Stem cells derived from human amniotic fluid appear to offer many of the benefits of embryonic stem cells -- including the ability to grow into brain, muscle, bone and other tissues -- according to a study published in the Jan. 7 online edition on the journal Nature Biotechnology, the Washington Post reports.
For the study, researchers from the Institute for Regenerative Medicine at Wake Forest University and Children's Hospital Boston found that amniotic cells in the laboratory can grow into all of the major types of cells, dividing at the rate of once every 36 hours. Researchers coaxed amniotic fluid stem cells to develop into brain cells and injected them into the skulls of mice with diseased brains. The stem cells replaced the diseased areas and appeared to create new connections with surrounding healthy neurons, the researchers reported. Researchers also coaxed amniotic fluid stem cells to become bone cells and implanted them in a mouse. The study found the stem cells calcified and turned into dense, healthy bone. The researchers also coaxed amniotic fluid stem cells to develop into muscle, fat, blood vessel and liver cells. Stem cells extracted from amniotic fluid can be isolated starting at 10 weeks' gestation from fluid taken during tests performed to identify birth defects, according to the study. The stem cells, even after more than two years in the laboratory, did not show signs of aging or of having the potential to grow into tumors, the study found. Amniotic stem cells can be frozen for later use, the Post reports.
According to the Post, amniotic fluid stem cells are "adding credence to an emerging consensus among experts that the popular distinction" between human embryonic stem cells and adult stem cells is "artificial" and that there is a "continuum of stem cell types" (Weiss, Washington Post, 1/8). Amniotic fluid stem cells are a "different kind of stem cell" that is "not as early as a human embryonic stem cell, and it's not as late as the adult stem cells," Anthony Atala, senior author of the study and director of the Institute for Regenerative Medicine at Wake Forest, said, adding, "So far, we've been successful with every cell type we've attempted to produce from these stem cells" (Kaplan, Los Angeles Times, 1/8). Atala said that if 100,000 women donated their amniotic stem cells to a cell bank, it would provide enough cells for "99% of the U.S. population with a perfect match for genetic transplantation" (Weise, USA Today, 1/8). He added that the stem cells can be found not only in amniotic fluid but also in the placenta, which is discarded after birth (Washington Post, 1/8). Richard Doerflinger, deputy director of the U.S. Conference of Catholic Bishops Secretariat for Pro-Life Activities, said that the study "is one in a line of studies showing very versatile stem cells can be obtained from a number of different products after live birth -- amniotic membrane, amniotic fluid, cord blood, placenta, even umbilical cord tissue," adding, "There is no reason why the amniotic fluid couldn't be obtained, raising no moral problem whatever" (Hall, San Francisco Chronicle, 11/8). Atala said it is unclear how many different cell types can be produced from amniotic stem cells, and researchers said that it will be several years before preliminary tests can be performed on patients, the AP/Houston Chronicle reports (Elias, AP/Houston Chronicle, 1/7). "[Amniotic fluid stem cells] can clearly generate a broad range of important cell types, but they may not do as many tricks as embryonic stem cells," Robert Lanza, head of scientific development for Advanced Cell Technology, said (Los Angeles Times, 1/8).
The study is available online.