â€œWhen we have the ability to replace failing organs or tissues, both the duration and quality of life should increase significantly.â€?
AD: What makes tissue engineering such an important field of research?
KA: Tissue engineering represents the next frontier in biomedicine. For the first time in medical history, we are hopeful that we will achieve regeneration of tissues and organs that have been traditionally considered to be non-healing. Examples include articular cartilage, tendons, kidney, nerves and even the heart.
AD: How far away are we from building whole organs, bones or even limbs? What are the problems with growing limbs in laboratories?
KA: We may not be as far from building a portion of a limb as one might think. Some experiments have already resulted in small, accurately built bones. The main issue with growing limbs in the lab is the sheer size of the tissue that needs to be grown. There are numerous scientific constraints on how large a tissue or organ one can produce. Equally, if not more complex, are issues of incorporating cartilage, tendons, ligaments, vascularity and nerves into the final product. Not an easy quest.
AD: How will engineered organs change the transplanting process?
KA: Mr. Doe, a young adult, is playing football, when he sustains a bad injury in his knee, fracturing one of his knee menisci. His orthopedic surgeon consults a catalog of standard sizes from his friendly tissue engineering company and orders an appropriate sized meniscus. The meniscus arrives the next day and the patient receives a brand-new, fully functional, fully biological and fully compatible meniscus, which is inserted and attached arthroscopically; essentially using a small portal in his knee. Where issues of acceptance or rejection are extremely important, the physician will extract primitive cells from the patient and send them to the tissue engineering company. There, the cells are placed on biodegradable scaffolds under appropriate conditions, until a fully functional organ is produced for subsequent transplantation into the patient. This prospect of ready-made or made-to-order tissues and organs gets me very excited and motivated.
AD: Which medical conditions will be the first to be treated or cured by tissue engineering?
KA: Already, engineered skin tissue products are available. Skin, cartilage and bone appear to be on top of the list. If these succeed, we will see a tremendous boon in treating a very large portion of our population, such as burn patients, young people with cartilage damage, osteoarthritic patients, and people with non-union fractures or missing bone due to cancer.
AD: What are some of the future non-medical uses of tissue engineering? Are there cosmetic uses?
KA: Cosmetic uses of tissue engineering involving the nose, ear, lip and breast have the potential of becoming routine in the future, although most of our efforts currently are in more basic medical problems.
AD: Will tissue engineering allow people to live longer? Couldn't tissue engineering be used to rebuild parts of the body as they wear out?
KA: Yes and yes. Many people die because of a failing organ or because of stress created by a failing organ. When we have the ability to replace failing organs or tissues, both the duration and quality of life should increase significantly. We may discover that many of our approaches suffer from intractable problems and need to be abandoned. Overall, however, I think that we are only beginning to realize the possibilities of tissue engineering.
In 1995, the first wholly engineered skin tissues were developed from scratch in a laboratory. This marked the unofficial beginning of the science of tissue engineering. As a result, burn victims and those with otherwise damaged skin can now receive lab-grown skin grafts.
Defined as the science of building body parts, tissue engineering uses stem cells as its raw material. These powerful cells divide and then transform into any number of different cells. Harvested from parts of the body, or from an embryo, these cells can turn into a heart valve as easily as an eardrum. That's why tissue engineering can potentially help those who need transplants. Each year some 6,000 Americans die waiting for organ donors. But tissue engineering could simplify the entire process.
The next generation of engineered tissues may include lab-born limbs and whole organs, including even hearts and brains. Eventually, tissue engineering could serve some superficial purposes. Want a different nose? Grow it and then graft it on. But of course, medical problems will come first. Someday, badly performing body parts may simply be replaced, predicts Rice University's Kyriacos Athanasiou, whose tissue engineering research focuses on the healing processes of cartilage. Athanasiou is founder of three private companies that develop tissue engineering therapies. American Demographics' David Whelan spoke with this pioneer about the future of tissue engineering.