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Cell Lines Replicate Human Skin

It’s a huge challenge: skin must be waterproof, flexible and a barrier against infection. Both the cells that make up the outermost layer of the skin and the structure of how the cells fit with each other must be duplicated. So far, no one has figured out how to synthetically make our body’s largest organ.

The lab-made skin available today only offers a partial solution. It’s grown from cells but often only consists of a base layer that the patients’ own skin is laid onto during the grafting process to give cells a foothold to grow into:

  • It serves the immediate need of closing wounds and facilitating the growth of patients’ new skin cells, but … lacks the proper three-dimensional structure,
  • These skins have no hair follicles or sweat glands, so recipients can’t sweat and cool themselves properly,
  • Even with artificial skin as a base layer, grafts often don’t take and skin will “slough off,” causing the surgeon to have to repeat the process.

Currently, the best treatment for patients involves painfully scraping off patches of their own healthy skin from other parts of their body and grafting it onto the injured areas. However, some severe burn patients, babies and elderly people don’t even have enough intact skin to use for grafting.

  • In these situations, cadaver skin is sometimes used, but …  may be rejected by the patient’s immune system.

Artificial skin could speed up healing for burn patients and people with chronic skin wounds, giving them a more natural appearance. And it could eventually replace animal testing for products like cosmetics and shampoos.

  • Lab-produced skin may one day be used to treat chronic skin wounds like peripheral arterial disease and diabetic foot ulcers; more than 10% of diabetics have a history of foot ulcers, according to a 2003 study by the Centers for Disease Control and Prevention.

Researchers including Dr. Lynn Allen-Hoffman at the University of Wisconsin, Madison are tackling the problem by developing cells that mimic the growth of our own skin cells. For more than 10 years, Dr. Allen-Hoffman, pathology and laboratory medicine professor and her colleagues were growing human skin cells from different donors in lab dishes;  noticing that one type appeared to live much longer and healthier lives than other skin cells they were studying.

  • These cells stopped growing at the point where they touched each other, which suggested they were unlikely to cause tumors,
  • The cells appeared to grow into all the strata of the outermost layer of natural skin, called the epidermis, creating a stronger and potentially more effective solution for patients than skins with just a single stratum of epidermal cells,
  • The serendipitous discovery led her to study the cell line in detail by cloning the cells in order to have an infinite supply of genetically identical ones. She also formed Stratatech Corp to try to develop the cells into a viable lab-produced skin product.

To figure out if the cells could grow into natural skin in a lab dish, the researchers needed to color code the skin.

  • By adding jellyfish DNA to the cells, the researchers were able to produce a layer of green skin,
  • Then, by grafting it onto a mouse, they showed that the skin cells continued to grow, forming new green skin on the animal.

The group is now studying if the cells are safe to use in humans, Dr. Allen-Hoffman says. They treated 15 severely burned patients with the skin for seven days and demonstrated that it was safe for short-term use. A longer-term study will follow patients up to three months post-grafting.

  • Key questions that researchers will be looking at in the trial: Will patients’ bodies reject the skin?
  • One of the benefits of using one’s own cells for grafting is that the body recognizes the skin. Skin derived from Dr. Allen-Hoffman’s cell line doesn’t have immune cells so it shouldn’t be acutely rejected,
  •  Also, will lab-derived skin grow hair follicles and sweat glands of normal skin,
  • It remains to be seen whether this type of lab-derived skin is as good as the skin from patients’ own cells. (HWM and SS Wang,WSJ)