For several decades, researchers have tried to find a source of living cells to coax into new tissues.
The difficulties the scientists faced could herald future problems in using embryonic stem cells to grow new tissues in humans.
After a while, Vacanti concluded that the cells had failed to form new tissues; the only tissues evident had clearly come from the host mouse.
Some of Dr de Grey's solutions, such as using stem cells to engineer new tissues, organs and nerve cells, are already in the works.
Therapeutic cloning -- the use of these cells in what might become new tissues or organs -- is heralded for social benefits: the goal presumably is to alleviate human suffering.
Dr. Mark Sobel, senior executive officer of the American Society for Investigative Pathology, agrees that informed consent should be required before new tissues are collected.
During healing, Dr. Hubbard said, "new tissues are laid down, and they need to be aligned with the action of the joint" through proper exercise.
Green asparagus spears, cut down just hours after they've hit daylight and turned color, are the most lively of all our vegetables, furiously turning the sugars absorbed from their roots into energy and new tissues.
Dr. Steven A. Teitelbaum, a plastic surgeon in Santa Monica, Calif., predicted that the next milestone would be the control of tissue formation, whether to reduce scarring or grow new tissues.
But embryonic stem cells should be able to generate all medically desired new tissues, once biologists can find the right natural signals to coax them into any desired cell type.
Young cell and molecular biologists are eager to devote their scientific careers to investigating cell differentiation, a process that will surely provide us with valuable information about stem cells and their use in generating new tissues and organs.
