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Nanny thinks janie needs a man to take care of her even though she is a strong woman

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"The team is hoping to boost the human contribution by switching off specific genes in the pig embryos..."

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KIra The pig-human embryos, were allowed to develop to 28 days (the first trimester of a pig pregnancy) before being removed"

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KIra The pig-human embryos, were allowed to develop to 28 days (the first trimester of a pig pregnancy) before being removed"

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The idea of having an animal being born composing of human cells creates some feelings that need to be addressed"

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The idea of having an animal being born composing of human cells creates some feelings that need to be addressed"

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Why are they calling the creature a chimera? Isn't the chimera a symbol of a bad omen or misfortune if it is seen? Could't they use a more fitting name ? What would happen if one of these "chimera" were to mature into it's adulthood what would happen to it's brain?

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Scientist have tried this before with rats " scientist created the first rat chimeras a decade ago" 

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Scientist have tried this before with rats " scientist created the first rat chimeras a decade ago" 

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But be acknowledged: "The idea of having an animal being born composing of human cells creates some feelings that need to be addressed."

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To grow human organs within animal bodies has long been the dream of scientists wanting to provide transplantable hearts, lungs, kidneys and other organs for patients in need. A glimpse of possible success in this elusive goal was seen Thursday.

Using stem cell technologies, researchers generated human cells and human tissues in the embryos of pigs and cattle. Their research appeared in the journal Cell.

Despite this milestone, integrating cells from human and animal species is proving difficult, and developing human organs remains at a considerable distance, said Dr. Jun Wu, a staff scientist in the gene expression laboratory at the Salk Institute and first author of the research.

"Species evolve independently, and many factors dictating the developmental programs might have diverged, which makes it difficult to blend cells from one species to a developing embryo from another," Wu said. "The larger the evolutionary distance, the more difficult for them to mix."

Or as senior author Juan Carlos Izpisua Belmonte, a professor in Salk's gene expression laboratory, sees it, "To try to imitate nature is not that easy."

Building block experiments

The project began with the research team attempting to prove that it could grow one animal's organ cells within a different species of animal. This is known as a chimera -- specifically an interspecies chimera, an organism containing cells from two or more species.

They began with two closely related species: rats and mice.

To create a rat-mouse chimera, the scientists began by creating a mouse embryo without a pancreas.

Similar work had been done before by other scientists, notably Hiromitsu Nakauchi, now at Stanford, who bred mutant mice that lacked a pancreas and then grew a rat pancreas inside a mouse.

Human organs grown in pigs may help transplant patients, scientists say

In the current study, Belmonte, Wu and their colleagues used gene-editing techniques known as CRISPR/Cas9 to generate mice embryos lacking a pancreas. Then they inserted rat stem cells that contained a gene for the pancreas into these mutant embryos.

Once implanted, the stem cells developed into a rat pancreas within a mouse embryo that ultimately (and importantly) grew into a healthy mouse with a normal lifespan. Taking their idea a few steps further, the researchers used the same method to develop rat eyes and rat hearts within mice embryos.

"We demonstrated the robustness of this system," Wu said. By "genetically disabling" the mouse host, they proved it was possible to generate rat organs within a host species.

Unexpectedly to the researchers, the mice delivered bonus organs after the injection of rat stem cells: gallbladders, which are present in mice but not in rats.

"This suggests that rats lack a gallbladder not because of an inherent genetic deficiency of rat cells," Wu said. Instead, "embryonic niches" may be orchestrating the tissues and organs that develop and grow within each animal species.

After the rat-mice experiments, the team turned its focus to human stem cells.

Small but significant

They began by generating different types of human induced pluripotent stem cells -- when adult cells are turned back into stem cells -- and inserting them into pig embryos. Pigs were used because both the size and the development time for their organs are more similar to our own than, say, rats.

Next, the team members implanted these embryos into sows. To test the safety and effectiveness of their work, they stopped the experiment at four weeks.

Chinese scientists use gene-editing techniques in humans for first time

Human cells within some of the embryos had begun to specialize and turn into tissue precursors, they discovered. However, the success rate and level of human stem cell contributions in pigs was much lower than with the rat-mouse chimeras.

Wu cautioned that the research is in its very early stages, and with many challenges ahead, the development of human organs within animals may not be possible for some time.

Though the experiment with human stem cells was interrupted at 28 days, it remains the first reported case in which human stem cells have begun to grow within another species. So it is a small but significant step toward the ultimate goal of growing human organs in animals, said Insoo Hyun, an associate professor of bioethics and philosophy at Case Western Reserve University.

"They just wanted to see if the cells would survive during gestation, and they did, and they kind of migrated here and there to various sites, except the brain, which is interesting," said Hyun, who was not involved in the research.

Hyun, who worked on developing international guidelines for the International Society for Stem Cell Research, said the Salk Institute researchers appear to be staying within international ethical boundaries.

"The next step would be then to see if they can get better at localizing where the human cells develop and, ideally, getting to organ genesis," he noted.

Ethical concerns

"The interesting thing is, it was not funded by American taxpayer money," Hyun said, at least not directly. The primary funding came from private Spanish sources.

One reason for this is the US National Institutes of Health examined chimera science in a 2015 workshop and "accompanied that with a pause" on funding of a "very narrow subset of animal human chimera research," said Carrie D. Wolinetz, the institutes' associate director for science policy.

Feds open talks on growing human organs in animals

This subset consists of scientists introducing human cells into animal embryos at a very early stage.

"There has been the use of human-animal chimeras in biomedical research for a very long time. We've introduced human cells into animal models to create models of human diseases and used them as research tools for decades now," Wolinetz said.

"But over time, what we've seen -- as stem cell technology has advanced and as gene editing technology has advanced -- we've seen the ability to create more sophisticated animal-human chimeras at a much earlier stage of embryonic development," she said.

The reason, then, the National Institutes of Health suspended funding was over ethical concerns.

The chimeras used in biomedical research have been created, typically, by putting the human cells in at a later stage of development: at the fetal stage or even after birth. At these stages, scientists have a lot more control in that the cells stay where they are put, and they don't "drift all over" the animal's body, explained Wolinetz.

In these new experiments, human cells are being introduced at a much earlier stage of development, when the cells are still sorting themselves out within the embryo.

"In particular, people were concerned about human cells populating the brain of the animal or the germline of the animal," Wolinetz said. In the first case, the animal might be humanized; in the second case, the animal might pass human genes on to its offspring.

As Hyun frames it, the ethical question is this: "If you up the biological contribution of the human stem cells, are you also somehow turning them morally into a human-like thing with human rights?" He noted, though, "It's so difficult to know how you would actually address that." It's not measurable.

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"I would argue, as long as you are avoiding the brain, or there's not a significant change to the brain, of structure and possible functioning, then I don't think you even need to go down that philosophical path," he said. Though as a philosopher, it might be "fun" for him, it's not a wise or practical thing to do for policy.

Instead, Hyun said, you want to stick with measurable criteria such as seeing a drop in animal function from the beginning of an experiment to the end. "The emphasis should still remain on animal welfare," he said, as it is currently for any kind of animal research.

Meanwhile, Wolinetz said the National Institutes of Health is hoping to finalize its policy on chimera research very soon in order to get back into the business of funding appropriate projects.

"We would like to make sure exciting research can go forward," she said, "but also make sure that we've got an appropriate oversight system so we can make sure it's proceeding responsibly."

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Using stem cell technologies, researchers generated human cells and human tissues in the embryos of pigs and cattle. Their research appeared in the journal Cell.

Despite this milestone, integrating cells from human and animal species is proving difficult, and developing human organs remains at a considerable distance, said Dr. Jun Wu, a staff scientist in the gene expression laboratory at the Salk Institute and first author of the research.

"Species evolve independently, and many factors dictating the developmental programs might have diverged, which makes it difficult to blend cells from one species to a developing embryo from another," Wu said. "The larger the evolutionary distance, the more difficult for them to mix."

Or as senior author Juan Carlos Izpisua Belmonte, a professor in Salk's gene expression laboratory, sees it, "To try to imitate nature is not that easy."

Building block experiments

The project began with the research team attempting to prove that it could grow one animal's organ cells within a different species of animal. This is known as a chimera -- specifically an interspecies chimera, an organism containing cells from two or more species.

They began with two closely related species: rats and mice.

To create a rat-mouse chimera, the scientists began by creating a mouse embryo without a pancreas.

Similar work had been done before by other scientists, notably Hiromitsu Nakauchi, now at Stanford, who bred mutant mice that lacked a pancreas and then grew a rat pancreas inside a mouse.

In the current study, Belmonte, Wu and their colleagues used gene-editing techniques known as CRISPR/Cas9 to generate mice embryos lacking a pancreas. Then they inserted rat stem cells that contained a gene for the pancreas into these mutant embryos.

Once implanted, the stem cells developed into a rat pancreas within a mouse embryo that ultimately (and importantly) grew into a healthy mouse with a normal lifespan. Taking their idea a few steps further, the researchers used the same method to develop rat eyes and rat hearts within mice embryos.

"We demonstrated the robustness of this system," Wu said. By "genetically disabling" the mouse host, they proved it was possible to generate rat organs within a host species.

Unexpectedly to the researchers, the mice delivered bonus organs after the injection of rat stem cells: gallbladders, which are present in mice but not in rats.

"This suggests that rats lack a gallbladder not because of an inherent genetic deficiency of rat cells," Wu said. Instead, "embryonic niches" may be orchestrating the tissues and organs that develop and grow within each animal species.

After the rat-mice experiments, the team turned its focus to human stem cells.

Small but significant

They began by generating different types of human induced pluripotent stem cells -- when adult cells are turned back into stem cells -- and inserting them into pig embryos. Pigs were used because both the size and the development time for their organs are more similar to our own than, say, rats.

Next, the team members implanted these embryos into sows. To test the safety and effectiveness of their work, they stopped the experiment at four weeks.

Human cells within some of the embryos had begun to specialize and turn into tissue precursors, they discovered. However, the success rate and level of human stem cell contributions in pigs was much lower than with the rat-mouse chimeras.

Wu cautioned that the research is in its very early stages, and with many challenges ahead, the development of human organs within animals may not be possible for some time.

Though the experiment with human stem cells was interrupted at 28 days, it remains the first reported case in which human stem cells have begun to grow within another species. So it is a small but significant step toward the ultimate goal of growing human organs in animals, said Insoo Hyun, an associate professor of bioethics and philosophy at Case Western Reserve University.

"They just wanted to see if the cells would survive during gestation, and they did, and they kind of migrated here and there to various sites, except the brain, which is interesting," said Hyun, who was not involved in the research.

Hyun, who worked on developing international guidelines for the International Society for Stem Cell Research, said the Salk Institute researchers appear to be staying within international ethical boundaries.

"The next step would be then to see if they can get better at localizing where the human cells develop and, ideally, getting to organ genesis," he noted.

Ethical concerns

"The interesting thing is, it was not funded by American taxpayer money," Hyun said, at least not directly. The primary funding came from private Spanish sources.

One reason for this is the US National Institutes of Health examined chimera science in a 2015 workshop and "accompanied that with a pause" on funding of a "very narrow subset of animal human chimera research," said Carrie D. Wolinetz, the institutes' associate director for science policy.

This subset consists of scientists introducing human cells into animal embryos at a very early stage.

"There has been the use of human-animal chimeras in biomedical research for a very long time. We've introduced human cells into animal models to create models of human diseases and used them as research tools for decades now," Wolinetz said.

"But over time, what we've seen -- as stem cell technology has advanced and as gene editing technology has advanced -- we've seen the ability to create more sophisticated animal-human chimeras at a much earlier stage of embryonic development," she said.

The reason, then, the National Institutes of Health suspended funding was over ethical concerns.

The chimeras used in biomedical research have been created, typically, by putting the human cells in at a later stage of development: at the fetal stage or even after birth. At these stages, scientists have a lot more control in that the cells stay where they are put, and they don't "drift all over" the animal's body, explained Wolinetz.

In these new experiments, human cells are being introduced at a much earlier stage of development, when the cells are still sorting themselves out within the embryo.

"In particular, people were concerned about human cells populating the brain of the animal or the germline of the animal," Wolinetz said. In the first case, the animal might be humanized; in the second case, the animal might pass human genes on to its offspring.

As Hyun frames it, the ethical question is this: "If you up the biological contribution of the human stem cells, are you also somehow turning them morally into a human-like thing with human rights?" He noted, though, "It's so difficult to know how you would actually address that." It's not measurable.

"I would argue, as long as you are avoiding the brain, or there's not a significant change to the brain, of structure and possible functioning, then I don't think you even need to go down that philosophical path," he said. Though as a philosopher, it might be "fun" for him, it's not a wise or practical thing to do for policy.

Instead, Hyun said, you want to stick with measurable criteria such as seeing a drop in animal function from the beginning of an experiment to the end. "The emphasis should still remain on animal welfare," he said, as it is currently for any kind of animal research.

Meanwhile, Wolinetz said the National Institutes of Health is hoping to finalize its policy on chimera research very soon in order to get back into the business of funding appropriate projects.

"We would like to make sure exciting research can go forward," she said, "but also make sure that we've got an appropriate oversight system so we can make sure it's proceeding responsibly."

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Using stem cell technologies, researchers generated human cells and human tissues in the embryos of pigs and cattle. Their research appeared in the journal Cell. Despite this milestone, integrating cells from human and animal species is proving difficult, and developing human organs remains at a considerable distance, said Dr. Jun Wu, a staff scientist in the gene expression laboratory at the Salk Institute and first author of the research.

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" The pig-human embroys were allowed to develop to 28 days before being removed."

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Challenge: Pregnancy time differs in pigs 112 days VS nine months

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"...the potential for bizarre hybrid creatures to be accidentally released to the wild."

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"Scientists have created a human-pig hybrid in a milestone study that raises the prospect of being able to grow human organs inside animals for use in transplants.

It marks the first time that embryos combining two large, distantly-related species have been produced. The creation of this so-called chimera – named after the cross-species beast of Greek mythology – has been hailed as a significant first step towards generating human hearts, livers and kidneys from scratch.

Analysis Human-pig embryos Q&A: how would 'chimeras' make transplant organs?

Scientists have successfully created part-pig, part-human embryos. How have they done this, and could viable human organs really be grown this way?

Read more

Juan Carlos Izpisua Belmonte, who led the work on the part-pig, part-human embryos at the Salk Institute for Biological Studies in La Jolla, California, said: “The ultimate goal is to grow functional and transplantable tissue or organs, but we are far away from that. This is an important first step.”

The study has reignited ethical concerns that have threatened to overshadow the field’s clinical promise. The work inevitably raises the spectre of intelligent animals with humanised brains and also the potential for bizarre hybrid creatures to be accidentally released into the wild. The US National Institutes of Health (NIH) placed a moratorium on funding for the controversial experiments last year while these risks were considered.

Izpisua Belmonte said that fears around chimeras were inspired largely by mythology rather than the realities of meticulously controlled experiments. But he acknowledged: “The idea of having an animal being born composing of human cells creates some feelings that need to be addressed.”

The paper, published in the journal Cell, outlines how human stem cells were injected into early-stage pig embryos, resulting in more than 2,000 hybrids that were transferred to surrogate sows. More than 150 of the embryos developed into chimeras that were mostly pig, but with a tiny human contribution of around one in 10,000 cells.

The pig-human embryos were allowed to develop to 28 days (the first trimester of a pig pregnancy) before being removed.

“This is long enough for us to try to understand how the human and pig cells mix together early on without raising ethical concerns about mature chimeric animals,” said Izpisua Belmonte.

The team believe that in future the approach could pave the way for incubating human organs, genetically matched to a patient, for use in transplants or for testing new medicines more safely and effectively.

Professor Daniel Garry, a cardiologist and head of a different chimera project at the University of Minnesota, said: “This is a significant advance that raises opportunities and ethical questions as well.”

Human-pig chimeras and the history of transplanting from animals

Read more

Garry said that the rapid progress in chimera research had prompted a range of troubling questions, including whether the progeny would look more human or more pig, what would happen if a chimera had a human thought and whether it was possible for the human cells to cannibalise the pig embryo, resulting in a mostly-human, slightly-pig offspring.

“These more fantastical possibilities are not a problem in reality,” he said, adding that Izpisua Belmonte’s group had taken a “responsible approach”.

Scientists created the first rat-mouse chimeras a decade ago, but until now have struggled to combine human cells with those of a large mammal.

Professor Bruce Whitelaw, interim director of the Roslin Institute at the University of Edinburgh, where Dolly the sheep was created, said: “The 10 years between these two studies is a testament of how difficult it has been to achieve the human-pig result.”

One challenge is that the pig pregnancy lasts about 112 days, compared to nine months in humans, meaning that the embryonic cells are developing at completely different rates. Izpisua Belmonte’s team found that the human stem cells need to be injected at exactly the right stage in their own development for them to survive and become part of the growing animal – although even then, the efficiency was low.

Jun Wu, the paper’s lead author and a scientist at Salk, said: “It’s like if you’re going onto a highway where the cars are travelling three times faster than you are, you need to choose the right timing, otherwise you cause an accident.”

The team is hoping to boost the human contribution by switching off specific genes in the pig embryos that would prevent the pig cells from contributing to target organs, such as the heart, potentially giving the human cells a competitive advantage.

'Chimera' monkeys created in lab by combining several embryos into one

Read more

Similarly, the human cells could be engineered to prevent them contributing to the chimera brain. This safeguard was not in place in the current study, since the embryos were only allowed to reach an early stage of development and the human contribution was minimal.

“We didn’t see any human cells in the brain region, but we cannot exclude the possibility that they may have gone to the brain,” said Izpisua Belmonte.

In a separate experiment, the team also created a host of mouse-rat chimeras and showed that rat cells could develop into a gall bladder – even though rats stopped developing this organ themselves at some point in the 18 million years since rats and mice separated evolutionarily.

This reveals that our genetic code retains the instructions to turn our cells into ancestral forms that have been lost over the course of evolution, raising the intriguing question of which ancient traits might be unlocked from human DNA.

“Many animals have this extraordinary ability to regenerate,” said Izpisua Belmonte. “Humans don’t have that. [This field of work] could provide a platform for human cells to do that.”

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human stem cells were injected into early stage pig embryos. 2000 hybrids that were transferred to surrogate sows.

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human stem cells were injected into early stage pig embryos. 2000 hybrids that were transferred to surrogate sows.

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A genetic chimerism or chimera is a single organism composed of cells from different zygotes. This can result in male and female organs, two blood types, or subtle variations in form.

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" The team believed that in the future the approach could pave the way for incubating human organs, genetically matched to the patient, for the use in transplants or for testing new medicines more safe and effectively."

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"Its like if you're going onto a highway where the cars are travelling three times faster than you are, you need to chose the right timing, otherwise you cause an accident"

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Why use pigs and not other animals ?

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"Fears around chimeras were inspired largely by mythology rather than the realities of meticulously controlled experiments"