Encapsulation of mammalian cells into synthetic polymer membranes using least toxic solvents

Immunoisolation, that is, enclosure of cells within a semipermeable membrane to protect them from immunological rejection, may enable the transplantation of cells without use of immunosuppressive drugs. Therefore, in addition to naturally-occurring ionic polymers, several synthetic nonionic polymers which can form dense and strong membranes in water have been studied as materials for immunoisolation. However, such nonionic polymers are required to be soluble in organic solvents which are mostly cytotoxic. In this report we describe enclosure of insulin-releasing cells into water-insoluble poly(2-hydroxyethyl methacrylate) and poly(2-hydroxyethyl methacrylate-co-methyl methacrylate) membranes using X-ray contrast medium as a solvent without use of any special apparatus. The contrast medium employed in our study is iopamidol aqueous solution. Insulin release was observed for 1 month when insulin-releasing cells were encapsulated into these membranes. The permeability of five solutes through the membranes prepared from the iopamidol aqueous solution was also studied to determine their potential immunoisolative efficacy.