Tuesday, February 05, 2008

Artificial Skin for Terminators (and People)

The basic plot of FOX's new series, The Sarah Connor Chronicles, has a familiar formula: Sarah and her son John - who will ultimately lead the human rebellion against the machines - are aided by a friendly and attractive cyborg from the future, Cameron, who helps protect them from a bad terminator, Cromartie.

In the series premiere Cromartie was shot with a high-energy rifle from the future and apparently destroyed. Not too surprisingly, his head - stripped of it's human-seeming flesh - survives, and contains programming for automated repair. Cromartie rebuilds the metal skeleton of his body, but still needs a flesh covering to appear human. To that end, he seeks out a scientist, Dr. Fleming, who is working on a formula for growing skin in vitro. In exchange for a formula that makes the skin grow extra super duper fast, the scientist helps Cromartie grow a covering of flesh. The process doesn't leave him very pretty, but at least he doesn't look like a robot any more:

The only thing Cromartie was missing was human eyes, which he also got from the docto - after killing him, of course.

In real life, skin can indeed be grown in a laboratory. The difference is that it takes a lot longer than a day. An example is a recent study that demonstrated growing new patches of skin from stem cells that are stuck to hair roots.
“We pluck a few hairs off the back of the patient’s head and extract adult stem cells from their roots, which we then proliferate in a cell culture for about two weeks. Then we reduce the nutrient solution until it no longer covers the upper sides of the cells, exposing them to the surrounding air. The increased pressure exerted by the oxygen on the surfaces of the cells causes them to differentiate into skin cells,” explains Emmendörffer. In this way, the researchers can grow numerous small pieces of skin, produced individually for each patient, which add up to a surface area of 10 to 100 square centimeters when pieced together.
A 10cm x 10cm (or 4 inch x 4 inch) patch would only replace a tiny portion of the 1.5-2 square meters of skin on an adult human. Starting with a larger piece of tissue the size of a postage stamp, enough skin to almost cover the entire body can be grown in just three weeks.

As yet, there are no artificial skins that can permanently replace human skin tissue, although biotech companies are working in that direction. An example of progress in that direction is Apligraf, an artificial living skin used to help heal ulcers and sores. Apligraf is constructed from human kerotinocytes and dermal fibroblasts grown from neonatal foreskin grown on a matrix of cow type I collagen. It has layers of cells like normal human skin, but has no sweat glands or hair follicles. Two other artificial skin products, TransCyte and Integra, help provide a scaffold for skin grown in burn patients, as CNN reported in 2003:

TransCyte contains skin cells called fibroblasts, which act as a kind of skin stem cell, growing, if conditions allow, into the variety of tissues that comprise healthy skin.

But they don't just grow; they need something to cling to, and TransCyte is made of a kind of scaffolding, not unlike a garden lattice that encourages vines to grow up around it.

Patients with third-degree burns, however, may require Integra to replace the dermal skin layer. It also provides a kind of scaffolding that helps the dermis regenerate itself, in part by tricking it into thinking there are healthy epithelial cells above it.

And while these products help promote skin growth, they only a temporarily replace normal skin. Artificial skins that can be permanently be integrated into the body are still in the testing stages. One such product is in development by British biotech firm Intercytex. As reported last summer:

Called ICX-SKN, the artificial skin mimics the process of natural wound healing. It is made up of a matrix of fibrin, which is a protein found in healing wounds. Fibroblasts – cells that produce collagen in natural skin – are integrated into the matrix.The matrix can be implanted into the wound, where it integrates with the patient’s own skin, closing the wound.In the study, the researchers cut small, oval sections of skin from the arms of six healthy volunteers, and inserted the artificial skin into their wounds. Within 28 days the wounds had fully closed, and showed relatively little scarring.

While further trials are ongoing, Intercytex already has related cosmetic products in the final testing phase, including ICX-TRC autologous hair regeneration therapy (cells used to treat male pattern baldness and female alopecia), and VAVELTA a "facial rejuvenation product" made of human dermal fibroblasts.

So, while it may be a while before skin can be replaced by simply bathing in cultured cells (cyborgs take note), the use of cultured cells to make us younger looking is right around the corner.

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