Suitability of cellulose molecular dialysis membrane for bioartificial pancreas: In vitro biocompatibility studies

The success of immunoisolation devices for islet transplantation depends on the properties and biocompatibility of semipermeable immunobarrier membran es. In the present study, we have evaluated the in vitro biocompatibility:o f the cellulose membrane Spectra/Por(R) 2 (MW no larger than 12- 14,000) fo r its possible application in islet immunoisolation. The membrane was found to be hydrophilic (octane contact angle: 153.2 +/- 0.66 degrees) and exhib ited decreased protein adsorption. It showed mechanical stability after 1 m onth of storage in PBS (pH 7.4) with tensile strength, percent elongation, and Young's modulus of 88.88 MPa, 36.22, and 291.8 MPa, respectively. It al lowed regulated transport of glucose and insulin in an in vitro diffusion a ssay. The high viability of NIH3T3 fibroblasts and the inability of lymphoc ytes to proliferate in vitro on exposure to the membrane leach-out products suggested its noncytotoxic and nonimmunogenic nature. Macrophages, when cu ltured on membranes, did not show increased expression of inflammatory surf ace marker such as CD11b/CD18, CD45, CD14, and B 7.2. Image analysis studie s showed integrity and intact morphology of mouse islets cultured on and in side the membranes with high viability (91%, 89.7%). These islets also reta ined their functionality, as judged by insulin secretion. The present study provides sufficient documentation to consider cellulose molecular dialysis membrane Spectra/Por(R) 2 (MW no larger than 12-14,000) as a potential can didate for immunoisolation of islets. (C) 2000 John Wiley & Sons, Inc. J Bi omed Mater Res 54: 436-444, 2001.