U.S. President Barack Obama will soon issue an executive order lifting an eight-year ban embryonic stem cell research imposed by his predecessor, President George W. Bush, a senior adviser said on Sunday.

"We're going to be doing something on that soon, I think. The president is considering that right now," Obama adviser David Axelrod said on Fox News Sunday.

In 2001, Bush limited federal funding for stem cell research only to human embryonic stem cell lines that already existed. It was a gesture to his conservative Christian supporters who regard embryonic stem cell research as destroying potential life, because the cells must be extracted from human embryos.

According to scientists, eventually the research on the cells might produce cures for a variety of diseases, including Parkinson's disease, diabetes, heart disease and spinal cord injuries. Stems cells give rise to all the tissues, organs and blood.  Embryonic stem cells are considered the most powerful of all stem cells, as they have potential to give rise to any type of tissue.

Research in the stem cell field grew in the 1960s. The two broad types of mammalian stem cells are: embryonic stem cells that are isolated from the inner cell mass of blastocysts, and adult stem cells that are found in adult tissues. In a developing embryo, stem cells can differentiate into all of the specialized embryonic tissues. In adult organisms, stem cells and progenitor cells act as a repair system for the body, replenishing specialized cells, but also maintain the normal turnover of regenerative organs, such as blood, skin or intestinal tissues.