Stem Cell Therapy Trial Reverses 'Irreversible' Damage to Cornea (newatlas.com) 15
Damaged corneas were repaired at a Harvard teaching hospital in a unique clinical trial, reports New Atlas:
Since it's on the frontline of potential hazards from the outside world, the cornea features a population of limbal epithelial stem cells, which repair minor damage to keep the surface smooth and functional... The new study, conducted by scientists at Massachusetts Eye and Ear, investigated a new treatment called cultivated autologous limbal epithelial cells (CALEC). This involves removing stem cells from a patient's uninjured eye, growing their population in the lab for a few weeks, then surgically transplanting them into the injured eye.
The phase 1/2 trial recruited 14 patients to undergo the procedure, and followed them for 18 months afterwards... By the first checkup at three months, the corneas of seven (50%) of the participants had been completely restored. By the 12-month mark, that number had increased to 11 (79%) patients. Two other participants met the definition for partial success, so the team claims an overall success rate of 92% for CALEC.
The phase 1/2 trial recruited 14 patients to undergo the procedure, and followed them for 18 months afterwards... By the first checkup at three months, the corneas of seven (50%) of the participants had been completely restored. By the 12-month mark, that number had increased to 11 (79%) patients. Two other participants met the definition for partial success, so the team claims an overall success rate of 92% for CALEC.
So why not do a cornea graft? (Score:2)
I know they don't always work.
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86%, 93%, and 92% of grafts resulted in complete or partial success at 3, 12, and 18 months, respectively.
I wonder if they could somehow revert some of the cells in that localized area (eye) back into stem cells? Would be as easy as eye drops. Its been found that most any cell in the body can de-differentiate with the right factors presented. Apparently that's also what cancer does. https://pmc.ncbi.nlm.nih.gov/a... [nih.gov]
Re:So why not do a cornea graft? (Score:5, Informative)
A few basic concepts:
1 - Epithelium - this the outer layer of cells, any part of the body, that interfaces between the ambient environment and tissues inside the body. E.g., for the skin, it is the epidermis. Inside your mouth, the oral mucosa - etc., every body surface has an epithelium.
The cornea has an epithelium, and it is very specialized to remain thin and optically clear.
The conjunctiva covering the sclera and eyelids also has an epithelium. One of its roles is to maintain moisture and lubrication over the eye, so it is more like oral mucosa, and in fact, mucosal grafts from inside the mouth are one of the important resources we use for reconstructing eyelids.
2 - Epithelial cells die and shed. That is their normal biology. That is why old skin flakes off, and new cells regenerating at the deep basal layer of the epidermis take their place. The human epidermis turns over, complete regeneration-replacement every 1-2 months. The intestinal epithelium is much zippier, turning over every several days.
Corneal epithelium does the same. But, to remain thin and optically clear, its source of regenerative basal or stem cells is not a diffuse underlying layer, as every elsewhere, but at the margin of the cornea, the limbus.
3 - Limbus - this where the cornea attaches to the sclera. That junction is highly specialized. It has special cells called LSC limbic stem cells. They have two purposes. One, they are the source of new cells for the corneal epithelium, and if they are deficient, the cornea eventually ulcerates or has other problems. Two, they are a barrier, telling conjunctival cells outside the perimeter to stay behaved and not grow up onto the cornea. If the LSC's are missing, then the cornea can become conjunctivalized, and it becomes opaque, and you cannot see.
4 - There are various conditions which damage, reduce, interfere with LSC's. There is along list of hierarchical treatments to address the causes, treat early, prevent damage, treat extant damage etc.
The report here discusses using the other good eye (assuming the problem is just unilateral, as it often is), as a source of LSCs to be grafted to the bad eye.
The concept is not new - it has 30-40 years of solid clinical work and success.
The problem is, that to get enough LSC's without damaging the good donor eye, you can only take small biopsies. So, taking a small donor then culturing it to grow more is the key.
This has been done elsewhere, e.g. Europe and Japan for a long time, but the methodology has not been approved in U.S. by FDA. This particular paper is not reporting on the concept of LSC transplant as a treatment mode - that is established - but on their homespun method of culturing the graft using only FDA approved methodology (and then confirming they had good results).
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As per your question - corneal transplant is not useful. It does indeed succeed in the short run, clear vision. But, cornea transplants do not transplant the limbus. Since these patients are missing limbic stem cells, the transplanted cornea succumbs to the same pathology, eventually getting conjunctivalized. Success after corneal transplant is maybe 1-3 years at best, then "back to square one". And, since these are donor organs, supply is not unlimited "off the shelf". So, that is why transplants are not part of the consensus on best treatments for LSC deficiencies.
Re: (Score:2)
Thanks for the explanation.
"thermal or chemical burns can damage the cornea beyond the capability of these resident stem cells"
This implies that there already are LSC's at the periphery of the cornea of the damaged eye. I am wondering why they wouldn't eventually be able to implement a repair. It seems like adding more from a culture would merely speed things up.
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And, a followup thought to my last comment -
The study done was good - the kind of nice incremental work that makes medicine and clinical results keep getting better.
The authors know what they are talking about.
Doctors reading know what they are talking about.
"Stem cells" are just a term for an anatomical structure, so nothing extraordinary.
BUT - if there is a non-technical website (New Atlas site linked to at the start of this post), and their correspondent or "science reporter" sees "Stem Cells", that beco
Re: (Score:2)
I know they don't always work.
Apparently some damage is too great for a cornea graft, and there is no rejection risk. Anyhow, here is a better link. https://www.nature.com/article... [nature.com]
Fantastic news (Score:3)
The next question will be what the cost/benefit ration is...
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Re: (Score:2, Troll)
If people want to keep their eyes they should pay for it. We have too many other things to pay for that are more important (that we still won't pay for anyway).
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The research will still be valuable to civilized societies who do not accept for-profit healthcare for their citizens
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Explain this being first available to patients in Boston.
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It's experimental and the people treated are free test subjects.