CTLA4Ig introduced by adenovirus vector locally to prolong the survival of xenogeneic skin grafts on rat burn wounds

Background. The purpose of this study was to explore an applicable approach for prolonging the survival of heterogenetic skin grafts on burn wounds with CTLA4Ig. Methods: An adenovirus vector named Ad-CTLA4Ig, which could express human CTLA4Ig fusion protein, was constructed. Infecting and replicating in 293 cells, more Ad-CTLA41g and recombinant human CTLA4Ig (rhCTLA4Ig) were prepared, respectively. In a rat flame thermal injury model, the effect of rhCTLA4Ig on survival time of human skin graft on the eschar-excised rat burn wound was observed. Meanwhile, the efficiency of Ad-CTLA41g infecting cultured skin fibroblasts, keratinocytes, and partial-thickness skin samples were checked by CTLA4Ig expression assay. Then, the Ad-CTLA41g was administered locally on the eschar-excised wound and dermis of the skin graft, and the survival time of the human skin graft on burn wound was measured. The influence of the systemic immune function by rhCTLA4Ig and Ad-CTLA4Ig were also determined. Results. The prepared rhCTLA4Ig from the supernatant of Ad-CTLA4Ig-infected 293 cells was verified by sodium dodecyl sulfate polyacrylamide gel electrophoresis sodium dodecyl sulfate polyacrylamide gel electrophoresis and Western blot. It was found that CTLA4Ig could significantly prolong the xenogeneic skin graft survival in a dosage-dependent manner. Interestingly, the survival time was longer when CTLA4Ig was used 24 hours post- transplantation than that at hour 0. The expression of CTLA4Ig could be observed in the cultured skin fibroblasts, keratinocytes, and skin pieces soon after Ad-CTLA4Ig transfection, as demonstrated by either immunocellular chemistry or immunohistochemistry assay. When Ad-CTLA4Ig was locally administered during skin transplantation on burn wound, the survival time was increased from 7.9 days of control group to 21.6 days, whereas the systemic immune function was not affected. Conclusion: Administration of Ad-CTLA4Ig locally could prolong the survival time of xenogeneic skin graft on burn wound without significantly influencing the systemic immune function.