Since its day of creation, cloning techniques have been hailed as a major breakthrough in the field of medicine. It was anticipated that the creation of perfectly matched tissues will someday help in discovering the cure for a variety of debilitating diseases like Alzheimer's and Parkinson's disease. But the quest for 'therapeutic' cloning has been shelved due to various reasons ranging from its ethical aspects, fraudulent objectives involved and the development of an alternative technique in the recent years. Thankfully, a team led by reproductive biology specialist, Shoukhrat Mitalipov, from the Oregon Health and Science University in Beaverton has rekindled the interest in 'therapeutic' cloning through the publication of a new paper alleging to have produced through cloning Patient-specific Embryonic Stem Cells.
Therapeutic cloning or Somatic Cell Nuclear Transfer (SCNT) took roots in 1996 with the birth of Dolly, the first cloned mammal. An unfertilized egg with its nucleus removed is fused with a donor cell body tissue like the skin. The DNA of the donor cell undergoes 'reprogramming' by the egg to its embryonic state and division ensues the early 8-celled blastocyst stage is reached. A stable cell line can be created to genetically match the donor through various harvesting and culturing and can become potentially all types of cell of the human body. With the success in the creation of Dolly, the first mammal clone a quest to replicate the success in humans ensued but with limited success. In South Korea's Seoul National University, Woo Suk Hwang reported 2 success attempts in 2004 and 2005 both of which turned out to be false starts. Mitalipov achieved some success with monkeys in 2007 and proceeded to replicate the same with humans last year.
Mitalipov and his team of dedicated work commenced work in this aspect from September 2012. The donor eggs were recruited through a advertising campaign in their university. After enduring initial failures, Mitalipov observed that of the engineered cells four of the cloned embryos began growing. Masahito Tachibana, a prominent member of the team, was instrumental in testing the growth patterns of the cultured cells. Being a fertility specialist from Sendai, Japan, the job of sectioning and transferring the cells to new culture media for detecting growth patterns was handled with expertise. Thus there was substantiation of the success of their efforts.
A few minor technical tweaks had to be undertaken to reach their success. Inactivated Sendai virus, which is known to cause cell-fusion, was used in the union of egg and donor cell. In order to activate embryo develop, electric jolts were used. The researchers added caffeine to ensure the production of cell lines by preventing premature activation. All the above techniques were systematically tested in various combinations on 1000 monkey eggs before ensuring the same in human cells to ensure high success rates. All of this was achieved in a matter of few months. A myriad number of tests were then undertaken to prove the theory that SCNT cells could lead to the production of various cell types. They created spontaneously contracting heart cells.
The initial cell lines used fetal skin cells which subsequently moved on to donor cells from a 8-month-old Leigh Syndrome patient substantiating the efficacy of adult mature cells as donor cells. The egg donors volunteering in the experiment received ample compensation ranging from US$3,000-7,000 which maybe considered as expensive. This in contrast to the postulates of bioethics risks creation of organ trade which exploits the poor.
Despite the ever present public fear of misutilization of cloning procedures, little success has been achieved in the animal cloning procedures thus lying to rest the hysteria associated with cloning. An area of researchers growing popular since 2006 are the advocates of other patient-specific and genetically similar cell lines creation: production of induced Pluripotent Stem cells (iPS) through reprogramming of adult cells. This is a major area of research in modern medicine and overcomes a major ethical issue associated with SCNT: destruction of embryos and cloning methods. While some researchers show the disadvantage of iPS cells as being not completely programmed as compared to genetically matched SCNT cells a thorough analysis and comparison is awaited between the 2 major therapeutic prospects for various debilitating diseases. Thus patients requiring specific cell lines for alleviating their disease can hope for brighter times ahead with a variety of tested and proven methods awaiting them.
About Author / Additional Info:
Maitree Baral holds a Masters in Bioinformatics and shows profound interest in discussing various aspects of biology.