REPROGRAMMED CELLS GROW IN TO NEW BLOOD VESSELS

By transforming human scar cells into blood vessel cells, scientists at Houston Methodist may have discovered a new way to repair damaged tissue. The method, described in an upcoming issue of Circulation, appeared to improve blood flow, oxygenation, and nutrition to areas in need

Cardiovascular scientists at Houston Methodist, with colleagues at Stanford University and Cincinnati Children's Hospital, learned that fibroblasts -- cells that causes scarring and are plentiful throughout the human body -- can be coaxed into becoming endothelium, an entirely different type of adult cell that forms the lining of blood vessels.

"To our knowledge, this is the first time that trans-differentiation to a therapeutic cell type has been accomplished with a small molecules and proteins," said Houston Methodist Research Institute Department of Cardiovascular Sciences Chair John Cooke, M.D., Ph.D., the study's principal investigator. "In this particular case, we've found a way to turn fibroblasts into 'shapeshifters' nearly on command."

Cooke said the regenerative medicine approach provides proof-of-concept for a small molecule therapy that could one day be used to improve the healing of cardiovascular damage or other injuries.

Other research groups have managed to generate endothelial cells cells using infectious virus particles specially engineered to deliver gene-manipulating DNA to cells. The DNA encodes proteins called transcription factors to alter gene expression patterns in such a way that cells behave more like endothelial cells.

"There are problems with using viruses to transfer genes into cells," Cooke said. "This gene therapy approach is more complicated, and using viral vectors means the possibility of causing damage to the patient's chromosomes. We believe a small-molecule approach to transforming the cells will be far more feasible and safer for clinical therapies."

The new method described by Cooke and his coauthors starts with exposing fibroblasts to poly I:C (polyinosinic:polycytidylic acid), a small segment of double-stranded RNA that binds to the host cell receptor TLR3 (toll-like receptor 3), tricking the cells into reacting as if attacked by a virus. Cooke and coauthors reported to Cell in 2012 that fibroblasts' response to a viral attack -- or, in this case, a fake viral attack -- appears to be a vital step in diverting fibroblasts toward a new cell fate. After treatment with poly I:C, the researchers observed a reorganization of nuclear chromatin, allowing previously blocked-off genes to be expressed. The fibroblasts were then treated with factors, such as VEGF, that are known to compel less differentiated cells into becoming endothelial cells.

Cooke and his colleagues reported to Circulation that about 2 percent of the fibroblasts were transformed from fibroblasts into endothelial cells, a rate comparable to what other research groups have accomplished using viruses and gene therapy. But Cooke said preliminary, as-yet-unpublished work by his group suggests they may be able to achieve transformation rates as high as 15 percent.

"That's about where we think the yield of transformed cells needs to be," Cooke said. "You don't want all of the fibroblasts to be transformed -- fibroblasts perform a number of important functions, including making proteins that hold tissue together. Our approach will transform some of the scar cells into blood vessel cells that will provide blood flow to heal the injury."

In a second part of the study, the scientists introduced the transformed human cells into immune-deficient mice that had poor blood flow to their hind limbs. The human blood vessel cells increased the number of vessels in the mouse limb, improving circulation.

"The cells spontaneously form new blood vessels -- they self assemble," Cooke said. "Our transformed cells appear to form capillaries in vivo that join with the existing vessels in the animal, as we saw mouse red blood cells inside the vessels composed of human cells."

Cooke, who is also the director of the Houston Methodist Center for Cardiovascular Regeneration, said that figuring out how to manipulate adult cells of one type into becoming a completely different type of cell will be an important part of the development of regenerative medicine as a scientific and clinical field. Humans are generally unable to regenerate heavily damaged tissue, whereas other animals, such as some newts and flat worms, can regenerate entire lost limbs -- even entire heads.

"It is likely that modifications of this small molecule approach may be used to generate other body cells of therapeutic interest," Cooke said. "What we are seeing is evidence of the fluidity of cell fate with the proper stimulation. If we can understand the underlying pathways and how to manipulate them, we may very well learn how reawaken primordial mechanisms for regeneration that are active in lower vertebrates such as newts."

Cooke said more animal model studies are needed before his group begins clinical trials.

"One of the next steps will be to see if we can rescue an animal from an injury," Cooke said. "We want to know if the therapy enhances healing by increasing blood flow to tissues that may have been damaged by a loss of blood because of ischemia."

Why Nerve Cells Die Important To Neuropathy Patients

Today's post from neurosciencenews.com (see link below) provides further information on the subject of an earlier post here on the blog (Sat. 25th April - scroll down to find), concerning the death of nerve cells and how learning about this can lead to new neuropathy treatments in the future. Finding out why nerve cells and axons either die or degenerate is vital to finding out ways to stop that process from happening. This article both fills in the gaps of the earlier article and explains the science in a much easier understood way. It teaches neuropathy patients what goes on in our nervous system and why that can cause such extreme symptoms but more importantly, gives us hope that serious research is being done to improve the situation. Worth a read.

Major Pathway Identified in Nerve Cell Death Offers Hope for Therapies
Neuroscience News April 23, 2015

New research highlights how nerves – whether harmed by disease or traumatic injury – start to die, a discovery that unveils novel targets for developing drugs to slow or halt peripheral neuropathies and devastating neurodegenerative disorders such as Alzheimer’s disease, Parkinson’s disease and amyotrophic lateral sclerosis (ALS).

Peripheral neuropathy damages nerves in the body’s extremities and can cause unrelenting pain, stinging, burning, itching and sensitivity to touch. The condition is commonly associated with diabetes or develops as a side effect of chemotherapy.

The research, by scientists at Washington University School of Medicine in St. Louis, is reported online April 23 in the journal Science.

Nerve cells talk to each other by transmitting signals along communication cables called axons. Such signals underlie vital activities, such as thinking and memory, movement and language.

As part of the study, the researchers showed they could prevent axons from dying, a finding that suggests therapies could be developed to counteract the withering away of nerve axons.

“We have uncovered new details that let us piece together a major pathway involved in axon degeneration,” said senior author Jeffrey Milbrandt, MD, PhD, the James S. McDonnell Professor and head of the Department of Genetics. “This is an important step forward and helps to identify new therapeutic targets. That we were able to block axon degeneration in the lab also gives us hope that drugs could be developed to treat patients suffering from a variety of neurological conditions.”

A common thread among many neurological disorders and traumatic nerve injuries is the degeneration of axons, which interrupts nerve signaling and prevents nerves from communicating with one another. Axon degeneration is thought to be an initiating event in many of these disorders. In fact, an unhealthy axon is known to trigger its own death, and researchers are keenly interested in understanding how this happens.

Working in cell cultures, fruit flies and mice, Milbrandt and co-author Aaron DiAntonio, MD, PhD, the Alan A. and Edith L. Wolff Professor of Developmental Biology, and their colleagues showed that a protein already known to be involved in axon degeneration, acts like a switch to trigger axon degeneration after an injury.


Axon degeneration (top), caused by nerve injury or disease, depletes the energy supply within axons, shutting down communication between nerve cells. Washington University scientists blocked axon degeneration by supplementing neurons with a chemical called nicotinamide riboside, which kept the axons energized and healthy (bottom). The image is for illustrative purposes only. Image credit: Milbrandt lab.

Moreover, they found that this protein, once unleashed, causes a rapid decline in the energy supply within axons. Within minutes after the protein – called SARM1 – is activated in neurons, a massive loss of nicotinamide adenine dinucleotide (NAD), a chemical central to a cell’s energy production, occurs within the axon.

“When a nerve is diseased or injured, SARM1 becomes more active, initiating a series of events that quickly causes an energetic catastrophe within the axon, and the axon undergoes self-destruction,” said first author Josiah Gerdts, an MD/PhD student in Milbrandt’s laboratory.

Working in neurons in which SARM1 was activated, the researchers showed they could completely block axon degeneration and neuron cell death by supplementing the cells with a precursor to NAD, a chemical called nicotinamide riboside. The neurons were able to use nicotinamide riboside to keep the axons energized and healthy.

Nicotinamide riboside has been linked in animal studies to good health and longevity, but its benefits have not been shown in people. The researchers said much more research is needed to know whether the chemical could slow or halt axon degeneration in the body.

“We are encouraged by the findings and think that identifying a class of drugs that block SARM1 activity has therapeutic potential in neurological disorders,” Milbrandt said. “The molecular details this pathway provides give us a number of therapeutic avenues to attack.”
About this neurology research

Funding: The research is funded by the National Institutes of Health (NIH), grants RO1DA020812, RO1AG013730, RO1NS065053, RO1NS087632, RO1NS078007 and F31NS074517, and a grant from Vertex Pharmaceuticals.

Source: Diane Duke Williams – Washington University School of Medicine in St. Louis
Image Credit: The image is credited to Milbrandt lab
Original Research: Abstract for “SARM1 activation triggers axon degeneration locally via NAD+ destruction” by Josiah Gerdts, E.J. Brace, Yo Sasaki, Aaron DiAntonio, and Jeffrey Milbrandt in Science. Published online April 23 2015 doi:10.1126/science.1258366

Abstract

SARM1 activation triggers axon degeneration locally via NAD+ destruction

Axon degeneration is an intrinsic self-destruction program that underlies axon loss during injury and disease. Sterile alpha and TIR motif–containing 1 (SARM1) protein is an essential mediator of axon degeneration. We report that SARM1 initiates a local destruction program involving rapid breakdown of nicotinamide adenine dinucleotide (NAD+) after injury. We used an engineered protease-sensitized SARM1 to demonstrate that SARM1 activity is required after axon injury to induce axon degeneration. Dimerization of the Toll–interleukin receptor (TIR) domain of SARM1 alone was sufficient to induce locally mediated axon degeneration. Formation of the SARM1 TIR dimer triggered rapid breakdown of NAD+, whereas SARM1-induced axon destruction could be counteracted by increased NAD+ synthesis. SARM1-induced depletion of NAD+ may explain the potent axon protection in Wallerian degeneration slow (Wlds) mutant mice.

“SARM1 activation triggers axon degeneration locally via NAD+ destruction” by Josiah Gerdts, E.J. Brace, Yo Sasaki, Aaron DiAntonio, and Jeffrey Milbrandt in Science. Published online April 23 2015 doi:10.1126/science.1258366

http://neurosciencenews.com/peripheral-neuropathy-sarm1-1987/

SCIENTISTS MAKE DISEASED CELLS SYNTHESIZE THEIR OWN DRUG

In  a new study that could ultimately lead to many new medicines, scientists from the Florida campus of The Scripps Research Institute (TSRI) have adapted a chemical approach to turn diseased cells into unique manufacturing sites for molecules that can treat a form of muscular dystrophy.

"We're using a cell as a reaction vessel and a disease-causing defect as a catalyst to synthesize a treatment in a diseased cell," said TSRI Professor Matthew Disney. "Because the treatment is synthesized only in diseased cells, the compounds could provide highly specific therapeutics that only act when a disease is present. This means we can potentially treat a host of conditions in a very selective and precise manner in totally unprecedented ways."

The promising research was published recently in the international chemistry journal Angewandte Chemie.

Targeting RNA Repeats

In general, small, low molecular weight compounds can pass the blood-brain barrier, while larger, higher weight compounds tend to be more potent. In the new study, however, small molecules became powerful inhibitors when they bound to targets in cells expressing an RNA defect, such as those found in myotonic dystrophy.

Myotonic dystrophy type 2, a relatively mild and uncommon form of the progressive muscle weakening disease, is caused by a type of RNA defect known as a "tetranucleotide repeat," in which a series of four nucleotides is repeated more times than normal in an individual's genetic code. In this case, a cytosine-cytosine-uracil-guanine (CCUG) repeat binds to the protein MBNL1, rendering it inactive and resulting in RNA splicing abnormalities that, in turn, results in the disease.

In the study, a pair of small molecule "modules" the scientists developed binds to adjacent parts of the defect in a living cell, bringing these groups close together. Under these conditions, the adjacent parts reach out to one another and, as Disney describes it, permanently hold hands. Once that connection is made, the small molecule binds tightly to the defect, potently reversing disease defects on a molecular level.

"When these compounds assemble in the cell, they are 1,000 times more potent than the small molecule itself and 100 times more potent than our most active lead compound," said Research Associate Suzanne Rzuczek, the first author of the study. "This is the first time this has been validated in live cells."

Click Chemistry Construction

The basic process used by Disney and his colleagues is known as "click chemistry" -- a process invented by Nobel laureate K. Barry Sharpless, a chemist at TSRI, to quickly produce substances by attaching small units or modules together in much the same way this occurs naturally.

"In my opinion, this is one unique and a nearly ideal application of the process Sharpless and his colleagues first developed," Disney said.

Given the predictability of the process and the nearly endless combinations, translating such an approach to cellular systems could be enormously productive, Disney said. RNAs make ideal targets because they are modular, just like the compounds for which they provide a molecular template.

Not only that, he added, but many similar RNAs cause a host of incurable diseases such as ALS (Lou Gehrig's Disease), Huntington's disease and more than 20 others for which there are no known cures, making this approach a potential route to develop lead therapeutics to this large class of debilitating diseases.

SALT CAN KILL CANCER CELLS

  The next weapon to effectively fight cancer could be salt as researchers have found that an influx of salt into a cell triggers its death.

The finding could lead to new anti-cancer drugs, said the researchers who created a molecule that can cause cancer cells to self-destruct by carrying sodium and chloride ions into the cells.

"This work shows how chloride transporters can work with sodium channels in cell membranes to cause an influx of salt into a cell," said study co-author professor Philip Gale from the University of Southampton in Britain.

"We found we can trigger cell death with salt," Gale added.

Cells in the human body work hard to maintain a stable concentration of ions inside their cell membranes.

Disruption of this delicate balance can trigger cells to go through apoptosis, known as programmed cell death, a mechanism the body uses to rid itself of damaged or dangerous cells.

Unfortunately, when a cell becomes cancerous, it changes the way it transports ions across its cell membrane in a way that blocks apoptosis.

The new synthetic ion transporter works by essentially surrounding the chloride ion in an organic blanket, allowing the ion to dissolve in the cell's membrane, which is composed largely of lipids, or fats.

The researchers found that the chloride transporter tends to use the sodium channels that naturally occur in the cell's membrane, bringing sodium ions along for the ride.

"We have shown that this mechanism of chloride influx into the cell by a synthetic transporter does indeed trigger apoptosis," said co-author of the study Jonathan Sessler from the University of Texas at Austin.

The study appeared in the journal Nature Chemistry.

VESICLES INFLUENCE FUNCTION OF NERVE CELLS

Tiny vesicles containing protective substances which they transmit to nerve cells apparently play an important role in the functioning of neurons. As cell biologists at Johannes Gutenberg University Mainz (JGU) have discovered, nerve cells can enlist the aid of mini-vesicles of neighboring glial cells to defend themselves against stress and other potentially detrimental factors. These vesicles, called exosomes, appear to stimulate the neurons on various levels: they influence electrical stimulus conduction, biochemical signal transfer, and gene regulation. Exosomes are thus multifunctional signal emitters that can have a significant effect in the brain.

The researchers in Mainz already observed in a previous study that oligodendrocytes release exosomes on exposure to neuronal stimuli. These exosomes are absorbed by the neurons and improve neuronal stress tolerance. Oligodendrocytes are a type of glial cell and they form an insulating myelin sheath around the axons of neurons. The exosomes transport protective proteins such as heat shock proteins, glycolytic enzymes, and enzymes that reduce oxidative stress from one cell type to another, but also transmit genetic information in the form of ribonucleic acids.

"As we have now discovered in cell cultures, exosomes seem to have a whole range of functions," explained Dr. Eva-Maria Krämer-Albers. By means of their transmission activity, the small bubbles that are the vesicles not only promote electrical activity in the nerve cells, but also influence them on the biochemical and gene regulatory level. "The extent of activities of the exosomes is impressive," added Krämer-Albers. The researchers hope that the understanding of these processes will contribute to the development of new strategies for the treatment of neuronal diseases. Their next aim is to uncover how vesicles actually function in the brains of living organisms.

SKIN CELLS CAN BE ENGINEERED IN TO PULMONARY VALVES FOR PEDIATRIC PATIENTS

Researchers have found a way to take a pediatric patient's skin cells, reprogram the skin cells to function as heart valvular cells, and then use the cells as part of a tissue-engineered pulmonary valve. A proof of concept study published in the September 2014 issue of The Annals of Thoracic Surgery provides more detail on this scientific development

"Current valve replacements cannot grow with patients as they age, but the use of a patient-specific pulmonary valve would introduce a 'living' valvular construct that should grow with the patient. Our study is particularly important for pediatric patients who often require repeated operations for pulmonary valve replacements," said lead author David L. Simpson, PhD, from the University of Maryland School of Medicine in Baltimore.

Dr. Simpson, senior co-author Sunjay Kaushal, MD, PhD, and colleagues designed a process to transform skin cells from a simple biopsy into cells that become an important ingredient in a tissue-engineered pulmonary valve.

The pulmonary valve is a crescent-shaped valve that lies between the heart's right ventricle and pulmonary artery. It is responsible for moving blood from the heart into the lungs.

While the study was conducted in vitro (outside of the body), the next step will be implanting the new valves into patients to test their durability and longevity.

"We created a pulmonary valve that is unique to the individual patient and contains living cells from that patient. That valve is less likely to be destroyed by the patient's immune system, thus improving the outcome and hopefully increasing the quality of life for our patient," said Dr. Kaushal. "In the future, it may be possible to generate this pulmonary valve by using a blood sample instead of a skin biopsy."

Dr. Simpson added that he hopes the study will encourage additional research in tissue engineering and entice more people to enter the field, "Hopefully, growing interest and research in this field will translate more quickly into clinical application."

It is estimated that nearly 800 patients per year could potentially benefit from bioengineered patient-specific pulmonary valves, according to data from the STS Congenital Heart Surgery Database. The Database, which collects information from more than 95% of hospitals in the US and Canada that perform pediatric and congenital heart surgery, shows that approximately 3,200 patients underwent pulmonary valve replacement during a 4-year period from January 2010 to December 2013.

Nerve Cells in Action

Today's post is a YouTube medical animation which appears on news-medical.net (see link below). It depicts nerve cells in action but to my mind doesn't really tell you anything unless you're an expert. It's an attractive series of images to back up yesterday's post about the nervous system in general.

The nervous system is an organ system containing a network of specialized cells called neurons that coordinate the actions of an animal and transmit signals between different parts of its body. In most animals the nervous system consists of two parts, central and peripheral.

The central nervous system contains the brain and spinal cord. The peripheral nervous system consists of sensory neurons, clusters of neurons called ganglia, and nerves connecting them to each other and to the central nervous system. These regions are all interconnected by means of complex neural pathways. The enteric nervous system, a subsystem of the peripheral nervous system, has the capacity, even when severed from the rest of the nervous system through its primary connection by the vagus nerve, to function independently in controlling the gastrointestinal system.

http://www.news-medical.net/health/What-is-the-Nervous-System.aspx

TOXIN SECRETING STEM CELLS TREAT BRAIN TUMORS IN MICE

Harvard Stem Cell Institute scientists at Massachusetts General Hospital have devised a new way to use stem cells in the fight against brain cancer. A team led by neuroscientist Khalid Shah, MS, PhD, who recently demonstrated the value of stem cells loaded with cancer-killing herpes viruses, now has a way to genetically engineer stem cells so that they can produce and secrete tumor-killing toxins.

In the AlphaMed Press journal Stem Cells, Shah's team shows how the toxin-secreting stem cells can be used to eradicate cancer cells remaining in mouse brains after their main tumor has been removed. The stem cells are placed at the site encapsulated in a biodegradable gel. This method solves the delivery issue that probably led to the failure of recent clinical trials aimed at delivering purified cancer-killing toxins into patients' brains. Shah and his team are currently pursuing FDA approval to bring this and other stem cell approaches developed by them to clinical trials.

"Cancer-killing toxins have been used with great success in a variety of blood cancers, but they don't work as well in solid tumors because the cancers aren't as accessible and the toxins have a short half-life," said Shah, who directs the Molecular Neurotherapy and Imaging Lab at Massachusetts General Hospital and Harvard Medical School.

"A few years ago we recognized that stem cells could be used to continuously deliver these therapeutic toxins to tumors in the brain, but first we needed to genetically engineer stem cells that could resist being killed themselves by the toxins," he said. "Now, we have toxin-resistant stem cells that can make and release cancer-killing drugs."

Cytotoxins are deadly to all cells, but since the late 1990s, researchers have been able to tag toxins in such a way that they only enter cancer cells with specific surface molecules; making it possible to get a toxin into a cancer cell without posing a risk to normal cells. Once inside of a cell, the toxin disrupts the cell's ability to make proteins and, within days, the cell starts to die.

Shah's stem cells escape this fate because they are made with a mutation that doesn't allow the toxin to act inside the cell. The toxin-resistant stem cells also have an extra bit of genetic code that allows them to make and secrete the toxins. Any cancer cells that these toxins encounter do not have this natural defense and therefore die. Shah and his team induced toxin resistance in human neural stem cells and subsequently engineered them to produce targeted toxins.

"We tested these stem cells in a clinically relevant mouse model of brain cancer, where you resect the tumors and then implant the stem cells encapsulated in a gel into the resection cavity," Shah said. "After doing all of the molecular analysis and imaging to track the inhibition of protein synthesis within brain tumors, we do see the toxins kill the cancer cells and eventually prolonging the survival in animal models of resected brain tumors."

Shah next plans to rationally combine the toxin-secreting stem cells with a number of different therapeutic stem cells developed by his team to further enhance their positive results in mouse models of glioblastoma, the most common brain tumor in human adults. Shah predicts that he will bring these therapies into clinical trials within the next five years.