Season 4, Episode 12: The Sounds of Science

Bob learns that Nina is not carrying their child, but rather is pregnant with his clone! Olivier Roth has used Bob's stem cells to produce the first human clone, and Nina agreed to carry it. David tries to convince Bob and Nina to terminate the pregnancy, but they insist on keeping the clone and plan on raising it. Meanwhile, Roth tells David that he has implanted many world leaders' brains with Bob's stem cells in order to activate their Jacobsen's Organ. One of his patients was the Moldovian Minister of Health, a corrupt politician who stages an epidemic to cover up genocide orchestrated by the government, and imprisons Carlos when he travels to Moldovia to investigate.

Image provided courtesy of Shaftesbury Films.

David confronts Nina and Bob about their plan to carry Bob's clone to term.

IS IT POSSIBLE TO CLONE HUMANS?

What is cloning?

Cloning is the creation of a genetic duplicate, whether it is a gene, a plant, or an animal. Cloning plants is quite common: regrowing a plant from a shoot or other graft will give a new plant with exactly the same DNA. Identical twins are also clones: they arise from a single embryo that separates into two or more identical embryos in the very early stage of embryonic development.

How can adult mammals be cloned?

The only technique available to clone an adult mammal, like Bob, is somatic cell nuclear transfer, or SNCT. In this technique, a nucleus, which contains the genetic material, is removed from the cell of an adult animal and transferred to an unfertilized egg cell from which the nuclear material has been removed - i.e. an enucleated oocyte. The egg cell with transplanted nucleus is then stimulated using chemicals or electricity to trick the cell into 'thinking' that it was fertilized by a sperm cell. The resulting embryo is then grown in the lab for five days until it forms what is called a blastocyst, which can then be transferred to an adult female uterus to develop and, eventually, be born. The genetic material of a clone produced by SCNT is not 100% identical to the cell from which the nucleus was taken: the mitochondrial DNA comes from the egg cell.

In 1996, Dolly the sheep was the world's first mammal cloned from an adult cell by SCNT. Dolly's DNA came from the nucleus of a cell from a six year old ewe's mammary gland. In the world of ReGenesis, Bob's clone would have been made from the nucleus of one of Bob's stem cells, with which Roth was doing experiments in his lab.

What animals have been successfully cloned using nuclear transfer?

As of mid-2008, many animals, including cats, dogs, cattle, mice, and monkeys, have been cloned using nuclear transfer; however, not all of them have produced full-grown animals using nuclei from adult cells. Dolly was the first animal to be cloned from an adult cell, but a few years before she was born, the same researchers cloned two sheep from nuclei of embryonic cells. Nuclear transfer of embryonic cells has also been used to successfully clone rhesus monkeys. These monkeys are the only primate clones grown beyond the blastocyst stage, but they were not cloned from adult cells.

In November 2007, researchers announced that they had cloned macaques using adult cells and nuclear transfer. But these clones were only grown to the blastocyst stage, and did not develop further into full-grown macaques.

What is the success rate of cloning?

Even though animals have been born after cloning procedures, the success rate is very low. To get an idea of how difficult it is, consider that the researchers who had previously cloned two sheep from embryonic cells had to try another 276 times before they were able to clone the first sheep from adult cells (Dolly). The team that cloned the macaques tried to implant the blastocysts into adult female macaques in hopes of having one or more give rise to a baby macaque, but after a hundred attempts they still hadn't succeeded.

What is the outlook for human cloning?

When Dolly was introduced to the world in 1997, many people believed that cloning humans from adult cells was only a step away. But, as mentioned above, it took another decade to successfully clone macaque embryos from adult cells, and no cloned primates have yet been born. At present, scientists don't yet understand cloning well enough to make human reproductive cloning feasible and safe.

Why might it be unsafe? One problem that could arise is faster aging of the clone. This is because the ends of the DNA molecules in our bodies - the telomeres - change over time. Found at the tips of chromosomes, telomeres are necessary to make sure that all the genetic material on the chromosome is copied when a cell divides. The telomeres get a little shorter with every cell division, until they get too short and the cell dies. Basically, the DNA ages! And as it ages, so do we.

When DNA from adult cells is used to produce a clone, the clone might have telomeres that are much shorter than normal babies have, which would make the clone age faster. Dolly had shortened telomeres - she was born with DNA that was already 6 years old - but, interestingly, when cows were cloned the clones had longer telomeres than the DNA from the donor cell! How cloning will affect aging through telomere length is important to know before proceeding with human cloning.

So?

It might be possible - though prohibited in many parts of the world - to clone humans from adult cells some day, but no primate, human or non-human, has yet been cloned. Remember, it took 276 attempts to impregnate a sheep with the clone of the first adult mammal. In this episode, Roth says that Nina is carrying the only human clone, but what he doesn't talk about is how many failed attempts there were before they were finally successful!

DID YOU KNOW?

In this episode, the Moldovian Minister of Health tries to cover up genocide by announcing an outbreak of Japanese Encephalitis.

Image provided courtesy of Shaftesbury Films.

A horrified Carlos looks at satellite images of dead bodies in Moldovia.

This is a disease found mainly in Far East Asia (not in Eastern Europe, where Moldovia is). It's caused by a virus that is spread by a mosquito bite, but only 5% of infected people get sick with symptoms of brain inflammation. When they do occur, symptoms can be quite severe: one in two patients develop neurological damage, and one in four die.

-- Eva Amsen

Want to read and learn more?

To find out the differences between cloning from adult stem cells and embryo splitting, visit:
http://science-education.nih.gov/home2.nsf/Educational+ ResourcesTopicsGenetics/BC5086E34E4DBA0085256CCD006F01CB

The WHO published an informative fact sheet about cloning, found here:
http://www.who.int/ethics/topics/cloning/en/

Read a news article about the recently cloned macaques:
http://www.thestar.com/News/article/276672

Learn about the risks of cloning, including telomere shortening:
http://learn.genetics.utah.edu/units/cloning/cloningrisks/

Find out more about Japanese Encephalitis through this fact sheet from the CDC:
http://www.cdc.gov/ncidod/dvbid/jencephalitis/qa.htm