Reconstructing an aging eye with Stem cells (3/20/2007)

Preoperative status of patient's eye showing vascularization and conjunctival invasion of the cornea surface.

11 months post-op the sight has been restored to a visual acuity similar to pre-condition sight.

The cornea, the area over the coloured part of the eye, is normally covered with a thin layer of "epithelial" cells similar to skin cells and as in the skin, the outer layer of cells are constantly shed and replaced from its surface. Due to damage from injuries or disease, the ability of the eyes to produce replacement corneal epithelial cells may be impaired. The cornea becomes cloudy, the vision deteriorates and the patient experiences considerable discomfort. A standard corneal graft will only temporarily replace the surface cells, as there will be no new cells to replace the old cells once they are shed. Stem cells on the surface of the eye are located at the limbus, the junction of where the corneal meets the sclera (where the white part of the eye meets the clear cornea).

Dr. Liz James, Head of Research at the Blond-McIndoe Centre, has worked to provide ophthalmic surgeons at the Corneoplastic Unit with sheets of corneal epithelial stem cells to graft onto the patient's cornea, in order to stabilize and protect the cornea surface with new cells. Often, the source of cells is a small biopsy the size of a pin-head from the patients other eye, providing this is healthy and not damaged. In other cases, the stem cell donor tissue may come from a close relative or from eyes donated to the Queen Victoria Hospital Eye Bank. In all cases, presumed stem cells from the small tissue sample are grown in culture and then grafted onto the eye of the patient.

In collaboration with Mr Sheraz Daya, Queen Victoria Hospital (Director of the Corneoplastic Unit and Centre for Sight), several patients have been treated using grafts of these cultured cells. The patients had severe deficiencies for many years, and other conventional treatments had failed. The first three patients were grafted more than 5 years ago, and after their corneal surfaces had stabilized using this new technique they were given a cornea graft in the centre of the eye to restore their vision. Importantly, these patients did not show any detrimental effects of the treatment.

The treatment has now been extended and stem cell transplants are offered to patients with serious corneal surface disease.

One biological question they have tried to answer is whether the cultured donor cells have survived sufficiently long to be able to stimulate the regeneration of the patient's own tissue. Using forensic DNA fingerprinting techniques, Justin Sharpe has been able to show that donor cells can be demonstrated on the cornea over the first 3 to 4 months, and that the good epithelial recoveries they have observed over the longer term seem due to the patient's own cells. This they believe is a breakthrough and has considerable future implications. At a minimum, the need for long term immunosuppression following surgery may not be necessary.

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