● Where do embryonic stem cells come from and why is their use controversial?● Are somatic stem cells a good alternative? Why or why not?●...

Stem Cells (SC) have the ability to develop into many
different cell types during early life.  They can replenish and repair different types
of tissue.  When a stem cell divides it can become a new stem cell, or differentiate
into another, more specific type of cell such as a blood cell, brain cell or liver
cell.

Stem cells are medically useful because they can be
stimulated to become a specific cell type needed to repair or replace tissue or an
organ.  They are uncommitted and therefore represent a cellular “wild-card” that can be
induced to become any needed cell type.

Embryonic Stem
Cells (ESS):  Embryos, by nature of their primitive stage of development are a rich
source of stem cells.  In SC research, embryos are harvested from in vitro
fertilization.  After the SC are harvested, the embryos are donated for research (with
donor consent).

Controversy:  The use of ESS is
controversial because many feel the embryos from which they came are living creatures
and should not be sacrificed for medical science.  Furthermore, some feel that creation
of “life “ and growing of these cells in the laboratory in this manner is
immoral.

Somatic (Adult) Stem Cells (SSC):  These have been
found in many adult organs that have the ability of rapid cellular turnover, and
self-repair.  They have been found in many organs, even the brain.  It is hoped that
science can learn how to harvest these cells, then induce them to become organ cell
types needed to replace or repair diseased or deficient organs.  An example this
treatment would be the use of spinal cord stem cells to treat
paralysis.

Induced Pleuripotent Stem Cells (iPSC):  These
are adult cells that have been genetically reprogrammed to become like embryonic SC.  It
is not yet known if they will be as useful as ECC in treatment of
disease.

Note:  Use of somaatic stem cells or iPSC bypasses
the moral/ethical issues associated with the use of embryonic stem
cells.

The reference is an exhaustive treatise on stem
cells, produced by the National Institutes of Health.