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For the first time, scientists have derived and cultured embryonic stem (ES) cells from rats, paving the way for genetically engineered rats that would more accurately model some human diseases than the currently available genetically engineered mice. Two collaborating teams developed a new approach to derive the ES cells, using a new cocktail of molecules to protect their precious pluripotency, the ability to differentiate into any type of cell. “This is a major development in stem cell research because we know that rats are much more closely related to humans than mice in many aspects of biology. The research direction of many labs around the world will change because of the availability of rat ES cells,” says Qilong Ying [Xinhua], who led one of the teams.

ES cells from mice have been available since 1981, and different researchers have created hundreds of different strains of “knock-out” mice—ones raised from ES cells in which certain genes are silenced to make apparent the genes’ functions. With mice, ES cells were grown with a mixture of growth signals to make them divide without differentiating. But transferring the same technique to rats and other mammals proved surprisingly difficult. To the great frustration of researchers, stem cells isolated from rat embryos and cultured with growth signals would quickly lose their pluripotency. The new strategy, reported in two studies in Cell [subscription required], involves growing the ES cells in a mixture of three key molecules that block the signals that normally induce differentiation. “Our discovery was that if you want to maintain cells in the undifferentiated state, you must block signals, not activate them,” says Ying… By repressing differentiation, the researchers could hold the cells in what they call a “ground state,” a blank slate ready to turn into any tissue in the body [Science News].

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The Vatican has issued new ethical guidelines in response to the biomedical advances of the last 20 years, and has come down hard on assisted reproduction technologies and genetic engineering. The document, Dignitas Personae (which translates as “human dignity”), reaffirm the church’s opposition to in vitro fertilization. It also tells Catholics that the church also doesn’t condone “adopting” leftover fertilized embryos from fertility clinics, and frowns upon the genetic testing of embryos before implantation, which could lead to the embryo being discarded. The Vatican says these techniques violate the principles that every human life — even an embryo — is sacred, and that babies should be conceived only through intercourse by a married couple [The New York Times].

These instructions stem from two fundamental theological principles: that life begins at conception and that the origin of human life is the “fruit of marriage.” … The document now makes clear that the morning-after pill, RU-486, and intrauterine devices (IUDs), which either intercept the embryo before implantation or eliminate it after implantation, “fall within the sin of abortion” [Scientific American]. The guidelines may come as a surprise to many Catholics who don’t realize that the church takes such a strict stance on medical technologies like in vitro fertilization that are often seen as routine and beneficial.

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Researchers have found a way to turn cells from human testes into adult stem cells, raising the possibility that men could eventually have spare cells from their own testicles converted into other kinds of tissue for medical treatments and bodily “repairs.” Lead researcher Thomas Skutella harvested spermatogonial cells, which normally mature into sperm, from men and used a series of chemicals to turn them into various cell types…. “We made them into skin, structures of the gut, cartilage, bone, muscle and neurons,” says Skutella [New Scientist].

The achievement is of particular interest because it avoids the ethical quandaries involved in using embryonic stem cells, which require destroying a human embryo. Using testicular cells isn’t the only promising method that avoids embryos; there have been impressive experiments in reprogramming ordinary body cells into stem cells by slipping certain genes into them. The new findings and the reprogrammed cells — which still have technical hurdles — “take some pressure off the stem cell issue,” said White House science adviser Jack Marburger [AP].

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Researchers have found a way to create stem cells from adult liver cells without triggering DNA changes that have caused mutations and tumors in previous studies. Though demonstrated only in mice so far, the result marks another key achievement in the fledgling science of cellular reprogramming. The hope is to create human, embryonic-like stem cells — which can be turned into all the other tissue types of the body — without using eggs or destroying embryos. That freshly derived tissue could then be transplanted into patients to treat various diseases [The Wall Street Journal].

A method of using adult cells to create stem cells was debuted by Japanese researchers in 2006. By using viruses to insert key developmental genes, researchers coaxed human skin cells into an embryonic state, capable of growing into almost any other type of tissue…. But there was a catch: Viruses used to reset the cells tended to fuse with their DNA, leading to unpredictable mutations and cancer. The cells were promising in principle, but couldn’t be used medically [Wired News]. In the new breakthrough, researchers used a different kind of virus to introduce the genes, and found that it didn’t leave behind any damaging genetic code.

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Using embryonic stem cells, researchers have created enough red blood cells to fill several test tubes, in a development that could eventually allow for the mass-production of blood and the end of blood donation drives. “We literally generated whole tubes in the lab, from scratch,” said Robert Lanza, chief science officer at Advanced Cell Technologies [Wired News].

The breakthrough raises the prospect of mass-producing supplies of the “universal donor” blood type O-negative, which is prized because it can be safely transfused into any patient, whatever their blood group. This type of blood is in short supply – around 8% of Caucasians have it, and just 0.3% of Asians [New Scientist]. Experts say the method would also help keep pathogens like HIV out of the blood supply, as blood banks would no longer have to screen the blood from thousands of donors.

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Several medical research institutions are reconsidering the use of five stem cell lines that are approved for federal-funded research by the National Institutes of Health, citing recently discovered problems with the consent forms signed by the patients at fertility clinics who donated their extra embryos to medical research. Now, ethics oversight committees at universities across the United States are questioning which lines should be permissible for research [Nature News].

Stanford and San Francisco-based [California Institute for Regenerative Medicine] — the $3 billion state agency created when California voters approved the sale of bonds to fund embryonic stem cell research — along with Johns Hopkins University have stopped or may stop research on five of the 21 lines that President Bush in August 2001 deemed acceptable for federal funding [San Jose Business Journal]. Researchers had already chafed at the narrow range of genetic diversity available from the 21 lines; this new development is likely to further limit their research options.

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