1 diabetes is an autoimmune chronic illness. Transplantation of encapsulated
islets has been proposed as a safe and effective method for treating these
patients without the need of immuno-suppressive therapy. But, the key
challenges encountered in this approach includes the inadequate
protection of islet against cytotoxic molecules due to their low molecular weights to
penetrate into the capsules and directly induce necrosis or apoptosis of the islet
cells. Also, it has been widely accepted that the cytokines milieu and the islet self-antigens cause severe malfunction
and death of encapsulated cells 12,13.
To address these problems, current approaches seek to create a stable
physical barrier with a minimum thickness around the islets and create an
immunoregulatory microenvironment that locally induce immune tolerance to shift
the immune system from inflammatory to anti-inflammatory milieu like the tumor tissue.
More recently, surface modification of islets has been proposed with this
vision for preventing immunogenic reactions. Similar to this strategy was used for CTLA4-Ig, TNF-alpha, FasL
and TGF-ß l for local
immunomodulation in islet transplantation