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Stem cells are cells that can develop into virtually any type of body tissue. Evenutally, it may be possible to use stem cells to create healthy tissues to replace dysfunctional ones in people with diseases. 

Many techniques are being developed to harvest stem cells, including taking them from zygotes made from eggs fertilized by sperm as well those made from unfertilized eggs implanted with a donor’s DNA. The new innovation, developed by a team of American and Russian scientists at International Stem Cell Corporation in Oceanside, California, allows stem cells to be gathered from eggs without sperm or donor DNA.

To prompt an unfertilized egg to yield stem cells by itself, the researchers applied chemicals to the egg. One such chemical mimics sperm-triggered spikes of calcium that occur naturally in eggs during fertilization. The chemicals prompted the egg to contribute both halves of the genetic material necessary for a complete zygote from both its nucleus and a polar body, an inactive cell in the egg. Stem cells from a number of such zygotes were cultured into three primary tissue types that were genetically similar to their donors, reducing the likelihood of rejection in by the donor’s immune system.

Although the technology’s practicality may be limited—only women could benefit from it—it could complement other methods used to obtain human stem cells. It also heralds new research approaches to stem cell production and sheds light on the earliest stages of human reproduction.