Using stem cells paves new approach to treating a blistering skin disease

Imagine a child not being able to run or jump or just roll around, for fear that any movement could strip away their skin and leave them with open, painful wounds. That’s what life is like for children with a nasty genetic disease called epidermolysis bullosa or EB. The slightest touch can cause their skin to peel off. People with the disease often die in their late teens or early 20’s from skin cancer, caused by repeated cycles of skin wounding and healing.

Now Stanford researchers, funded by the stem cell agency, have found a way to correct the faulty gene and grow healthy skin, a technique that could completely change the lives of children with EB. This new approach, which the researchers call “therapeutic reprogramming”, is reported in the journal Science Translational Medicine

In the study the researchers took skin cells from patients with EB and reprogrammed them to become induced pluripotent stem (iPS) cells that have the ability to become any of the other cells in the body. They then replaced the faulty gene that caused that particular form of EB and then turned the cells into keratinocytes, the cells that make up most of our outer layer of skin. When they grafted these cells onto the back of laboratory mice they grew into normal human skin.

In a news release about the work, Dr. Anthony Oro, one of the senior authors of the paper, says the work represents a completely different approach to treating EB.

“Normally, treatment has been confined to surgical approaches to repair damaged skin, or medical approaches to prevent and repair damage. But by replacing the faulty gene with a correct version in stem cells, and then converting those corrected stem cells to keratinocytes, we have the possibility of achieving a permanent fix — replacing damaged areas with healthy, perfectly matched skin grafts.”

One of the key words in that quote is “healthy”. Because the skin cells that they got from the patient probably already included some that had a skin cancer-causing mutation, the researchers carefully screened the cells to make sure they removed any that looked suspicious.

Oro says tests showed the resulting skin from these iPS cells was very similar to human skin made from normal keratinocytes.

“The most difficult part of this procedure is to show not just that you can make keratinocytes from the corrected stem cells, but that you can then use them to make graftable skin. What we’d love to do is to be able to give patients healthy skin grafts on the areas that they bang a lot, such as hands and feet and elbows — those places that don’t heal well. That alone would significantly improve our patients’ lives. We don’t know how long these grafts might last in humans; we may need some improvements. But I think we’re getting very close.”

Having seen that this works in mice the team are now eager to see if they can replicate their results in people. With CIRM support they have already been working with the Food and Drug Administration (FDA) to pave the way for that to happen. Dr. Marius Wernig, one of the senior authors of the paper, says that focus on patients is driving their work:

“CIRM made sure that we were always keeping in mind the need to translate our results to the clinic. Now we’ve shown that this approach that we call ‘therapeutic reprogramming’ works well with human cells. We can indeed take skin cells from people with epidermolysis bullosa, convert them to iPS cells, replace the faulty collagen 7 gene with a new copy, and then finally convert these cells to keratinocytes to generate human skin. It is almost like a fountain of youth that, in principle, produces an endless supply of new, healthy skin from a patient’s own cells.”

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