Discarded Placentas Deliver Researchers Promising Cells

[Guest guest]

Routinely discarded as medical waste, placental tissue could feasibly

provide an abundant source of cells that may have the potential to

treat diseases and regenerate tissues as their more controversial

counterparts, embryonic stem cells, suggests a University of

Pittsburgh study to be published in the journal Stem Cells and

available now as an early online publication in Stem Cells Express.

A part of the placenta called the amnion, or the outer membrane of the

amniotic sac, is comprised of cells that have strikingly similar

characteristics to embryonic stem cells, including the ability to

express two key genes that give embryonic stem cells their unique

capability for developing into any kind of specialized cell, the

researchers report. And according to the results of their studies,

these so-called amniotic epithelial cells could in fact be directed to

form liver, pancreas, heart and nerve cells under the right laboratory

conditions.

" If we could develop efficient methods that would allow amnion-derived

cells to differentiate into specific cell types, then placentas would

no longer be relegated to the trashcan. Instead, we'd have a useful

source of cells for transplantation and regenerative medicine, " said

senior author C. Strom, Ph.D., associate professor of

pathology at the University of Pittsburgh School of Medicine and a

researcher at the university's McGowan Institute for Regenerative

Medicine.

According to U.S. census figures, there are more than 4 million live

births each year. For each discarded placenta, the researchers

calculate there are about 300 million amniotic epithelial cells that

potentially could be expanded to between 10 and 60 billion cells

relatively easily.

" Provided that research advances to the point that we can demonstrate

these cells' true therapeutic benefit, parents could conceivably

choose to bank their child's amniotic epithelial cells in the event

they may someday be needed, as is sometimes done now with umbilical

cord blood, " commented Dr. Strom.

The amnion is derived from the embryo and forms as early as eight days

after fertilization, when the fate of cells has yet to be determined,

and serves to protect the developing fetus. According to the

researchers' studies using placentas from full-term pregnancies,

amniotic epithelial cells have many of the telltale surface markers

that define embryonic stem cells, and also express the Oct-4 and nanog

genes that are known to be required for self-renewal and

pluripotency—the ability to develop into any type of cell.

Yet the authors are careful to point out that despite their remarkable

similarities to embryonic stem cells, amniotic epithelial cells are

not stem cells per se, because they can't grow indefinitely. This may

be due to the fact that these amnion-derived cells do not express a

certain enzyme, called telomerase, that is important for normal DNA

and chromosome replication, and by extension, ultimately, cell division.

With the addition of various growth factors, the authors report the

amnion-derived cells could differentiate to become liver cells, heart

cells, the glial and neuronal cells that make up the nervous system,

and pancreatic cells with genetic markers for insulin and glycogen

production.

Further research will help to determine the efficacy of using cells

from placenta tissue to treat diseases and regenerate tissue.

Adapted from the following source: University of Pittsburgh Medical Center