Stem Cells - Brutes or Angels: Human Possibility in the Age of Biotechnology - page 46

had safety issues. The procedure to create iPs cells used viruses with
health risks and a gene known to cause cancer. Dramatic progress in solv-
ing these problems came in 2009. 4 mouse and human iPs cells were pro-
duced without using viruses, and a way was found to remove the added
genes from the cells after genetic reprogramming was completed (Pera
2009). 5 Also, German and south Korean researchers created iPs cells by
introducing a single, non-cancer-causing gene into human adult stem cells
from nervous system tissue (Kim et al. 2009). however, work in 2011 un-
covered several genetic abnormalities in iPs cells that currently preclude
their safe use clinically (Pera 2011).
in view of iPs cells' pluripotency, is continued research on human esCs
needed? in addition to the safety issues with iPs cells, there are at least
three reasons why research on human esCs should be continued:
1. The enormous developmental potential of esCs and the prospective
contributions of esCs to regenerative medicine are still “gold standards”
against which all other types of pluripotent cells will be compared for
years to come. Also, some biochemical indicators suggest that iPs cells
do not equal esCs in developmental potential and, therefore, in clinical
value.
2. human embryos and the stem cells derived from them will be invaluable
for solving future problems in developmental biology, reproductive bi-
ology, and medicine; therefore, it is important to learn more about esC
biology and to continue examining the ethical issues surrounding their
use in research and medicine.
3. As we see later, iPs cells bring up significant ethical issues of their own.
Therapeutic Cloning: What Is It and Why Do It?
Although many mammals have been cloned, humans have not yet been
cloned. But this could change any day. Groups of esC researchers around
the world work toward cloning humans to the blastocyst stage in order to
obtain esCs for medical purposes. it is important to consider what clon-
ing is and how the two types of cloning, therapeutic cloning (embryo cloning)