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    Credit: Peter Arkle

Skin is a miraculous substance. Not only does this vital organ protect the body against disease and water loss, it also possesses the multiple functions of sensation, insulation, temperature regulation, and self-healing. When skin is badly damaged, however, the healing process is inhibited, resulting in discolored scar tissue.

Recently, scientists from Johns Hopkins University in Baltimore discovered that a new formulation of hydrogel encourages skin growth for burned areas that might otherwise be treated by grafts. The substance—which consists of water and a polymer called dextran—grows new skin in three weeks, complete with integral blood vessels, oil glands, and hair follicles. Moreover, the new growth is not scar tissue, but rather healthy skin that will likely be much less noticeable than traditional skin grafts.

“Our goal was to induce the growth of functional new blood vessels within the hydrogel to treat wounds” and diseases, says Guoming Sun, a postdoctoral fellow at Johns Hopkins. “These tests on burn injuries just proved its potential.”

The researchers believe that the hydrogel will be inexpensive to produce and can be manufactured at large volumes in only a few years. Sharon Gerecht, assistant professor of chemical and biomolecular engineering, predicts that U.S. Food and Drug Administration approval may be expedited since the hydrogel requires no biological components or drugs to function.

In addition to regenerating skin, hydrogel is also a material of choice for repairing cartilage, which, like skin, is difficult to regrow. The University of Bradford in England and a spin-off company, Advanced Gel Technology, have developed a method to replace damaged cartilage with hydrogel as a way to postpone joint-replacement surgery. Particularly suited to traumatic injuries, the procedure involves insertion of the gel through a small drilled hole in order to curtail pain caused by friction between bones.

“Total joint replacement is very successful, but may not be appropriate for younger, more active people,” says Pete Twigg, lead researcher at the university’s Cartilage Repair Project. “They are often encouraged to put off surgery until the pain is disabling, but a conservative replacement treatment could relieve pain and restore function at a much earlier stage.”

A more far-fetched human-tissue replacement material is “e-skin,” developed by scientists at the University of Tokyo. A kind of conductive elastic film created by adding an ionic solution filled with carbon nanotubes to rubber, the material is heat- and pressure-sensitive. Originally developed as a more humanlike surface material for robots, the electric rubber is being assessed for future incorporation in the human body.

In the meantime, e-skin will likely show up in flexible interfaces, from steering wheels to mattresses. “Objects that come into contact with humans are often not square or flat,” says University of Tokyo research associate Tsuyoshi Sekitani. “We believe interfaces between humans and electronics should be soft.”