Early in vitro testing for adverse effects on embryos

ETH researchers have combined embryonic cells and liver cells in a new cell culture test. This combination lets them detect adverse effects that new medications may have on embryos early on in the drug development process.

Embryos' signals take multiple paths

Rice University scientists have found significant differences between the methods signaling pathways use to prompt cells to differentiate – that is, whether to become organs, bone, blood vessels, nerves or skin.

Chimpanzee 'mini-brains' hint at secrets of human evolution

At some point during human evolution, a handful of genetic changes triggered a dramatic threefold expansion of the brain's neocortex, the wrinkly outermost layer of brain tissue responsible for everything from language to ...

How stem cells self-organize in the developing embryo

Embryonic development is a process of profound physical transformation, one that has challenged researchers for centuries. How do genes and molecules control forces and tissue stiffness to orchestrate the emergence of form ...

The source of stem cells points to two proteins

Mammalian embryos are unlike those of any other organism as they must grow within the mother's body. While other animal embryos grow outside the mother, their embryonic cells can get right to work accepting assignments, such ...

Honeybee protein keeps stem cells youthful

An active protein component of royal jelly helps honeybees create new queens. Stanford researchers have identified a similar protein in mammals, which keeps cultured embryonic stem cells pluripotent.

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Embryonic stem cell

Embryonic stem cells (ES cells) are stem cells derived from the inner cell mass of an early stage embryo known as a blastocyst. Human embryos reach the blastocyst stage 4–5 days post fertilization, at which time they consist of 50–150 cells.

Embryonic Stem (ES) cells are pluripotent. This means they are able to differentiate into all derivatives of the three primary germ layers: ectoderm, endoderm, and mesoderm. These include each of the more than 220 cell types in the adult body. Pluripotency distinguishes ES cells from multipotent progenitor cells found in the adult; these only form a limited number of cell types. When given no stimuli for differentiation, (i.e. when grown in vitro), ES cells maintain pluripotency through multiple cell divisions. The presence of pluripotent adult stem cells remains a subject of scientific debate; however, research has demonstrated that pluripotent stem cells can be directly generated from adult fibroblast cultures.

Because of their plasticity and potentially unlimited capacity for self-renewal, ES cell therapies have been proposed for regenerative medicine and tissue replacement after injury or disease. However Diseases treated by these non-embryonic stem cells include a number of blood and immune-system related genetic diseases, cancers, and disorders; juvenile diabetes; Parkinson's; blindness and spinal cord injuries. Besides the ethical concerns of stem cell therapy (see stem cell controversy), there is a technical problem of graft-versus-host disease associated with allogeneic stem cell transplantation. However, these problems associated with histocompatibility may be solved using autologous donor adult stem cells or via therapeutic cloning.

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