… e, into beating heart cells, and whole dishes full of replacement neurons that could treat Parkinson’s disease,’ says Lanza. ‘We ” ve also created new cartilage, skin, kidney, and heart tissue that was transplanted back into adult steers without rejection. This isn’t some futuristic dream. We are doing this right now.’ The dream has its detractors, and not just among politicians.
Some biologists are set on avoiding moral issues by trying to coax adult stem cells back to an embryonic state. Even James Thomson — one of the stem cell pioneers funded by West — believes that he may be able to tinker with the genetics of generic stem cells to make them less likely to be rejected, thus making DNA-specific matches unnecessary. But in the absence of a proven better alternative, to halt the work now, says West, would be like taking penicillin away from doctors in the last century. Indeed, many medical developments have been at least temporarily halted because of ethical qualms. Religious leaders found vaccines objectionable because they interfered with God’s plan for who should get sick, and in vito fertilization was condemned in the 1970 s by many of the same conservative ethicist’s who today oppose therapeutic cloning.
Organ transplants were once seen as objectionable. And recombinant DNA technology — the ability to create synthetic genes — was banned from top universities like Harvard and MIT for years, for fear that horrible and dangerous creatures would be produced. But much of the opposition melted when the technology was used to create a synthetic form of insulin to treat diabetics, and today recombinant DNA is used in virtually every research lab in the world. It’s still too early to say whether the United States will accept or reject therapeutic cloning.
Cibelli and colleagues still have mountains of work ahead of them. It takes not just an embryo but the nurturing of stem cells and the ability to transform those stem cells into specialized types before any clinical applications can be used in humans. ‘I’m overjoyed, but I’m not getting drunk yet,’ says Cibelli. ‘When I have neurons for Judson [Somerville] and islet cells for Pablo [Naumann], that’s when I’ll celebrate.’ If history is any guide, that is also when the public attitudes will warm toward this new and intimidating medical technology. The art of cloning The idea behind cloning are simple: Remove DNA from an egg and replace it with the DNA from a body cell. But actually getting that process to work is still as much a guessing game as an exact science, dependent on timing as well as technique.
Here are some of the main challenges. THE STEPS; THE CHALLENGES (Step 1) Remove DNA from a human egg The Challenges (A) A human egg is very fragile. It can take hundreds of tries to extract the 2 meters of chromosomes with a microscopic needle without destroying the egg. (B) There is a tiny window of time — just a few hours — during which an egg can be prepared for cloning. Then the egg loses its ability to repair and regenerate DNA. (C) If one too many drops of cellular material are accidentally removed along with the DNA, the egg can be rendered useless.
(Step 2) Deliver new genes into the egg The Challenges (A) No one knows which body cells are the most amenable to cloning. The easiest cells to get from donors — skin cells — are not ideal because they are very large and hard to work with. (B) Some scientists use an electric current to fuse an entire body cell into the egg cell, but the line between too little and too much current is perilously thin. (C) Other scientists take the genes out of the body cell and inject them into the egg, but the chromosomes are often damaged by the process. (Step 3) Trick the egg into action The Challenges (A) No sperm is involved in cloning. So scientists must find another way to make the egg think it has been fertilized.
(B) Some scientists use an electric current to make the egg grow. Other suse a mixture of chemicals. But it is all too easy to kill the egg with either method. (C) There appears to be only about a four-hour period during which an egg will respond to activation signals.
Prodding the egg before or after that doesn’t work. (4) Collect stem cells The Challenges (A) Dozens of nutrient mixtures have been developed to help embryonic cells proliferate, but no one yet knows which is best. (B) Biologists disagree about how much oxygen the growing cells should be exposed to in order to develop the healthiest stem cells. (C) Stem cells must be separated from the other cells without damage and kept alive until they become a self-sustaining colony. (5) Get the stem cells to specialize The Challenges (A) Any one of thousands of different ‘growth factors’ may be involved in spurring a stem cell to become a brain cell or a blood cell.
(B) Even if the right chemicals are found, the stem cells may not respond unless the chemicals interact with the cells’ DNA in precisely the right sequence. (C) The body has over 200 types of specialized cells, and the recipe for growing certain types may remain a mystery for years. Source: Jose Cibelli, Advanced Cell Technology MILESTONES IN CLONING February 1997 The first cloning of a mammal, Dolly the sheep, from an adult body cell is announced. March 1997 President Clinton bans federal funding of human-cloning research. 1998-2000 Researchers clone mice, calves, goats, and pigs. A bull is ‘re cloned ” from a cloned bull.
April 2000 Scientists find that cloning can restore body cells to a youthful state. October 2001 The first cloned human embryos are created at Advanced Cell Technology ” slab in Worcester, Mass. Source: Jose Cibelli, Advanced Cell Technology medical research director believes that cloning could end transplant rejection. (JONATHAN SAUNDERS FOR USN&WR); Picture: Michael West.
The head of ACT is an entrepreneur with a mission: to find cures for the ravages of aging. (JONATHAN SAUNDERS FOR USN&WR) Reproduced with permission of the copyright owner. Further reproduction or distribution is prohibited without permission. End of Document 4 Abstract: So far, though, it is a curiously one-sided debate. As the Senate considers legislation to ban any kind of cloning, either for reproduction or research, there appears to be widespread agreement that making babies by cloning is wrong. Even the company that conducted the experiment, Advanced Cell Technology, has come out against human cloning Still, cloning provokes a visceral reaction, and some of the nation’s most respected ethicist’s, including Leon R.
Kass, an adviser to President Bush, contend that it is an affront to humanity. At the same time, the people who speak the loudest in favor hardly do their cause a service. They include grieving parents who want to bring back dead children and several maverick scientists — including one who believes in extraterrestrial visitors — who insist on pushing ahead despite evidence from animal experiments showing that cloning is not safe. That view, however, is unlikely to hold sway with Congress. In July, the House of Representatives approved, by a broad margin, a bill that would make any type of cloning, including so-called therapeutic cloning for research, a crime. President Bush supports the bill, and as the Senate prepares to consider it, the biotechnology industry has come out against human cloning, apparently calculating that in doing so, it can preserve its research.
Copyright New York Times Company Dec 2, 2001 Full Text: small group of bioethicist’s were having dinner about a month ago when, out of the blue, one of them gingerly raised the topic of reproductive cloning. ”I don’t know how to say this,’ ‘ he said, according to someone who was present, ”but in my heart of hearts, I don’t think cloning is inherently wrong.’ ‘ After a few nervous glances, the diners went around the table, each offering a similar confession. None saw human cloning as intrinsically evil or immoral. Few would say so in public, however.
As the person who related this story said, ”It’s a little bit like the McCarthy period. There’s nobody on the other side.’ ‘ Ever since the birth of Dolly the sheep in 1997, the specter of human cloning — the creation of babies that are genetic replicas of adults — has loomed large in the public psyche, like a creepy science fiction movie about to become real life. Last week, a Massachusetts biotechnology company announced it had created the world’s first cloned human embryos, not for reproduction, but to make tissues for treating disease. All the embryos died, but the debate over human cloning is once again alive. So far, though, it is a curiously one-sided debate. As the Senate considers legislation to ban any kind of cloning, either for reproduction or research, there appears to be widespread agreement that making babies by cloning is wrong.
Even the company that conducted the experiment, Advanced Cell Technology, has come out against human cloning. Nonetheless, some legitimate scientists, bioethicist’s and advocates for infertile people have quietly put forth a defense of human cloning that has all but been lost in the din. If cloning could be made safe (a big if), these proponents say, it could bring the joys of parenthood to infertile couples, single people and gay people — in short, anyone who cannot now have a genetically-related child. The technique will not upend society, they say; nobody will use cloning to mass-produce a man like Saddam Hussein. But it could help a small number of people, giving them children who, like children everywhere, bear an uncanny resemblance to one parent or the other.’ ‘The only purpose that cloning serves, and I think people should be allowed to do it for this reason, is to let infertile people have children,’ ‘s aid Lee M. Silver, a professor of molecular biology and public policy at Princeton University.’ ‘Everybody is afraid that this child is going to be a replica of the person cloned, and that’s not true,’ ‘ Dr.
Silver added, ”because people are more than their genes.’ ‘s till, cloning provokes a visceral reaction, and some of the nation’s most respected ethicist’s, including Leon R. Kass, an adviser to President Bush, contend that it is an affront to humanity. At the same time, the people who speak the loudest in favor hardly do their cause a service. They include grieving parents who want to bring back dead children and several maverick scientists — including one who believes in extraterrestrial visitors — who insist on pushing ahead despite evidence from animal experiments showing that cloning is not safe.’ ‘The lineup of people who want to clone somebody is a bunch of losers,’ ‘s aid Glenn R. McGee, an assistant professor of bioethics at the University of Pennsylvania who has edited a book on human cloning.
”If you eliminated them, this would be a very different debate. ”The irony is that the best candidates for human cloning are the people who have no intent of making a clone,’ ‘ Professor McGee added. ”They just want a way to make a baby.’ ‘ Were the issue not so politically charged, some fertility specialists might be willing to help them, although most think the market for human cloning is small. The American Society for Reproductive Medicine, which represents fertility doctors, is on record opposing human cloning.
But John A. Robertson, a law professor at the University of Texas and the chairman of the society’s ethics committee, has outlined a careful argument in favor. As a first step, Professor Robertson said, he would allow cloning for the small number of couples who suffer ”gametic infertility,’ ‘s uch as a man who can produce no sperm. Instead of using an unrelated sperm donor, he said, scientists could create an embryo by inserting DNA from the man into his wife’s egg. The baby, carried by the woman, would be a genetic replica of her husband. BUT that first step would inevitably lead to a second and a third, raising questions about who else should be granted permission to clone.
Single mothers? Old people? Gay people? Professor Robertson’s plan is to ”deal with that later,’ ‘ but another ethicist, Prof. Gregory Pence of the University of Alabama, would open the door to everyone.’ ‘As far as I can see,’ ‘ Professor Pence said, ”there is absolutely no Constitutional basis for the government to tell you how you can originate children. If you decide to replicate Uncle Harry because he was brilliant and funny and lived until 90, I don’t see why somebody shouldn’t be able to do it as long as it’s safe.’ ‘ That view, however, is unlikely to hold sway with Congress. In July, the House of Representatives approved, by a broad margin, a bill that would make any type of cloning, including so-called therapeutic cloning for research, a crime.
President Bush supports the bill, and as the Senate prepares to consider it, the biotechnology industry has come out against human cloning, apparently calculating that in doing so, it can preserve its research. At least one senator thinks this strategy will work. ”I predict that Congress will ban reproductive cloning, and I’m all for it,’ ‘ Tom Harkin, Democrat of Iowa, said. ”If senators felt comfortable that there was a good solid iron door against reproductive cloning, then I believe you will open the door for scientists to move ahead with these therapies.’ ‘ In any case, not many people really want to clone Uncle Harry, or even themselves.
Pamela Madsen, executive director of the American Infertility Association, a patient advocacy group, said most couples prefer ”that magic mix of him and her” — even if the mix comes from donated egg or sperm. And for those who are not infertile, having babies is simply more fun, and cheaper, the old-fashioned way. Ms. Madsen’s group has issued a statement opposing human cloning, not for philosophical reasons, but on the ground that it is not safe. But she wonders if, decades from now, those looking back on all the noise and passion of the cloning controversy will find it all silly.’ ‘Ever since I have been a child, what was considered impossible or immoral or unimaginable by some has become a part of regular life,’ ‘s he said. ”Think about when we first started to do blood transfusions, or organ transplants and, yes, Louise Brown” — the first baby born by in-vito fertilization.’ ‘Every time we have made a leap that has benefited mankind, it has always been with a loud voice behind us saying, ‘You’d better watch out.’ ” Captioned as: Girls using a mirror to perfect their form in a dance class in a poor Rio de Janeiro neighborhood.
(Associated Press) Reproduced with permission of the copyright owner. Further reproduction or distribution is prohibited without permission. End of Document The following article has been sent by a user at SANTA BARBARA CITY COLLEGE via Proquest, an information service of the Pro Quest Company Human-Cloning Firm Received Federal Aid; Biotechnology: A $1. 8- million grant awarded before disclosure of the controversial research. [Home Edition]The Los Angeles Times# 5 SEE CORRECTION APPENDED; Biotech companies — A story in Thursday’s Business misstated the size of Im Clone Systems’ potential stake in Advanced Cell Technology, which resulted in an erroneous estimate of Advanced Cell’s market value.
Im Clone may convert its $1-million investment for an equity stake of just more than 3%. That would give Advanced Cell a market capitalization of about $30. 7 million. The story also misidentified Miller Quarles. The retired Texas oilman was an early investor in Advanced Cell but does not own a controlling stake. Under [Michael West]’s leadership, the company has pushed itself to the forefront of human cloning.
But animal cloning remains its chief business-though it has produced little, if any, profit. Advanced Cell made a considerable investment in the business this year when it acquired a Pennsylvania dairy breeding company. But dairy farmers are a tough sell; they want better animals, not clones, said John Meyer, chief executive of the Holstein Assn. USA. What Advanced Cell may lack in business success it has in media savvy. It assured itself a splash with its human cloning experiment by simultaneously publishing an West and his co-authors on the Scientific American piece called their own account in Scientific American and granting an exclusive to U.
S. News and World Report. To be sure no one missed the significance, work ‘the dawn of a new age in medicine’ that showed ‘therapeutic cloning is within reach.’ Advanced Cell said it isn’t interested in helping couples clone offspring. The firm said it created clones to extract stem cells, which can turn into any type of tissue and can be used to treat diseases such as diabetes. In Scientific American, however, West and his co-authors left the door to reproductive cloning ajar, a decision likely to inflame controversy. Due to potential health risks, they wrote, reproductive cloning is ‘unwarranted at this time’ and should be restricted ‘until the safety and ethical issues surrounding it are resolved.’ (Copyright, The Times Mirror Company; Los Angeles Times 2001 Allrightsreserved) Full Text: SEE CORRECTION APPENDED; Biotech companies — A story in Thursday’s Business misstated the size of Im Clone Systems’ potential stake in Advanced Cell Technology, which resulted in an erroneous estimate of Advanced Cell’s market value.
Im Clone may convert its $1-million investment for an equity stake of just more than 3%. That would give Advanced Cell a market capitalization of about $30. 7 million. The story also misidentified Miller Quarles. The retired Texas oilman was an early investor in Advanced Cell but does not own a controlling stake.
The Massachusetts company condemned by the Bush administration for its efforts to clone a human embryo received a federal grant last month to conduct biotechnology research. Advanced Cell Technology’s human cloning experiments set off a national controversy this week that is renewing demands that Congress ban all cloning of human cells. But before the cloning experiment was disclosed, the company was awarded $1. 8 million under a Commerce Department program intended to accelerate research and development in private companies, said Michael Baum, a Commerce Department spokesman.
The company said Wednesday that the grant would not be used for any human cloning research. Rather, the money is to fund experiments into reprogramming adult human cells in an effort to develop therapies for diseases. Both the adult cell research and the human cloning experiments are part of an effort by the company — whose main revenue source has been cloning cows — to break into the business of disease therapy. Thus, the federal funding represents an important capital infusion for the small company.
But researchers and industry officials say administering such grants and keeping salaries, equipment and other expenses separate is a difficult accounting chore. It is one reason some universities that receive federal funds have moved embryonic research off campus, avoiding any potential for conflicts with allowable work under such grants. The Commerce Department issued the grant under its Advanced Technology Program. Baum said the terms of the grant specifically forbid the company from using the federal money to conduct research on human cloning.’ We have audit procedures in place to make sure that doesn’t happen,’ Baum said.
The biotechnology start-up reignited a furor over cloning this week when an online science journal published an account of the company’s experiment. The article in e-Biomed: The Journal of Regenerative Medicine said that the company created only a few clones, that all died and none consisted of more than six cells. President Bush condemned the experiment and Sen. Sam Brownback, a Kansas Republican, vowed to push for a six-month ban on human cloning while law makes consider legislation calling for a total ban.
The House passed legislation banning human cloning in July, but it moved to the back burner after the Sept. 11 terrorist attacks. As a privately held company, Advanced Cell has disclosed little about its finances. According to information posted on its Internet site, it has $6 million available for agricultural research.
Also, the company disclosed in 1997 a five-year, $10-million collaboration with Genzyme Transgenic’s, a biotechnology company. But within the last six months, Advanced Cell sold a New York biotechnology company about a 7% stake for $1 million. The deal with Im Clone Systems, which includes a research collaboration, gives Advanced Cell an estimated market value of $14. 3 million. Im Clone Chief Executive Sam Was kal said Advanced Cell, like many start-ups, sold Im Clone convertible preferred stock because it needed investment capital. ‘This is significant to them,’ he said.
Advanced Cell wouldn’t comment on its finances. Michael West, president and chief executive, was in meetings and not available, a spokeswoman said. A vice president said he could not provide details, but reiterated that only private funds from venture capitalists and individual investors are used to support human cloning projects. ‘There were no research grants at all on this, obviously,’ said Dr. Robert Lanza, vice president for medical and scientific development. Details of the federal grant are posted on the Internet sites of the Commerce Department and Advanced Cell, but have attracted little notice.
Founded in 1994, Advanced Cell is a spinoff of a chicken-breeding operation called Avian Farms. The company had hoped to bioengineer chickens using cloning techniques developed at the University of Massachusetts. West, who joined Advanced Cell in 1998, and New York venture capitalist i ller Quarles took control of the company last year, after a Boston bank initiated foreclosure proceedings against some Avian Farms properties to collect a $3-million debt. Terms of the transaction weren’t disclosed. Under West’s leadership, the company has pushed itself to the forefront of human cloning. But animal cloning remains its chief business-though it has produced little, if any, profit.
Advanced Cell made a considerable investment in the business this year when it acquired a Pennsylvania dairy breeding company. But dairy farmers are a tough sell; they want better animals, not clones, said John Meyer, chief executive of the Holstein Assn. USA. What Advanced Cell may lack in business success it has in media savvy. It assured itself a splash with its human cloning experiment by simultaneously publishing an account in Scientific American and granting an exclusive to U. S.
News and World Report. To be sure no one missed the significance, West and his co-authors on the Scientific American piece called their own work ‘the dawn of a new age in medicine’ that showed ‘therapeutic cloning is within reach.’ In the days since, Advanced Cell executives have made the rounds of morning talk shows and media events. According to his assistant, West has been booked solid for three days — raising questions among people in the scientific community as to whether the company hopes to use the publicity to attract investors. Advanced Cell said it isn’t interested in helping couples clone offspring. The firm said it created clones to extract stem cells, which can turn into any type of tissue and can be used to treat diseases such as diabetes. In Scientific American, however, West and his co-authors left the door to reproductive cloning ajar, a decision likely to inflame controversy.
Due to potential health risks, they wrote, reproductive cloning is ‘unwarranted at this time’ and should be restricted ‘until the safety and ethical issues surrounding it are resolved.’ Research to be covered by the federal grant takes Advanced Cell down another scientific path. The company proposes to reprogram an adult cell, such as a skin cell, into a functioning nerve cell. That cell could be used to treat such ailments as Parkinson’s disease, in which cells in the brain do not produce enough of the key neurological chemical dopamine. Baum, of the government’s Advanced Technology Program, said the company hopes to transform the cells by ‘dousing them with chemicals’ in a process that does not involve cloning or the use of embryonic stem cell tissue, which, with limited exceptions, also is under a federal funding ban. Other companies and institutions are racing to understand how cells program themselves, so they can produce cell therapies without using embryos. Message No: 94915 End of Document 7 Abstract: For Advanced Cell Technology, these uncertainties loom large.
The company is betting that it can perfect human cloning, creating embryos not for reproductive purposes but as a source of stem cells. Human embryonic stem cells could, in theory, grow into any of the body’s tissues and organs, and the company wants to provide them as replacement cells to patients suffering from any of a wide variety of diseases. The company tried to clone with two types of adult cells: skin cells and cumulus cells, which are cells that cling to human eggs. The researchers added skin cells to 11 eggs; none divided even once. They added cumulus cells to eight eggs; three divided once or twice, the others not at all. Stem cells appear only after an embryo grows for about five days and, more important, forms a blastocyst, a sphere of cells with a ball of stem cells inside it.
The Advanced Cell Technology embryos that were created by cloning were not even close to that developmental stage. Copyright New York Times Company Nov 27, 2001 Full Text: When Advanced Cell Technology, a small biotechnology company in Worcester, Mass. , announced on Sunday that it had taken the first steps in producing human embryos through cloning, it could not report lasting success; all the embryos it created had died. It could not even report that it had used groundbreaking techniques; its methods had already been used in animals. Some scientists even suggested that what the company was doing was not cloning at all. But if there is a future in human cloning, either for reproductive purposes or to create cell lines for use in treating diseases, people may one day say it started in Worcester.
Despite the storm of protest that the company’s announcement has provoked, that would be just fine with Advanced Cell Technology. Its president, Dr. Michael D. West, says the company feels pressure to keep the world informed about what it is doing in so controversial a field. But he concedes that the desire to be the first to claim to have created a human embryo by cloning was a factor in the company’s decision to publish its results so far. Whatever the scientific significance of Dr.
West’s announcement, its political significance was profound. President Bush denounced the work as immoral, and there were loud calls for Congress to outlaw it. [Page A 12. ]Shadowing the raging dispute on whether such work should be outlawed is a major scientific question: Is the human-cloning attempt a milestone or a forgettable blunder? The answer, cloning experts say, is that it is impossible to know. or with animals has shown that cloning is something of an art. There are no rules or formulas.
Success, when it comes, can be unpredictable and nearly inexplicable. It could be that human cloning is extraordinarily difficult and that it will take years and thousands of attempts to make it work. Or it could be that a simple change in the laboratory procedure will turn failure into success. That has been the experience of scientists who work at cloning animals. For Advanced Cell Technology, these uncertainties loom large.
The company is betting that it can perfect human cloning, creating embryos not for reproductive purposes but as a source of stem cells. Human embryonic stem cells could, in theory, grow into any of the body’s tissues and organs, and the company wants to provide them as replacement cells to patients suffering from any of a wide variety of disease s. The small company has a track record of achievement in the world of cloning animals; some of the leading cloning researchers are on its payroll. But it also has a track record of astute dealings with the news media. In interviews, Dr. West acknowledged that scientists for the company had published their results in a little-known online publication — E-biome d: The Journal of Regenerative Medicine — because E-biome d had agreed to arrange for distribution to coincide with articles in Scientific American and U.
S. News and World Report. Like many other small biotechnology concerns, privately held Advanced Cell Technology attracts investors with promise, not profits. And though Dr.
West said the company had just completed a round of fund-raising, he noted that it would have continuing needs for money to finance its work. ”We ” re going to require hundreds of millions in investments,’ ‘ he said, ”before we become profitable.’ ‘ In the work reported on Sunday, the company’s scientists, led by Dr. Jose Cibelli, used a standard technique that involves taking the genetic material out of an unfertilized egg and inserting in its place the DNA of an adult cell. In theory, the egg then uses the genes from the adult cell to direct its development, turning into an embryo that is an exact genetic copy of the donor of the adult cell. The company tried to clone with two types of adult cells: skin cells and cumulus cells, which are cells that cling to human eggs. The researchers added skin cells to 11 eggs; none divided even once.
They added cumulus cells to eight eggs; three divided once or twice, the others not at all. Stem cells appear only after an embryo grows for about five days and, more important, forms a blastocyst, a sphere of cells with a ball of stem cells inside it. The Advanced Cell Technology embryos that were created by cloning were not even close to that developmental stage. Dr. Ronald M. Green, a Dartmouth professor who heads the company’s ethics board, says he prefers not even referring to the cells as embryos.
He would like to call them ”cleaving eggs,’ ‘ he said. In fact, scientists say, eggs can divide a few times without making any use of their genes, so the fact that a few eggs divided a few times does not at all mean that the goal of the experiment — to add a new set of functioning genes to an egg — was even close. But cloning failures can suddenly turn to successes, as those who have cloned other species attest. That was the experience of Dr.
Randall Prather, a cloning expert at the University of Missouri, in years of efforts to clone pigs. Over and over again, Dr. Prather would start the cloning process, and then the cells, like those in the Advanced Cell Technology study, would simply die. Now he and others can clone pigs, but he does not know which changes in his laboratory procedures made the difference.
All he can say, Dr. Prather remarked, is, ”Yeah, now it works.’ ‘Cloning also depends on scientists’ having a delicate touch, experts said. One scientist now with Advanced Cell Technology, Dr. Tony Perry, who worked on mouse cloning experiments at the University of Hawaii, said it took endless hours of practice to do the careful manipulations of microscopic cells involved in cloning.
Some people develop a feel for the work, while others, no matter how hard they try, are never very good. ”It requires a kind of eye-hand coordination” and constant practice, Dr. Perry said, recalling months of practice, seven days a week, 10 hours a day. ”If you lapse in your practice for two weeks,’ ‘ he said, ”you don’t return to point zero, but you ” re a little bit rusty.’ ‘ There are also puzzling and unpredictable differences between species. Dr.
Ryu zo Yanagimachi, who cloned the mice with Dr. Teruhiko Wakayama, also now with Advanced Cell Technology, said about 2 to 3 percent of efforts to clone cattle resulted in the birth of a live animal. Most of the rest die very early: only about 20 percent of the embryo clones make it to the blastocyst stage. With mice, Dr.
Yanagimachi said, about 50 to 60 percent of the embryo clones make it to the blastocyst stage. But even more die afterward. In the end, he said, the same percentage of mouse cloning attempts succeed as cattle cloning at temp.