Alginate-poly-L-lysine microcapsule biocompatibility: A novel RT-PCR method for cytokine gene expression analysis in pericapsular infiltrates

Transplantation of microencapsulated islets of Langerhans is impaired by a pericapsular host reaction that eventually induces graft failure. We are st udying the role of cytokines in the pathogenesis of this reaction, using th e model of alginate-polylysine microcapsule implantation in rat epididymal fat pads. The objectives were: (1) to develop a method to measure, by semiq uantitative PCR, TGF-beta(1) gene expression in fat pad pericapsular infilt rates, and (2) to use this method to evaluate TGF-beta(1), gene expression 14 days after microcapsule implantation. TGF-beta(1) mRNA level was signifi cantly higher in pericapsular infiltrate cells than in nonimplanted tissue cells and saline-injected tissue cells (p < 0.0001 and p < 0.01, respective ly). There was no significant difference between the TGF-beta 1 mRNA levels of the two types of controls (p = 0.0945). These results suggest that TGF- beta 1 plays a role in the pathogenesis of the pericapsular reaction. The m ethod developed can be used to study the role of other fibrogenic cytokines potentially involved. This will shed light on the mechanisms underlying th e pericapsular reaction and will serve as a basis for the development of st rategies to control this reaction. (C) 1999 John Wiley & Sons, Inc.