PROTEIN DELIVERY BY MICROENCAPSULATED CELLS

Mammalian cells encapsulated within polymeric membranes are a novel wa y for in vivo controlled release of therapeutic agents. A permselectiv e polymeric membrane, by acting as a permeability barrier for large mo lecules (such as antibodies), can protect the encapsulated cells from the cytotoxic components of the host without immunosuppressants. The h igh membrane permeability for small molecules (such as nutrients, horm ones etc.), on the other hand, will ensure the maintenance of a normal physiological state and the secretion of bioactive peptides by the en capsulated cells. In this review, particular attention is given to an interfacial precipitation technique for encapsulating mammalian cells in a polyacrylate membrane. This technique is based on the co-extrusio n of a cell suspension and polymer solution through a concentric needl e assembly and subsequent formation of an immuno-isolation membrane ar ound the cells in a precipitation bath. Here, experience with the enca psulation and subsequent in vitro performance of various mammalian cel ls in polyacrylate microcapsules is summarized.