History of Cloning and Ethical Issues of Human Cloning
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Describes the history of cloning, How it developed to date. For Scientific Free Lectures, Visit - http://bit.ly/VisitZofirAcademy
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History of Cloning and Ethical Issues of Human Cloning
- 1. Process Religious issues Experiments conducted Federal and governmental regulations Medical issues World view Pros and Cons PRESENTED BY ARMAN FIROZ – M.Sc.BIOMEDICAL GENETICS History
- 2. History of Cloning: 1885 - First-ever demonstration of artificial embryo twinning. Sea urchin Hans Adolf Edward Dreisch This experiment showed that each cell in the early embryo has its own complete set of genetic instructions and can grow into a full organism. 1902 - Artificial embryo twinning in a vertebrate. Salamander Hans Spemann This experiment showed that embryos from a more-complex animal can also be “twinned” to form multiple identical organisms—but only up to a certain stage in development. 1928 - The cell nucleus controls embryonic development. Essentially the first instance of nuclear transfer, this experiment showed that the nucleus from an early embryonic cell directs the complete growth of a salamander, effectively substituting for the nucleus in a fertilized egg. Salamander Hans Spemann
- 3. First successful nuclear transfer Frog - Robert Briggs and Thomas King 1952 - Briggs and King transferred the nucleus from an early tadpole embryo into an enucleated frog egg (a frog egg from which the nucleus had been removed). The resulting cell developed into a tadpole Most importantly, this experiment showed that nuclear transfer was a viable cloning technique. It also reinforced two earlier observations. First, the nucleus directs cell growth and, ultimately, an organism’s development. Second, embryonic cells early in development are better for cloning than cells at later stages. Nuclear transfer from a differentiated cell 1958 - This experiment showed that, despite previous failures, nuclei from somatic cells in a fully developed animal could be used for cloning. Importantly, it suggested that cells retain all of their genetic material even as they divide and differentiate (although some wondered if the donor DNA came from a stem cell, which can differentiate into multiple types of cells). John Gurdon
- 4. Rabbit J. Derek Bromhall This experiment showed that mammalian embryos could be created by nuclear transfer. To show that the embryos could continue developing, Bromhall would have had to place them into a mother rabbit's womb. He never did this experiment. First mammalian embryo created by nuclear transfer 1975 - First mammal created by nuclear transfer 1984 - This experiment showed that it was possible to clone a mammal by nuclear transfer—and that the clone could fully develop. Even though the donor nuclei came from early embryonic cells, the experiment was considered a great success. Sheep Steen Willadsen Nuclear transfer from embryonic cell This experiment added cows to the list of mammals that could be cloned by nuclear transfer. Still, mammalian cloning was limited to using embryonic cells as nuclear donors. Cloning using nuclei from differentiated adult somatic cells still wasn’t thought possible Cow Neal First, Randal Prather, and Willard Eyestone 1987-
- 5. Dolly: First mammal created by somatic cell nuclear transfer Of 277 attempts, only one produced an embryo that was carried to term in a surrogate mother. This famous lamb, named Dolly, brought cloning into the limelight. Her arrival started conversations about the implications of cloning, bringing controversies over human cloning and stem cell research into the public eye. Sheep Ian Wilmut and Keith Campbell 1996- 1998-1999 - More mammals cloned by somatic cell nuclear transfer 2001 - Endangered animals cloned by somatic cell nuclear transfer Primate embryonic stem cells created by somatic cell nuclear transfer 2007 - This experiment showed that nuclear transfer in a primate, which researchers had tried for years without success, was possible. It opened the door to the possibility of human therapeutic cloning: creating individual-specific stem cells that could be used to treat or study diseases. Rhesus monkey Shoukhrat Mitalipov and colleagues
- 6. Human embryonic stem cells created by somatic cell nuclear transfer 2013 - In this experiment, researchers took a skin cell from the patient and fused it with a donated egg cell. Key to the success of the experiment were modifications to the culture liquid in which the procedure was done and to the series of electrical pulses used to stimulate the egg to begin dividing. Shoukhrat Mitalipov and colleagues No one truly knows the future of human cloning, but many believe models will be cloned to make designer babies. It is highly probable that a cloned human being lives among us now. You might read breaking headlines about cloning but most of those are A few years behind. Some say they just discovered a new process to human cloning in 2010, but in reality it was completed in 2005. In 2001, there was such a stir in the human cloning idea that hundreds of scientist did their work with out anyone knowing. Thousands of dollars, eggs, adult cells ect. have been donated to human cloning research. As citizens of the world we can not ignore scientific research, but instead regulate it. “Either we control gene technology today, or technology will redesign us by tomorrow.” Future of Human Cloning
- 8. Religious issues Some people believe that cloning is similar to playing God. They believe that God should be the creator of all living and natural things. It is believed that a human has the right for the full human development in a natural environment and that the human embryo should be left alone after the 14th day of fertilization. Some religious people believe that if you clone a human being it has no soul. People believe human cloning takes away from an Individual being unique and stresses Psychological and social development.
- 9. Medical issues Technically, human gene grows older with age. It’s feared that the cloned individual would retain the age of the donor’s genes. Cloning animals through somatic cell nuclear transfer is simply inefficient. The success rate ranges from 0.1 percent to 3 percent, which means that for every 1000 tries, only one to 30 clones are made. Some reasons include •The enucleated egg and the transferred nucleus may not be compatible •An egg with a newly transferred nucleus may not begin to divide or develop properly •Implantation of the embryo into the surrogate mother might fail •The pregnancy itself might fail Problems during later development •Cloned animals that do survive tend to be much bigger at birth than their natural counterparts. Clones with LOS(Large Offspring Syndrome)have abnormally large organs. This can lead to breathing, blood flow and other problems. .
- 10. Abnormal gene expression patterns • one challenge is to re-program the transferred nucleus to behave as though it belongs in a very early embryonic cell. This mimics natural development, which starts when a sperm fertilizes an egg. • In a naturally-created embryo, the DNA is programmed to express a certain set of genes. Later on, as the embryonic cells begin to differentiate, the program changes. • In cloning, the transferred nucleus doesn't have the same program as a natural embryo. It is up to the scientist to reprogram the nucleus Complete reprogramming is needed for normal or near- normal development. Incomplete programming will cause the embryo to develop abnormally or fail. Telomeric differences • As cells divide, their chromosomes get shorter. The telomere lengths of cloned animals, found no clear answers. Chromosomes from cloned cattle or mice had longer telomeres than normal. These cells showed other signs of youth and seemed to have an extended lifespan compared with cells from a naturally conceived cow
- 11. Pros Cons Defective genes could be eliminated There is a possibility of faster aging. Faster recovery from traumatic injury There is a reduced sense of individuality. Infertility could be eliminated. It may reduce the overall value of human life. Cloned body parts can serve as backup systems for humans Weaken diversity and ability of adaptation. Combat genetic diseases Production of undesirable traits. Replicate animals for research purposes & also alterations of plants & animals Invites malpractices into society. Produce people with desirable traits. Humans acting as God
- 12. World views Australia Australia has prohibited human cloning, therapeutic cloning is now legal in some parts of Australia. Canada Canadian law prohibits the following: cloning humans, cloning stem cells, growing human embryos for research purposes, and buying or selling of embryos, sperm, eggs or other human reproductive material. India India does not have specific law regarding cloning but has guidelines prohibiting whole human cloning or reproductive cloning. India allows therapeutic cloning and the use of embryonic stem cells for research proposes Argentina Prohibits:: “experiments concerning cloning of human cells in order to generate human beings .”
- 13. REFERENCE • Wilmut I; Schnieke AE; McWhir J; Kind AJ; et al. (1997). "Viable offspring derived from fetal and adult mammalian cells". Nature 385(6619): 810–3 • Campbell KH; McWhir J; Ritchie WA; Wilmut I (1996). "Sheep cloned by nuclear transfer from a cultured cell line". Nature 380(6569): 64–6. Supported by a Science Education Partnership Award (SEPA) Grant No. R25RR016291 from the National Center for Research Resources, a component of the NIH. The contents provided here are solely the responsibility of the authors and do not necessarily represent the official views of NIH. • Religious Opposition to Cloning, Journal of Evolution and Technology - Vol. 13 – October 2003 http://jetpress.org/volume13/bainbridge.htm by William Sims Bainbridge, Ph.D. • Bainbridge, William Sims. 2003. "Sacred Algorithms: Exchange Theory of Religious Claims," in Defining Religion edited by Aurthur L. Greil and David G. Bromley. Oxford: JAI/Elsevier (Volume 10 of Religion and the Social Order). • Benin, Mary Holland. 1985. "Determinants of Opposition to Abortion," Sociological Perspectives, 28: 199-216.
Editor's Notes
- Clones are organisms that are exact genetic copies. Every single bit of their DNA is identical. Clones can happen naturally—identical twins are just one of many examples. Or they can be made in the lab. Many people first heard of cloning when Dolly the Sheep showed up on the scene in 1997. Artificial cloning technologies have been around for much longer than Dolly, though. So lets see how the cloning developed all these days.
- 1. The sea urchin is a relatively simple organism that is useful for studying development. Dreisch showed that by merely shaking two-celled sea urchin embryos, it was possible to separate the cells. Once separated, each cell grew into a complete sea urchin. 2. Spemann’s first challenge was to figure out how to split the two cells of an embryo much stickier than sea urchin cells. Spemann fashioned a tiny noose from a strand of baby hair and tightened it between two cells of a salamander embryo until they separated. Each cell grew into an adult salamander. Spemann also tried to divide more advanced salamander embryos using this method, but he found that cells from these embryos weren’t as successful at developing into adult salamanders. 3. Again using a strand of baby hair tied into a noose, Spemann temporarily squeezed a fertilized salamander egg to push the nucleus to one side of the cytoplasm. The egg divided into cells—but only on the side with the nucleus. After four cell divisions, which made 16 cells, Spemann loosened the noose, letting the nucleus from one of the cells slide back into the non-dividing side of the egg. He used the noose to separate this “new” cell from the rest of the embryo. The single cell grew into a new salamander embryo, as did the remaining cells that were separated.
- 1952- The scientists created many normal tadpole clones using nuclei from early embryos. But just like Spemann’s salamander experiments, cloning was less successful with donor nuclei from more advanced embryos: the few tadpole clones that did survive grew abnormally. 1958- Gurdon transplanted the nucleus of a tadpole intestinal cell into an enucleated frog egg. In this way, he created tadpoles that were genetically identical to the one from which the intestinal cell was taken.
- 1975- Mammalian egg cells are much smaller than those of frogs or salamanders, so they are harder to manipulate. Using a glass pipette as a tiny straw, Bromhall transferred the nucleus from a rabbit embryo cell into an enucleated rabbit egg cell. He considered the procedure a success when a morula, or advanced embryo, developed after a couple of days. 1984- Willadsen used a chemical process to separated one cell from an 8-cell lamb embryo. The he used a small electrical shock to fuse it to an enucleated egg cell. As luck would have it, the new cell started dividing. By this time, in vitro fertilization techniques had been developed, and they had been used successfully to help couples have babies. So after a few days, Willadsen placed the lamb embryos into the womb of surrogate mother sheep. The result was the birth of three live lambs. 1987- Using methods very similar to those used by Willadsen on sheep, First, Prather, and Eyestone produced two cloned calves. Their names were Fusion and Copy.
- 1996- Dolly was born on 5 July 1996 and had three mothers (one provided the egg, another the DNA and a third carried the cloned embryo to term). She was created using the technique of somatic cell nuclear transfer, where the cell nucleus from an adult cell is transferred into an unfertilized oocyte (developing egg cell) that has had its cell nucleus removed. The hybrid cell is then stimulated to divide by an electric shock, and when it develops into a blastocyst it is implanted in a surrogate mother, Dolly was the first clone produced from a cell taken from an adult mammal. The production of Dolly showed that genes in the nucleus of such a mature differentiated somatic cell are still capable of reverting to an embryonic totipotent state, creating a cell that can then go on to develop into any part of an animal. Dolly's existence was announced to the public on 22 February 1997. It gained much attention in the media. A commercial with Scottish scientists playing with sheep was aired on TV, and a special report in TIME Magazine featured Dolly the sheep. Science featured Dolly as the breakthrough of the year. Even though Dolly was not the first animal to be cloned, she gained this attention in the media because she was the first to be cloned from an adult cell. After the successes leading up to Dolly and Polly, other scientists wanted to see if similar techniques could be used to clone other mammalian species. Before long, several more animals had been successfully cloned. Among them were transgenic animals, clones made from fetal and adult cells, and a male mouse; all previous clones had been female. As the list of successfully cloned animals grew, scientists began to explore cloning as a way to create animals belonging to endangered or extinct species. A challenge to cloning endangered and extinct species is finding closely related animals to serve as egg donors and surrogates. The gaur and mouflon were chosen in part because they are close relatives of domestic cattle and sheep, respectively. In 2009, using goats as egg donors and surrogates, another group of researchers cloned the first extinct animal, a Spanish mountain goat called the bucardo. Sadly, the one kid that survived gestation died soon after birth due to a lung defect. 2007- Researchers took a cell from an adult monkey and fused it with an enucleated egg cell. The embryo was allowed to develop for a time, then its cells were grown in a culture dish. These cells, because they can differentiate to form any cell type, are called embryonic stem cells.
- Overcoming decades of technical challenges, Mitalipov and colleagues were the first to use somatic cell nuclear transfer to create a human embryo that could be used as a source of embryonic stem cells. The resulting stem cell lines were specific to the patient they came from, a baby with a rare genetic disorder.
- Sheep Cloned by Nuclear Transfer from a Cultured Cell Line" (1996), by Keith Campbell, Jim McWhir, William Ritchie, and Ian Wilmut - See more at: https://embryo.asu.edu/pages/sheep-cloned-nuclear-transfer-cultured-cell-line-1996-keith-campbell-jim-mcwhir-william#sthash.BIqOuI3I.dpuf
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