Cytoplasmic transfer was originally developed in the 1980s in the course of basic research conducted with mice to study the role that parts of the cell outside of the nucleus played in embryonic development. In this technique, cytoplasm, including proteins, messenger RNA (mRNA), mitochondria and other organelles, is taken from a donor egg and injected into the recipient egg, resulting in a mixture of mitochondrial genetic material. This technique started to be used in the late 1990s to "boost" the eggs of older women who were having problems conceiving and led to the birth of about 30 babies. Concerns were raised that the mixture of genetic material and proteins could cause problems with respect to epigenetic clashes, or differences in the ability of the recipient and donor materials to effect the development process, or due to the injection of the donor material. After three children born through the technique were found to have developmental disorders (two cases of Turner's syndrome and one case of pervasive developmental disorder (an autism spectrum disorder), the FDA banned the procedure until a clinical trial could prove its safety. As of 2015 that study had not been conducted, but the procedure was in use in other countries.
A related approach uses autologous mitochondria taken from healthy tissue to replace the mitochondria in damaged tissue. Transfer techniques include direct injection into damaged tissue and injection into vessels that supply blood to the tissue.