Scientists and biomedical engineers have taken 3-D printing to a whole new level: They've developed a printer that can print human skin. Bioprinting live skin is revolutionary not only because it represents one of the first bioprinted organs but also because of its important potential in the treatment of burn victims.

Traditional 3-D printing works by creating layers with resin and inks. Input an image of a circle, and voila — out comes a tangible ball made of resin. Bioprinting works in the same layering manner; however, cells and biological components replace inks and resin.

The natural structure of the skin is produced with an external layer, the epidermis, then with a deeper layer, the dermis. This last layer consists of cells that produce collagen, the protein that gives elasticity and mechanical strength to the skin.

Getting the exact biological mix can be the difference between live skin and a soup of dead cells. Juan Francisco del Cañizo, of the Hospital General Universitario Gregorio Marañón and Universidad Complutense de Madrid, a researcher on the project said, "Knowing how to mix the biological components, in what conditions to work with them so that the cells don't deteriorate, and how to correctly deposit the product is critical to the system."

The "skin printer" is the brainchild of Spanish researchers at Spain's University of Madrid, and it holds tremendous promise for burn victims who currently rely on skin harvested from other parts of their bodies to replace burned, dead skin. With biomedical printing, a small patch of cells would be all that's needed for replicating and biomedical printing.

Printed skin can find practical application in the cosmetics and pharmaceutical industries — useful for testing without animals. The skin could also be used in consumer chemical applications.

The breakthrough was published in the electronic version of the scientific journal Biofabrication.