Membrane Immunoisolation of a Diffusion Chamber for a Bioartificial Pancreas

Abstract

Immunoisolation is a potentially important approach to transplanting islets without any immunosuppressive therapy. The concept of immunoisolation is outlined in systems in which the transplanted tissue is separated from the immune system of the host by an artificial barrier. We previously described a diffusion chamber as a bioartificial endocrine pancreas (Bio-AEP), which was constructed by placing pancreatic endocrine cells, trapped in a mixed matrix, in the center of a ring holder sandwiched between nucleopore membranes, which were shielded by silicone. This experiment was designed to evaluate a suitable pore size for the nucleopore membrane to ensure immunoisolation during xenoimplantation of the Bio-AEP in vitro and in vivo. A nucleopore membrane of pore size 0.1 microm or 0.2 microm was employed as the semipermeable membrane which provided a mechanical barrier between the endocrine pancreas graft and the host immune system. The protective effect of the Bio-AEP from humoral immunity was determined in vitro, using sensitized sheep erythrocytes (EAs). A complement protein did not destroy the cell membranes of the EAs in the diffusion chamber containing the mixed matrix with the nucleopore membrane of 0.1 microm pore size. In an in vivo experiment, 6 streptozotocin (STZ) induced diabetic rats were implanted with Bio-AEPs constructed with nucleopore membranes of pore size 0.1 microm and containing MIN6 cells in the mixed matrix. In the STZ diabetic rats with Bio-AEPs, a return to normoglycemia was observed up to 50 weeks after implantation without the use of any immunosuppressant. Also, the body weights of the rats gradually increased. During the observation, when the Bio-AEPs were removed from the STZ diabetic rats, the blood glucose immediately returned to preimplantation levels, and the body weights of the rats also decreased. The membranes of the Bio-AEPs removed from the STZ diabetic rats showed a very thin layer of fibroblastic cells on the outer surfaces. The results indicated that the Bio-AEP, in which pancreatic endocrine cells were trapped in a mixed matrix and with a 0.1 microm pore size membrane, should be useful for xenoimplantation into diabetic animals and may open a new field in the therapy of human diabetics.

Effect of the Extracellular Matrix on Pancreatic Endocrine Cell Function and its Biocompatibility in Dogs

“…Within the chamber, PE cells are bovine serum and incubated for 7 days at 37°C in 5% suspended and cultured in collagen gel as a major com-CO 2 and humidified air. Insulin levels in the medium ponent of the synthetic ECM (3, [12][13][14]. over a 7-day period were measured by radioimmunoas-In our previous studies, type I LA was used as an say (RIA; AB Beads insulin "Eiken"; Eiken Chemical ECM in a Bio-AEP (3,13).…”

“…The preparation and purification methods for adult In another study, Bio-AEPs containing type I LA (n = 2) or Matrigel (n = 2) but not PE cells were im-PE cells have been described elsewhere (8)(9)(10)(11)16). Briefly, pancreases were obtained from a local slaugh-planted into the abdominal cavities of four healthy Bea-gle dogs.…”

A novel alginate hollow fiber bioreactor process for cellular therapy applications

“…16 Cell immobilization in a matrix irrigated by hollow fibers has been reported for bioartificial pancreases designed to isolate transplanted islets from the host immune system. 17,18 Agarose or gelatin/agarose cell immobilization has been used to investigate mass transfer or cell concentration gradients in HFBRs. [19][20][21] However, these systems were not designed for cell recovery.…”

Unusual Permeability of Porcine Endogenous Retrovirus Subgroup A Through Membrane Filters

“…To overcome immunological rejection, Ohgawara and coworkers developed a bio-artificial endocrine pancreas (Bio-AEP), in which pancreatic endocrine cells are encapsulated within a semipermeable membrane [13,14]. They found that the immune reaction between the recipient and transplanted cells was prevented by a semipermeable membrane of 100 nm pore size.…”