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Limbal stem cells

What are limbal stem cells?

The limbus is the junction between the cornea (clear part of the eye) and the sclera (white part of the eye). The limbus is the site of stem cells for the cornea. These cells have the capacity to keep on dividing throughout a person’s lifetime, replenishing cells that are being sloughed off .

What is limbal stem cell deficiency (LSCD)?

The limbal stem cells are few in number and can be damaged by a number of different disease processes, chemical injury, thermal burns, extended contact lens wear, aniridia, etc.

How can limbal stem cell deficiency (LSCD) be treated?

If you have LSCD, conventional treatments like corneal transplants may not work as well, since you are not able to renew the outer layer (the epithelium) of your new cornea using your own limbal stem cells. This might lead to repeated corneal breakdown of the corneal epithelium, pain, loss of vision and/or photophobia.

Current available treatment modalities include lubricating drops in cases of mild LSCD, or a surgical procedure in cases of severe LSCD where a piece of donor limbus is grafted onto the eye.  This new treatment strategy involves taking a small piece of the donor limbus and growing the limbal stem cells from the biopsy onto an amniotic membrane. This membrane, along with the stem cells, is transplanted onto the eye and covered with a bandage contact lens. 

Description of the research

Taking the biopsy

A very tiny limbal  biopsy is removed under local anaesthesia in the operating room

Autologous transplant

In cases where one of your eyes is aff ected and the other has a normal population of stem cells, an “autologous cultivated limbal stem cell transplant” will be done. This means that a tiny biopsy is removed from the limbus of your good eye and sent to the laboratory.

Allogenic transplant

In cases where either, both your eyes are aff ected, or you have only one eye, an  “allogenic cultivated limbal stem cell transplant” will be performed. This means the limbal biopsy will be taken from either the limbus of a close relative or a donor eye from the cornea bank. 

Growing the Stem Cells

In the laboratory, your stem cells from the biopsy will be stimulated to grow, under optimal growth conditions, onto an amniotic membrane. It will take 2 weeks before your stem cells have expanded and formed a thin layer on the amniotic membrane, ready for transplantation.

The surgery

During the surgery, the cultivated stem cells along with the amniotic membrane will be transplanted onto your eye. You will be asked to wear a bandage contact lens in order to protect the transplanted cells for a few days.

After the surgery

You will be observed closely by your doctor following the surgery and will receive some drops and will be given directions on how to instil them into your eye. Please inform your doctor if you are experiencing:

• pain
• light sensitivity
• decreasing vision

Follow-up examinations after completion of the treatment will be performed on a weekly basis for the fi rst month. You will be given a schedule for further follow-up visits by your doctor.

Special tests

There are a number of special tests that will have to be performed in order to monitor your eye before and after the surgery.

• Anterior Optical Coherence Tomography
• Ocular Confocal Scanning
• Schirmer’s test
• Collection of tear samples

Medication

Autologous serum drops

These drops are prepared from the clear part of your blood. This autologous serum provides nourishment for the transplanted cells and promotes good cell growth. Since these drops are preservative free, you will be required to thaw a new bottle each day and throw away any unused serum after 24hours. This is done to prevent contamination.

Immunosuppression

If the donor is not well matched, in order to prevent an “immune response” and eventual rejection of the transplant, drugs will be given to suppress your immune system. These drugs are called immunosuppressants.

Pretreatment assessment

Since immunosuppression means that your body’s normal defence mechanisms will be reduced, before you can receive this treatment, you will have to undergo a series of tests:

• a chest X ray
• blood and urine tests for signs of infection
• a complete physical examination

More information

For more information on limbal stem cell transplantation (LSCD), please read the brochure 'Limbal stem cell transplantation'.