Chimera's

Medical Facts - "A person composed of two genetically distinct types of cells" are called 'Chimeras'.

Human chimeras were first discovered with the advent of blood typing when it was found that some people had more than one blood type. Most of them proved to be "blood chimeras."

A chimera is a mixture of two or more species in one body. Not all are considered troubling, though. For example, faulty human heart valves are routinely replaced with ones taken from cows and pigs. The surgery—which makes the recipient a human-animal chimera—is widely accepted. And for years scientists have added human genes to bacteria and farm animals. [See Cellular Memory]

Ethical Concerns arise from the possibility that eventually, chimeras will be created who are essentially human but will be treated as if they were animals. These chimeras could undergo physical and psychological suffering as a result of being created from two different species.

Guidelines for Embryonic Stem Cell Research

The Office of News and Public Information of the National Academies, comprising the National Academy of Sciences, National Academy of Engineering. The Academies' guidelines also address how far scientists should go in mixing human and animal cells to create so-called chimeras, which researchers may need to do in order to test the therapeutic potential of human stem cells in animal models. The guidelines say no animal embryonic stem cells should be transplanted into a human blastocyst, and approval by an ESCRO committee should be secured before any human embryonic stem cells are put into an animal.

Also, no animal into which human embryonic stem cells have been introduced should be allowed to breed.

In addition, no human embryonic stem cells should be put into nonhuman primate blastocysts.

Human embryonic stem cells should be introduced into nonhuman mammals only under circumstances where no other experiment can provide the information needed, the guidelines say.

Experiments in which there is a possibility that human cells could contribute in a "major organized way" to the brain of an animal require strong scientific justification, the committee added. www4.nationalacademies.

Spare Parts

Scientists feel that, the more humanlike the animal, the better research model it makes for testing drugs or possibly growing "spare parts," such as livers, to transplant into humans.

Monday, 3 April 2006, 23:02 GMT 00:02 UK
Lab-grown bladders 'a milestone' grown from patients' own cells

US scientists have successfully implanted bladders grown in the laboratory from patients' own cells into people with bladder disease. The researchers, from North Carolina's Wake Forest University, have carried out seven transplants, and in some the organ is working well years later. The achievement, details of which have been published online by The Lancet, is being described as a "milestone".

The team is now working to grow organs including hearts using the technique.

This is one small step in our ability to go forward in replacing damaged tissues and organs - Dr Anthony Atala

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