“It may be that, some ages hence... the restoration of grey hairs to juvenility and the renewing of the exhausted marrow may at length be elicited without a miracle”
Joseph Glanvill,
1661AD
Background guide to Human Embryonic Stem Cells
HESCs have the remarkable property of being able to proliferate indefintely in vitro and, as far as is known, the ability to ultimately form all the cells of the body (pluripotency). Their discovery was one of the most significant biology breakthroughs of the late 20th century as they hold the promise of treatment and eventual cure for many chronic degenerative diseases and injuries.
HESCs are derived from the inner cell mass (ICM) of the early embryo and keep in vitro the ability to self renew and to differentiate into each of the cell types found in the adult body.
Multiple differentiated derivatives arise within hES cultures. Neurons, glia and muscle are among the most readily accessible cell types. Here, the cells are labelled with antibodies recognising specific cellular proteins.
HESCs have been derived for a number of species. however, significant differences have also become apparent between human and animals. For example, some of the cell surface markers that characterise mouse and human ESCs are different and furthermore, HESCs undergo spontaneous trophectodermal differentiation, whilst mouse ESCs do not. These differences demonstrate that extrapolation of animal biology to human biology can be misleading and underline the importance of human cell systems as research tools.
HESCs can be maintained indefinitely in vitro, providing the potential unlimited source of materials. Also, the pluripotency of HESCs is an innate rather than engineered property and consequently, the process of differentiation that HESCs undergo is more likely to resemble normal development than is the case for cells requiring reprogramming or other manipulation.