title: Nanoporous alumina capsules for cellular macroencapsulation: transport and biocompatibility.
abstract: BACKGROUND
  Currently, the most widely used treatment for diabetes is the daily subcutaneous injection of recombinant human insulin. Daily injections, however, cannot match the physiological biphasic behavior of normal insulin release, nor can they precisely meet the demands of food intake, exercise, and stress. Cellular encapsulation, or immunoisolation, is a possible solution to this problem. This cell-based therapy allows patients to receive the benefits of more physiological insulin and blood glucose regulation, without the need for immunosuppressants that are associated with organ or cell transplantation.
  
  
  METHODS
  Immunoisolation capsules were fabricated out of aluminum and aluminum oxide using a two-step anodization procedure. The diffusion behavior of glucose, immunoglobulin G (IgG), and insulin were measured. Furthermore, the functionality and viability of encapsulated MIN6 cells were tested. Finally, live cells were stained and imaged using confocal microscopy.
  
  
  RESULTS
  Data indicated that this device is effective in allowing the transport of relevant molecules such as glucose and insulin, while at the same time significantly impeding the transport of IgG, suggesting that it would be efficacious in protecting cell grafts in vivo. Furthermore, encapsulated cells were able to respond dynamically to glucose input signals. Finally, cell staining showed that the viability of encapsulated cells is maintained after 24 h, although the cells appear to be more heavily concentrated at the area that is closest to the membrane.
  
  
  CONCLUSIONS
  This study has shown that nanoporous alumina membranes, with well-controlled pore sizes, can be used for the encapsulation of therapeutic cells and may provide an alternative encapsulation strategy for the treatment of diabetes.
authors.affiliation: Department of Biomedical Engineering, Boston University, Boston, Massachusetts 02215, USA.
authors.forename: Kristen E
authors.initials: KE
authors.lastname: La Flamme
authors.forename: Gopal
authors.initials: G
authors.lastname: Mor
authors.forename: Dawei
authors.initials: D
authors.lastname: Gong
authors.forename: Thomas
authors.initials: T
authors.lastname: La Tempa
authors.forename: Vincent A
authors.initials: VA
authors.lastname: Fusaro
authors.forename: Craig A
authors.initials: CA
authors.lastname: Grimes
authors.forename: Tejal A
authors.initials: TA
authors.lastname: Desai
mesh_terms: D000537:Aluminum Oxide / Q000737:chemistry*; D001672:Biocompatible Materials / Q000008:administration & dosage / Q000737:chemistry*; D001692:Biological Transport; D002214:Capsules; D045744:Cell Line, Tumor; D003094:Collagen / Q000737:chemistry; D003922:Diabetes Mellitus, Type 1 / Q000188:drug therapy / Q000628:therapy; D005947:Glucose / Q000008:administration & dosage / Q000737:chemistry*; D006801:Humans; D007074:Immunoglobulin G / Q000008:administration & dosage / Q000737:chemistry*; D007328:Insulin / Q000008:administration & dosage / Q000737:chemistry* / Q000378:metabolism; D000078790:Insulin Secretion; D007340:Insulinoma / Q000378:metabolism; D008567:Membranes, Artificial; D036103:Nanotechnology; D010539:Permeability
chemical_list: D001672:Biocompatible Materials; D002214:Capsules; D007074:Immunoglobulin G; D007328:Insulin; D008567:Membranes, Artificial; D003094:Collagen; D005947:Glucose; D000537:Aluminum Oxide