Alternatives to Using Embryos in Stem Cell Research

To address ethical concerns about  the destruction of blastocysts, scientists are trying to find new ways of obtaining  ste
m  cells  that   behave   like  embryonic stem cells but  that  don’t  require  harming  a blasto- cyst.  As the  science  progresses,  ethical  issues  sur- rounding these  alternatives may  also  arise.  Some possible alternatives include:

• Cells collected from the morula (MOR-yoo-la), the developmental stage prior to the blastocyst.  The morula,  a solid ball of about 16–30 cells, seems able to sustain the loss of a few cells without developmental damage so that the remaining cells can continue  to develop. Cell extraction from the morula is already being used in some clinics to screen for genetic disorders in embryos produced  by in vitro fertilization.  Researchers have recently shown that cells isolated from a mouse morula can give rise to embryonic stem cells while the
  remaining morula cells develop into a healthy mouse. However, this process may still be morally objec- tionable to some because of the chance of harm to the morula,  and because the long-term effects of removing cells from a morula are not yet known.
• The creation of embryonic stem cells through  a process called altered nuclear transfer (ANT). In this variation  of the nuclear transfer  technique, scientists create a blastocyst  whose genetic material  has been changed so that further development  and implantation into the uterus is not possible. It aims to create embryo-like entities that are not truly embryos but that can be a source of pluripotent stem cells. ANT, so far only tested with mouse blastocysts,  could allow the creation of embryonic stem cells without destroy- ing a viable human blastocyst.  Some who object to embryonic stem cell research support  ANT because the resulting blastocyst  could never develop into a full human being and therefore would not have the moral status of a human embryo.  However,  this procedure  is objectionable to some because they believe that it involves the creation of an imperfect blastocyst  that is designed to be destroyed.
• Causing an adult cell to act like an  embryonic stem cell. During development, as cells become more and more specialized, they gradually lose the ability to turn on the genes that allow embryonic stem cells to be so versatile. The silencing of these genes seems to be responsible  for keeping specialized cells specialized and limiting the differentiation capacities of adult stem cells. By “reprogramming” adult stem cells so that they can turn on the genes that allow versatility, scientists hope to cause them to revert to a more flexible state. It is even possible that scientists could one day “reprogram” any cell, not only stem cells. However,  research in this area is in the early stages and scientists may be many years away from making an adult cell as versatile as an embryonic stem cell.