Implantation of microfabricated immunoisolating biocapsules

Silicon-based biocapsules have been microfabricated with uniform and well-controlled pore dimensions in the tens of nanometer range to provide effective immunoisolation of cell xenografts. Surface and bulk micromachining were integrated in the fabrication process, resulting in a diffusion membrane with mechanical and chemical stability, surrounded by an anisotropically-etched silicon wafer, which serves as the encapsulation cavity. The membrane allows the diffusion of essential nutrients while blocking the passage of immune molecules, which may destroy cellular transplants. Preliminary short term studies on both primary pancreatic islets and insulinoma cell lines encapsulated within microfabricated biocapsules were conducted to determine the toxicity and biocompatibility of biocapsules, the viability and functionality of encapsulated cells, as well as the overall immunoprotective capabilities of the biocapsule. Results seem to indicate that microfabricated biocapsules are non-toxic and do not elicit any adverse inflammatory reactions when implanted. Furthermore, encapsulated insulinoma cells remained viable and functional within microfabricated environments in vivo. These results show the feasibility and potential application of microfabricated biocapsules for several pathologies.