Self-folding immunoprotective cell encapsulation devices

Cell encapsulation therapy (CET) provides an attractive means to transplant cells without the need for immunosuppression. The cells are immunoisolated by surrounding them with a synthetic, semipermeable nanoporous membrane that allows selective permeation of nutrients and therapeutics while isolating the cells from hostile immune components. This communication describes the fabrication and in vitro characterization of lithographically structured and self-folded containers for immunoprotective cell encapsulation. Lithographic patterning ensured identical shapes, sizes, tunable porosity, and precise volumetric control, whereas self-folding enabled transformation of two-dimensional porous membranes into cubes, ensuring that pores were present in all three dimensions for adequate diffusion of O(2) and other nutrients to encapsulated cells. We fabricated containers with varying pore sizes and observed that pores sizes of approximately 78 nm were sufficient to significantly inhibit diffusion of IgG (the smallest antibody) and permit adequate diffusion of insulin, highlighting the possibility to utilize these containers to develop a lithographically structured bioartificial pancreas. From the Clinical Editor: In this paper, a novel immunoisolation technique is presented to enable cell transplant survival by surrounding them with a synthetic, semipermeable nanoporous membrane that allows selective permeation of nutrients and therapeutics while isolating the cells from hostile immune components. This method may pave the way to effective pancreatic islet cell transplantation. (C) 2011 Elsevier Inc. All rights reserved.