This morning, President Obama lifted the Bush administration's ban on federal funding for embryo-derived stem cell research. This executive order marks an important step forward in the search for new lifesaving medicines. But by itself, it is not enough. As policy makers debate health care reforms, they should renew their support for regenerative medicine, a broader field of which embryonic stem cell research is only one important part.
Last week, I witnessed some of the most promising research in this field when I paid a visit to the Wake Forest University Institute for Regenerative Medicine. My host was Dr. Anthony Atala, the Institute's director. Ten years ago, when Dr. Atala was a pediatric surgeon and urologist at Harvard, he and I cofounded the Society for Regenerative Medicine in the hopes of catalyzing the rapid development of a new specialty. The goal of regenerative medicine is to create new organs to replace those lost to disease, trauma, or age. Ambitious as this ideal may be, it is now being pursued at dozens of new university departments and research centers around the world.
Scientists and doctors at Wake Forest have already successfully implanted the first laboratory-made human organs--bladders and urethras. Coming soon: synthetic corneas, heart valves, skin, cartilage, tracheas, and vaginas. More ambitious plans are underway to replace lost digits, muscles, and nerves, and to build entirely new complex organs such as livers, kidneys, and human hearts.
How are new organs built? Take the bladder, a simple balloon-like organ that is made of two layers of tissue: an outer layer of muscle and an inner layer of epithelial cells connected by an elastic matrix. The process begins with a tiny snippet of the patient's own bladder--a sample of what remains behind after injury or surgery. Muscle and epithelial stem cells are then located, separated, and used to grow large sheets of pure muscle and epithelial cells. It takes six to seven weeks to grow enough new tissue to make a new bladder.
When the tissue is ready, scientists wrap it around a bladder-sized support made from fine fibers of a collagen-like material. The outside of this support is covered with a layer of muscle, while the inner cavity is lined with the sheet of epithelial cells. The new organ is then inflated and deflated repeatedly while being bathed in a body-temperature nutrient fluid. Just before implantation, doctors drape the bladder with a blood-vessel-rich section of membrane, taken from either the intestinal or abdominal wall, to ensure adequate blood supply.
Over time, the artificial support dissolves and is replaced with the natural matrix. Within six months to a year, the tissue of the new bladder is virtually indistinguishable from the original. Urethras can be made in a similar manner. New urethras and bladders have now been implanted in more than two hundred patients, and success rates for this surgery exceed 80 percent.
Although these developments are exciting, the most spectacular advances still lie ahead. There is real hope that stem cells will soon be available to regenerate tissue for any part of the body. Throughout the past eight years, funding restrictions have forced researchers to develop workarounds. By inserting two or three specific genes into normal skin cells, scientists have managed to turn mature cells into the equivalent of embryo-derived stem cells. Meanwhile, Dr. Atala and his staff have isolated a new kind of stem cell from readily available amniotic fluid and used it to create muscle, bone, fat, blood vessel, nerve, and liver cells in their laboratories.
While stem cells derived from adult cells and amniotic fluid hold their own promise, there is still much to be learned about how early-stage stem cells operate in their most natural embryonic state. For that reason, the ban on federal funding has had a chilling effect on all stem cell research in the United States. Other countries without such funding bans have moved ahead aggressively in this area while our own laboratories, staffed with our most brilliant doctors and scientists, have been slowed by funding limitations.
President Obama's executive order presents an excellent opportunity to renew America's commitment to this whole promising field. Even in these tight times, universities, states and counties should continue to invest in biomedical research. Over the past six years, Wake Forest University has invested close to $100 million in the Institute of Regenerative Medicine. The state of Florida, meanwhile, has made a large-scale investment in biomedical research (see my previous post, "Renewing Florida"), and other states would do well to follow this example.
At the same time, the federal government should not only continue but expand its support. Federal funding has already proven key in the success of biomedical science. Grants from the National Institutes of Health, the Department of Defense and other federal agencies provide most of the $40 million annual research budget of the Wake Forest Institute. The new health care reforms should allot even more funds to this lifesaving work.
Training and continued support for staff will also be key as more researchers join the field. Progress at the Wake Forest Institute would not be possible without teams of dedicated professionals who are both scientists and surgeons. Like Dr. Atala, these dual-trained professionals are inspired by the clinical problems they have encountered and can move discoveries quickly from the laboratory to the clinic.
In our search for economic efficiency, we cannot afford to sacrifice the future of medical science. With thoughtful reform, the goals of scientists like Dr. Atala may be fulfilled--otherwise, the bright future of regenerative medicine may never be realized.
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