Purpose: To measure the levels of mRNA for genes important in cellular and extracellular matrix regulation in human corneal epithelium before and after photorefractive keratectomy (PRK) in order to explain myopic regression following surgery.
Methods: Scrapings from 26 normal corneas before a first photorefractive keratectomy were randomly pooled in two samples of 16 and 10 scraping, respectively, and compared to another 23 scrapings from corneas with myopic regression after a previous photorefractive keratectomy, also randomly pooled in another 2 samples of 16 and 7 scrapings each. The scrapings were analysed for seven different messenger RNAs involved in extracellular matrix using competition-based quantitative reverse-transcription polymerase chain reaction.
Results: Messenger RNAs for TGFalpha (Transforming growth factor-alpha), TGFbeta1 (Transforming growth factor-beta1), EGF-R (Epidermal growth factor-receptor) and TIMP1 (Tissue inhibitor metalloproteinase-1) were present in all samples. No mRNA for MMP9 (Metalloproteinase 9) or MMP2 (Metalloproteinase 2) were detected in any sample. Messenger RNA for collagen (alpha1) III was present in one sample following photorefractive keratectomy.
Conclusions: The detection and measurement of levels of messenger RNA for selected growth factors, receptors, metalloproteinases and extracellular matrix proteins in ex vivo samples of human corneal epithelium is important and possible with a modified polymerase chain reaction technique. Messenger RNAs for Collagen III and for TGF-beta1 were elevated in one sample after photorefractive keratectomy.