Comparing Two Reproductive Cloning Methods: SCNT and iPS
I presumed that many of us still remember the infamous scientific research fraud in 2005, which originated in South Korea when some researchers claimed that they have created human embryonic stem cells via nuclear transfer.
Since the geniture of Dolly with somatic cell nuclear transfer (SCNT) in 1996, generations of scientists have devoted to this field. And our clone technique also advanced several innovations, such as in 1998 when scientists announced that they had harvested the cells from days-old human embryos, called blastocysts, obtained from fertility clinics. But the cell line turned out to be fewer and of poorer quality than people have expected, then in 2007 when Shinya Yamanaka produced human embryonic stem cells in a way that did not require eggs or embryos. He added four genes— Oct3/4 Sox2 ,c-Myc and Klf4 . The adult cells, which he called induced pluripotent (iPS) cells, showed all the properties of embryonic stem cells, an achievement for which Yamanaka shared last year's Nobel Prize in medicine. After this, the research transferred their focus on iPS.
Now turn back, scientists improved the dolly technique in which they carefully inserted an adult skin cell into a donated human egg whose DNA had been removed. The unfertilized eggs, stimulated by electric pulses to start dividing, developed to about the 150-cell stage. The research team figured out how to get the egg to act as if it had been fertilized. The secret was to keep the eggs in the phase of their growth cycle called "metaphase," which is when DNA aligns in the middle of the cell before the cell divides. The scientists got the best results when they grew the eggs in a little of a substance that tends to be abundant in labs: caffeine.
Compared with iPS, Dolly technique is quicker to culture, but short in supply and hard to obtain in human eggs. In addition, iPS tends to age prematurely and die and cancer-causing.
But does the variation of the Dolly technique inferior to iPS, we have no certain answer. The new finding can’t be called advancement for reproductive cloning. But it might accelerate clinical trials and related scientific research.
Article Link: Comparing Two Reproductive Cloning Methods: SCNT and iPS
Tags: Stem Cells, DNA, SCNT and iPS, Oct3/4, Sox2, c-Myc, Klf4, Clone