Human embryonic stem cell

Human embryonic stem cells (hESCs) are pluripotent stem cells derived from the inner cell mass of a blastocyst, an early-stage pre-implantation embryo. Human embryos reach the blastocyst stage 4–5 days post fertilization, at which time they consist of 50–150 cells.

Characteristics

hESCs are characterized by their capacity for self-renewal and their ability to differentiate into all types of cells of the body. The full potential of hESCs in research and clinical applications requires a detailed understanding of the genetic and epigenetic events underlying the unique properties of these cells.

Derivation

hESCs are derived from a four- or five-day old embryo called a blastocyst. The extraction process destroys the embryo, which raises a variety of ethical issues. Many researchers hope to bypass the controversy by finding ways to coax adult cells to behave more like embryonic stem cells (see induced pluripotent stem cells).

Applications

hESCs are thought to have much potential in treating a range of diseases, including diabetes, heart disease, rheumatoid arthritis, and spinal cord injuries. However, much research is needed to understand the potential benefits and limitations of using these cells in regenerative medicine.

Ethical and legal issues

The use of hESCs has been the subject of ethical debate. The main issues concern the destruction of human embryos for stem cell derivation. In many countries, the production of embryonic stem cell lines is regulated by laws and guidelines.

See also

• Stem cell controversy
• Stem cell treatments
• Induced pluripotent stem cells
• Adult stem cell
• Cell potency