Nuclear transfer of somatic cell nuclear transfer (SCNT) involves the removal of the DNA from anyone cell of a person and transferring it by a microscopic glass tube into an unfertilized egg (whose own DNA had been previously removed). The egg is then allowed to develop into a blastocyst. The inner cell mass of the blastocyst is then removed and embryonic stem cells are grown from it (Mollard, 2005). Parthenogenesis is a process by which some animals (lizards and birds) can reproduce without a male. In mammals, parthenogenesis refers to the embryonic development of eggs, which have been activated (artificially or aberrantly) without fertilization by a sperm (Cheng, 2008). Somatic cell dedifferentiation is the “direct reprogramming of an adult somatic cell to return to the state of a pluripotent stem cell” (Mertes, Pennings, Steirteghem, 2006)
The pros of nuclear transfer are that these embryonic stem cells, which contain the patient’s DNA, match the patient’s immunological profile and will not be rejected by the immune system of the patient (Mollard, 2005). The cons are that nuclear transfer may not be able to generate complete organs from culture, and the culture conditions are not as developed when compared to the environment regulating cells during organogenesis (Mollard, 2005).
The proof parthenogenesis is that it provides a source to derive embryonic stem cells with an exact match to the oocyte donor’s genome (both nuclear and mitochondrial), and it could provide a source of cells that are homozygous for major histocompatibility alleles-HLA-A, B, or DRB (Cheng, 2008). The cons are that mammalian parthenotes cannot develop into a full organism (Cheng, 2008).
The pros of somatic cell dedifferentiation are that it is not necessary to create an embryo to obtain stem cells, and there is a reduced risk of an immune reaction or graft-versus-host disease because dedifferentiated cells would have the same genetic information as the donor.
Also, the procedure is simpler and better suited for large-scale applications because SCNT is bypassed (Mertes, Pennings, Steirteghem, 2006). However, it is technically difficult to remove the original embryonic stem cell’s chromosomes from the hybrid cell (Mertes, Pennings, Steirteghem, 2006).
References
Cheng, L (2008). More new lines of human parthenogenetic embryonic stem cells.Cell Research. 18: 215–217. Web.
Mertes, H, Pennings, G, Steirteghem, AV (2006). An ethical analysis of alternative methods to obtain pluripotent stem cells without destroying embryos. Oxford Journals. 21 (11). Web.
Mollard, R (2005). Nuclear Transfer -Stem Cells or Somatic Cell Nuclear Transfer (SCNT). Web.