Human cloning - can it work?

Dolly the sheep was the first succeccfully cloned mammal. Gradual improvements in cloning technology have enabled researchers to clone mice, cattle, goats, pigs, deer, rabbits, cats, mules, and horses.  Recent successes by South Korean researchers in generating stem cells from cloned human embryos have heightened concerns that human cloning is not impossible.

Even with recent technological advances, animal cloning is still extremely inefficient. For every 100 experiments, only 1, 2, or if lucky, maybe 3 appear to produce a viable offspring in surrogate mothers. While scientific explanations for these failures remain to be defined, many researchers think they represent nothing but technical hurdles that will one day be solved. Even then, its survival beyond the perinatal period is unlikely. These is no reason to believe that any different outcomes will occur if and when human cloning begins.

Scientists believe that the resultant cloning abnormalities are not traceable to the donor nuclei, but it more likely involves failures in genomic reprogramming. Genomic reprogramming in the natural way prior to embryogenesis, involves a stage of development of the egg and the sperm known as gametogenesis, which can take months to years to develop into a mature gamete. This process is sped up during cloning, and it takes only minutes to hours. The process of configuring the exact state of the inner workings of the cell including such complex processes as methylation of the DNA may not be correct for the development of the embryo. Methylation of DNA and other complex functions are now known to be essential to the correct functioning of each human cell, as they ultimately control gene expression. And thus successful cloning may be dependent upon the donated DNA being correctly altered to the state of an early embryo. It is thought by some cloning experts that failure of the nuclear clones to produce viable offspring is due to inappropriate reprogramming of cells, which leads to unregulated gene expression.

It is reasonable to conclude that future human cloning experiments will have the same high failure rates as animal clones. The possibility of performing prenatal genetic screening exists as a way to control quality. If these groups plan on using current routine prenatal diagnosis for the detection of chromosomal and/or other genetic abnormalities, they will not detect the types of epigenetic disturbances that may occur with cloning as there are no extra tools in the developmental pipeline to help improve detection. Research is ongoing to develop reprogramming of certain cells to turn into specific tissues types, which could regenerate nerves, muscles, and other cell types, alleviating Parkinson's, Alzheimer's, and heart disease among other chronic illnesses. There are many potential benefits of therapeutic cell cloning, and this research should not be jeopardized with human cloning activities.

Acknowledgement
http://www.ama-assn.org/ama/pub/physician-resources/medical-science/genetics-molecular-medicine/related-policy-topics/stem-cell-research/human-cloning.page

Why clone?

Have you ever thought what is it about cloning that is so important that scientists all over the world are still experimenting, up till today? Why do we have to clone things? Well, there's definitely a reason. 

One reason is to help those people who want a child but are unable to. Infertile couples are able to have a kid as reproductive cloning does not require the fusion of the sex cells.

Another reason that cloning can benefit us is that it can help treat diseases. Therapeutic cloning can be used to treat degenerative diseases like spinal cord injury, organ failure or the nervous system. It would be able to save so many people with diseases or injuries.

Cloning would be able to replace the defective genes in someone that causes illness to him or her. The defective can be replaced with healthy ones.

One other example is also the reason for cloning the famous Dolly the sheep. Dolly had been genetically modified to produce milk that contains a human protein essential for blood clotting and it can be given to humans whose blood does not clot properly. 

Cloned animals can also be used to test new drugs and treatments. It is very useful as cloned animals are genetically identical so the response to the drugs would be the same,  instead of using animals with all different genetics.

If cloning really becomes successful in the future, all the things listed above can be achieved and it can benefit us. However, although there are many benefits, there is also a number not-so-good points. There is also the issue of moral and ethical implications of cloning and some people are against the idea of cloning. I hope this has helped you to understand more about cloning and its benefits. 

Acknowledgements:

http://www.buzzle.com/articles/human-cloning-facts.html

http://www.genome.gov/25020028

Another Method of Cloning

Therapeutic Cloning

Well, you might be asking what is the big word in front of cloning. Nothing wrong with that, because I too did not know what it means at first. In this post, I'll be explaining about therapeutic cloning, or formally known as Somatic cell nuclear transfer(SCNT). Somatic Cell Transfer Introduction Animation


Somatic Cell Nuclear Transfer

Process of  Somatic Cell Nuclear Transfer

Step 1: Take a chicken egg. Nope, not eggs from supermarkets! A human egg from the ovary.
Step 2: Remove the nucleus from the egg and discard it.
Step 3: Remove the nucleus from another cell and insert it into the egg without a nucleus(enucleated egg)
Step 4:Once inside the egg cell, the nucleus would be reprogrammed by a shock, which would cause it to begin to divide until it becomes a blastocyst, which is an early stage of an embryo.
Step 5: At this point, stem cells can be remove from the blastocyst. The stem cells are undifferentiated cells which can grow into a variety of cells   Understand what stem cells are in this animation (:

Somatic cell nuclear tranfer can save the lives of people by recreating a certain part their body that are not working properly. For example, if you ever need  a new liver, SCNT can help you by taking the nucleus of a certain cell from you, let's say your skin cell, and inserting it into a host egg cell. The stems cells that are harvested can grow to replace your damaged liver cells. The plus point of SCNT is that, because your the nucleus of your own cells are used, chances of your body rejecting the new organ is much lower!

Acknowledgements:

ü  http://www.ehow.com/about_5525217_embryo-cloning.html (last accessed on 23 Feb 2013)

ü  http://www.wisegeek.org/what-is-therapeutic-cloning.htm (last accessed on 23 Feb 2013)

ü  http://science.howstuffworks.com/life/genetic/human-cloning2.htm (last accessed on 23 Feb 2013)

ü  http://global.britannica.com/EBchecked/topic/1382860/somatic-cell-nuclear-transfer-SCNT (last accessed 22 Feb 2013)

 

BIOETHICS

  Here's an article for you guys to think about. Is cloning really ethical or not? There are many ethical issues concerned about cloning, what is your opinion?

Can society accept '3-parent' offspring?

Section:	Opinion
By:	ANDY HO
Publication:	The Straits Times 20/10/2012
Page:	A42
No. of words:	971

By ANDY HO
SENIOR WRITER

IN BRITAIN, there is an ongoing public consultation till December over a fertility treatment that involves two biological mothers and one biological father.

This technology will help mothers with defective mitochondria, which are tiny, precisely functioning "machines" found in every cell that generate energy in a form called ATP that cells can use. Without mitochondria and thus ATP, life would not be possible.

All mitochondria sit in a cell's cytoplasm, the jelly-like soup holding a cell's contents together. Cytoplasm nourishes the nucleus in the cell's centre.

The nucleus carries chromosomes containing DNA, or the 20,000 genes that code for most of our human traits. This nuclear DNA comes from both parents.

Uniquely, mitochondria are the only sites outside the nucleus that also carry DNA. But this mitochondrial DNA (mDNA) differs from that found in the nucleus. It carries only 37 genes, which code for various metabolic purposes, so mDNA mutations can lead to muscular dystrophy, epilepsy, strokes, mental retardation and so on.

Uniquely, mDNA is derived from the mother only. In women whose eggs have faulty mDNA, serious conditions may be passed to their offspring. One in 6,500 children worldwide is afflicted by this.

To overcome this, defective mDNA must be removed from the mother's egg during in-vitro fertilisation (IVF) and substituted with healthy mDNA from a donor egg. But the baby thus made would have nuclear DNA from its father and mother, as well as mDNA from the woman egg donor.

Britain announced in 2008 it had made 10 such "trigamous" or three-gamete human embryos, which were never implanted in a womb. But in 2002, scientists in Guangzhou, China had taken an egg from a barren woman and fertilised it in a petri dish with her husband's sperm. Next the fertilised nucleus was removed from her egg and transferred into a donor egg emptied of its own nucleus (along with its nuclear DNA).

The hybrid egg – with the father and mother's DNA combined in the nucleus with the donor egg's healthy mDNA in the cytoplasm outside the nucleus – was then implanted into the mother's womb, which became a twin pregnancy. Sadly, she lost both at the 24th and 29th weeks, which however were tested to be genetically normal. So the technique is clearly viable.

No genes are altered in this process: Some bad ones are just swopped for some good ones. But if the "trigamous" offspring is female, she can also theoretically transmit the donor's mDNA to future generations in perpetuity.

In 2005, Australia reviewed its laws and re-affirmed its ban on making "embryos with more than two genetic parents... for reproductive purposes". Law-breakers may be jailed up to 10 years.

It is banned in the United States too, a ban that is unusual given that the fertility industry is self-regulated in most countries as reproductive liberty is highly cherished in the West. The industry sees bans only on human cloning and rules on experimentation with human embryos. Most fertility treatments are quickly pressed into service without having their safety firmly established. So why is this technique so unsettling?

The reason is that it involves transferring one nucleus (a fertilised one in this case) into an "empty" egg, this being the crucial step in cloning. Once the technology is approved for use, a scofflaw scientist could take the nucleus from a cell of some organ of an adult or child, transfer it into an "empty" egg and the hybrid egg would start dividing as if it were fertilised. This embryo could then be implanted in a womb and the human clone brought to term.

Cloning is already banned by law in Singapore and elsewhere. If this trigamous technology is made available without legalising human cloning too, some infertile couples could be helped. The fear of renegade cloners abusing it should not hinder women with mDNA issues from having babies.

The fear of cloning aside, a technology that results in possibly three adults having parental rights does not pose insuperable legal or policy issues. Prior contracts could be written in which the egg donor gives up parental claims, for a fee or out of altruism. Or, if two lesbians with healthy eggs use it to procreate with DNA from both women, they could get a prior contract written with the sperm donor to give up his parental claims.

Then all will be well unless separation or divorce occurs, when the courts will decide child support, custody and visitation rights in the child's best interests.

For example, in a US case, VC versus MJB (2000), made anonymous to protect the identities of the twins involved, a lesbian couple who had separated fought for custody.

One of the women had been impregnated with donor sperm and gave birth to the twins but both women had equally parented them. The New Jersey Supreme Court ruled that genetics was not determinative, so the gestational mother did not have priority: "Where there is a conflict over custody and visitation between the legal parent and a psychological parent, the standard to be applied is the best interests of the child."

Unless legislators write laws to regulate this and other reproductive technologies, courts will have to dispose with each case based on the specifics. While biology may matter, the courts are likely to adopt fluid understandings of parenthood in such domestic units and decide each case in the best interests of the child.

If Britain permits this "trigamous" technology, then its society will see these new family configurations soon enough. Since Singapore tends to adopt British life science practices, we might follow suit too. For us, there is a bright side: We could have more babies.

Acknowledgements:
http://newslink.asiaone.com/user/OrderArticleRequest.action?order=&_sourcePage=%2FWEB-INF%2Fjsp%2Fuser%2Fsearch_type_result.jsp&month=10&year=2012&date=20&docLanguage=en&documentId=nica_ST_2012_25859881

World's Most Famous Sheep

Dolly The Sheep

           Dolly was a female domestic Finnish Dorset and the first mammal to be cloned from an adult somatic (non-reproductive) cell through the process of nuclear transfer. Although Dolly was the world's most famous clone, many other animals had been cloned before her. She lived for 6 years, while the normal lifespan of a sheep is 11-12 years. 

Dolly and her firstborn, Bonnie

Timeline of Dolly

5 July 1996: Dolly was born to three mothers in Roslin Institute

22 February 1997: News of Dolly the Sheep's existence was made known to the public

April 1998: She gave birth to her first lamb, Bonnie. The next year, she gave birth to Sally and Rosie, both twins. And the year after, she gave birth to triplets Lucy, Darcy and Cotton.

Autumn 2001: Dolly was confirmed to suffer from arthritis.

14 February 2003: Dolly was diagnosed with progressive lung disease (sheep pulmonary  adenomatosis, a virus-induced lung tumour which sheep kept indoors are prone to have) and severe arthritis and was euthanised.

How Dolly was born

         Nuclear transfer

        Dolly was cloned from an adult cell, rather than an embryo. Cloning from an adult cell is more complex than the other processes. Dolly was the only lamb born out of the 277 attempts. 

The steps taken for the cloning of Dolly the sheep:

1. Cell is taken from the udder of a Finn-Dorset ewe, placed in a nutritional solution and isolated. The nucleus of this cell containing all the genetic material of the Finnish Dorset ewe is removed from the cell with a very small needle and a suction device.
2. An unfertilised egg cell is taken from a Scottish Blackface ewe. The nucleus of the egg cell is taken out using a very small needle and a suction device. 
3. The nucleus of the cell from the Finn-Dorset ewe is inserted in the nucleus-free egg cell.
4. The cells are given an electric shock and the egg cell starts to divide.
5. The egg is then implanted into a surrogate mother, also a Blackface ewe where the egg cell continues to develop into an embryo.
6. Dolly is born a few months later as a Finn-Dorset ewe, as her DNA was originally taken from a Finn-Dorset ewe.

Cloning Process

Why Dolly was cloned and how is it important?

        Dolly was cloned for the research of producing medicines in milk of farm animals at the Roslin Institute. The researchers are able to transfer human genes that produce useful proteins into the farm animals, such as sheep and cows so that they can produce milk with properties or factors to treat illnesses. 

        The cloning of Dolly has also led to the cloning of other larger mammals like horses and bulls and the development of cloning. Cloning if successful might be able help preserve endangered species and might even be able to bring extinct animals back to life! 

  References:

http://www.roslin.ed.ac.uk/public-interest/dolly-the-sheep/a-life-of-dolly/

http://en.wikipedia.org/wiki/Dolly_(sheep)

http://www.animalresearch.info/en/medical-advances/151/cloning-dolly-the-sheep/

http://www.iptv.org/exploremore/ge/what/clone.cfm

  Images:

http://bootstrike.com/Genetics/Cloning/dolly_the_sheep.php

http://www.roslin.ed.ac.uk/public-interest/dolly-the-sheep/a-life-of-dolly/



 



Artificial Embryo Twinning

 

Let's take a look at what is Artificial Embryo Twinning and how it works!

 

References
1) http://learn.genetics.utah.edu/content/tech/cloning/whatiscloning
2) http://hplusbiopolitics.wordpress.com/2008/06/25/inconsistancy-in-the-life-begins-at-conception-argument/

Illustrations by Corinna Ng

Cloning: The Specifics

Now that you have gotten a brief idea of cloning, lets get down to the specifics. There are 3 types of cloning, DNA cloning, embryo cloning and reproductive cloning.

Firstly, DNA cloning. Scientists extract a certain strand of DNA and injects it into a bacteria or virus and the DNA is reproduced many times. This allows the production of many medication, like insulin for diabetes.

Secondly, embryo cloning is used to produce stem cells for research. You may ask what exactly are stem cells? Well, they are building blocks for the body. They can amazingly develop into any cell, tissue or organ in the body!

Lastly, reproductive cloning has 5 steps.
1) Get an egg. (Not the ones chickens lay, but the egg,or ooceyte, produced by a female)
2) Carefully extract egg's nucleus with the help of a microscope and fine needle. Hence, no genetic material is present.
3) Insert the DNA that you want to copy into the now empty egg.
4) Hence, the egg is ready and carefully taken care of to start cell division.
5) When this happens, the cell is implanted into the organism you want to use. There, it will develop to its full term.
This may sound easy, but there were many failed attempts at cloning animals other than frogs until Dolly the Sheep...
Until next week!

http://bruceleeeowe.files.wordpress.com/2009/11/cloning.gif

Acknowledgements: Dolly: The 1st Cloned Sheep, Written by Joeming Dunn, Published by magic wagon