Ever since Dolly the sheep was cloned eighteen years ago, scientists have been trying and failing to use that same technique to create cloned human embryos from adult cells. Now, they’ve finally succeeded, in what could a major step toward personalized organ transplants and other therapies that rely on a pool of stem cells.
Last year, a different team of scientists reported a breakthrough in creating the first cloned human embryos ever. That team used cells taken from a fetus and an eight-month-old infant. This new result, published in the journal Cell Stem Cell, tweaks the procedure to make it also work with skin cells from two adult men, ages 35 and 75.
Confirming that human clone embryos can indeed be made with adult cells means we could potentially someday scrape off a bit of your skin, put it in a cloned embryo, and extract stem cells personalized with your DNA. Those stem cells can then theoretically be programmed grow into any type of tissue—including an organ for transplant.
The basic process is the same as the one used to clone Dolly. The nucleus, which contains DNA, is sucked out of the adult cell and carefully placed in a donor egg, whose own nucleus has been removed. Scientists have gotten this process to work in over 20 different species, but humans, until recently, have proven tricky.
This result does not mean that cloned babies will be born anytime soon, however. The resulting embryo was missing some types of cells and would not have been able to implant in the womb. The difficulty of getting embryos to grow in the womb is, in fact, why partly scientists still haven’t been able to clone monkeys.
The most promising use of this human cloning technique is in creating embryos as a source of personalized stem cells. Currently, we get stem cells from embryos leftover from in vitro fertilization (IVF)—or we reprogram them from adult cells. Both techniques have their drawbacks, however, as IVF stem cells do not perfectly match the patient’s, and the reprogramming may not ever be entirely complete in adult cells, according to some studies.
Any therapies that may result from cloning adult cells is still far, far off on the horizon. Even with this basic lab research, plenty of questions about the moral implications of human cloning remain. It’s been 18 years since Dolly—but the ethical dilemmas haven’t changed a bit. [Cell Stem Cell via Wall Street Journal, TIME]
First Human Clone Embryos Created From Adults’ Skin Cells
“Scientists have created cloned embryos from the cells of two adults. This feat is the first hard evidence that it’s possible to create clones from cells taken from adult humans. The idea is that in the future, doctors could create cloned embryos of patients when the patients need an organ transplant, for example, or a set of new immune cells. The cloned embryos would serve as a source of stem cells for creating perfectly personalized transplants, no matter how old people are when they first get sick.”
A new study by cell and systems biologists at the University of Toronto (U of T) investigating stem cells in mice shows, for the first time, an instance of such a relationship between the Sox2 gene which is critical for early development, and a region elsewhere on the genome that effectively regulates its activity. The discovery could mean a significant advance in the emerging field of human regenerative medicine, as the Sox2 gene is essential for maintaining embryonic stem cells that can develop into any cell type of a mature animal.
“We studied how the Sox2 gene is turned on in mice, and found the region of the genome that is needed to turn the gene on in embryonic stem cells,” said Professor Jennifer Mitchell of U of T’s Department of Cell and Systems Biology, lead invesigator of a study published in the December 15 issue of Genes & Development.
Researchers from the Babraham Institute show that the first cell fate decision in development is much more robust than previously appreciated.
The initial cell fate decision in development creates two distinct cell populations: trophoblast cells that go on to form the yolk sac and placenta, and embryonic cells that develop into the embryo itself and all subsequent cell types of the body.
Dr Hemberger and her team attempted to reprogram embryonic stem (ES) cells to become trophoblast-like stem cells (TS) and found that the ES cells were virtually impossible to fully overwrite.
The image shows ES cells reprogrammed for 5-6 weeks towards a TS-like fate. Markers of true TS identity (shown as green and red, cell nucleic are in blue) were unstable and frequently lost in these reprogrammed TS-like cells showing that the identity of ES cells cannot be overwritten.
This new understanding of the first cell fate decision is instrumental in developing the ability to manipulate stem cells for regenerative medicine approaches, and will help to advance our understanding of the most common pregnancy complications such as pre-eclampsia and foetal growth restriction.
Since the discovery of human embryonic stem cells, scientists have had high hopes for their use in treating a wider variety of diseases because they are pluripotent, which means they are capable of differentiating into one of many cell types in the body.
However, the acquisition of human embryonic stem cells from an embryo can cause the destruction of the embryo, thus raising ethical concerns. In 2006, researchers introduced an alternative to harvesting embryonic stem cells called induced pluripotent stem (iPS) cells. They provided evidence that it was possible to send a normal adult cell back to an undifferentiated, pluripotent stem cell state by introducing genetic material (“outside” DNA) into the cell, a process that alters the original state of the cell. To avoid the use of embryonic stem cells, other researchers have focused more on the use of adult stem cells, but the use is of these cells is limited because unlike embryonic stem cells that grow into any type of mature cell, adult stem cells can only grow into certain cell types.
Now, researchers from Brigham and Women’s Hospital (BWH), in collaboration with the RIKEN Center for Developmental Biology in Japan, have demonstrated that any mature adult cell — a “somatic” cell — has the potential to turn into the equivalent of an embryonic stem cell.
Human embryonic stem cells can be produced without damage to early stage embryos created by in vitro fertilisation. A single cell can be carefully removed from an eight-cell embryo (pictured is a sixteen-cell embryo), allowing IVF clinics to test whether embryos are healthy enough to implant. Researchers have recently used the technique to extract a stem cell they successfully cultivated on a bed of a human laminin: LN-521, a protein common to early stage embryos. The single stem cell multiplied without contamination, a common problem when cells are cultured with human or animal protein. This research demonstrates that embryos can yield tissue for research and still develop into healthy individuals. A fact that should help to expedite the search for cures for serious illnesses such as Parkinson’s disease. In the US, human embryos can’t legally be used for research if they have to be destroyed.
A new way to make muscle cells from human stem cells
As stem cells continue their gradual transition from the lab to the clinic, a research group at the University of Wisconsin-Madison has discovered a new way to make large concentrations of skeletal muscle cells and muscle progenitors from human stem cells.
The new method, described in the journal Stem Cells Translational Medicine, could be used to generate large numbers of muscle cells and muscle progenitors directly from human pluripotent stem cells. These stem cells, such as embryonic (ES) or induced pluripotent stem (iPS) cells, can be made into virtually any adult cell in the body.
Adapting a method previously used to make brain cells, Masatoshi Suzuki, an assistant professor of comparative biosciences in the School of Veterinary Medicine, has directed those universal stem cells to become both adult muscle cells and muscle progenitors.
Importantly, the new technique grows the pluripotent stem cells as floating spheres in high concentrations of two growth factors, fibroblast growth factor-2 and epidermal growth factor. These growth factors “urge” the stem cells to become muscle cells.
“Researchers have been looking for an easy way to efficiently differentiate stem cells into muscle cells that would be allowable in the clinic,” says Suzuki. The novelty of this technique is that it generates a larger number of muscle stem cells without using genetic modification, which is required by existing methods for making muscle cells.
“Many other protocols have been used to enhance the number of cells that go to a muscle fate,” says co-author Jonathan Van Dyke, a post-doctoral fellow in Suzuki’s laboratory. “But what’s exciting about the new protocol is that we avoid some techniques that would prohibit clinical applications. We think this new method has great promise for alleviating human suffering.”
Last year, Suzuki demonstrated that transplants of another type of human stem cells somewhat improved survival and muscle function in rats that model amyotrophic lateral sclerosis (ALS). Also known as Lou Gehrig’s disease, ALS destroys nerves and causes a loss of muscle control. The muscle progenitors generated with Suzuki’s new method could potentially play a similar role but with enhanced effect.
The new technique can also be used to grow muscle cells from iPS cells from patients with neuromuscular diseases like ALS, spinal muscular atrophy and muscular dystrophy. Thus, the technique could produce adult muscle cells in a dish that carry genetic diseases. These cells could then be used as a tool for studying these diseases and screening potential drug compounds, says Suzuki. “Our protocol can work in multiple ways and so we hope to provide a resource for people who are exploring specific neuromuscular diseases in the laboratory.”
The new protocol incorporates a number of advantages. First, the cells are grown in defined supplements without animal products such as bovine serum, enhancing the clinical safety for the muscle stem cells. Second, when grown as spheres, the cells grow faster than with previous techniques. Third, 40 to 60 percent of the cells grown using the process are either muscle cells or muscle progenitors, a high proportion compared to traditional non-genetic techniques of generating muscle cells from human ES and iPS cells.
Suzuki and his group hope that by further manipulating the chemical environment of the spheres of stem cells, they may increase that number, further easing the path toward human treatment
Image: Muscle cells are stained green in this micrograph of cells grown from embryonic stem cells in the lab of Masatoshi Suzuki at the University of Wisconsin – Madison. Cell nuclei are stained blue; the muscle fibers contain multiple nuclei. Nuclei outside the green fibers are from non-muscle cells.
They’ve already begun testing it in a small number of diabetic patients. If it works as well in patients as it has in animals, it would amount to a cure, ending the need for frequent insulin injections and blood sugar testing.
ViaCyte and Johnson & Johnson’s Janssen BetaLogics group said Thursday they’ve agreed to combine their knowledge and hundreds of patents on their research under ViaCyte, a longtime J&J partner focused on regenerative medicine.
The therapy involves inducing embryonic stem cells in a lab dish to turn into insulin-producing cells, then putting them inside a small capsule that is implanted under the skin. The capsule protects the cells from the immune system, which otherwise would attack them as invaders — a roadblock that has stymied other research projects.
Researchers at universities and other drug companies also are working toward a diabetes cure, using various strategies. But according to ViaCyte and others, this treatment is the first tested in patients.
If the project succeeds, the product could be available in several years for Type 1 diabetes patients and down the road could also treat insulin-using Type 2 diabetics.
“This one is potentially the real deal,” said Dr. Tom Donner, director of the diabetes centre at Johns Hopkins University School of Medicine. “It’s like making a new pancreas that makes all the hormones” needed to control blood sugar.
The fact that there are still people who oppose stem cell research because they consider embryos to be human life but they DON’T support something that could save actual sentient living beings who already exist makes me not want to live on this planet anymore.
Embryonic stem (ES) cell lines are cultures of cells derived from the epiblast tissue of the inner cell mass (ICM) of a blastocyst or earlier morula stage embryos. A blastocyst is an early stage embryo—approximately four to five days old in humans and consisting of 50–150 cells. ES cells are pluripotent and give rise during development to all derivatives of the three primary germ layers: ectoderm, endoderm and mesoderm. In other words, they can develop into each of the more than 200 cell types of the adult body when given sufficient and necessary stimulation for a specific cell type. They do not contribute to the extra-embryonic membranes or the placenta. The endoderm is composed of the entire gut tube and the lungs, the ectoderm gives rise to the nervous system and skin, and the mesoderm gives rise to muscle, bone, blood—in essence, everything else that connects the endoderm to the ectoderm.
Nearly all research to date has made use of mouse embryonic stem cells (mES) or human embryonic stem cells (hES). Both have the essential stem cell characteristics, yet they require very different environments in order to maintain an undifferentiated state. Mouse ES cells are grown on a layer of gelatin as an extracellular matrix (for support) and require the presence of leukemia inhibitory factor (LIF). Human ES cells are grown on a feeder layer of mouse embryonic fibroblasts (MEFs) and require the presence of basic fibroblast growth factor (bFGF or FGF-2).Without optimal culture conditions or genetic manipulation, embryonic stem cells will rapidly differentiate.
A human embryonic stem cell is also defined by the expression of several transcription factors and cell surface proteins. The transcription factors Oct-4, Nanog, and Sox2 form the core regulatory network that ensures the suppression of genes that lead to differentiation and the maintenance of pluripotency. The cell surface antigens most commonly used to identify hES cells are the glycolipids stage specific embryonic antigen 3 and 4 and the keratan sulfate antigens Tra-1-60 and Tra-1-81. The molecular definition of a stem cell includes many more proteins and continues to be a topic of research.
There are currently no approved treatments using embryonic stem cells. The first human trial was approved by the US Food and Drug Administration in January 2009. However, the human trial was not initiated until October 13, 2010 in Atlanta for spinal injury victims. On November 14, 2011 the company conducting the trial announced that it will discontinue further development of its stem cell programs. ES cells, being pluripotent cells, require specific signals for correct differentiation—if injected directly into another body, ES cells will differentiate into many different types of cells, causing a teratoma. Differentiating ES cells into usable cells while avoiding transplant rejection are just a few of the hurdles that embryonic stem cell researchers still face. Many nations currently have moratoria on either ES cell research or the production of new ES cell lines. Because of their combined abilities of unlimited expansion and pluripotency, embryonic stem cells remain a theoretically potential source for regenerative medicine and tissue replacement after injury or disease.
Douglas Melton is as impatient as anyone for a cure for diabetes. His son developed the disease as an infant, and his daughter was diagnosed at age 14. For most of the past 2 decades, the developmental biologist at the Harvard Stem Cell Institute has focused his research on finding a cure. This week, he and his colleagues report a potentially significant step toward that goal: a recipe that can turn human stem cells into functional pancreatic β cells—the cells that are destroyed by the body’s own immune system in type 1 diabetes patients such as Melton’s son and daughter. The cells the researchers produced respond to glucose by producing insulin, just as normal β cells do. And when implanted into mice with a form of diabetes, the cells can cure the disorder.
“The diabetes research community has been waiting for ages for this type of breakthrough,” says Jorge Ferrer, who studies the genetics of β cells at Imperial College London. The lab-generated cells should be a valuable tool for studying diabetes and, Melton hopes, could eventually be used to treat patients.
Rat primary embryonic stem cells derived from cortex of GFP–expressing rat. Transplanted in rat normal spinal cord and sectioned by Koichi Hasegawa. Images of optical slices taken with a 40X C-Apochromat objective lens (N.A. 1.2) on LSM 510 confocal microscope were processed for 3-D volume rendering (Imaris, Bitplane). Imaging by Noriko Kane-Goldsmith.
Researchers have produced the world’s first chimeric monkeys. The bodies of these monkeys, which are normal and healthy, are composed of a mixture of cells representing as many as six distinct genomes. The advance holds great potential for future research as chimeric animals had been largely restricted to mice, the researchers say. The report, published online ahead of the release of the January 20th issue of Cell, a Cell Press publication, also suggests there may be limits to the use of cultured embryonic stem cells.
The chimeric monkeys were born after the researchers essentially glued cells from separate rhesus monkey embryos together and successfully implanted these mixed embryos into mothers. The key was mixing cells from very early stage embryos when each individual embryonic cell is totipotent, capable of giving rise to a whole animal as well as the placenta and other life-sustaining tissues. (This is in contrast to pluripotent stem cells, which can differentiate into any tissue type in the body, but not extra-embryonic tissues or entire organisms.)…
-Top: Roku and Hex. Bottom: Chimero. (Credit: Images courtesy of Oregon Health & Science University)
Neuron corona - neurons extending from human embryonic stem cell spheres (20x) by Dr Daniel Webber, Cambridge Centre for Brain Repair, University of Cambridge. Nikon Small World 2009, Image of Distinction.
Decoding Diabetes: a Conversation with Doug Melton, part 1 of 3
“Stem Cells, Beta Cells and the Cure”
November is National Diabetes Awareness Month and this year is a uniquely exciting time to raise awareness for the future of diabetes care. Earlier this fall, Harvard’s Xander University Professor Doug Melton, PhD, published a discovery that is the final precursor to a cure for Type 1 diabetes.