing cells such as mammalian cells. The reducing agent is preferably dithiothreitol, dithioerythritol or 2-mercaptoethanol. Dialyzing is preferably carried out for more than 1 hour and more preferably twice, each time for 2 hours. Cells are encapsulated by forming a suspension of cells in an aqueous solution of the gum, forming droplets from the suspension, gelling the droplets with a multivalent cation, contacting the gelled droplets with a polymer containing cationic groups, such as poly-1-lysine chloride, that cross-link with anionic groups of the gum to form a semi-permeable membrane around the droplets, and coating the membrane with a layer of the dialyzed gum. Islets of Langerhans cells can be encapsulated for implanting to produce insulin. In addition to encapsulating cells, the purified gum can be used in making dressings, swabs, sutures, stitches, controlled or sustained release devices and artificial vascular grafts that come in contact with body fluids such as blood.
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