DOI: 10.1097/01.BONEJ.0000296703.81018.4e
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Issn Print: 1938-8659
Publication Date: 2007/11/01
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Excerpt
In an ORS press release, lead researcher Robert E. Guldberg, PhD, a professor of mechanical and biomedical engineering at the Georgia Institute of Technology, said, “This study demonstrates the remarkable potential of amniotic fluid stem cells and raises the possibility of a cell-based treatment for bone defects or fractures that fail to heal.” (See Orthopaedic Research Society, 2007.)
The research team compared human amniotic fluid-derived stem (AFS) cells with mesenchymal stem cells. After growing both types of cells, researchers concluded that AFS cells require more time than mesenchymal stem cells to start producing mineral, the process needed to aid bone growth. However, AFS cells yielded more bone. Amniotic fluid-derived stem cells, like mesenchymal stem cells, have the capacity to differentiate into distinct types of cells. In addition, AFS cells do not demonstrate tertoma (tumor) formation when implanted into living hosts.
Guldberg also said, “Reliable, abundant, immune-acceptable cell sources are needed for the regeneration of bone and cartilaginous tissues associated with a variety of musculoskeletal injuries and disorders. Although their ability to restore function remains to be tested, amniotic fluid stem cells may very well be the source we have been looking for.”
In related research, scientists at Wake Forest Institute for Regenerative Medicine, in collaboration with those at Harvard Medical School, reported that they used stem cells found in amniotic fluid to create muscle, bone, fat, blood vessel, nerve, and liver cells in the laboratory. (See De Coppi et al., 2007.) In a press release, Anthony Atala, MD, senior researcher and director of the institute, said that he and his colleagues discovered a small number of stem cells in amniotic fluid (estimated at 1%) that can give rise to many specialized cells found in humans. (See Wake Forest Institute for Regenerative Medicine, 2006.) The scientists believe that the AFS cells may represent an intermediate stage between embryonic stem cells and adult stem cells, as they have markers consistent with both cell types.
One advantage associated with harvesting AFS cells is their availability. Researchers used cells harvested from backup amniotic fluid specimens obtained from amniocentesis. (The study reported that AFS cells can be isolated as early as 10 weeks after conception.) Similar cells were harvested from the placenta and other membranes expelled after childbirth. Atala said a cell bank with 100,000 donated specimens could theoretically supply 99% of the U.S. population with perfect genetic matches for transplantation. With more than four million births in the United States each year, it may not take long to collect this many specimens.
Amniotic fluid-derived stem cells also grow at an astounding rate, doubling every 36 hours. They also do not require guidance from other cells (called “feeders”), and they do not produce tumors, which can occur with other types of stem cells. “The full range of cells that AFS cells can give rise to remains to be determined,” said Atala. “So far, we've been successful with every cell type we've attempted to produce from these stem cells. The AFS cells can also produce mature cells that meet tests of function, which suggests their therapeutic values.”
Functional tests included implanting neural cells created from AFS cells and injecting them into the skulls of mice with degenerative brain disease. The cells repopulated the diseased areas, creating new connections with surrounding healthy neurons.
