Embryonic Stem Cells

Embryonic stem cells (ESC) are derived from human preimplantation embryos formed during infertility treatment of couples for in vitro fertilization (IVF). They are donated by the couples, with informed consent, for research on embryonic stem cells. In addition, couples having treatment for preimplantation genetic diagnosis (PGD) of their embryos, to avoid the birth of babies with severe genetic disease, may consent to provide their discarded earlycleavage-stage embryos for derivation of disease-specific ESC, such as those with Huntington s disease, thalassaemia, or cystic fibrosis. These ESC may be renewed in vitro and expanded indefinitely by regular passage in coculture with a wide range of feeder cells (e.g., mouse or human embryonic fibroblasts) and, more recently, in feeder- and serumfree culture conditions in the presence of fibroblast growth factor (FGF) and neurotrophic growth factors (NGFs). It is now strongly recommended that regular assays of karyotypic normality and the absence of genetic deletions be undertaken prior to experiments, to confirm the genomic type and normality of the ESC being studied. It is also possible to introduce reporter genes in a targeted manner into regulatory sequences of genes of interest for ESC renewal and differentiation. ESC are pluripotential and immortal, so they can potentially form very large numbers of ...