Time course of transforming growth factor-beta(1) (TGF-beta(1)) mRNA expression in the host reaction to alginate-poly-L-lysine microcapsules following implantations into rat epididymal fat pads

Microencapsulation of islets of Langerhans within semipermeable membranes h as been proposed to prevent their immune destruction after transplantation. However, the successful application of this method is impaired by a perica psular reaction, which eventually induces graft failure. Our goal is to stu dy the role of cytokines in the pathogenesis of this reaction, using the mo del of alginate-poly-L-lysine microcapsule implantation into Wistar rat epi didymal fat pads (EFP). The specific objective of this study was to determi ne the time course of transforming growth factor (TGF)-beta(1) mRNA express ion by semi-quantitative reverse transcriptase-polymerase chain reaction. M icrocapsules induced an increase of TGF-beta(1) mRNA expression that reache d a maximum 14 days after implantation. Seven, 14, 30, and 60 days after mi crocapsule implantation, the expression of TGF-beta(1) mRNA was significant ly higher in pericapsular infiltrate cells than in nonimplanted EFP cells ( p < 0.05, p < 0.0001, p < 0.005, and p < 0.01, respectively). Injection of physiological saline induced a small and gradual augmentation of TgF-beta(1 ) mRNA expression with a maximum 30 days after injection (p < 0.01 vs. noni mplanted EFP cells). These results demonstrated that microcapsule implantat ion, in comparison with saline injection, induce an early, extended, and am plified TGF-beta(1) mRNA expression This suggests that TGF-beta(1) plays a role in the pathogenesis of the pericapsular host reaction. (C) 2000 John W iley & Sons, Inc.