Scientists Repair Eyesight Using Human Cornea From Stem Cells

Constant shortage of donated corneas have led researchers in Sweden and Spain to explore the possibilities of cultivating corneas from human stem cells.

Two separate studies from the University of Navarra Hospital, Spain and Sahlgrenska Academy University of Gothenburg, Sweden, have attempted to cue in on developing the epithelial cells that keep the cornea in its transparent form.

While Swedish scientists have grown stem cells on human corneas, their Spanish counterparts have regenerated the corneal epithelium using cells from the healthy limbus of patients with corneal damage.

A corneal transplant is the only way to prevent total blindness. The result is that nearly 100,000 corneal implants are impacted globally each year. The process calls for replacing the damaged cornea with a healthy and transparent one, relying heavily on donors. Religious or political views have also attacked the medical outcomes of corneal implants adding to long waiting periods for donor-led corneal transplants.

Swedish Scientists Grow Cornea in the Laboratory

In a first-time effort, scientists at the Sahlgrenska Academy have grown stem cells on human corneas which could perhaps do away with donated corneas in the long run.

The Swedish study published in the journal Acta Ophthalmologica explored ways to develop epithelial cells using laboratory cultures for 16 days, which were further cultured on the human cornea for another six days.

Lead scientists Charles Hanson and Ulf Stenevi used defective corneas from the ophthalmology clinic at Sahlgrenska University Hospital in Mölnda for their experiment.

Similar experiments have been carried out on animals, but this is the first time that stem cells have been grown on damaged human corneas. It means that we have taken the first step towards being able to use stem cells to treat damaged corneas, said Hanson.

If we can establish a routine method for this, the availability of material for patients who need a new cornea will be essentially unlimited. Both the surgical procedures and the aftercare will also become much more simple, added Stenevi.

Spanish Researchers Transplant Adult Stem Cells From The Limbus Of A Healthy Eye

Spanish ophthalmologists at the University of Navarra Hospital attempted to regenerate the corneal epithelium by using cells from the healthy sclerocorneal limbus of patients with corneal damage. Limbus is the ocular or visual area that is responsible for cell regeneration of the corneal epithelium.

Limbal insufficiency may manifest itself at various levels, depending on the number of stem cells affected. In some cases, the patient can completely lose the sight of the affected eye, explained Doctor Adriano Guarnieri, cornea specialist at the Ophthalmology Department, University of Navarra Hospital.

Considered as one of the largest monitoring programs for the transplant of cultured corneal cells in Spain, ophthalmologists at the University of Navarra Hospital have been experimenting with this transplant technique for the past eight years.

The transplant technique involves a small biopsy sample of about 2 mm2 from the healthy limbus. The sample is small enough and does not harm the healthy eye. Stem cells extracted from the healthy limbus are suitably grown for several weeks following which, the newly obtained stem cells are transplanted on to a support medium such as an amniotic membrane.

Guarnieri explained that these stem cells are re-grown in the amniotic membrane and on achieving a good enough cell population, the stem cells are transplanted onto the affected eye in the same amniotic membrane itself.

We thus manage to maintain the limbal cells transplanted to the surface of the eye, in such a way that these stem cells cover the ocular surface and lodge themselves in the affected limbus, until the damaged epithelium regenerates and recreates a transparent and homogeneous corneal surface. The end result is achieving enhancement in the vision of the patient and their symptoms, noted Guarnieri.