Cloning

Biologists come close to cloning primates

Posted by

0


Cloned monkey embryos transferred into mother

Researchers had been struggling to make cloned monkey embryos.

US biologists have created cloned monkey embryos, and successfully transferred them into monkey mothers. Although none of the resulting pregnancies lasted more than a month, this is by far the closest scientists have come to cloning a primate.

The study was unveiled yesterday by reproductive biologist Gerald Schatten of the University of Pittsburgh, Pennsylvania, at the annual meeting of the American Society for Reproductive Medicine in Philadelphia. Schatten’s group copied a technique used earlier this year to clone a human embryo and extract embryonic stem cells.

If researchers are able to repeat this process in monkeys, it might help them to refine the tricky technique without experimenting on human eggs and embryos, which are very difficult to obtain and raise a host of ethical objections. This in turn might help to resolve whether human embryonic stem cells, which can grow into a variety of tissues, will prove useful in medicine.

Cross-pollination

Previously, Schatten and his colleagues had struggled to create healthy monkey embryos by cloning, which involves removing the DNA-containing nucleus from an adult cell and inserting it into an egg stripped of its own nucleus.

In a 2003 study published in Science, Schatten suggested that extracting the nucleus from a monkey egg also robs it of two proteins essential for survival1. He found that all the resulting embryos had fatal chromosomal defects, and speculated that cloning any primate, including humans, might be impossible.

That view proved false in February this year, when scientists from South Korea announced in Science that they had successfully cloned human embryos, and used them to grow embryonic stem cells capable of morphing into numerous different tissue types2. One aim of such research is to grow replacement tissues to fight human disease.

In the Korean work, the cloned human embryos were allowed to divide in culture for just five or six days before being terminated. But, by adopting the Koreans’ technique, Schatten’s team made 135 cloned monkey embryos and transferred them into 25 mothers. The team experimented with transferring the nuclei from skin cells and from cumulus cells, which are found in the ovary.

Why does it work?

Schatten says he is not yet sure why the Korean method is so successful. Rather than sucking the nucleus out of the recipient eggs, the technique involves gently squeezing it out. This may remove less of the cell’s cytoplasm and leave more of the essential molecules needed by the egg to direct embryo development; or it may simply cause less damage to the eggs.

None of the cloned monkey embryos resulted in a pregnancy that lasted more than a month. But Schatten says it is too early to say whether cloned monkeys will ever be born; it may just take more attempts. It is also impossible, he says, to use these results to predict whether a cloned human baby could survive long in development.

Schatten adds that his preliminary attempts to make embryonic stem cells from cloned monkey embryos failed. But at least his study confirms that the Korean cloning method works, something that has been difficult to prove because very few research groups work in such areas. “It shows that at least part of the technique is reproducible,” he says

Cloning Isn’t As Risky As We Used To Think

Posted by

0


When Dolly the Sheep was created in a lab in 1996, the world changed. The fact that scientists successfully cloned a mammal from an adult cell, not an embryonic cell, proved that the nucleus of an adult cell has all the DNA necessary to create another animal. But a few years later, the future didn’t look so bright. Dolly had issues when it came to her DNA, especially her telomeres. Telomeres are caps on the ends of chromosomes that act like a bomb fuse; the shorter they get, the less time you have left. Dolly’s telomeres were shorter than other animals her age, suggesting she was aging more quickly than normal. She suffered from osteoarthritis in her knees and hips, and eventually contracted an incurable lung virus that led veterinarians to put her down at the age of six. This caused enough concern that the UN banned cloning of humans and several other countries banned reproductive cloning of animals.

But in July of 2016, scientists announced that 13 cloned sheep, including four cloned from the same DNA source as Dolly, were healthy and aging normally. Even when nearing the ripe old age of 10, the sheep showed normal blood pressure, heart function, metabolism, and joint health. This means that cloning doesn’t automatically cause health problems, and that Dolly’s issues may have just been a fluke. To scientists, this is nothing surprising. Reproductive biologist Mark Westhusin, who helped create the first cloned cat who was also healthy at age 15, put it this way to Science News: “This is a nice paper to confirm in a more formal scientific setting what most people involved with cloning have believed for a long time.”

Cloning Breakthrough: Adult Stem Cells Perfectly Replicated, Moving Science Toward Disease-Specific Cells

Posted by

0


In a cloning first, scientists at Research Institute for Stem Cell Research at CHA Health Systems in Los Angeles have perfectly duplicated adult stem cells using subjects’ own DNA.

The study, published in the journal Cell Stem Cell, sits as part of a shifting scientific paradigm where stem cells are no longer used to pursue reproductive cloning, but “therapeutic cloning.” Under this new model, formally known as somatic-cell nuclear transfer, researchers attempt to use a patient’s own DNA to create cells that can fight diseases, such as vision loss, heart disease, diabetes, and multiple sclerosis. The latest advances were minimal but legitimate.

Led by researcher Young Gie Chung, the team extracted skin cells from two men, ages 35 and 75. The process of therapeutic cloning then involves taking those cells and fusing them, with a jolt of electricity, to an ovum whose DNA has been removed. The egg then divides and multiplies, until it creates an embryo that looks like a hollow sphere.

shutterstock_161038706

These embryos still contain the patient’s DNA, which means if they were implanted into a uterus, they could develop into perfect clones of the original subject. However, this process has been officially banned by the United Nations following the original controversy of the 1997 cloning of Dolly, a sheep. In 2005, the U.S. banned the use of federal funds for either reproductive or therapeutic cloning.

So with funding from the South Korean government and a separate foundation, the team set to work on generating healthy embryos from the two men’s DNA. It worked — though not until exhausting 39 tries, producing stem cells only once for each donor. This has led to some skepticism about the study’s success, as stem cell biologist George Daley of the Harvard Stem Cell Institute called it “an incremental advance” and “not earth-shattering,” Reuters reported.

  

Meanwhile, other experts believe the pluripotent cells — chameleon-like cells that can adapt to become any type of cell — open new doors for future research. “The advance here is showing that (nuclear transfer) looks like it will work with people of all ages,” Shoukhrat Mitalipov, a reproductive biologist of Oregon Health and Science University, told Reuters.

Ultimately, one of the largest hurdles is cost. The limited success at present suggests the only people who can currently enjoy the therapeutic effects are wealthy older men, as trials involving women have yet to run. What’s more, egg donation is highly invasive and a process many women choose not to undergo. But this second hurdle may be less logistical and more scientific, according to co-author of the study, Dr. Robert Lanza.

Immune systems only come in a limited amount of flavors, meaning not all women would need to donate their eggs in order for everyone to find a match. By Lanza’s measure, “100 human embryonic stem cell lines would generate a complete match for over half the (U.S.) population.”

Source: Chung Y, Eum J, Lee J, et al. Human Somatic Cell Nuclear Transfer Using Adult Cells. Cell Stem Cell. 2014.

China cloning on ‘industrial scale’

Posted by

0


The cloning methods may not be novel – but the application of mass production is

You hear the squeals of the pigs long before reaching a set of long buildings set in rolling hills in southern China.

Feeding time produces a frenzy as the animals strain against the railings around their pens. But this is no ordinary farm.

Run by a fast-growing company called BGI, this facility has become the world’s largest centre for the cloning of pigs.

The technology involved is not particularly novel – but what is new is the application of mass production.

The first shed contains 90 animals in two long rows. They look perfectly normal, as one would expect, but each of them is carrying cloned embryos. Many are clones themselves.

This place produces an astonishing 500 cloned pigs a year: China is exploiting science on an industrial scale.

“Start Quote

If it tastes good you should sequence it… you should know what’s in the genes of that species”

Wang Jun Chief executive, BGI

To my surprise, we’re taken to see how the work is done. A room next to the pens serves as a surgery and a sow is under anaesthetic, lying on her back on an operating table. An oxygen mask is fitted over her snout and she’s breathing steadily. Blue plastic bags cover her trotters.

Two technicians have inserted a fibre-optic probe to locate the sow’s uterus. A third retrieves a small test-tube from a fridge: these are the blastocysts, early stage embryos prepared in a lab. In a moment, they will be implanted.

The room is not air-conditioned; nor is it particularly clean. Flies buzz around the pig’s head.

My first thought is that the operation is being conducted with an air of total routine. Even the presence of a foreign television crew seems to make little difference. The animal is comfortable but there’s no sensitivity about how we might react, let alone what animal rights campaigners might make of it all.

I check the figures: the team can do two implantations a day. The success rate is about 70-80%.

Embryo implantation
Sows are implanted with early stage embryos known as blastocysts

Dusk is falling as we’re shown into another shed where new-born piglets are lying close to their mothers to suckle. Heat lamps keep the room warm. Some of the animals are clones of clones. Most have been genetically modified.

The point of the work is to use pigs to test out new medicines. Because they are so similar genetically to humans, pigs can serve as useful “models”. So modifying their genes to give them traits can aid that process.

One batch of particularly small pigs has had a growth gene removed – they stopped growing at the age of one. Others have had their DNA tinkered with to try to make them more susceptible to Alzheimer’s.

Back at the company headquarters, a line of technicians is hunched over microscopes. This is a BGI innovation: replacing expensive machines with people. It’s called “handmade cloning” and is designed to make everything quicker and easier.

The scientist in charge, Dr Yutao Du, explains the technique in a way that leaves me reeling.

“We can do cloning on a very large scale,” she tells me, “30-50 people together doing cloning so that we can make a cloning factory here.”

A cloning factory – an incredible notion borrowed straight from science fiction. But here in Shenzhen, in what was an old shoe factory, this rising power is creating a new industry.

Infographic

The scale of ambition is staggering. BGI is not only the world’s largest centre for cloning pigs – it’s also the world’s largest centre for gene sequencing.

In neighbouring buildings, there are rows of gene sequencers – machines the size of fridges operating 24 hours a day crunching through the codes for life.

To illustrate the scale of this operation, Europe’s largest gene sequencing centre is the Wellcome Trust Sanger Institute near Cambridge. It has 30 machines. BGI has 156 and has even bought an American company that makes them.

BGI’s chief executive, Wang Jun, tells me how they need the technology to develop ever faster and cheaper ways of reading genes.

Again, a comparison for scale: a recently-launched UK project seeks to sequence 10,000 human genomes. BGI has ambitions to sequence the genomes of a million people, a million animals and a million plants.

Wang Jun is keen to stress that all this work must be relevant to ordinary people through better healthcare or tastier food. The BGI canteen is used as a testbed for some of the products from the labs: everything from grouper twice the normal size, to pigs, to yoghurt.

I ask Wang Jun how he chooses what to sequence. After the shock of hearing the phrase “cloning factory”, out comes another bombshell:

Chinese scientists at cloning centre BGI has ambitions to sequence the genomes of a million people, a million animals and a million plants

“If it tastes good you should sequence it,” he tells me. “You should know what’s in the genes of that species.”

Species that taste good is one criterion. Another he cites is that of industrial use – raising yields, for example, or benefits for healthcare.

“A third category is if it looks cute – anything that looks cute: panda, polar bear, penguin, you should really sequence it – it’s like digitalising all the wonderful species,” he explains.

I wonder how he feels about acquiring such power to take control of nature but he immediately contradicts me.

“No, we’re following Nature – there are lots of people dying from hunger and protein supply so we have to think about ways of dealing with that, for example exploring the potential of rice as a species,” the BGI chief counters.

China is on a trajectory that will see it emerging as a giant of science: it has a robotic rover on the Moon, it holds the honour of having the world’s fastest supercomputer and BGI offers a glimpse of what industrial scale could bring to the future of biology.

Cloning Mice.

Posted by

0


For the First Time, a Donor Mouse Has Been Cloned Using a Drop of Peripheral Blood from Its Tail.

From obesity to substance abuse, from anxiety to cancer, genetically modified mice are used extensively in research as models of human disease. Researchers often spend years developing a strain of mouse with the exact genetic mutations necessary to model a particular human disorder. But what if that mouse, due to the mutations themselves or a simple twist of fate, was infertile?

Currently, two methods exist for perpetuating a valuable strain of mouse. If at least one of the remaining mice is male and possesses healthy germ cells, the best option is intracytoplasmic sperm injection (ICSI), an in vitro fertilization procedure in which a single sperm is injected directly into an egg.

However, if the remaining mice cannot produce healthy germ cells, or if they are female, researchers must turn to cloning. Somatic-cell nuclear transfer (SCNT) produces cloned animals by replacing an oocyte’s nucleus with that of an adult somatic cell. An early version of this process was used to produce Dolly the sheep in 1996.

Since then, SCNT techniques have continued to advance. Earlier this year, researchers at the RIKEN Center for Developmental Biology in Kobe, Japan, even devised a technique to avoid the diminishing returns of recloning the same cell; success rates increased from the standard three percent in first-generation clones to ten percent in first-generation and 14 percent in higher-generation clones.

The type of somatic cell used for this process is critical and depends largely on its efficiency in producing live clones, as well as its ease of access and readiness for experimental use. While cumulus cells, which surround oocytes in the ovarian follicle and after ovulation, are currently the preferred cell type, Drs. Satoshi Kamimura, Atsuo Ogura, and colleagues at the RIKEN BioResource Center in Tsukuba, Japan, questioned whether white blood cells (a.k.a., leukocytes) collected from an easily accessed site, such as a tail, would be effective donor cells. Such cells would allow for repeated sampling with minimal risk to the donor mouse.

There are five different types of white blood cells and, as expected, the researchers found that lymphocytes were the type that performed the most poorly: only 1.7 percent of embryos developed into offspring. The physically largest white blood cells, and thus the easiest to filter from the blood sample, were granulocytes and monocytes. The nuclei of these cells performed better, with 2.1 percent of the embryos surviving to term, compared to 2.7 percent for the preferred cell type, cumulus cells.

The granulocytes’ performance was poorer than expected due to a much higher rate of fragmentation in early embryos (22.6 percent): twofold higher than that of lymphocyte cloning and fivefold higher than cumulus cell cloning. The researchers were unable to determine what could be causing the fragmentation and intend to perform further studies to improve the performance of granulocyte donor cells.

Although the blood cells tested did not surpass the success rate of cumulus cells in this study, the researchers have demonstrated, for the first time, that mice can be cloned using the nuclei of peripheral blood cells. These cells may be used for cloning immediately after collection with minimal risk to the donor, helping to generate genetic copies of mouse strains that cannot be preserved by other assisted reproduction techniques.