Sárospataki Füzetek 14. (2010)
2010 / 1. szám - TANULMÁNYOK - Rusthoven, James J.: Mit jelent embernek lenni a technika korában? Református keresztyén megközelítés.
Rusthoven, James J. Induced Pluripotent Stern Cells — The Ethical Stem Celli More recently, embryoids have been produced known as induced pluripotent stem cells or IPS cells.1 Unlike those produced by SCNT, these embryoids start as regular cells, like skin cells, but rather than the nucleus being removed as in SCNT, the skin cell is injected with four foreign genes attached to viruses to facilitate their entry into the cell and nucleus. These genes then produce proteins that cause the cell to de-differentiate and take on the characteristics of embryonic cells. Thus, with this technique there is no need to seek human egg donations, avoiding that ethical problem. In the initial reports, however, the foreign genes remained in the cell as did the viruses required to insert the genes. So these foreign genes became part of that cell and its progeny. Furthermore, the viruses used to insert the genes also remained in the cell and are known to cause cancers. As a result, if these cellular constructs would be developed into treatments, the human recipients would be receiving genetically-modified treatment that also might be associated with an increased risk of developing cancer. However, this technology has moved so quickly that within months a technique was reported showing that only the active proteins produced by those specific foreign genes were needed to produce such embryoids. These proteins could be inserted into the skin cells without the need for the foreign genes or viruses, making these embryoids theoretically much safer to develop into therapies. Like regular embryos and other embryoids such as those produced by SCNT, iPS cells are pluripotent. That is, under the right laboratory conditions they can be directed to re-differentiate into one of many mature types of functional cells. In fact reports have already begun to appear showing that human iPs cells can be redirected to re-differentiate into cells with new, specific functions. For example, this past summer, human iPS cells were directed to differentiate into pancreatic beta cells, the cells that produce insulin, making these cells possible treatments for patients who suffer from diabetes because their own cells can no longer produce insulin.7 8 While this is very rapidly progressing, promising, and exciting biological research, it is associated with practical and ethical concerns. The production of iPS cells is very inefficient if viruses and genes are not used, bringing up practical concerns about their commercial viability for developing new treatments. Also, theoretically these embryoids could be induced to implant in a uterus and become a viable fetus, a human clone. But what would be the status of such human clones constructed in the laboratory? What safeguards could be established to exclude the possibility of such technology being used for reproductive purposes? And even if embryoids themselves are not considered to be human beings, there remain many scientists and non-scientists who believe that human embryonic stem cells should still be used for research purposes. They believe that embryonic stem cells produced naturally by the union of sperm and eggs have the greatest potential to produce the 7 Cyranoski, D.(2007) “Simple Switch Turns Cells Embryonic: Technique Removes Need for Eggs or Embryos,” Nature (doi:10.1038/447618a). 8 Maehr, R., S. Chen, M. Snitow, et al (2009) “Generation of Pluripotent Stem Cells from Patients with Type 1 Diabetes,” Proceeding of the National Academy of Sciences (doi/10.1073/ pnas.0906804106). 58 SÁROSPATAKI FÜZETEK
