Readily available corneas for transplant is a crucial factor in vision care of corneal impaired patients. Current technology depends on a reserve of donor corneas at local eye banks that strain to keep up with demand. Innovative research is targeted to grow and maintain artificial corneas to increase available supplies. It is now possible to grow artificial cornea-like organs with all the major cell types found In the cornea with nerve cell processes. Not all the details of this work have been completed. Endothelial cells used for these artificial corneas originated from SV40 transfected cells whose karyotype and genetic makeup is questionable since these cells tend to express the antigen to develop numerous structural chromosomal abnormalities. Unfortunately, normal in vivo human corneal endotheal cells resist division past the 2nd decade of life. These cells also show a strong resistance to grow in cultures. Although it is possible to grow such cells in culture without SV40 transfection, the cells grow for only a limited period (about 2-4 doublings) and they are further limited by donor age. In 1998, it was shown that the life span of somatic cells could be immortalized, without the appearance of chromosomal abnormalities, by transfection of the hTERT gene. The hTERT gene is the human telomerase, reverse transcriptase catalytic subunit that, together with its RNA component, causes maintenance and lengthening of DNA telomeres. The length of telomeres, on the ends of cell chromosomes, is associated with both cell senescence and cell immortalization wherein longer lengths favor cell division. The gene (hTERT) for the catalytic component of human telomerase is normally silent in somatic cells. This study proposes to transfect human Corneal endothelial cells with hTERT in order to immortalize these cells (i.e. to convert them to actively dividing cells) in order to place them into cornea-like organs. It is anticipated that producing such immortalized cells will be instrumental in determining why these cells are reluctant to divide both in vivo and in culture. This will be done by studying the influence of telomeres on those cell-cycle control proteins whose genes are located close to telomeres.
| McGowan, Sara L; Edelhauser, Henry F; Pfister, Roswell R et al. (2007) Stem cell markers in the human posterior limbus and corneal endothelium of unwounded and wounded corneas. Mol Vis 13:1984-2000 |
| Paull, Amanda C; Whikehart, David R (2005) Expression of the p53 family of proteins in central and peripheral human corneal endothelial cells. Mol Vis 11:328-34 |
| Whikehart, David R; Parikh, Chirag H; Vaughn, Alexia V et al. (2005) Evidence suggesting the existence of stem cells for the human corneal endothelium. Mol Vis 11:816-24 |
