Embryonic Stem (ES) Cells are isolated from a preimplantation embryo at approximately 5 or 7 days after fertilization (Human and Monkey respectively). By definition ES cells must be able to fulfill three characteristics:

1) renew themselves
2) when induced to differentiate, generate cell derivatives from the three germ layers, endoderm, mesoderm and ectoderm
3) when introduced into a host embryo, generate chimeras whose germline is capable of making germ cells derived from the ES cells (this last requirement has only been described in mice).

It is then a prerequisite that these cells have a very ‘plastic’ nucleus, a nucleus that has the capacity to turn into many different cell types. This property is called pluripotency.

Our laboratory is focused on understanding pluripotent activity. This activity is accepted bona fide in primate and mouse ES cells; unfortunately it is easily perturbed in a non-reversible fashion. Our goal is to be able to identify genes and gene products that maintain pluripotency in these cells. We use primate embryonic stem cells to accomplish this goal.

With the tantalizing possibility of having an unlimited supply of human cells capable of generating any cell type in the body, the development of new human cell therapies is currently broadly discussed. Though the promise is great, so are the challenges. Much remains to be done in the laboratory before these cells reach the patients. Among them, culture conditions for expansion and differentiation must be improved and the efficacy and safety of these cells when transplanted into animal models of human disease must be thoroughly tested. There are currently no clinical trails using ES cells anywhere in the world.