Introduction: Xenocorneal transplantation has emerged as a promising alternative to address the global shortage of corneal donors. This study analyzes prognostic factors influencing survival rates in xenocorneal anterior lamellar transplantation using a genetically modified pig to non human primate.
Methods: In this study, various gene-modified pig corneas were used, including GTKO (α1,3-galactosyltransferase gene-knockout; n=1), GTKO/CD46 (n=10), GTKO/CD46/CD73 (n=2), GTKO/CD46/TBM (Thrombomodulin; n=3), TKO (GGTA1/CMAH/B4GalNT2; n=1), TKO/CD46/TBM (n=1), and QKO (TKO+iGb3S)/CD46/TBM (n=2). For minimal immunosuppression, a subconjunctival injection of dexamethasone (1.5 mg/0.3 mL) was administered, together with 0.5% levofloxacin and 1% prednisolone acetate eye drops for two months. If signs of rejection, such as graft edema or initial corneal opacity, were observed, the initial immunosuppressive regimen was re-administered. The occurrence and timing of rejection, as well as the graft survival period after rejection, were compared by dividing the subjects into long-term and short-term survival groups. Histopathological analysis was also performed.
Results
Key findings include:
In this study, consistent long-term survival was not achieved.
Analysis of survival rates in xenogeneic partial-thickness corneal transplantation revealed that the long-term survival group (>180 days) had a mean survival period of 585.33 days (±135.10 days, n=9), while the short-term survival group (<180 days) showed a mean survival period of 51.82 days (±10.45 days, n=11).
The frequency of subconjunctival dexamethasone injections and the pattern of steroid eye drop usage showed an association with graft survival.
In the long-term survival group, initial intensive immunosuppressive therapy and continuous immunosuppression were found to be effective in extending graft survival.
Histopathological analysis confirmed minimized tissue damage in the long-term survival group.
Conclusions: Xenocorneal anterior lamellar transplantation using genetically-modified pig demonstrates clinical potential. However, to achieve consistent long-term survival further genetic modifications, optimized immunosuppressive protocols, and deeper understanding of survival mechanisms is required.