Stems Cells Successfully Transplanted onto Human Cornea

Scientists for the first time successfully cultivated human embryonic stem cells (hESCs) on damaged human corneas. The procedure may in the future lead to removal of the current dependence on donated corneas of which there continues to be a shortage.

Of the approximately 100,000 corneal transplantations carried out worldwide each year, about 500 take place in Sweden, many of which are carried out at the ophthalmology clinic at Sahlgrenska University Hospital (Mölndal, Sweden). The damaged and cloudy cornea that is turning the patient blind is replaced with a healthy, transparent one. In collaboration with scientists at the Sahlgrenska Academy of the University of Gothenburg (Sweden) and others, defective corneas obtained from the clinic were used in a study to investigate whether cells originating from hESCs could be successfully transplanted onto a partially wounded human cornea, and to examine the ability of the transplanted cells to further differentiate into corneal epithelial-like cells. It is the epithelial cells that maintain the transparency of the cornea.

The method involved in vitro transplantation of differentiated hESCs onto a human corneal button (without limbus) from which the epithelial layer was partially removed. The cells were cultured on Bowman's membrane and the culture dynamics were documented in a time-lapse system. The transplanted cells originated from a genetically engineered hESC line that expresses green fluorescent protein, which facilitated their identification. To detect differentiation into corneal epithelial-like cells, the transplanted cells were analyzed periodically for several days by immunohistochemistry using antibodies specific for relevant markers. The transplanted cells established and expanded on Bowman's membrane, forming a 1-4 cell layer surrounded by host corneal epithelial cells, and expression of a corneal marker began to appear 3 days after transplantation.

The success of these experiments represents an important step towards replacing donated corneas with corneas cultivated from stem cells. “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 Charles Hanson, first author of the study and Associate Professor at the Sahlgrenska Academy.

“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 Ulf Stenevi, senior author of the study and Professor at the Sahlgrenska Academy.

The study was published in the journal Acta Ophthalmologica online ahead of print January 26, 2012.

Related Links:
Sahlgrenska Academy, University of Gothenburg
Sahlgrenska University Hospital