Micromachined interfaces: new approaches in cell immunoisolation and biomolecular separation

As a novel therapeutic application of microfabrication technology, a microm achined membrane-based biocapsule is described for the transplantation of p rotein-secreting cells without the need for immunosuppression. This new app roach to cell encapsulation is based on microfabrication technology whereby immunoisolation membranes are bulk and surface micromachined to present un iform and well-controlled pore sizes as small as 10 nm, tailored surface ch emistries, and precise microarchitecture. Through its ability to achieve hi ghly controlled microarchitectures on size scales relevant to living system s (from mu m to nm), microfabrication technology offers unique opportunitie s to more precisely engineer biocapsules that allow free exchange of the nu trients, waste products, and secreted therapeutic proteins between the host (patient) and implanted cells, but exclude lymphocytes and antibodies that may attack foreign cells. Microfabricated inorganic encapsulation devices may provide biocompatibility, in vivo chemical and mechanical stability, ta ilored pore geometries, and superior immunoisolation for encapsulated cells over conventional encapsulation approaches. By using microfabrication tech niques, structures can be fabricated with spatial features from the sub-mic ron range up to several millimeters. These multi-scale structures correspon d well with hierarchical biological structures, from proteins and sub-cellu lar organelles to the tissue and organ levels. (C) 2000 Published by Elsevi er Science B.V.