embryonic stem cells

T.D. Laing tdlaing at nospam.dres.dnd.ca
Fri Nov 6 10:51:53 EST 1998


In article <71u81l$e26$1 at nnrp1.dejanews.com>, andrewmason at my-dejanews.com wrote:

> Geron today (Nov 5th) announced the results of two research programs
> 
> 1)DERIVATION OF HUMAN EMBRYONIC STEM CELLS
> 
> 2) DERIVATION OF HUMAN PLURIPOTENT STEM CELLS FROM CULTURED PRIMORDIAL GERM
> CELLS

[snip]

> My question regards the application of this research. If embryonic stem cells
> are harvested from an embryo and can be encouraged to replicate
> without differentiating, it may be possible to provide a
> suitable volume of cells which can then be encouraged to differentiate into
> bone marrow cells for a bone marrow transplant(as an example). What about
> issues of rejection? How many different lines of stem cells is it necessary to
> maintain to ensure that one of them is compatible with a given patient.

What you mention below, using a fertilized embryo with the patient being
one parent, and the other "donor" parent being HLA-matched as closely as
possible, might help to overcome rejection issues.

> I note that the hES cells came from in vitro fertilized blastocysts, not from
> aborted fetuses, getting around one ethical problem. However it raises the
> possibility that the best source for compatible hES cells for a given patient
> would be an in vitro fertilised embryo with the patient being one parent. An
> even better would be a cloned embryo formed using the nucleus of a
> differentiated cell from the patient(as per Dolly the sheep).

Ah, but you'd have to get around the human cloning issue first.

> How much of an ethical problem will this raise? If an embryo is allowed to
> replicate its cells in vitro only a few times before the hES cells are
> harvested, but it was created with the sole intent of harvesting those cells,
> will this be viewed by some as unethical? Or will it result in a relaxing of
> the restriction on human cloning if the clone is never intended to progress
> past the level of blastocyst?

IMHO it would be a very sticky ethical problem.  We already have cases of
parents getting pregnant in the hopes that their baby will be a donor
source of cells (bone marrow mainly) for an older, ill sibling.  Some have
even proposed purposely aborting a fetus to harvest its neural cells to
treat Parkinson's disease.  The question there being, of course, was
whether the baby or fetus was conceived for its own sake, or just to be
"used".  Also, given that the Roman Catholic Church holds that humanity
begins at conception, there is definitely the religious problem of whether
it's ethical to conceive a human embryo just to harvest its cells.  The
same problems would hold with cloning--who's to stop people from allowing
some cloned blastocysts to develop further?  As always, it's not a
question of whether we *can*, but whether we *should*.

T.

-- 
T.D. Laing
tdlaing at dres.dnd.ca

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