Over the past several years, medical research using human embryonic stem cells, obtained from discarded fertilized egg cells after in vitro fertilization procedures, has become a politically and ethically charged issue. But controversy aside, a dramatic new study has found that the normal behavior of these basic cells of life depends in large part on vitamin C.
Human embryonic stem cells are essentially generic cells. They are among the most fundamental unspecialized living cells, which serve as "parent" cells for what will eventually become an entire body. In a developing fetus, small numbers of stem cells divide and give rise to trillions of highly specialized cells, including those that form the heart, lungs, brain, and other organs.
Scientists have labored over exactly how embryonic stem cells start to differentiate and form many different types of cells. It is now clear that vitamin C is essential for that process.
In the study, Richard T. Lee, MD, and his colleagues at the Harvard Medical School, tested 880 chemical compounds for their effect on embryonic stem cells derived from mice. The stem cells were pretreated so that they would emit a green color if they grew into heart muscle cells.
Of all 880 compounds, which are approved for use in people, only one promoted activity in the stem cells, and that was vitamin C.
In the experiment, Lee and his colleagues treated embryonic stem cells with vitamin C for 12 days. During this time, large numbers of the stem cells began transforming into heart muscle cells called myocytes. The cells even began to beat rhythmically, as normal heart cells do.
In addition, vitamin C prompted the expression, or activation, of several cardiac genes, which would have further directed the behavior of the heart cells.
To rule out an antioxidant effect, Lee and his colleagues tested vitamin E and other antioxidants on the stem cells. Again, only vitamin C prompted stem cells to differentiate into heart cells.
The study's findings are significant for a number of reasons. According to Lee, treating embryonic stem cells with vitamin C could facilitate the large-scale production of heart cells, which someday might be administered to treat heart failure.
The findings are significant, also, because vitamin C is well-known as a cell-protecting antioxidant. However, research has shown that vitamin C has many nonantioxidant properties, such as being an enzymatic cofactor in the body's production of collagen, a key protein in tissue.
This particular study showed that vitamin C plays a key role in one of the most basic processes in life, the transformation of stem cells into heart cells and, potentially, into the many other specialized cells forming the body.
REFERENCE
Takahashi T, Schulze C, Lord B, et al. Ascorbic acid enhances differentiation of embryonic stem cells into cardiac myocytes. Circulation, March 31, 2003. Electronic publication in advance of print.