Scientists have developed the first lab-grown sample of human skin that they say could replace animal testing in the cosmetic and topical drug industries. 

A team of researchers from King’s College London and the San Francisco Veteran Medical Center announced on Thursday that they were able to grow an epidermis that had the same permeability as real human skin, by using pluripotent stem cells.  Pluripotent stem cells are cultured from adult cells and can develop into any type of cell or tissue. 

Researchers say the artificial human skin offers a cost-effective alternative technique for testing drugs and cosmetics. 

“Our new method can be used to grow much greater quantities of lab-grown human epidermal equivalents, and thus could be scaled up for commercial testing of drugs and cosmetics,” Dusko Ilic, leader of the team at King's College London, said in a statement. “ We can use this model to study how the skin barrier develops normally, how the barrier is impaired in different diseases and how we can stimulate its repair and recovery.” 

The new study, published in the journal Stem Cell Reports, details how researchers triggered pluripotent stem cells to generate an unlimited supply of pure keratinocytes -- the primary cell type of the epidermis.  In a high-humidity environment, scientists grew three-dimensional epidermal samples. 

The samples engineered in the lab showed no significant differences in structure or function compared with real human skin samples, according to researchers. 

Since the 1920s, the U.S. and other industrialized nations have used animals to test the safety and effectiveness of various drugs and vaccines.  In the cosmetic industry, nonhuman test subjects, including rabbits, monkeys, rats and dogs, undergo skin and eye irritation tests in which chemicals are rubbed onto sections of shaved skin or dripped into the eyes of restrained test subjects.  Some are even forced to swallow large amounts of certain chemicals to determine what constitutes a lethal dose. 

While the use of animal testing, particularly Draize Testing, in which test substances are administered to the eye or skin has declined in recent years in the U.S. and Europe, it is still legal in 80 percent of countries.  According to the Humane Society, in China alone, an estimated 300,000 animal die each year in cosmetic tests. 

“Human epidermal equivalents representing different types of skin could also be grown, depending on the source of the stem cells used,” Ilic said. “[ They can] be tailored to study a range of skin conditions and sensitivities in different populations.”