Starts in 2018, when surgeons from Massachusetts eye and ear perform this trial with four patients who experienced chemical burns in one eye. Surgeons replace their ocular surface with their own stem cells taken from their healthy eye using a technique known as 'cultivated autologous limbal epithelial cell transplantation (CALEC). This whole trial is funded by the National Eye Institute.
This is the first trial in the United States to use cultivated stem cells from a patient's own body to replace the damaged cornea. The cultivated stem cell technology has not been yet used in the United States; it has been in other countries but not in the US.
Massachusetts eye and ear achieved this big success by collaborating with, Boston Children's Hospital and Dana-Farber Cancer Institute.
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What is CALEC stem cell surgery?
Before getting into CALEC it’s important to know that our cornea is constantly renewing itself by corneal epithelial cells just like skin cells do and a lot of have corneal blindness from loss of limbal epithelial cells because when there's a loss of the stem cells of a cornea, the cornea becomes opaque and people lose vision.
Limbal stem cells deficiency: Causes
- Chemical burn-in eye.
- Complications from contact lenses.
- Various eye infections.
- Eye injury.
Before CALEC, Surgeons do not have a good way of replacing damaged cornea stem cells because in order to repair a damaged cornea in one eye they require lots of stem cells from other eye but with this new technology named CALEC, they can regenerate these cells in the laboratory.
CALEC developed by researchers at Massachusetts Eye and Ear, Boston Children's Hospital, and Dana-Farber Cancer Institute. They performed the first CALEC procedure as part of an ongoing clinical trial in April 2018.
CALEC
A small amount of stem cells is taken from a healthy eye of a patient and make more of them in the laboratory, and then replace these newly regenerated stem cells onto the damaged eye.
The complete process of CALEC involves five important steps:
1. Safely securing limbal stem cells from a healthy eye in a patient or taking a small biopsy from the healthy cornea of a healthy eye.
2. Putting these extracted stem cells on the membrane in the laboratory.
3. Using an ex-vivo cultivation system to expand these stem cells on the membrane in the laboratory.
4. The media needs to be changed and replaced with fresh media to keep them growing.
5. Safely transplant these regenerated stem cells back to the affected eye of a patient.
It's a very detailed process there are a lot of checks of the cells at various times as they're growing. All of that requires about three weeks and a very specialized laboratory that has the people that are trained and have the skills to do this.
The procedure restores vision for the patient as well as reduces their discomfort.
Treatments Available Today
1. Transplantation of an artificial cornea in the eye.
2.Conjunctival limbal autograft (CLAU) technique.
Using transplantation of an artificial cornea have the risk of developing infection and there is also a risk of glaucoma.
Comparison between CLAU and CALEC
CLAU technique is pretty much similar to the CALEC but in CLAU a large number of stem cells secured from healthy and then these limbal stem cells replace directly in the damaged cornea.
But on the other hand, CALEC required a very small portion of these limbal stem cells reduce complications and also reduce risk on healthy eye.
Advantages of CALEC:
- Since these stem cells are taken from patients healthy eye hence does not carry the risk of rejection like some other procedures.
- Long-term steroids or immunosuppressive medications are not needed.
We can potentially bypass the need for a transplant. In many of these CALEC patients if we're able to reverse the corneal haze as a result of stem cell insufficiency that'll be a great contribution to ophthalmology.
- Dr. Reza Dana, professor, director at Mass. Eye and Ear
Conclusions made so far
Dr. Jurkunas (affiliate faculty member of the Harvard Stem Cell Institute) shared some conclusions they get after successful trials on the first three patients:
- CALEC is safe and feasible.
- The early results have been really fantastic.
- Patients do not have any type of side effects so far.
- Results really have been very compelling and very positive thus far.
After their successful trial now researchers have begun to recruit more patients with corneal damage into a second phase of the trial, which will continue through 2021.
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