Wellington, Oct 14 (IANS): Vitamins A and C could improve the conversion of adult cells into stem cells, opening the way to advances in biomedical treatments for human diseases, according to a New Zealand-led study released on Friday.

The research team discovered that the two vitamins complemented each other in erasing "memory" associated with DNA, an important effect for improving technologies geared towards regenerative medicine and stem cell therapy, Xinhua news agency reported.

Ordinary adult cells, such as those in the skin or blood, could be artificially coerced in a culture dish to resemble embryos only a few days old, said study co-author Tim Hore of the University of Otago.

Since the 2006 discovery that reprogramming was possible, there had been much interest in using induced embryonic stem cells to cure human disease.

"However, hampering these efforts is the reality that adult cells are resistant to changes in their identity, partly because of chemical alterations to their DNA," Hore said in a statement.

These alterations, known as "DNA methylation", were acquired during development and provided a form of cellular memory that helped cells faithfully maintain a specialised function.

Removal of this memory was critical in order to create a developmentally potent stem cell, or to change one kind of adult cell to another.

With collaborators in Britain and Germany, Hore determined that adding vitamins A and C to culture dishes removed DNA methylation from embryonic stem cells.

When applied to cells during the reprogramming process, those with the desired "naive" embryonic characteristics were created in much greater numbers, he said.

"We found that both vitamins affect the same family of enzymes which actively remove DNA methylation. It turns out that vitamin A increases the number of these enzymes within the cell and vitamin C enhances their activity," he said.

In addition to regenerative medicine, the work could have implications for other areas of biomedical importance.

Loss of DNA methylation and cellular memory were a hallmark of certain cancers, so a better understanding of how this process occurred could prove significant.