[Combined rapamycin eye drop in nanometer vector and poly (lactic acid) wafers of cyclosporine A effectively prevents high-risk corneal allograft rejection in rabbits].

OBJECTIVE

To evaluate the combined effect of topical rapamycin (RAPA) eye drop in nanometer vector and poly (lactic acid) (PLA) wafers of cyclosporine A (CsA) in the prevention of acute allograft rejection after rabbit corneal transplantation. Methods It was an experimental study. RAPA was incorporated into the nanometer particles and CsA was incorporated into PLA wafers. A was syngeneic control whose both donor and recipient are New Zealand rabbit. Gray donor corneas were implanted into the 102 recipients of New Zealand albino rabbits with corneal neovascularization who were randomly divided into B, C, D, E, F, G 6 groups to receive the different types of therapy: B was no therapy control; C was eye drop of nanometer vector but no RAPA twice a day, 28 days; D was PLA wafers in the anterior chamber of rabbit eyes but no drugs; E was 0.5% RAPA eye drop of nanometer vector twice a day, 28 days; F was PLA wafers of CsA in the anterior chamber of rabbit eyes; G was PLA wafers of CsA in the anterior chamber of rabbit eyes and 0.5% RAPA eye drop of nanometer vector eye drop twice a day for 28 days together. Postoperative evaluation included slit-lamp biomicroscopy, histopathology and immunohistology, Cytokines related with neovascularization and immunosuppression in the corneal tissue by RT-PCR. The graft survival was assessed by One-Way ANOVA and q test.

RESULTS

Corneal allograft survival time: A (100.00 +/- 0.00), B (8.44 +/- 1.24), C (8.89 +/- 2.57), D (8.56 +/- 2.30), E (43.11 +/- 5.58), F (43.67 +/- 9.54), G (72.00 +/- 15.34) d. Group G led to a statistically significant prolongation of transplant survival and was superior than group E and F which was a statistical prolongation compared with group B, C and D (qGE = 11.42, qGF = 11.24, qEB = 13.64, qEC = 13.38, qED = 13.46, qFB = 13.82, qFC = 13.56, qFD = 13.64; P < 0.01). Immunohistopathologically, the grafts were subjected to an immune response contained a dense infiltrate of neutrophils, CD4+ and CD8+ T lymphocytes in the group B, C and D. This cellular infiltrate was a significant reduction in group E,F,G. RT-PCR showed that the gene expression of IL-2 was inhibited earlier (3 days) in group F, G and VEGF gene expression being suppressed later (14 days) in group E, G.

CONCLUSIONS

Combined therapy with topical application of RAPA eye drop of nanometer vector and CsA PLA wafers can significantly prolong the survival of allograft at high-risk. Moreover, topical combined treatment of them is more effective, lower dosage, less side-effects and cheaper than the treatment with topical individual immunosuppressive drug.