A RAPID IN-SITU, COLORIMETRIC ASSAY FOR THE DETERMINATION OF MAMMALIAN-CELL VIABILITY IN ALGINATE-IMMOBILIZED AND ENCAPSULATED SYSTEMS

A convenient, rapid colorimetric assay system has been developed in or der to determine cell viability of populations of mammalian cells enca psulated using a poly-L-lysine/alginate encapsulation system. The meth od is based on the use of (4,5-dimethylthiozol-2-yl)-2,5-diphenyltetra zolium bromide (MTT) and involves direct incubation of the capsules wi th the reagent. This is followed by direct solubilization of the resul ting formazan product in dimethyl sulfoxide (DMSO). In order to demons trate that this assay method may be generally applicable to alginate-b ased carrier systems, viability of cells immobilized in alginate beads , as distinct from encapsulation in the poly-L-lysine/alginate system, was also determined using the in situ method.