Stem Cell Teeth Grow at a Science Soiree

From growing teeth to creating push-button technology for dogs, this year's U.K. Royal Society Summer Science jamboree had it all, following a tradition that dates back more than two centuries.

Each year, a select group of scientists and technologists take over the Royal Society's marbled premises near Pall Mall in London to show off their latest scientific endeavors to thousands of visitors. In the Society, the oldest academy on the planet, the public can mingle with scientists from a couple of dozen research groups and also get hands-on access to some of the innovative gadgets that usually stay locked away in the lab.

This year, visitors could enjoy a mind-controlled video game; find out about a hitherto unrecognized hearing organ of the Amazonian bush cricket; discuss what happens after a breakdown in the complex relationship between our immune system and the 100 trillion microbes living in our guts; and witness the uplifting effects of ultrasonic levitation in which, thanks to the power of sound, small objects can defy gravity.

They could chat with Paul Sharpe, the Dickinson Professor of Craniofacial Biology at King's College London Dental Institute, who has spent the past decade attempting to grow human teeth from stem cells—which have the potential to put an end to dentures and expensive implants that have to be screwed directly into the jaw.

Sharks and snakes have the ability to constantly grow teeth in a conveyor belt-like fashion to replace those that are broken or drop out. Humans don't. Our new teeth originate in the dental lamina—a tissue packed with stem cells—and those precious cells die off as our adult teeth come through.

Sharpe has found that two types of cell are required to grow a tooth: epithelial cells and mesenchymal stem cells. Working with Ana Angelova Volponi, he has already shown that epithelial cells collected from adult patients' gum tissues during routine dental surgery can respond to instructions from embryonic mesenchymal cells to grow new teeth.

But, of course, embryonic stem cells are hard to come by, and expensive, making this type of procedure impractical for use by dentists. And the chemical instructions of the stem cells are too nuanced and finely tuned to easily reproduce. So the team is now searching for a source of adult mesenchymal cells that will trigger the same responses, such as those in bone marrow or in tooth pulp.

Like so much of medical science, this advance will be tested on rodents first. Bioengineered teeth are already growing in the mouths of mice and, explains Sharpe, "we have to get what we can do in mice to a point where we can realistically start to work with appropriate human cells." He estimates that will take at least five years.

One of the more surprising exhibits provides a dog's eye view of the world to help them to help us, whether they are medical alert dogs or guide dogs. Clara Mancini and colleagues at the Open University near Milton Keynes, England, provided visitors with commercially-available goggles that serve to imitate canine red-green colorblindness, and boxing gloves to imitate dog paws. The point was to give their visitors a feel for how difficult it is for dogs to perform humdrum tasks such as spotting buttons for automatic doors and fire alarms that are colored red and green, and opening and closing doors, where handles are designed for humans with opposable thumbs. Dogs also find it harder to tell between different shapes, whereas they recognize different sizes more intuitively.

Working with the charity Dogs for the Disabled, Mancini and her colleagues at the university's Animal-Computer Interaction Lab have developed prototype buttons colored blue and yellow, which dogs can see more clearly, and which range in size rather than in shape, to operate doors, lights or household appliances. This has the potential to dramatically reduce the time it takes to train a service dog.

In a separate study, Mancini and team worked with the Medical Detection Dogs charity to investigate whether dogs could help detect prostate cancer in urine as an alternative to current diagnostic tests. Under the urine sample lies a metal pressure pad that the dog presses when it smells the cancer. "We expect the domestic controls/interfaces we are developing to be at the product stage in a year or two," she says, "and the cancer detection interface to be at that same stage in two to three years."

Nearby, an unusual camera to hone an equally unusual form of cancer radiotherapy was displayed by Nigel Allinson from the University of Lincoln, working with an international consortium of universities.

Half of all cancer patients are treated with radiotherapy, in which high-energy radiation permanently damages the DNA of cancer cells, causing them to die. Meanwhile, nearby healthy tissues are usually able to repair the damage and continue growing normally, but there are effects, from fatigue to skin problems to hair loss, while in young patients there is also the risk of developing other forms cancer later in life.

Most current radiotherapy uses beams of X-rays but Allinson's team is attempting to bombard tumors with protons—positively charged particles of the kind that circulate in the Large Hadron Collider (LHC) in Geneva—as an alternative. Proton-beam therapy has the ability to deliver high doses of radiation directly to a tumor, with very little radiation being absorbed into healthy tissue. Unlike X-rays, which become weaker the deeper they penetrate, protons are like depth charges which deposit their energy at a precise spot, explains Allinson.

To study in detail how protons deposit their energy into a tumour, his team is developing a specialised £1.6 million ($2.75 million) camera, based on the same kind of technology used in the LHC to track the protons (and containing enough silicon to make 22,000 smartphone cameras) and how they deposit their energy. The hope is that they can refine proton radiotherapy so it is shorter and more effective within the next five years.

In another area of the exhibition, Graham Hutchings and his team from Cardiff University in Wales showed off the novel uses they've found for gold. The noble metal is traditionally regarded as being chemically boring due to its poor ability to react with other substances, which of course is also the reason humans have coveted the metal down the millennia: its luster does not tarnish. Now the Cardiff team has found that, when it is broken down into nanoparticles of a few hundred atoms, gold can be used as a catalyst in a range of industries.

It turns out the precious metal is also the best catalyst for the formation of vinyl chloride, the main ingredient for the production of PVC, and has the potential to replace an environmentally harmful mercury catalyst. The Cardiff Catalysis Institute is also exploring the possibility of using gold in a "cold start" catalyst in car exhausts to reduce carbon emissions because, unlike current catalysts, they do not rely on the heat of the exhaust to become active.

Another chemist, Ken Seddon of the Queen's University of Belfast, Northern Ireland, showcased a remarkable way to scrub toxic mercury from natural gas using a new class of fluids called "ionic liquids." These are essentially salts that remain liquid at room temperature. Mercury contamination of gas reserves is a global problem and ranges from 0.02 micrograms per cubic meter in the Gulf of Mexico to more than 100 in Europe, South America, the Gulf of Thailand, Malaysia and Indonesia. In extreme cases, such as in North Germany, levels can reach 5,000 micrograms per cubic meter.

Even one part per million of mercury contamination has significant cumulative effects if a plant processes 2,000 tons every day. In addition to its well-known health and environmental effects, mercury also damages industrial facilities through corrosion, such as embrittlement of aluminium heat exchangers, and it poisons catalysts. The chemical companies Petronas and Clariant both recently signed licensing agreements for the team's mercury-removal technology.

Seddon's team, the biggest of its kind on the planet, has also developed a suite of ionic liquids capable of capturing carbon dioxide from power-station flue gases as well as deep-sea oil wells. Seddon stresses the potential of these designer solvents is huge: "While there are 300 conventional molecular solvents used in industry, there are over a trillion available ionic liquids."

This is all a far cry from the day that the Royal Society's presidents had "at-home" exhibitions in the late 18th century, then held politely-named conversaziones and soirées where 19th century scientists carried out demonstrations alongside William Morris tiles, paintings by Lord Leighton and models of celebrated diamonds.

The popular appeal of the annual summer science fest has also grown hugely in the century since Rudyard Kipling wrote in the novel Kim that "nine out of ten would flee from a Royal Society soirée in extremity of boredom."

Even then, however, there was the tenth who "yearned for the crowded rooms in easy London where silver-haired, bald-headed gentlemen...move among spectroscopic experiments, the lesser plants of the frozen tundras, electric flight-measuring machines, and apparatus for slicing into fractional millimetres the left eye of the female mosquito."