Ooplasmic transfer: animal models assist human studies.

Abstract

Ooplasmic transplantation is based on the premise that ooplasmic components are compromised in some individuals. In theory, the transfer of small amounts of healthy ooplasm can correct such deficits, allowing for improved development and implantation. The technique is based on a well-established background of experimental embryology demonstrating that cytoplasmic manipulation in oocytes and early embryos can be entirely compatible with normal development. Cytoplasm has been manipulated via karyoplast and cytoplast transfer and by cytoplasmic injection. Term development has been obtained following such manipulations in a variety of mammalian species. While some manipulative scenarios have exhibited compromised development, others have exhibited improved development. Developmental problems involving specific epigenetic and mitochondrial incompatibilities have been observed in a very limited subset of animal studies. These studies are based on genetic and physical models that have little relation to the actual substance of ooplasmic transplantation in the human. In fact, the majority of animal studies suggest that ooplasmic transplantation is well-founded and unlikely to result in negative developmental consequences. Furthermore, there are considerable physical, physiological and developmental differences between human and rodent eggs and embryos. These differences suggest that potentially negative issues raised by rodent results may not be relevant in the human.