Abstract
Purpose: :
To examine the feasibility of lyophilized porcine cornea as a substrate for ocular surface reconstruction by using xenotransplantation models.
Methods: :
Pig cornea deprived of epithelial and endothelial cells was freeze–dried, vaccum–packed, and sterilized with ethylene oxide. The localization of alpha–gal epitope in the lyophilized and fresh pig cornea was determined using biotinylated Griffonia simplicifolia 1 isolection B4. Lyophilized pig corneas were then implanted into intrastromal pocket in the corneas of rats. The scores of transparency and neovascularization after transplantation were recorded by slit lamp microscopy. Host cell infiltration was examined by hematoxylin–eosin and immunohistochemical staining. RT–PCR was performed to evaluate the cytokine transcription. Control grafts were transplanted pig cornea.
Results: :
The immunoreactivity to alpha–gal epitope was recognized at several keratocytes in the fresh pig cornea. In contrast, immunoreactivity to alpha–gal epitope was not found in lyophilized pig cornea. In the group of lyophilized pig cornea, the mean survival time was 19.37±3.67 days, and in the group of fresh pig cornea, the mean survival time was 2.69±0.39 days. Immunohistochemical staining showed that T–lymphocyte, macrophaage, and angiogenesis related factors are expressed in the group of lyophilized pig cornea, wherease neutrophils were dominant in the group of fresh pig cornea. PCR analysis demonstrated that the mRNA expression of Th1 related cytokines were up regulated in all experimental groups. The mRNA of IL–10 was down–regulated in all experimental groups, especillay in fresh pig cornea inserted group.
Conclusions: :
The lyophilized pig corneal stroma, which is devoid of living cells, is less antigenic and may be used as a useful biomatrial for ocular surface reconstruction to supplement corneal collagen.
Keywords: transplantation • cornea: clinical science • immune tolerance/privilege