A new method of adult stem cell growth efficacious in treatment of disorders of the cornea

In concrete, the thesis defended by doctor Fernández Hortelano at the Faculty of Medicine of the University of Navarra, proves the therapeutic efficiency in using corneal stem cells in patients with pathologies of the cornea, such as caustications or ocular herpes, by using stem cells from a healthy contralateral eye. The technique is being currently applied to patients with satisfactory results.

The research has two essential parts. On the one hand, it describes the design of a new method of cell growth and, on the other, explains the clinical application of the procedure.

Growth in two stages

The research undertaken by the ophthalmologist has shown that, from a small biopsy sample, the new growth technique enables the growth of the number of stem cells thus obtained to the point of obtaining sufficient for the treatment to be effective. The cell sample is taken from the limb of the healthy eye – the ocular structure responsible for the transparency of the cornea.

The importance of this growth method lies in the fact that it enables the characterisation of the cells obtained, i.e. determining the quantity and viability of the units to be used.

The method developed combines culture on a plastic chip with that of an amniotic membrane one. The novelty of the technique focuses on the first stage – where the plastic chip is used. The fragment of tissue obtained from the healthy eye divides into smaller fractions which are grown on the chip. Thus a greater number of halos of stem cells are obtained (as many as the fragments of tissue). A sample of the cells obtained are then sent the Anatomic Pathology laboratory where the viability and quality of the cell units are verified.

The cells are transferred to the amniotic membrane growth culture, one that is highly suitable when dealing with stem cells that are to be transplanted for ocular regeneration treatment.

Once in the amniotic membrane, the stem cells expand in a homogeneous manner, enabling a better cell identification in order to select the most suitable units for the treatment. This method permits finding out with precision the cell population that we are implanting in the eye and to verify, thereby, both the quality and quantity of the cells transplanted.

Clínical application

The second part of the research involved the clinical application of the adult stem cells transplant in rabbits, which previously have had an epithelial corneal lesion induced, causing loss of corneal transparency. This is a pathology that does not respond to a corneal transplant nor to other conventional treatment.

The procedure used by Dr Fernández Hortelano involved obtaining this type of cell – corneal stem cells – by means of a biopsy of cells from a healthy eye of the rabbit. This is a small sample of cells – 3 by 4 mm – and so the contrateral eye is not in danger. A tiny number of cells thus being involved, it is necessary to grow the samples in order to obtain greater numbers of cells, an expansion achieved by transferring the culture to the amniotic membrane.

The adult stem cells obtained are implanted in the damaged eye and the limb is regenerated, this leading to the recovery of the corneal epithelium and, thereby, the transparency of the cornea. The results to date achieved amongst the group of rabbits, with induced limbic insufficiency and which then had a transplant of adult stem cells, showed recovery of the corneal epithelium in 60% of the treated animals. The corneal epithelium is the layer that is damaged with limbic insufficiency, a problem which, in the long term, results in opacity of the cornea.