MadSci Network: Development

Re: With stem cells couldnīt you create a human in vitro?

Date: Tue Jun 12 09:35:15 2001
Posted By: Paul Szauter, Staff, Mouse Genome Informatics, The Jackson Laboratory
Area of science: Development
ID: 990641778.Dv

There are a very large number of humans that have been 'created' in vitro in 
the sense that the fertilization of an egg cell by a sperm cell occurred in 
vitro. Since 1981, 45,000 babies have been born in the US using in vitro 

Please see:

Mice are routinely created that are derived from embryonic stem cells. In 
this case, the embryonic stem cells have been modified genetically to 
produce mice of interest to researchers in which a specific gene has been 
knocked out. The part of this process that applies to your question is the 
technique used to get live mice from the embryonic stem cells, which are 
grown in tissue culture.

Once a line of genetically modified mouse stem cells has been identified, 
they are used to make mouse embryos by incorporating the cells into a 
chimeric embryo in which the other cells are those of a mouse blastocyst, 
typically from a strain with a different coat color. (A chimera is a 
creature from mythology that has a snake for a tail, a lion's head and body, 
and a goat's head in the midsection. Biologists now use this word to 
represent an animal containing cells from two different strains or even two 
different species.) The mixed embryo is implanted into a foster mother and 
is born as a mouse made up of two different cell types: the stem cells and 
the blastocyst cells. If the germ line of the chimeric mouse include cells 
derived from the stem cells, the mouse will produce at least some progeny 
whose genes are derived from the stem cells when it is bred. There is a 
cartoon of this process at:

This process, if applied to humans, would produce a chimeric individual 
having some cells derived from the stem cells and some cells derived from 
the blastocyst cells. The chimeric blastocyst would have to be implanted in 
a foster mother, just as embryos from IVF are implanted today. It is not 
possible to bring a human embryo, or any other mammalian embryo, to term in 
vitro; a foster mother must be used.

Although this experiment could be carried out today, there is absolutely no 
reason to do so, as there could not possibly be any benefit to the 
individual created in this way. There would be no benefit to society, and no 
advancement of scientific knowledge, by carrying out such an experiment.

You might also be interested to learn that it is possible to create embryos 
that are wholly derived from a donor cell that need not be a stem cell. This 
is the process popularly referred to as cloning. So far, sheep, mice, 
cattle, pigs and goats have been cloned. It would certainly be possible to 
clone a human, but this experiment is also regarded as unethical, because 
there is a risk that the individual would not be normal, and there wouldn't 
be any benefit to anyone or to society in general from doing this. Please 
see the following answers in the MadSci archive for further information on 

You might find the MGI Glossary useful in understanding this answer:

Thank you for an interesting question.


Paul Szauter
Mouse Genome Informatics

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