April 3, 2006 -- The news is being hailed as a medical milestone: Several years after receiving new bladders engineered entirely in a laboratory, seven young patients are all still healthy.
It marks the first long-term success of total-organ tissue regeneration, an area of medicine that until now was more the stuff of science fiction than clinical reality.
Dr. Anthony Atala, the director of the Institute for Regenerative Medicine at Wake Forest University in North Carolina, reports in tomorrow's issue of the medical journal The Lancet on the success of the new procedure, which was performed on children born with birth defects that resulted in damaged bladders.
How it works: Atala and his team of researchers first remove a portion of the child's damaged bladder and single out cells that will turn into muscle cells and epithelial cells, or cells that line the bladder wall. These groups of cells are then grown in a laboratory culture to make enough cells to mold onto a "scaffold" of biodegradable material that resembles the size and thickness of a normal bladder sac.
It takes about eight weeks to grow enough cells to layer over the scaffold. Once ready, the new bladder is stitched to the patient's old bladder, and the scaffold basically melts away, leaving behind a bladder that, while not perfect, works better than what the patients were born with.
Atala was unavailable for comment, but Gary Sender, chief financial officer of the biotechnology firm Tengion, explained how it worked. His firm is developing the "neo-bladder" technology and seeking approval from the Food and Drug Administration to test it further in humans, including adults.
Once implanted in the body, "the regenerative process continues, the body knows what to do with the new cells, and it grows into new tissue layers," Sender said. "It kickstarts the body's regenerative process ... by using the right type of bladder cell types, the body knows this is the beginning of a regenerative process."
On the Horizon
The neo-bladder is just one of many different forms of tissue engineering currently being explored. Bone and skin regeneration already exists, and in the future, parts of or entire complex organs like the heart may even be replicated in a laboratory.
Atala's success represents a significant advance in the field of tissue engineering, said A. Hari Reddi, professor and director of the Center for Tissue Regeneration and Repair at the University of California-Davis Medical Center.
"I think this is really important work," Reddi said. "In the future the challenge is going to be the tissue engineering of complex tissue such as the heart, kidney or liver. Of course, the ultimate is the brain, which I'd say is 30 or 40 years away."
While the entire process is technically complex, one of the biggest challenges is finding a way to deliver nutrients to the new cells, said Lawrence B. Schook, a professor of animal science at the Institute for Genomic Biology at the University of Illinois at Urbana-Champaign.
This is normally done by the vascular system, the body's blood supply.
"We can isolate and grow cartilage and muscle cells and that's great, but we have them in a petri dish with lots of nutrients," Schook said. His team is working on how to keep the cells alive even without a normal blood supply feeding into the cells.
Eventually, tissue enginering technology could even replace organ transplants, Sender said.
"The technology uses ... cells that come from the patient," he said. "One of the great advantages is that there's no risk for rejection."