Method for expansion of epithelial stem cells
Patent Number: 7,347,876
Corneal transplants are performed as a result of chemical or inflammatory injury to the clear part of the eye. Efficacy of corneal transplantation is decreased when the limbal stem cells which produce corneal epithelium are damaged or defective. Accordingly, transplantation of limbal stem cells has been performed clinically. A report in 1999 documented positive effects in some of the 70 patients treated. One of the issues with limbal stem cell transplantation is lack of donors or poor quality of the donor graft. The current patent addresses this problem by expanding ex vivo corneal epithelial stem cell.
The current patent has 2 independent claims. The first one covers "a surgical graft" that is made of:
- an amniotic membrane
- an extracellular matrix
- epithelial stem cells.
The second independent claim covers "a method for creating a surgical graft" through the steps of
- placing healthy epithelial stem cells in an isolated amniotic membrane
- enabling healthy epithelial stem cells to expand on the membrane
A very interesting point is that while the filing date of the patent is 2001, a recent publication (Yeh et al. Cryopreservation of Human Limbal Stem Cells Ex Vivo Expanded on Amniotic Membrane. Cornea 2008 Apr;27(3):327-333) not only demonstrated that limbal stem cells can be expanded in vitro on amniotic membranes but also that they can be cryopreserved for later use.
Noteworthy for people interested in this patent, an issued patent exists covering methods of collecting limbal stem cells, as well as the expansion of conjunctival stem cells is also patented.
View this patent on the USPTO website.
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jrowley said...
I think I have said this before, but this is a great service. I like the info on the claims that you are adding, as well as the added context with other patents that it relates to.
As for the technology, I wonder:
1) how scalable the amniotic matrix is to make and use
2) if it is similar to the placenta-derived biomaterials that Celgene acquired as part of the Anthrogenesis technology, and
3) if the cells need to be continually expanded on these materials or if they can be 'weened' from the membrane onto tissue culture plastic for later passages.
Interesting technology....