Skin Factory A Stuttgart Lab's Pioneering Effort to Cultivate Human Flesh
Part 2: 'Incredibly Difficult, Time-Consuming Work'
Walles speaks about how she also tried one of these projects once. She reaches for a blood-red object on her desk, a tube approximately the width of a finger, with delicate capillaries woven around it. The object is a replica of a trachea transplant Walles once developed with her husband, cardiothoracic surgeon Thorsten Walles.
For example, a suicidal 28-year-old man had swallowed drain cleaner because his girlfriend had left him. Though doctors were able to save his life, his trachea had suffered irreparable corrosion.
The bioengineers at the IGB promised to create a replacement. As their basis, they took a section of pig intestine and the veins that supplied it. Then, they stripped it of its porcine cells until all that was left was a fiber framework, which they sowed with human vascular, connective tissue and muscle cells.
The researchers created custom-made transplants of this kind for four patients, of which the 28-year-old was the third. "It was an incredible amount of very difficult, time-consuming work," Walles says. Doing so might make sense for helping a couple of seriously injured patients, she says, but it would be very hard to introduce as a standard technique in clinical practice.
Walles' experience in tissue engineering has only strengthened her conviction that this type of laborious tinkering will never lead to the emergence of a new branch of medicine. Indeed, she believes it will only be possible to create new products satisfying the requirements for widespread medical use if machines can be made to do the arduous, hands-on work now performed by lab technicians.
To that end, Walles set her sights on learning everything she could about stress tests and error analysis from engineers and process technicians. For their part, the technicians now had to teach their robots to handle human tissues rather than the fiber optics and condensers they were used to. The result is a manufacturing process bearing little resemblance to a traditional scientific laboratory.
Legal Hurdles to Testing
This laboratory produces strictly standardized compounds designed to meet legal requirements. In the beginning, regulatory authorities weren't quite sure how to approach these various synthetic cells, organs and tissues. "The question was: What are we really dealing with here? Are these body parts, drugs or medical-technology products?" explains Klaus Cichutek, head of the Paul Ehrlich Institute (PEI), the agency within Germany's Federal Ministry of Health responsible for regulating vaccines and other biological medicine products.
Since then, the EU has decided that tissues grown outside the human body -- regardless of whether they are skin, bone, liver or nerves -- are to be treated as pharmacological substances. This means that instead of simply trying out new methods on patients, as is common with surgery, tissue engineers must pass a licensing procedure set forth in pharmaceutical law.
"At the moment, the European Medicines Agency is perhaps our biggest hurdle," says Michael Sittinger, a cell biologist at Berlin's Charité Hospital who has been involved in tissue engineering for 20 years. Sittinger recently patented a type of cell specific to heart tissue that he hopes to use to treat cases of chronic cardiac insufficiency, and he is drafting a proposal for a clinical study.
The tissue engineers in Stuttgart believe that the chances that their industrially manufactured skin will receive approval are very good. Even so, they are not planning on rushing their products into standard clinical practice. They first have their sights set on finding clients in the chemical, pharmaceutical and cosmetic industries before putting them on the market for skin grafts for burn victims or people with wounds that are difficult to heal.
In 2006, the European Parliament passed a new regulation on chemicals and their safe use that drastically increased the number of animal tests required before a product can be approved for market use. Since then, an urgent search has been on for alternative methods of testing how new substances affect skin. This is precisely where the manufacturing facility in Stuttgart could come into play.
In other words, this method of tissue engineering is unlikely to start saving human lives any time soon. But it may stand between thousands of animals and death.
Translated from the German by Ella Ornstein
- Part 1: A Stuttgart Lab's Pioneering Effort to Cultivate Human Flesh
- Part 2: 'Incredibly Difficult, Time-Consuming Work'