SCIENTISTS REVERT HUMAN STEM CELLS TO PRISTINE STATE

Researchers at EMBL-EBI have resolved a long-standing challenge in stem cell biology by successfully 'resetting' human pluripotent stem cells to a fully pristine state, at point of their greatest developmental potential. The study, published in Cell, involved scientists from the UK, Germany and Japan and was led jointly by EMBL-EBI and the University of Cambridge.

Embryonic stem (ES) cells, which originate in early development, are capable of differentiating into any type of cell. Until now, scientists have only been able to revert 'adult' human cells (for example, liver, lung or skin) into pluripotent stem cells with slightly different properties that predispose them to becoming cells of certain types. Authentic ES cells have only been derived from mice and rats.

"Reverting mouse cells to a completely 'blank slate' has become routine, but generating equivalent naïve human cell lines has proven far more challenging," says Dr Paul Bertone, Research Group Leader at EMBL-EBI and a senior author on the study. "Human pluripotent cells resemble a cell type that appears slightly later in mammalian development, after the embryo has implanted in the uterus."

At this point, subtle changes in gene expression begin to influence the cells, which are then considered 'primed' towards a particular lineage. Although pluripotent human cells can be cultured from in vitro fertilised (IVF) embryos, until now there have been no human cells comparable to those obtained from the mouse.

Wiping cell memory

"For years, it was thought that we could be missing the developmental window when naïve human cells could be captured, or that the right growth conditions hadn't been found," Paul explains. "But with the advent of iPS cell technologies, it should have been possible to drive specialised human cells back to an earlier state, regardless of their origin -- if that state existed in primates."

Taking a new approach, the scientists used reprogramming methods to express two different genes, NANOG and KLF2, which reset the cells. They then maintained the cells indefinitely by inhibiting specific biological pathways. The resulting cells are capable of differentiating into any adult cell type, and are genetically normal.

The experimental work was conducted hand-in-hand with computational analysis.

"We needed to understand where these cells lie in the spectrum of the human and mouse pluripotent cells that have already been produced," explains Paul. "We worked with the EMBL Genomics Core Facility to produce comprehensive transcriptional data for all the conditions we explored. We could then compare reset human cells to genuine mouse ES cells, and indeed we found they shared many similarities."

Together with Professor Wolf Reik at the Babraham Institute, the researchers also showed that DNA methylation (biochemical marks that influence gene expression) was erased over much of the genome, indicating that reset cells are not restricted in the cell types they can produce. In this more permissive state, the cells no longer retain the memory of their previous lineages and revert to a blank slate with unrestricted potential to become any adult cell.

Unlocking the potential of stem cell therapies

The research was performed in collaboration with Professor Austin Smith, Director of the Wellcome Trust-Medical Research Council Stem Cell Institute.

"Our findings suggest that it is possible to rewind the clock to achieve true ground-state pluripotency in human cells," said Professor Smith. "These cells may represent the real starting point for formation of tissues in the human embryo. We hope that in time they will allow us to unlock the fundamental biology of early development, which is impossible to study directly in people."

The discovery paves the way for the production of superior patient material for translational medicine. Reset cells mark a significant advance for human stem cell applications, such as drug screening of patient-specific cells, and are expected to provide reliable sources of specialised cell types for regenerative tissue grafts.

SCIENTISTS DISCOVER A NEW SLEEP NODE IN THE BRAIN

A sleep-promoting circuit located deep in the primitive brainstem has revealed how we fall into deep sleep. Discovered by researchers at Harvard School of Medicine and the University at Buffalo School of Medicine and Biomedical Sciences, this is only the second "sleep node" identified in the mammalian brain whose activity appears to be both necessary and sufficient to produce deep sleep.

Published online in August in Nature Neuroscience, the study demonstrates that fully half of all of the brain's sleep-promoting activity originates from the parafacial zone (PZ) in the brainstem. The brainstem is a primordial part of the brain that regulates basic functions necessary for survival, such as breathing, blood pressure, heart rate and body temperature.

"The close association of a sleep center with other regions that are critical for life highlights the evolutionary importance of sleep in the brain," says Caroline E. Bass, assistant professor of Pharmacology and Toxicology in the UB School of Medicine and Biomedical Sciences and a co-author on the paper.

The researchers found that a specific type of neuron in the PZ that makes the neurotransmitter gamma-aminobutyric acid (GABA) is responsible for deep sleep. They used a set of innovative tools to precisely control these neurons remotely, in essence giving them the ability to turn the neurons on and off at will.

"These new molecular approaches allow unprecedented control over brain function at the cellular level," says Christelle Ancelet, postdoctoral fellow at Harvard School of Medicine. "Before these tools were developed, we often used 'electrical stimulation' to activate a region, but the problem is that doing so stimulates everything the electrode touches and even surrounding areas it didn't. It was a sledgehammer approach, when what we needed was a scalpel."

"To get the precision required for these experiments, we introduced a virus into the PZ that expressed a 'designer' receptor on GABA neurons only but didn't otherwise alter brain function," explains Patrick Fuller, assistant professor at Harvard and senior author on the paper. "When we turned on the GABA neurons in the PZ, the animals quickly fell into a deep sleep without the use of sedatives or sleep aids."

How these neurons interact in the brain with other sleep and wake-promoting brain regions still need to be studied, the researchers say, but eventually these findings may translate into new medications for treating sleep disorders, including insomnia, and the development of better and safer anesthetics.

"We are at a truly transformative point in neuroscience," says Bass, "where the use of designer genes gives us unprecedented ability to control the brain. We can now answer fundamental questions of brain function, which have traditionally been beyond our reach, including the 'why' of sleep, one of the more enduring mysteries in the neurosciences."

The work was funded by the National Institutes of Health.

SCIENTISTS INVENT BIO SPLEEN DEVICE THAT USES MAGNET TO CLEANSE BLOOD

Scientists recently unveiled a device called 'bio-spleen,' which uses a magnet to cleanse the blood by bacteria, fungi and toxins.

Researchers hope that the external gadget, potentially throwing a lifeline to patients with sepsis and other infections, could be adapted one day for stripping Ebola and other viruses from blood, News24.com reported.

Acting rather like a spleen, the invention uses magnetic nanobeads coated with a genetically-engineered human blood protein called MBL.

Donald Ingber said that this treatment could be carried out even before the pathogen has been formally identified and the optimal antibiotic treatment has been chosen.

They could potentially treat patients with this bio-spleen during the most infectious, viraemic phase of the disease and reduce the amount of virus in their blood, he further added.

The device was developed to treat sepsis, or blood infection, which affects 18 million people in the world every year, with a 30 percent-50 percent mortality rate

SCIENTISTS GENERATE FIRST HUMAN TISSUE IN L AB WITH STEM CELLS

Scientists used pluripotent stem cells to generate functional, three-dimensional human stomach tissue in a laboratory -- creating an unprecedented tool for researching the development and diseases of an organ central to several public health crises, ranging from cancer to diabetes.

Scientists at Cincinnati Children's Hospital Medical Center report Oct. 29 in Nature they used human pluripotent stem cells -- which can become any cell type in the body -- to grow a miniature version of the stomach. In collaboration with researchers at the University of Cincinnati College of Medicine, they used laboratory generated mini-stomachs (called gastric organoids) to study infection by H. pylori bacteria, a major cause of peptic ulcer disease and stomach cancer.

This first-time molecular generation of 3D human gastric organoids (hGOs) presents new opportunities for drug discovery, modeling early stages of stomach cancer and studying some of the underpinnings of obesity related diabetes, according to Jim Wells, PhD, principal investigator and a scientist in the divisions of Developmental Biology and Endocrinology at Cincinnati Children's.

It also is the first time researchers have produced 3D human embryonic foregut -- a promising starting point for generating other foregut organ tissues like the lungs and pancreas, he said.

"Until this study, no one had generated gastric cells from human pluripotent stem cells (hPSCs)," Wells said. "In addition, we discovered how to promote formation of three-dimensional gastric tissue with complex architecture and cellular composition."

This is important because differences between species in the embryonic development and architecture of the adult stomach make mouse models less than optimal for studying human stomach development and disease, Wells added.

Researchers can use human gastric organoids as a new discovery tool to help unlock other secrets of the stomach, such as identifying biochemical processes in the gut that allow gastric-bypass patients to become diabetes-free soon after surgery before losing significant weight. Obesity fueled diabetes and metabolic syndrome are an exploding public health epidemic. Until now, a major challenge to addressing these and other medical conditions involving the stomach has been a relative lack of reliable laboratory modeling systems to accurately simulate human biology, Wells explained.

The key to growing human gastric organoids was to identify the steps involved in normal stomach formation during embryonic development. By manipulating these normal processes in a petri dish, the scientists were able to coax pluripotent stem cells toward becoming stomach. Over the course of a month, these steps resulted in the formation of 3D human gastric organoids that were about 3mm (1/10th of an inch) in diameter. Wells and his colleagues also used this approach to identify what drives normal stomach formation in humans with the goal of understanding what goes wrong when the stomach does not form correctly.

Along with study first author Kyle McCracken, an MD/PhD graduate student working in Wells' laboratory, and Yana Zavros, PhD, a researcher at UC's Department of Molecular and Cellular Physiology, the authors report they were impressed by how rapidly H. pylori bacteria infected stomach epithelial tissues.

Within 24 hours, the bacteria had triggered biochemical changes to the organ, according to McCracken. The human gastric organoids faithfully mimicked the early stages of gastric disease caused by the bacteria, including the activation of a cancer gene called c-Met and the rapid spread of infection in epithelial tissues.

Another significant part of the team's challenge has been the relative lack of previous research literature on how the human stomach develops, the authors said. Wells said the scientists had to use a combination of published work, as well as studies from his own lab, to answer a number of basic developmental questions about how the stomach forms. Over the course of two years, this approach of experimenting with different factors to drive the formation of the stomach eventually resulted in the formation of 3D human gastric tissues in the petri dish.

Wells emphasized importance of basic research for the eventual success of this project, adding, "This milestone would not have been possible if it hadn't been for previous studies from many other basic researchers on understanding embryonic organ development."

SCIENTISTS GROW CARTILAGE TO RECONSTRUCT NOSE

Scientists at the University of Basel report first ever successful nose reconstruction surgery using cartilage grown in the laboratory. Cartilage cells were extracted from the patient's nasal septum, multiplied and expanded onto a collagen membrane. The so-called engineered cartilage was then shaped according to the defect and implanted. The results will be published in the current edition of the academic journalThe Lancet

A research team from the University of Basel in Switzerland has reported that nasal reconstruction using engineered cartilage is possible. They used a method called tissue engineering where cartilage is grown from patients' own cells. This new technique was applied on five patients, aged 76 to 88 years, with severe defects on their nose after skin cancer surgery. One year after the reconstruction, all five patients were satisfied with their ability to breathe as well as with the cosmetic appearance of their nose. None of them reported any side effects.

Cells from the nasal septum

The type of non-melanoma skin cancer investigated in this study is most common on the nose, specifically the alar wing of the nose, because of its cumulative exposure to sunlight. To remove the tumor completely, surgeons often have to cut away parts of cartilage as well. Usually, grafts for reconstruction are taken from the nasal septum, the ear or the ribs and used to functionally reconstruct the nose. However, this procedure is very invasive, painful and can, due to the additional surgery, lead to complications at the site of the excision.

Together with colleagues from the University Hospital, the research team from the Department of Biomedicine at the University of Basel has now developed an alternative approach using engineered cartilage tissue grown from cells of the patients' nasal septum. They extracted a small biopsy, isolated the cartilage cells (chondrocytes) and multiplied them. The expanded cells were seeded onto a collagen membrane and cultured for two additional weeks, generating cartilage 40 times the size of the original biopsy. The engineered grafts were then shaped according to the defect on the nostril and implanted.

New possibilities for facial reconstruction

According to Ivan Martin, Professor for Tissue Engineering at the Department of Biomedicine at the University and University Hospital of Basel, "The engineered cartilage had clinical results comparable to the current standard surgery. This new technique could help the body to accept the new tissue better and to improve the stability and functionality of the nostril. Our success is based on the long-standing, effective integration in Basel between our experimental group at the Department of Biomedicine and the surgical disciplines at the University Hospital. The method opens the way to using engineered cartilage for more challenging reconstructions in facial surgery such as the complete nose, eyelid or ear."

The same engineered grafts are currently being tested in a parallel study for articular cartilage repair in the knee. Despite the optimistic perspectives, the use of these procedures in the clinical practice is still rather distant. "We need rigorous assessment of efficacy on larger cohorts of patients and the development of business models and manufacturing paradigms that will guarantee cost-effectiveness," says Martin.