Abstract
Abstract: :
Purpose: To characterize changes over time in the genomic expression profile of rat corneas during healing of excimer laser wounds. Methods: Corneal gene expression profiles of 8799 known genes and ESTs at days 0, 1, 2, 3, 4, 5, 6, 7, 14, 21, 42 and 98 following PRK were determined by interrogating cDNA chip arrays prepared by Affymetrix with labeled target cDNA prepared from pooled total RNA harvested from the respective treatment groups of adult male rats. Gene expression patterns were based on the hybridization intensities of the probes on the cDNA chip arrays. The hybridization signals were normalized, filtered, and the data were analyzed using hierarchical and K-means clustering algorithms before and after variance normalization. Results: Of the 8799 known genes and ESTs, 5808 were identified as being expressed above background levels on at least one of the experimental time points. There was a clear trend separating the early days of corneal wound healing (days 1, 2, 3, 4,and 5) from the intermediate days of healing (days 6, 7, 14, 21) and from the very late days of healing and non-wounded cornea (days 0, 42, and 98). Cluster analysis of selected genes previously studied in corneal wound healing revealed close relationships in gene expression profiles among several key genes. The expression of genes such as transketolase, aldehyde dehydrogenase 1, beta crystallin genes, and gamma crystallin genes decreased sharply at day 1 and slowly returned to their original levels by day 98. MMPs and TIMPs such as MMP-7, MMP-9, MMP-2, TIMP-1 and TIMP-2 tended to rise during the early stages of wound healing while genes such as the collagen genes and genes from the TGF b family increased in expression at the intermediate stages of wound healing. Several ESTs were also identified as possible candidates for genes involved in corneal wound healing not previously identified. Conclusion: Microarray analysis of gene expression following excimer laser surgery identified distinct expression profiles of several key families of genes in healing rat corneas and may aid in the understanding of the molecular environment during corneal wound healing.
Keywords: 417 gene/expression • 631 wound healing • 552 refractive surgery: PRK