Abstract
Purpose::
In this study, we have examined the immunohistochemical profile of numerous growth factors, receptors, and structural proteins in 18 and 20 week gestation normal human fetal cornea.
Methods::
Formalin-fixed, paraffin-embedded sections of four normal fetal human corneas (gestational age 18-20 weeks) were stained with antibodies reactive against vimentin, FB5, fibroblast growth factor 2 (FGF-2), transforming growth factor beta 2 (TGF-B2), transforming growth factor beta receptor (TGF-BR), smooth muscle actin (SMA), cytokeratin 7, cytokeratin 20, pan-cytokeratin (CK-mix) insulin-like growth factor 1 (IGF-1), insulin-like growth factor 1 receptor (IGF-1R), and platelet derived growth factor (PDGF). The qualitative degree of immunoreactivity was assessed using light microscopy.
Results::
Fetal corneal epithelium stained with FB5, pancytokeratin, TGF-B2, TGF-BR, and IGF-1R. 20 week corneal epithelium stained lightly with vimentin, whereas epithelium of a younger gestational age did not. Keratocytes stained positive for FB5, TGF-B2, TGF-BR, IGF-1R, and very strongly for vimentin. Occasional keratocytes demonstrated staining of FGF2, suggesting the presence of distinct subsets of keratocytes in fetal corneal stroma at 18-20 weeks. Corneal endothelium displayed staining with FB5, TGF-B2, TGF-BR, IGF-1R, and very strongly for vimentin and FGF-2. 18 week corneas displayed scant staining for PDGF in all cell layers examined, whereas this was not observed in 20 week corneas. All specimens examined did not stain with SMA, CK7, or CK20.
Conclusions::
Patterns of protein expression in developing human cornea are not well-defined. We have initiated a project to characterize protein expression in human cornea by immunohistochemistry. Defining normal patterns of immunohistochemistry during corneal differentiation will help guide future studies into mechanisms of development and pathology in the human cornea.
Keywords: cornea: basic science • development • gene/expression