US scientists have successfully completed a study where they showed targeted nanoparticles injected directly into a patient’s bloodstream navigated into tumors, delivered double-stranded small interfering RNAs and turned off a gene that drives cancer growth.

The results reported in this study are from a Phase 1 clinical trial that began treating patients with nanoparticles in May 2008. As well as intending to establish scientific proof of concept in humans, like all Phase 1 trials, the goal is to test safety and determine toxicity levels of the therapy. The trial is being sponsored by Calando Pharmaceuticals, a Caltech startup company.

A UCLA statement describes the study as the first to prove that a targeted nanoparticle can be used as an experimental therapeutic in human cancer tumors: it demonstrates the “feasibility of using both nanoparticles and RNA interference-based therapeutics in patients”.

Another first by the team is that they showed the therapeutic can be used in a dose-dependent fashion: the more nanoparticles they injected, the more they found in the cancer cells.

In 2006, American scientists Andrew Fire and Craig Mello won the Nobel Prize for medicine for their discovery of RNA interference (RNAi), the mechanism by which double strands of RNA silence genes by targeting the messenger RNAs (MRNAs) that code proteins.

Fire and Mello first reported their discovery in a 1998 Nature study, and since then there have been high hopes that this way of silencing genes could be developed to treat diseases like cancer.

The reason RNAi could be so powerful is that it does not target a protein directly but the mechanism that codes the protein. Targeting proteins with therapeutics is tricky as often the target areas can be inacessible, perhaps tucked away inside three-dimensional folded structures. But RNAi offers the opportunity to target the mRNA that encodes the information for making the protein: destroy the mRNA and you effectively switch off the corresponding gene and the production of its particular protein.

Lead author Dr Mark E Davis, the Warren and Katharine Schlinger told the press that in principle:

“Every protein now is druggable because its inhibition is accomplished by destroying the mRNA.”

“And we can go after mRNAs in a very designed way, given all the genomic data that are and will become available,” he added.

However, as is often the case, what looks straightforward in theory is fraught with obstacles when you try and apply it in practice. One such difficulty, when trying to apply RNAi technology to humans is, how do you deliver such tiny, fragile molecules, the small interfering RNAs (siRNAs), to the tumors?

Senior author Dr Antoni Ribas,said:

“There are many cancer targets that can be efficiently blocked in the laboratory using siRNA, but blocking them in the clinic has been elusive.”

Davis and colleagues had a solution: they had already been working on ways to deliver nucleic acids into cells before RNAi was discovered. They eventually came up with a method featuring four components, one of which is a unique polymer that can assemble itself into a targeted nanoparticle that carries siRNA.

Davis explained that their nanoparticles can take the siRNAs into the targeted site within the body, and when they reach their target, the cancer cells inside the tumor, the nanoparticles enter the cells and release the siRNAs.

The researchers used a new method developed at Caltech to find and image the nanoparticles inside cells biopsied from the tumors of several patients taking part in the trial.

They also found that the more nanoparticles a patient was given, the more were present in the tumor cells: thus establishing there was a dose-dependent response.

But what was even better, said Davis, was they found evidence the siRNAs had done their job: in the cells they analyzed, which had been targeted to prevent production of the cell-growth protein ribonucleotide reductase, they found the corresponding mRNA had been degraded. Thus effectively the siRNAs had silenced the gene that was fuelling cancer growth.

Davis explained that this was the first time that anyone has found an RNA fragment from patient cells showing that the RNAi mechanism had severed the mRNA at exactly the correct base:

“It proves that the RNA interference mechanism can happen using siRNA in a human,” said Davis.

Ribas said:

“This research provides the first evidence that what works in the lab could help patients in the future by the specific delivery of siRNA using targeted nanoparticles.”

“We can start thinking about targeting the untargetable,” he added.

However, the researchers stressed that while these results are promising, it is still early days and there is a lot of work still to do. However, they are hoping these findings will open the door for future “game-changing” therapeutics that attack cancer and other diseases at the genetic level.

“Evidence of RNAi in humans from systemically administered siRNA via targeted nanoparticles.”

Scientists have shed light on a key control process within cells that helps ensure our bodies function efficiently.

They have defined the shape of a protein molecule at different stages as it performs a key activity within a cell – breaking down sugar to turn it into energy.

The findings – which enable scientists to create graphics of the molecular structure at various stages of the process – could prove vital in informing the quest for new medicines.

Scientists hope that this initial development will lead them to gain insights into how the cells in our bodies function appropriately in response to changing needs.

Precisely how cells are regulated is a mystery which has puzzled scientists for decades. The findings help to pinpoint how cells control their activities, for example how our heart is able to pump faster when we climb stairs, or how our digestive system breaks down a big meal.

The way proteins communicate within a cell is known as the ‘second secret of life’ – its importance in explaining the science of living things is ranked by scientists as second only to the discovery of DNA.

Scientists reached their findings by studying a protein from the parasite that causes sleeping sickness, which may aid the search for treatments for the disease.

The study, carried out in collaboration with the de Duve Institute, Brussels, is published in the Journal of Biological Chemistry and funded by the Medical Research Council, the Wellcome Trust, the Biotechnology and Biological Sciences Research Council and the European Commission.

Professor Malcolm Walkinshaw, of the University of Edinburgh’s School of Biological Sciences, who took part in the research, said: “While this study looked at a protein linked to sleeping sickness, the basic principle applies to all cells, including those in our bodies. This helps us understand how our organs work to perform everyday tasks according to the needs of our bodies, such as how our liver cells process toxins, or lung cells enable us to breathe.”

Two UK researchers who developed a mathematical model to investigate why men appear to be the weaker sex where disease is concerned suggest there may be good reasons behind the “man flu” of popular imagination: it could be the result of evolution where ability to pursue adventure and be competitive has given them greater survival advantage than building immunity to disease.

Previous studies have shown that men tend to be more exposed to infection risk than women and when they become infected their symptoms tend to be more severe and longer lasting: this has probably led to the so-called “man flu” myth.

But as Restif and Amos point out, it doesn’t make sense: why would men evolve lower immunity if they are more often exposed to infection? Surely common sense tells us that more exposure translates into more opportunity for the immune system to develop counter-measures?

So they developed a mathematical model showing why differences between male and female responses to infection may have evolved.

According to the Royal Society, this is the first such model to take an “ecological” approach to the way infectious agents or pathogens “and their hosts interact by accounting for the effect that immunity has on pathogens and vice-versa”.

The authors also point out that previous models have tended not to take into account the dynamic relationship between host and pathogens and consider this a serious omission because the level of pathogens in the environment will clearly affect the benefits of immunity.

“… a point often overlooked is that the benefits of immunity, and possibly the costs, depend not only on the host genotype but also on the presence and the phenotype of pathogens,” write the authors, who to address this issue developed an “adaptive dynamic model that includes host-pathogen population dynamics and host sexual reproduction”.

They also fed into the model various documented characteristics of males and females, including the extent of risk taking behaviour (men are more adventure seeking), and hormonal differences.

The result showed that while the more adventurous lifestyle of males means that they are more exposed to infection, it also, paradoxically, leads to them having lower immunity.

According to a report in the Telegraph, Restif told the press that:

“An increase in male susceptibility or exposure to infection favours the spread of the pathogen in the whole population and therefore tends to select for higher resistance or tolerance in both sexes if the cost of immunity is essential.”

But, and here is where the model reveals the apparent departure from common sense, “above a certain level of exposure”, said Restif, “the benefit of rapid recovery in males decreases owing to constant reinfection”.

Even men with strong immune systems that clear infection will become reinfected quickly, so the benefit of immunity is low in comparison to the cost.

“This selects for lower resistance in males, ultimately leading to the counterintuitive situation where males with higher susceptibility or exposure to infection than females evolve lower immunocompetence,” he added.

In other words, what the model appears to be saying is that in evolutionary terms, it is more important for men to maintain the ability to mate than to recover from illness, whereas in women it is the other way around.

Restif and Amos suggest that currently their model only deals with diseases that pass directly from host to host, but it could be adapted to deal with sexually transmitted diseases and “vertical transmission” from mother to offspring. This could lead to valuable insights into how viruses spread, for instance in HIV and other areas:

“We believe our framework will prove both versatile and flexible enough to be used in a range of future studies on sexual host species,” they commented.

“The evolution of sex-specific immune defences.”

The key to human individuality may lie not in our genes, but in the sequences that surround and control them, according to new research by scientists at the Stanford University School of Medicine and Yale University. The interaction of those sequences with a class of key proteins, called transcription factors, can vary significantly between two people and are likely to affect our appearance, our development and even our predisposition to certain diseases, the study found.

The discovery suggests that researchers focusing exclusively on genes to learn what makes people different from one another have been looking in the wrong place.

“We are rapidly entering a time when nearly anyone can have his or her genome sequenced,” said Michael Snyder, PhD, professor and chair of genetics at Stanford. “However, the bulk of the differences among individuals are not found in the genes themselves, but in regions we know relatively little about. Now we see that these differences profoundly impact protein binding and gene expression.”

Snyder is the senior author of two papers – one in Science Expressand one in Nature – exploring these protein-binding differences in humans, chimpanzees and yeast. Snyder, the Stanford W. Ascherman, MD, FACS, Professor in Genetics, came to Stanford in July 2009 from Yale, where much of the work was conducted.

Genes, which carry the specific instructions necessary to make proteins do the work of the cell, vary by only about 0.025 percent across all humans. Scientists have spent decades trying to understand how these tiny differences affect who we are and what we become. In contrast, non-coding regions of the genome, which account for approximately 98 percent of our DNA, vary in their sequence by about 1 to 4 percent. But until recently, scientists had little, if any, idea what these regions do and how they contribute to the “special sauce” that makes me, me, and you, you.

Now Snyder and his colleagues have found that the unique, specific changes among individuals in the sequence of DNA affect the ability of “control proteins” called transcription factors to bind to the regions that control gene expression. As a result, the subsequent expression of nearby genes can vary significantly.

“People have done a lot of work over the years to characterize differences in gene expression among individuals,” said Snyder. “We’re the first to look at differences in transcription-factor binding from person to person.” What’s more, by selectively breeding, or crossing, yeast strains, Snyder and his colleagues found that many, but not all, of these differences in binding and expression levels are heritable.

In the Science Express paper, which was published online March 18, Snyder and his colleagues compared the binding patterns of two transcription factors in 10 people and one chimpanzee. They identified more than 15,000 binding sites across the genome for the transcription factor called NF-kB and more than 19,000 sites for another factor called RNA PolII. They then looked to see if every site was bound equally strongly by the proteins, or if there were variations among individuals.

They found that about 25 percent of the PolII sites and 7.5 percent of the NF-kB sites exhibited significant binding differences among individuals – in some cases greater than two orders of magnitude from one person to another. (For comparison, the binding differences between the humans and the chimpanzee were about 32 percent.) Many of these binding differences could be traced to differences in sequences or structure in the protein binding sites, and several were directly correlated to changes in gene expression levels.

“These binding regions, or chunks, vary among individuals,” said Snyder, “and they have a profound impact on gene expression.” In particular, the researchers found that several of the variable binding regions were near genes involved in such diseases as type-1 diabetes, lupus, leukemia and schizophrenia.

The researchers confirmed and extended their findings in the Nature paper, which was published online March 17. In this study, they used yeast to determine that many of the binding differences and variations in gene expression levels in individuals are passed from parent to progeny, and they identify several control proteins that vary – a study that would have been impossible to perform in humans.

“We conducted the two studies in parallel,” said Snyder, “and found the same thing. Many of the binding sites differed. When we mapped the areas of difference, we found that they were associated with key regulators of variation in the population. Together these two studies tell us a lot about the so-called regulatory code that controls variation among individuals.”

Mosquitoes transmit infectious diseases to millions of people every year, including malaria for which there is no effective vaccine. New research published in Insect Molecular Biology reveals that mosquito genetic engineering may turn the transmitter into a natural ‘flying vaccinator’, providing a new strategy for biological control over the disease.

The research, led by Associate Professor Shigeto Yoshida from the Jichi Medical University in Japan, targets the saliva gland of the Anopheles stephensi mosquitoes, the main vectors of human malaria.

“Blood-sucking arthropods including mosquitoes, sand flies and ticks transmit numerous infectious agents during blood feeding,” said Yoshida. “This includes malaria, which kills between 1-2 million people, mostly African children, a year. The lack of an effective vaccine means control of the carrier has become a crucial objective to combating the disease.”

For the past decade it has been theorized that genetic engineering of the mosquito could create a ‘flying vaccinator,’ raising hopes for their use as a new strategy for malaria control. However so far research has been limited to a study of the insect’s gut and the ‘flying vaccinator’ theory was not developed.

“Following bites, protective immune responses are induced, just like a conventional vaccination but with no pain and no cost,” said Yoshida. “What’s more continuous exposure to bites will maintain high levels of protective immunity, through natural boosting, for a life time. So the insect shifts from being a pest to being beneficial.”

In this study Dr. Yoshida’s team successfully generated a transgenic mosquito expressing the Leishmania vaccine within its saliva. Bites from the insect succeeded in raising antibodies, indicating successful immunization with the Leishmania vaccine through blood feeding.

While ‘flying vaccinator’ theory may now be scientifically possible the question of ethics hangs over the application of the research. A natural and uncontrolled method of delivering vaccines, without dealing with dosage and consent, alongside public acceptance to the release of ‘vaccinating’ mosquitoes, provide barriers to this method of disease control.

“For the past decade it has been postulated that the salivary gland could be the way to gain biological control over this important infectious disease,” concluded Yoshida. “In this study we have shown, for the first time, the achievement of the original concept of the ‘flying vaccinator.”

For the first time, scientists have succeeded in growing empty particles derived from a plant virus and have made them carry useful chemicals.

The external surface of these nano containers could be decorated with molecules that guide them to where they are needed in the body, before the chemical load is discharged to exert its effect on diseased cells. The containers are particles of the Cowpea mosaic virus, which is ideally suited for designing biomaterial at the nanoscale.

“This is a shot in the arm for all Cowpea mosaic virus technology,” says Professor George Lomonosoff of the John Innes Centre, one of the authors on a paper to be published in Small.

Scientists have previously tried to empty virus particles of their genetic material using irradiation or chemical treatment. Though successful in rendering the particles non-infectious, these methods have not fully emptied the particles.

Scientists at the John Innes Centre discovered they could assemble empty particles from precursors in plants and then extract them to insert chemicals of interest. Scientists at JIC and elsewhere had also previously managed to decorate the surface of virus particles with useful molecules.

“But now we can load them too, creating fancy chemical containers,” says lead author Dr Dave Evans.

“This brings a huge change to the whole technology and opens up new areas of research,” says Prof Lomonossoff. “We don’t really know all the potential applications yet because such particles have not been available before. There is no history of them.”

One application could be in cancer treatment. Integrins are molecules that appear on cancer cells. The virus particles could be coated externally with peptides that bind to integrins. This would mean the particles seek out cancer cells to the exclusion of healthy cells. Once bound to the cancer cell, the virus particle would release an anti-cancer agent that has been carried as an internal cargo.

Some current drugs damage healthy cells as well as the cancer, leading to hair loss and other side effects. This technology could deliver the drug in a more targeted way.

“The potential for developing Cowpea mosaic virus as a targeted delivery agent of therapeutics is now a reality,” says Dr Evans.

Another weapon in the arsenal against cancer: Nanoparticles that identify, target and kill specific cancer cells while leaving healthy cells alone.

Led by Carl Batt, the Liberty Hyde Bailey Professor of Food Science, the researchers synthesized nanoparticles shaped something like a dumbbell made of gold sandwiched between two pieces of iron oxide. They then attached antibodies, which target a molecule found only in colorectal cancer cells, to the particles. Once bound, the nanoparticles are engulfed by the cancer cells.

To kill the cells, the researchers use a near-infrared laser, which is a wavelength that doesn’t harm normal tissue at the levels used, but the radiation is absorbed by the gold in the nanoparticles. This causes the cancer cells to heat up and die.

“This is a so-called ‘smart’ therapy,” Batt said. “To be a smart therapy, it should be targeted, and it should have some ability to be activated only when it’s there and then kills just the cancer cells.”

The goal, said lead author and biomedical graduate student Dickson Kirui, is to improve the technology and make it suitable for testing in a human clinical trial. The researchers are now working on a similar experiment targeting prostate cancer cells.

“If, down the line, you could clinically just target the cancer cells, you could then spare the health surrounding cells from being harmed that is the critical thing,” Kirui said.

Gold has potential as a material key to fighting cancer in future smart therapies. It is biocompatible, inert and relatively easy to tweak chemically. By changing the size and shape of the gold particle, Kirui and colleagues can tune them to respond to different wavelengths of energy.

Once taken up by the researchers’ gold particles, the cancer cells are destroyed by heat just a few degrees above normal body temperature while the surrounding tissue is left unharmed. Such a low-power laser does not have any effect on surrounding cells because that particular wavelength does not heat up cells if they are not loaded up with nanoparticles, the researchers explained.

Using iron oxide which is basically rust as the other parts of the particles might one day allow scientists to also track the progress of cancer treatments using magnetic resonance imaging, Kirui said, by taking advantage of the particles’ magnetic properties.

A new method of growing arteries could lead to a “biological bypass” – or a non-invasive way to treat coronary artery disease, Yale School of Medicine researchers report with their colleagues in the April issue of Journal of Clinical Investigation.

Coronary arteries can become blocked with plaque, leading to a decrease in the supply of blood and oxygen to the heart. Over time this blockage can lead to debilitating chest pain or heart attack. Severe blockages in multiple major vessels may require coronary artery bypass graft surgery, a major invasive surgery.

“Successfully growing new arteries could provide a biological option for patients facing bypass surgery,” said lead author of the study Michael Simons, M.D., chief of the Section of Cardiology at Yale School of Medicine.

In the past, researchers used growth factors – proteins that stimulate the growth of cells – to grow new arteries, but this method was unsuccessful. Simons and his team studied mice and zebrafish to see if they could simulate arterial formation by switching on and off two signaling pathways – ERK1/2 and P13K.

“We found that there is a cross-talk between the two signaling pathways. One half of the signaling pathway inhibits the other. When we inhibit this mechanism, we are able to grow arteries,” said Simons. “Instead of using growth factors, we stopped the inhibitor mechanism by using a drug that targets a particular enzyme called P13-kinase inhibitor.”

“Because we’ve located this inhibitory pathway, it opens the possibility of developing a new class of medication to grow new arteries,” Simons added. “The next step is to test this finding in a human clinical trial.”

The thousands of bacteria, fungi and other microbes that live in our gut are essential contributors to our good health. They break down toxins, manufacture some vitamins and essential amino acids, and form a barrier against invaders. A study published in Nature shows that, at 3.3 million, microbial genes in our gut outnumber previous estimates for the whole of the human body. Scientists at the European Molecular Biology Laboratory (EMBL) in Heidelberg, Germany, working within the European project MetaHIT and in collaboration with colleagues at the Beijing Genomics Institute at Shenzhen, China, established a reference gene set for the human gut microbiome a catalogue of the microbe genes present in the human gut. Their work proves that high-throughput techniques can be used to sequence environmental samples, and brings us closer to an understanding of how to maintain the microbial balance that keeps us healthy.

“Knowing which combination of genes is necessary for the right balance of microbes to thrive within our gut may allow us to use stool samples, which are non-invasive, as a measure of health,” says Peer Bork, whose group at EMBL took part in the analysis. “One day, we may even be able to treat certain health problems simply by eating a yoghurt with the right bacteria in it.”

This catalogue of the microbial genes harboured by the human gut will also be useful as a reference for future studies aiming to investigate the connections between bacterial genetic make-up and particular diseases or aspects of people’s lifestyles, such as diet.

To gain a comprehensive picture of the microbial genes present in the human gut, Bork and colleagues turned to the emerging field of metagenomics, in which researchers take samples from the environment they wish to study and sequence all the genetic material contained therein. They were the first to employ a high-throughput method called Illumina sequencing to metagenomics, dispelling previous doubts over the feasibility of using this method for such studies.

From a bacterium’s point of view, the human gut is not the best place to set up home, with low pH and little oxygen or light. Thus, bacteria have had to evolve means of surviving in this challenging environment, which this study now begins to unveil. The scientists identified the genes that each individual bacterium needs to survive in the human gut, as well as those that have to be present for the community to thrive, but not necessarily in all individuals, since if one species produces a necessary compound, others may not have to. This could explain another of the scientists’ findings, namely that the gut microbiomes of individual humans are more similar than previously thought: there appears to be a common set of genes which are present in different humans, probably because they ensure that crucial functions are carried out. In the future, the scientists would like to investigate whether the same or different species of bacteria contribute those genes in different humans.

In newborn mice, at least, mother’s milk appears to have some rather immediate and potentially far-reaching metabolic consequences. The milk intake kick-starts the liver to produce a molecule that then turns on heat-generating brown fat.

“A key phenomenon required after birth is to adapt the body to a lower environmental temperature with respect to that experienced when the fetus is inside the mother’s womb,” said Francesc Villarroya of the University of Barcelona. “We find that a key inducer of heat production in neonates is FGF21, released by the liver in response to the initiation of suckling.”

FGF21 (short for fibroblast growth factor 21) has recently emerged as a novel regulator of metabolism, Villarroya explained. Scientists knew that FGF21 is produced primarily in the liver, where it is induced after fasting in adult rodents and humans. FGF21 can also correct metabolic disorders of obese and diabetic mice.

In the new study, the researchers wanted to know whether FGF21 also has a role in metabolic shifts as newborn animals transition to life in the world. It appears that it does.

Plasma FGF21 levels and FGF21 gene expression in the liver rise dramatically after birth in mice, the researchers report. That increase is initiated by suckling and depends on the intake of lipid-rich milk. When the researchers mimicked the FGF21 postnatal rise by injecting FGF21 into fasting neonates, they found that the treatment enhanced the expression of genes involved in heat generation, or thermogenesis, within brown fat, to increase body temperature. Brown fat cells treated with FGF21 showed increased expression of thermogenesis genes. The cells also expended more energy and burned more glucose.

Villarroya’s team thinks what happens in those first hours of life may have consequences for the individual that carry over into adulthood, noting that FGF21 is a powerful antidiabetic agent.

“There are many evidences that alterations of dietary, genetic, environmental, or other origin in the metabolic performance during the fetal and early neonatal life can make an individual prone to develop diabetes and obesity in adulthood,” he said. “The precise mechanisms by which this happens are not fully understood. We observe that a ‘natural’ event in the postnatal life is a burst in FGF21 levels in response to suckling. It will be important to know whether any disturbance in the intensity of this naturally occurring event may have negative consequences in adulthood.”

Villarroya said that there has been something of a revolution in thinking about brown fat in recent years. That’s because scientists have found active brown fat in adult humans and have reported evidence that greater activity within brown fat can lend an individual greater resistance to obesity.

He says he suspects the pathways observed in neonatal mice do play similar roles in newborn humans, and maybe in adults, too. “It remains to be demonstrated if FGF21 is also an activator of brown fat in adult humans, but this would be of utmost importance for studies on complex metabolic diseases in adult humans,” he says.