Vitamin C, role in early development of heart?
- researchers report that it helped convert lab-based mouse stem
cells into heart muscle cells. This raises questions about the role
of the vitamin in embryo heart development.
The powers of vitamin C have been highlighted in an early release study showing that the nutrient helped convert mouse embryonic stem cells growing in the laboratory to heart muscle cells.
The discovery could lead to future research on ways to treat people suffering from damaged heart muscle, suggest authors writing in today's rapid track publication of Circulation: Journal of the American Heart Association.
"Although the findings of this study are very preliminary with respect to their impact on human lives, this line of research has enormous implications for the future care of thousands of patients who develop heart failure each year," said Dr Robert O. Bonow, president of the American Heart Association. "Identifying mechanisms to transform stem cells into differentiated heart muscle cells is an important step toward clinical reality."
Dr Richard T. Lee, senior author of the study, added: "We have been taught for decades that when your heart cells are dead, they are dead and there is nothing we can do about it. We are excited about anything suggesting that we can grow more heart cells."
Lee and his colleagues tested 880 bioactive substances, both drugs and vitamins, to see if they stimulated the mouse stem cells to become heart muscle cells. The cells were genetically altered to give off a fluorescent bright green colour when viewed under a microscrope if they had become heart muscle cells.
"We only got one out of the 880 to light up, and that was from ascorbic acid, the chemical commonly known as vitamin C," said Lee, an associate professor of medicine at Harvard Medical School and Brigham and Women's Hospital in Boston.
He stressed, however, that the finding is preliminary and it should not encourage people to take vitamin C hoping to strengthen or protect their hearts. "There is no clinical evidence that it would help," he said.
The ability to grow or implant new heart muscle could save or improve the quality of life of countless people suffering from heart failure - the inability of a weakened heart to pump enough blood to supply the body, often caused by a damaging heart attack.
Embryonic stem cells are derived from the very early stages of foetal development and can become any type of cell in the body through differentiation. The researchers placed about 2,000 stem cells, from a well-established line of mouse embryonic cells, in tiny 'wells' and treated each well with a different compound.
The stem cells had a gene inserted that would fluoresce bright green if the cell converted into the heart-muscle cell. Beyond finding the green glow of the vitamin C-treated cells, the researchers also found that both cardiac myosin and actin (proteins involved in relaxing and contracting muscle) were present in the cells. They also detected three other heart-muscle genes that activated in proper sequence. The differentiated cells also beat spontaneously and rhythmically.
Vitamin C's beneficial activity has been attributed to its ability to neutralise oxidants, which are damaging substances produced by the body. However, other antioxidant compounds tested, including vitamin E, did not trigger the development of heart cells.
"This suggests that the effect of vitamin C on cardiac differentiation is independent of its antioxidant effect," Lee said.
He and his colleagues repeated their experiment many times, always with the same results. "The real significance of the study is that it indicates that we will be able to find other ways to generate heart cells from stem cells more efficiently. It also raises interesting questions about the role of vitamin C in the development of the embryo's heart," he said.
The team is investigating other so-called "chemical libraries" that contain far larger numbers of compounds than the group initially tested.
