Stem cell researchers have invented a new method for producing apparently safe alternatives to human embryonic stem cells without destroying embryos, a big step to regenerate tissue.

Stem cells are the body’s master cells from which everything from blood to bone to brain, grow in early development and throughout life. The use of embryonic stem cells the most useful type for generating replacement tissues, but obtaining them requires the controversial destruction of embryos.

"This is going to be very exciting to the research community," said Derrick J. Rossi of Harvard Medical School, who led the research published in the journal Cell Stem Cell. "We now have an experimental paradigm for generating patient-specific cells highly efficiently and safely and also taking those cells to clinically useful cell types."

Researchers hope stem cells will lead to cures for diabetes, Alzheimer's disease, spinal cord injuries, heart attacks and many other ailments as they can turn into almost any tissue in the body, potentially providing an invaluable source of cells able to replace those damaged by disease or injury.

The cells can however only be obtained by destroying days-old embryos.