A US appeals court has just suspended a ban imposed by US District Judge Royce Lamberth last month, meaning that for the moment federal funds can continue supporting embryonic stem cell research. A Washington court has placed a temporary stay on Lamberth's decision.

Experts throughout the USA have criticized the ban, which former President George Bush kept in place, saying numerous patients with serious and often chronic disease were having their hopes of a cure, or at least better treatment than currently available, delayed.

The American government has asked the Washington appeals court to cancel a preliminary order by Judge Lamberth which blocked federal funding for embryonic stem cell research.

The appeals judges, consisting of three members, say they need more time to deal with the US government's appeal; meanwhile the ban is lifted.

The appeals judges - Karen LeCraft Henderson, Janice Rogers Brown, and Thomas B. Griffith - wrote:

(this move) should not be construed in any way as a ruling on the merits.

The recent ban resulted in 22 stem cell projects suddenly having their September funding monies stopped. Had this ban not been temporarily lifted, they would probably have stopped work, several newspapers have commented. About Stem Cells Stem cells are a type of undifferentiated cells that have the capacity to differentiate into specialized cell types. Stem cells come from two main sources: Embryos formed during the blastocyst phase of embryological development - these are known as embryonic stem cells Adult tissue - these are known as adult stem cells. Both types are generally characterized by their potency, or potential to become different cell types (such as skin, muscle, bone, nerve, etc.).

Adult stem cells - adult or somatic stem cells exist throughout the body after embryonic development and are found inside different types of tissue. These stem cells have been found in tissues such as the brain, bone marrow, blood, blood vessels, skeletal muscles, skin, and the liver. They remain in a quiescent or non-dividing state for years until activated by disease or tissue injury.

Adult stem cells can divide or self-renew indefinitely, enabling them to generate a range of cell types from the originating organ or even regenerate the entire original organ. It is generally thought that adult stem cells are limited in their ability to differentiate based on their tissue of origin, but there is some evidence to suggest that they can differentiate to become other cell types.

Embryonic stem cells - embryonic stem cells are derived from a four- or five-day-old human embryo that is in the blastocyst phase of development. The embryos are usually extras that have been created in IVF (in vitro fertilization) clinics where several eggs are fertilized in a test tube, but only one is implanted into a woman.

Sexual reproduction begins when a male's sperm fertilizes a female's ovum (egg) to form a single cell called a zygote. The single zygote cell then begins a series of divisions, forming 2, 4, 8, 16 cells, etc. After four to six days - before implantation in the uterus - this mass of cells is called a blastocyst. The blastocyst consists of an inner cell mass (embryoblast) and an outer cell mass (trophoblast). The outer cell mass becomes part of the placenta, and the inner cell mass is the group of cells that will differentiate to become all the structures of an adult organism. This latter mass is the source of embryonic stem cells - totipotent cells (cells with total potential to develop into any cell in the body).

In a normal pregnancy, the blastocyst stage continues until implantation of the embryo in the uterus, at which point the embryo is referred to as a fetus. This usually occurs by the end of the 10th week of gestation after all major organs of the body have been created.

However, when extracting embryonic stem cells, the blastocyst stage signals when to isolate stem cells by placing the "inner cell mass" of the blastocyst into a culture dish containing a nutrient-rich broth. Lacking the necessary stimulation to differentiate, they begin to divide and replicate while maintaining their ability to become any cell type in the human body. Eventually, these undifferentiated cells can be stimulated to create specialized cells.

Click here to read a more comprehensive explanation about stem cells.