Scientists clone mice from adult skin stem cells

Sur le même thème que "Scientists clone mice from adult skin stem cells"

Master switches found for adult blood stem cells

Scientists have found a set of “master switches” that keep adult blood-forming stem cells in their primitive state. Unlocking the switches’ code may one day enable scientists to grow new blood cells for transplant into patients with cancer and other bone marrow disorders. The scientists located the control switches not at the gene level, but farther down the protein production line in more recently discovered forms of ribonucleic acid, or RNA. MicroRNA molecules, once thought to be cellular junk, are now known to switch off activity of the larger RNA strands which allow assembly of the proteins that let cells grow and function. “Stem cells are poised to make proteins essential for maturing into blood cells. [lien] [EN]

Scientists eliminate viral vector in stem cell reprogramming

Previously, Dr. Shinya Yamanaka of Kyoto University and the Gladstone Institute of Cardiovascular Disease, had shown that adult cells can be reprogrammed to become embryonic stem cell–like using a cancer-causing oncogene as one of the four genes required to reprogram the cells, and a virus to transfer the genes into the cells. In the last year, Dr. Yamanaka and other labs showed that the oncogene, c-Myc, is not needed. However the use of viruses that integrate into the genome prohibit use of iPS cells for regenerative medicine because of safety concerns: its integration into the cell’s genome might activate or inactivate critical host genes. Now Dr. Yamanaka’s laboratory in Kyoto has eliminated the need for the virus. In a report published this week in Science. [lien] [EN]

Scientists unlock mystery of embryonic stem cell signaling pathway

A newly discovered small molecule called IQ-1 plays a key role in preventing embryonic stem cells from differentiating into one or more specific cell types, allowing them to instead continue growing and dividing indefinitely, according to research performed by a team of scientists who have recently joined the stem-cell research efforts at the Keck School of Medicine of the University of Southern California. Their findings are being published in the Proceedings of the National Academy of Sciences. This discovery takes scientists another step closer to being able to grow embryonic stem cells without the “feeder layer” of mouse fibroblast cells that is essential for maintaining the pluripotency of embryonic stem cells. [lien] [EN]

Scientists discover new, readily available source of stem cells

Scientists have discovered a new source of stems cells and have used them to create muscle, bone, fat, blood vessel, nerve and liver cells in the laboratory. The first report showing the isolation of broad potential stem cells from the amniotic fluid that surrounds developing embryos was published in Nature Biotechnology. “Our hope is that these cells will provide a valuable resource for tissue repair and for engineered organs as well,” said Anthony Atala, M.D., senior researcher and director of the Institute for Regenerative Medicine at Wake Forest University School of Medicine. Atala announced the breakthrough with colleagues from Wake Forest University School of Medicine and Harvard Medical School. “It has been known for decades that both the placenta and amniotic fluid contain multiple progenitor cell types from the developing embryo. [lien] [EN]

Scientists Discover Key to Growing New Stem Cells

Scientists at Duke University Medical Center have demonstrated they can grow human stem cells in the laboratory by blocking an enzyme that naturally triggers stem cells to mature and differentiate into specialized cells. The discovery may enable scientists to rapidly grow stem cells and transplant them into patients with blood disorders, immune defects and select genetic diseases, said the Duke researchers. Stem cells are the most flexible cells in the body, continually dividing into new stem cells or into specialized cells that carry out specific roles in the body. But little is known about how stem cells choose their fate. The Duke team focused on “hematopoietic” or blood stem cells. [lien] [EN]

Scientists identifies gene that regulates blood-forming fetal stem cells

In the rancorous public debate over federal research funding, stem cells are generally assigned to one of two categories: embryonic or adult. But that’s a false dichotomy and an oversimplification. A new University of Michigan study adds to mounting evidence that stem cells in the developing fetus are distinct from both embryonic and adult stem cells. In the last several years, stem cell researchers have realized that fetal stem cells comprise a separate class. They recognized, for example, that fetal blood-forming stem cells in umbilical cord blood behave differently than adult blood-forming stem cells after transplantation into patients. Now a U-M team led by Sean Morrison has identified the first known gene. [lien] [EN]

Scientists create 3-D scaffold for growing stem cells

Stem cells grew, multiplied and differentiated into brain cells on a new three-dimensional scaffold of tiny protein fragments designed to be more like a living body than any other cell culture system. An MIT engineer and Italian colleagues will report the invention-which may one day replace the ubiquitous Petri dish for growing cells-in the Dec. 27th issue of the PLoS ONE. Shuguang Zhang, associate director of MIT’s Center for Biomedical Engineering, is a pioneer in coaxing tiny fragments of amino acids called self-assembling peptides to organize themselves into useful structures. Working with visiting graduate student Fabrizio Gelain from Milan, Zhang created a designer scaffold from a network of protein nanofibers, each 5,000 times thinner than a human hair and containing pores up to 20. [lien] [EN]

Medium is the message for stem cells in search of identities

Embryonic stem cells, prized for their astonishing ability to apparently transform into any kind of cell in the body, acquire their identities in part by interacting with their surroundings - even when they are outside of the body in a laboratory dish, University of Florida scientists report. Using an animal model of embryonic stem cell development, researchers with UF’s McKnight Brain Institute have begun to answer one of the most fundamental questions in science - how does a batch of immature cells give rise to an organ as extraordinarily complex as the human brain? The findings, to be published this week in the Proceedings of the National Academy of Sciences, may one day help scientists create laboratory environments to grow specialized cells that can be transplanted into patients to treat epilepsy. [lien] [EN]

Scientists Clone Mouse from Damaged Frozen Cells, Mammoth, Sabertooth Next In Line [Pleistocene Park]

Apparently, genetic scientist Teruhiko Wakayama hasn't read Jurassic Park, as he is working to create technology to clone mammoths, sabertooth tigers, giant deers, and steppe lions from frozen genetic material. The DNA in cells subjected to permafrost gets extremely damaged, making it impossible to use for cloning. Until now, that is, because Wakayama and his team of researchers used new technology to successfully clone a healthy mouse from a carcass that was frozen for 16 years at -4 ºF. Now he's saying that a mammoth is possible, opening the door to the realization of the Pleistocene Park, a project that seeks to create a sanctuary with those animals and more in northern Siberia: There are many technical challenges involved in resurrecting a mammoth, but we have shown that the nuclear transfer method can be used to create healthy clones. [lien] [EN]

Protein that controls hair growth also keeps stem cells slumbering

Like fine china and crystal, which tend to be used sparingly, stem cells divide infrequently. It was thought they did so to protect themselves from unnecessary wear and tear. But now new research from Rockefeller University has unveiled the protein that puts the brakes on stem cell division and shows that stem cells may not need such guarded protection to maintain their potency. This research, to be published in the January 25 issue of Cell, raises questions about what stem cells need in order to maintain their ability to regenerate tissue. It may also be key in developing new treatments for thinning hair. The impetus for the work began five years ago when Elaine Fuchs, head of the Laboratory of Mammalian Cell Biology and Development, and several researchers in her lab discovered that the protein NFATc1 was one of only a few that are highly expressed within the stem cell compartment of the hair follicle. [lien] [EN]

Neural stem cell differentiation factor discovered

Neural stem cells represent the cellular backup of our brain. These cells are capable of self-renewal to form new stem cells or differentiate into neurons, astrocytes or oligodendrocytes. Astrocytes have supportive functions in the environment of neurons, while oligodendrocytes form the myelin layer around axons in order to accelerate neuronal signal transmission. But how does a neural stem cell „know” which way it is supposed to develop? On the molecular level receptors of the Notch family play a significant role in this process. So far, only stimulating extracellular ligands of Notch receptors had been described. Biochemists of Goethe University Medical School now describe a long time assumed but not yet identified soluble Notch inhibitor. Franfurt scientists led by Mirko Schmidt and Ivan Dikic reported in the renowned journal „Nature Cell Biology” that the secreted protein EGFL7 (Epidermal Growth Factor. [lien] [EN]

Researchers replace organ in adult mice using ’single-parent’ stem cells

Researchers at the University of Pennsylvania School of Veterinary Medicine have derived uniparental embryonic stem cells - created from a single donor’s eggs or two sperm - and, for the first time, successfully used them to repopulate a damaged organ with healthy cells in adult mice. Their findings demonstrate that single-parent stem cells can proliferate normally in an adult organ and could provide a less controversial alternative to the therapeutic cloning of embryonic stem cells. “Creating uniparental embryonic stem cells is actually much more efficient than generating embryonic stem cells by cloning,” said K. John McLaughlin, an assistant professor in Penn’s Department of Animal Biology and researcher at the Center for Animal Transgenesis and Germ Cell Research at Penn’s New Bolton Center. [lien] [EN]

Elusive pancreatic stem cells found in adult mice

Just as many scientists had given up the search, researchers have discovered that the pancreas does indeed harbor stem cells with the capacity to generate new insulin-producing beta cells. If the finding made in adult mice holds for humans, the newfound progenitor cells will represent an obvious target for therapeutic regeneration of beta cells in diabetes, the researchers report in the Jan. 25 issue of Cell, a publication of Cell Press. One of the most interesting characteristics of these [adult] progenitor cells is that they are almost indistinguishable from embryonic progenitors, said Harry Heimberg of the JDRF Center at Vrije Universiteit Brussel in Belgium and the Beta Cell Biology Consortium. �In terms of their structure and gene expression. [lien] [EN]

In a major breakthrough scientists reprogram human adult cells into embryonic stem cells

Acclaimed stem cell researcher Shinya Yamanaka, MD, PhD, has reported that he and his Kyoto University colleagues have successfully reprogrammed human adult cells to function like pluripotent embryonic stem (ES) cells. Because it circumvents much of the controversy and restrictions regarding generation of ES cells from human embryos, this breakthrough, reported in the journal Cell, should accelerate the pace of stem cell research. Last year, Yamanaka, who is also a senior investigator at the Gladstone Institute of Cardiovascular Disease (GICD), reported that he and his Kyoto colleagues had reprogrammed mouse skin cells into pluripotent stem cells, laying the foundation to apply this methodology in human cells. [lien] [EN]