In a laboratory at the Fraunhofer Institute for Interfacial Engineering and Biotechnology (IGB) in the southwestern German city of Stuttgart machines have just begun to produce an unusual product: human skin.
Each month, this skin factory will produce 5,000 discs of tissue about the size of a one-cent coin, with a projected price of €50 ($72) per unit. The product is a whitish color, almost transparent, though project director Heike Walles says it can also come in shades of brown. A biochemist, Welles has dedicated her entire career to culturing tissue.
15 years ago, brothers Jay and Chuck Vacanti created an ear-shaped cartilage structure and grafted it onto the back of a mouse.
When the Vacantis presented the world with photographs of their project, they also offered a bold vision of the future of medicine. They promised the dawning of a new era in the history of transplant medicine. Since human tissue could be custom-made, they said, there would never be a shortage donor organs again.
The Vacantis also described how fully functional human hearts would grow in flasks and how livers would rise in incubators like loaves of bread. Chuck Vacanti even said it would be possible to produce entire limbs and provided a sketch of a synthetic arm. The brothers called their new industry “tissue engineering.”
All of the tissue engineering efforts so far have been isolated cases and heroic pioneering acts that never made their way into daily clinical practice. Indeed, tissue engineering remains a refined handcraft, one that requires a great deal of tinkering and patience. Bioengineering laboratories now grow dozens of different cell types on spongy, rubbery or gelatinous frameworks, but most of these constructions are not suited for use in humans.
Blood circulation, in particular, has presented researchers with many problems, and attempts have repeatedly failed to produce blood vessels that can supply synthetic organs with oxygen and nourishment.
Cartilage is the only type of tissue uncomplicated enough to be manipulated with relative ease. Each year, surgeons in Germany implant around 600 pieces of artificial cartilage, and the number of patients with lab-grown cartilage cells infused into their damaged knee joints or spinal disks has climbed into the thousands. But scientists looking to make other types of tissue ready for clinical use find themselves facing far greater obstacles.
Automating Tissue Engineering
Walles 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.
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.
In Germany, a mechanical arm snaps up a small plastic container full of a sloshing pink solution. A laser beam flits over the liquid, then another robot rolls up on a steel track, motor purring, and drizzles a few drops through hair-thin pipettes. A monitor records temperature, carbon dioxide and humidity levels.
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.
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.