Wednesday, October 13, 2010

Self-renewing solar cells grow like plants

'Self-repairing' photovoltaics not damaged by the Sun

Self-renewing solar cells grow like plants

Scientists at MIT mimic plant processes to build solar cells that renew themselves like living beings.

Living things don't have that many advantages over machines. We're not as quick, or as precise, and we don't have as good a memory. Moreover, while they are made of tough stuff, we are mostly composed of things that go squish. One of the limited advantages we have is that when we go squish, we have built-in repair shops. When they go crunch, they're crunched.

Self-renewal has been a goal of many different technology manufacturers, but especially the makers of solar cells. For years scientists have looked resentfully at their solar cells, the components of which wear out or break, and envied plants, which have a built-in systems that take apart and renew any worn-out bits.

MIT researchers have found a way to imitate this process:

The complexes are made up of light-harvesting proteins, single-walled nanotubes and disc-shaped lipids. The proteins (which are isolated from a purple bacterium, Rhodobacter sphaeroides) contain a light reaction centre (carried by the lipids) comprising bacteriochlorophylls and other molecules. . . . The nanotubes also serve to align the lipid discs in neat rows, ensuring that the reaction centres are uniformly exposed to sunlight.

Or at least that's what they do when there isn't a surfactant present. Surfactants are chemicals which lower the surface tension of liquids. The most commonly used surfactants are in soaps and laundry detergents. By lowering the surface tension of liquids, they let water leak into and break apart grease and debris, as well as breaking up the debris itself. That's how soap cleans your hands - by using a surfactant to break things down.

The surfactant does the same in these solar cells. It breaks down the structures into pieces and stops the cell from working. When the surfactant is removed, the pieces reassemble on their own, like new. This process can be repeated without end. The result is a three hundred percent increase in efficiency and a limitless lifespan.

Researchers at the Massachusetts Institute of Technology have fabricated the first synthetic photovoltaic cell capable of repairing itself. The cell mimics the self-repair system naturally found in plants, which capture sunlight and convert it into energy during photosynthesis. The device could be 40% efficient at converting solar power into energy – a value that is two times better than the best commercial photovoltaic cells on the market today.

During photosynthesis, plants harness solar radiation and convert it into energy. Scientists have been trying to mimic this process in synthetic materials, but this has proved difficult because the Sun's rays damage and gradually destroy solar-cell components over time. Naturally occurring plants have developed a highly elaborate self-repair mechanism to overcome this problem that involves constantly breaking down and reassembling photodamaged light-harvesting proteins. The process ensures that these molecules are continually being refreshed, and so always work like "new".

Michael Strano and colleagues have now succeeded in mimicking this process for the first time by creating self-assembling complexes that convert light into electricity. The complexes can be repeatedly broken down and reassembled by simply adding a surfactant (a solution of soap molecules). The researchers found that they can indefinitely cycle between assembled and disassembled states by adding and removing the surfactant, but the complexes are only photoactive in the assembled state.

Light reaction centre

The complexes are made up of light-harvesting proteins, single-walled nanotubes and disc-shaped lipids. The proteins (which are isolated from a purple bacterium, Rhodobacter sphaeroides) contain a light reaction centre (carried by the lipids) comprising bacteriochlorophylls and other molecules. When the centre is exposed to solar radiation, it converts the sunlight into electron-hole pairs (excitons).

The excitons then shuttle across the reaction centre and subsequently separate back out again into electrons and holes. The nanotubes – which act as wires – channel the electrons, so producing a current. The nanotubes also serve to align the lipid discs in neat rows, ensuring that the reaction centres are uniformly exposed to sunlight.

"The beauty of this system is that a jumbled solution of components can spontaneously arrange itself into highly organized structures, containing thousands of molecules in a specific arrangement, by simply removing the surfactant," team member Ardemis Boghossian explained.

Apples and oranges

"Using the regeneration process, we are able to prolong the lifetime of our solar cell indefinitely, increasing our efficiencies by more than 300% over 164 hours of continuous illumination compared to a non-regenerated cell," added Boghossian. "If we were to increase the concentration of these complexes to make a completely stacked, highly packed formation, we could approach the theoretical limit of 40% – which is well beyond the efficiencies we see in commercial solar cells on the market today."

Comparing the MIT complexes to existing solar cells is like "comparing apples to oranges" though, she insists. "Most solar cells are static because they are made of solid slabs of silicon or thin films. Our solar cells are dynamic, just like plant leaves that can recycle their proteins as often as every 45 minutes on a really sunny day."

"We're basically imitating tricks that nature has discovered over millions of years – in particular 'reversibility', the ability to break apart and reassemble," added Strano.

Beetle Juice Inspired!

The onymacris unguicularis is a beetle found in the Namibian desert and has the most unique way of procuring water. Early in the morning, when the dew enriched fog is settled over the dunes, the beetle goes to the peak and positions its body in such a way that it helps in dew formation, and slurps up the water thus formed. Using this technique is the Dew Bank Bottle. It’s made is such a way that the steel body helps to assimilate the morning dew and channel it into the bottle immediately. Ideal for the nomads in the desert!

Be sure to watch the BBC clip at the end of the post, which explains this ingenious tactic.

The Dew Bank Bottle won the Bronze Prize at the Idea Design Awards 2010

Dew Bank Bottle by Kitae Pak

dew_bank2

dew_bank3

dew_bank4

You need to a flashplayer enabled browser to view this YouTube video

Five biomimetic ideas to make the world a cooler-looking place

Five biomimetic ideas to make the world a cooler-looking place

Eastgate Centre, Biomimetic Architecture, Biomimicry, Biomimetic Design, Biomimicry of Termite Mounds, Green Building With Termites, Eco Building, Sustainable Design, Harare, Zimbabwe, Africa, sustainable architecture, biomimicry, termite mound, construction, natural cooling, natural ventilation

Biomimicry’s Cool Alternative: Eastgate Centre in Zimbabwe
The Eastgate Centre in Harare, Zimbabwe, typifies the best of green architecture and ecologically sensitive adaptation. The country’s largest office and shopping complex is an architectural marvel in its use of biomimicry principles. The mid-rise building, designed by architect Mick Pearce in conjunction with engineers at Arup Associates, has no conventional air-conditioning or heating, yet stays regulated year round with dramatically less energy consumption using design methods inspired by indigenous Zimbabwean masonry and the self-cooling mounds of African termites!

Eastgate Centre, Biomimetic Architecture, Biomimicry, Biomimetic Design, Biomimicry of Termite Mounds, Green Building With Termites, Eco Building, Sustainable Design, Harare, Zimbabwe, Africa, sustainable architecture, biomimicry, termite mound, construction, natural cooling, natural ventilation

Termites in Zimbabwe build gigantic mounds inside of which they farm a fungus that is their primary food source. The fungus must be kept at exactly 87 degrees F, while the temperatures outside range from 35 degrees F at night to 104 degrees F during the day. The termites achieve this remarkable feat by constantly opening and closing a series of heating and cooling vents throughout the mound over the course of the day. With a system of carefully adjusted convection currents, air is sucked in at the lower part of the mound, down into enclosures with muddy walls, and up through a channel to the peak of the termite mound. The industrious termites constantly dig new vents and plug up old ones in order to regulate the temperature.

Eastgate Centre, Harare, Zimbabwe, Africa, sustainable architecture, biomimicry, termite mound, construction, natural cooling, natural ventilation, termitemound_cross3.jpg

The Eastgate Centre, largely made of concrete, has a ventilation system which operates in a similar way. Outside air that is drawn in is either warmed or cooled by the building mass depending on which is hotter, the building concrete or the air. It is then vented into the building’s floors and offices before exiting via chimneys at the top. The complex also consists of two buildings side by side that are separated by an open space that is covered by glass and open to the local breezes.

Termite Mound

Air is continuously drawn from this open space by fans on the first floor. It is then pushed up vertical supply sections of ducts that are located in the central spine of each of the two buildings. The fresh air replaces stale air that rises and exits through exhaust ports in the ceilings of each floor. Ultimately it enters the exhaust section of the vertical ducts before it is flushed out of the building through chimneys.

The Eastgate Centre uses less than 10% of the energy of a conventional building its size. These efficiencies translate directly to the bottom line: Eastgate’s owners have saved $3.5 million alone because of an air-conditioning system that did not have to be implemented. Outside of being eco-efficient and better for the environment, these savings also trickle down to the tenants whose rents are 20 percent lower than those of occupants in the surrounding buildings.

Eco-friendly structures don't have to look like ugly gray boxes. In fact, saving the enviromment can inspire some of the best design out there. Here are five ways biomimetics takes the elegance of nature, and makes it work for us.

1. Termite mounds as buildings


Five biomimetic ideas to make the world a cooler-looking place

Termite mounds are gigantic heaps of mud, out in the sun all day in the desert. We have a word for what they should be like: ovens. Instead, they're cooled by a complicated system of passageways and materials designed to funnel hot air out, and let cool air in.

Already, there are buildings based on this concept. During the day, they store hot air in certain areas and save it up in materials that absorb a lot of heat. At night, vents open at the top of the building and the hot air shoots out. This creates a minor vacuum that sucks in cool, dense, night air from vents at the bottom of the building.

As you can see, these buildings look good on the inside. On the outside, so far, they look like regular buildings. Some day, with luck, the designers will get over their human hang-ups and design them to look like termite mounds. That will be a fun day.

2. Windmills of whale flukes.


You know what's huge and heavy, but gets around the ocean efficiently? A whale.

Five biomimetic ideas to make the world a cooler-looking place

The folks at Whale Power noticed this, as well as the bumps on the front of whale's flukes. The tubercles reduce drag, allowing the whale to move more efficiently through the ocean. Whale Power wants to use that to make fans use less energy, and help windmills provide more energy. By cutting out the waste, they can make everything more efficient and beautiful, from wind turbines to the little fan cooling your computer.

Five biomimetic ideas to make the world a cooler-looking place


3. Giant metal seaweed and fishtails that harvest energy


Five biomimetic ideas to make the world a cooler-looking place

A new way to solve the energy crisis will liven up the scuba-diving experience. Metal structures placed on the sea floor will use the motion of the waves to harvest energy from the ocean. As they get pushed back and forward, they will drive generators. This particular model uses the shape and bouyancy of seaweed. As an added bonus, it will, like kelp, lie flat against the ocean floor when the seas get too rough, minimizing damage.

Another design by the same company, BioPower, doesn't have the advantage of laying low.

Five biomimetic ideas to make the world a cooler-looking place

It will, however, gain extra energy from the motion of any shark that chooses to attack it.

4. Batplane


ANN ARBOR, Mich.—A six-inch robotic spy plane modeled after a bat would gather data from sights, sounds and smells in urban combat zones and transmit information back to a soldier in real time.

bat robot.jpg
Engineers envision a six-inch, robotic spy plane modeled after a bat that could gather data and send it back to soldiers in real time. Credit: Eric Maslowski, research computer specialist in the University of Michigan 3D Lab.

That's the Army's concept, and it has awarded the University of Michigan College of Engineering a five-year, $10-million grant to help make it happen. The grant establishes the U-M Center for Objective Microelectronics and Biomimetic Advanced Technology, called COM-BAT for short. The grant includes an option to renew for an additional five years and $12.5 million.

U-M researchers will focus on the microelectronics. They will develop sensors, communication tools and batteries for this micro-aerial vehicle that's been dubbed "the bat." Engineers envision tiny cameras for stereo vision, an array of mini microphones that could home in on sounds from different directions, and small detectors for nuclear radiation and poisonous gases.

Low-power miniaturized radar and a very sensitive navigation system would help the bat find its way at night. Energy scavenging from solar, wind, vibration and other sources would recharge the bat's lithium battery. The aircraft would use radio to send signals back to troops.

COM-BAT also involves the University of California at Berkeley and the University of New Mexico. It is one of four centers the Army launched as a collaborative effort among industry, academia and the Army Research Laboratory to work toward this vision of a small, robotic aircraft that could sense and communicate. Each of the four centers is charged with developing a different subsystem of the bat, a self-directed sensor inspired by the real thing.

"Bats have a highly-attuned echolocation sense providing high-resolution navigation and sensing ability even in the dark, just as our sensor must be able to do," Sarabandi said.

The bat robot's body would be about six inches long. It would weigh about a quarter of a pound and use about 1 W of power.

U-M researchers intend to improve on current technologies. They'll work to develop quantum dot solar cells that double the efficiency of current cells. They expect their autonomous navigation system, which would allow the robot to direct its own movements, to be 1,000 times smaller and more energy efficient than systems being used now. They believe they can deliver a communication system that's 10 times smaller, lighter and more energy efficient than today's technologies.

bat robot2.jpg
Credit: Eric Maslowski, research computer specialist in the University of Michigan 3D Lab.

The bat would be designed to perform short-term surveillance in support of advancing soldiers. Or it could perch at a street corner or building for longer assignments and send back reports of activity as it takes place.

COM-BAT will support 12 faculty members and 18 graduate students at U-M.

This solar powered spy robot would fly over combat zones, taking pictures and getting back information. And it . . . okay. It's a solar-powered, bat-shaped spy plane. Yes, it's only six inches long, but do I really have to explain why it's cool?

5. Helios car


I know that cars are supposed to be like cheetahs and mustangs and thundercougarfalconbirds, but aren't those concepts a bit tired at this point? I know that, when I fantasize about driving along the coastline of Monaco, perhaps so I can get to my massive airship which will take me to my quaint hideway palace sunken under the waters of the Philipines, I don't want my car to look like this:

Five biomimetic ideas to make the world a cooler-looking place

I want it to look like this:

Five biomimetic ideas to make the world a cooler-looking place

Or, more specifically, like this:

The Helios Concept is a design study of a solar energy-powered off-road sporty vehicle. The body integrates a system of large photovoltaic panels that increases the energy charging capacity. It was designed by Kim Gu-Han from Universität Duisburg-Essen – Germany. The Helios is an electric off-road vehicle use powered by solar energy. To increase the surface area of the photovoltaic panels, when not in motion the upper surface of the car transform into a large “fan” with four wings to store more energy or to serve as an energy station. This transformable design was inspired by natural evolution – some animals have developed a stretchable skin to absorb more sunlight.

The Helios car uses solar energy. I think you can spot the panels. They fold down into the car, but who would ever want them to? If these things were tooling around, I think we'd finally get an end to all those road trip movies that have teenagers going across country in VW vans and 60's convertibles. At long last, we would have invented something cooler.



How to build a brain with neural networks

How to build a brain with neural networks

When training a future robot overlord, you want it to learn to make complex decisions. No one likes an android whose only call is ‘shoot it.' Neural networks allow problem solving, prioritizing, and hopefully mercy.

There's a midnight showing of the next Twilight movie in a theater on the other side of town, and you have to catch it, because although nothing matters more to you than seeing Edward and Bella get married, it's being shown as ironic so you won't lose face in front of your friends. If you ask a computer to map out the route to the theater, so you can figure out if you should bus, walk, or take a cab, it will do so accurately and quickly.

If you ask it to do that while checking the weather - reminding you of the times someone has puked on the bus, calling up stories of cab drivers who murdered people, and street crime in the neighborhoods you're going through, and calculating the probability that someone will see you in your Twilight t-shirt and not know that you're supposedly wearing it ironically - it won't be nearly as quick.

If you ask it to make a decision for you, you are going get one of those annoying whitish screens that dings whenever you try to click on something.

Artificial neural networks are built to solve these problems. They calculate and weight each risk and come up with a solution. They do so by imitating the structure of a human brain.

How to build a brain with neural networks

A neuron is basically a collection of triggers waiting to fire. When something presses its outer structures, the dendrites, they inform the cell body. If the disturbance is enough, the cell body shoots electric impulses down the axon to the synapse, the connection between nerves. This alerts other dendrites, and they set off the next neuron. The exact sequences of the each dance of dendrites is stored up as information that lets people distinguish a free balloon from a monkey with a gun, and figure out what to do in each situation.

How to build a brain with neural networks

A basic computer cell mimics that neuron. Impulses that go in, and if those impulses are strong enough in the right places, they continue onward. If X1 and X2 come in, the computer tells you to reach out your hand, because everyone loves balloons. If XN and X(N-1) are fired, the computer lets you know that you shouldn't have worn the banana-scented body lotion.

But that's just a basic simulated neuron. A more sophisticated one understands that not every impulse is important. In this case, the impulses are weighted. The shade of the balloon matters to you, since you're not fond of orange. You'll skip it. The shade of the monkey, or the gun, don't really matter to you in the least. With a weighted system, you shrink from both the balloon and the monkey.

How to build a brain with neural networks

But what if the shade of the gun does matter? This is where feedback loops come in. What if this computer brain would tell you to get away from the monkey, but when it informed some of it's ‘neurons' about it, they came back with the knowledge that the monkey's gun has an orange tip, and orange tips are on toy guns.

Feedback loops are another addition to the process, when the neural network has to take a part of the decision and send it back to the kitchen. It's not a monkey with a gun, it's a monkey with a toy. Maybe it's still time to get away, or maybe it's time to stick around and see how this plays out.

That depends on what exactly the artificial neural network is taught.

There are two kinds of networks; self-organizing networks and back-propagation networks. Self-organizing networks just take in a lot of information and its weights, and get down to business. Back-propagating networks have to be taught. They are given problems to solve, again and again. If the solutions are something that the people analyzing the data think works, the decision that each neuron made, and the weight given to that decision, is reinforced. If they don't care to converse with a monkey with a gun, even though the computer tells them it has been proven to make for a very funny story, the weight of funniness is decreased when there is a gun involved. In time, the back-propagating network is trained to make reliable and correct conclusion, often with data sets that humans aren't able to process as quickly.

They are based on the brain. They mimic the brain. They even come to have certain sets of values, like an individual human mind does.

But is this intelligence. Some people see the above description as a series of on and off switches, being pressed in certain ways to achieve certain results. They're complicated calculators, but they're still just calculators.

Other people will look at the above and see neurons made of inorganic material. They will see that they are given priorities that mimic those of their creators, that they are educated through instruction or experience, and that they come to have an expertise the way humans do. Some see this as artificial intelligence. Some see it as intelligence, however limited. If it is intelligence, what does that make us? If it's not, why? What's so special about us that the mechanics of our brain can't be duplicated?

A Drug That Could Give You Perfect Visual Memory

Imagine if you could look at something once and remember it forever. You would never have to ask for directions again. Now a group of scientists has isolated a protein that mega-boosts your ability to remember what you see.

A group of Spanish researchers reported today in Science that they may have stumbled upon a substance that could become the ultimate memory-enhancer. The group was studying a poorly-understood region of the visual cortex. They found that if they boosted production of a protein called RGS-14 (pictured) in that area of the visual cortex in mice, it dramatically affected the animals' ability to remember objects they had seen.

Mice with the RGS-14 boost could remember objects they had seen for up to two months. Ordinarily the same mice would only be able to remember these objects for about an hour.

The researchers concluded that this region of the visual cortex, known as layer six of region V2, is responsible for creating visual memories. When the region is removed, mice can no longer remember any object they see.

If this protein boosts visual memory in humans, the implications are staggering. In their paper, the researchers say that it could be used as a memory-enhancer – which seems like an understatement. What's particularly intriguing is the fact that this protein works on visual memory only. So as I mentioned earlier, it would be perfect for mapping. It would also be useful for engineers and architects who need to hold a lot of visual images in their minds at once. And it would also be a great drug for detectives and spies.

Could it also be a way to gain photographic memory? For example, if I look at a page of text will I remember the words perfectly? Or will I simply remember how the page looked?

I can't see much of a downside for this potential drug, unless the act of not forgetting what you see causes problems or trauma.

Role of Layer 6 of V2 Visual Cortex in Object-Recognition Memory

Manuel F. López-Aranda,1,2,4 Juan F. López-Téllez,1,2,4 Irene Navarro-Lobato,1 Mariam Masmudi-Martín,1 Antonia Gutiérrez,3,4 Zafar U. Khan1,2,4,*

Cellular responses in the V2 secondary visual cortex to simple as well as complex visual stimuli have been well studied. However, the role of area V2 in visual memory remains unexplored. We found that layer 6 neurons of V2 are crucial for the processing of object-recognition memory (ORM). Using the protein regulator of G protein signaling–14 (RGS-14) as a tool, we found that the expression of this protein into layer 6 neurons of rat-brain area V2 promoted the conversion of a normal short-term ORM that normally lasts for 45 minutes into long-term memory detectable even after many months. Furthermore, elimination of the same-layer neurons by means of injection of a selective cytotoxin resulted in the complete loss of normal as well as protein-mediated enhanced ORM.

Tuesday, October 12, 2010

Lung-on-a-chip leads to new insights on pulmonary diseases

Biomedical engineers used the device to show that the respiratory crackles stethoscopes pick up in patients with diseases including asthma, cystic fibrosis, pneumonia and congestive heart failure aren't just symptoms, but may actually cause lung damage.

Lung-on-a-chip

"Our lung-on-a-chip causes the cells to really become lung-like in terms of function and protein secretion. They form the tight tissue connections that they do in the human lung. That doesn't happen in a dish. This device gives you the convenience and control of a dish but in physical conditions that are more like the body," said Shuichi Takayama, associate professor of biomedical engineering and principal investigator on this study.

Takayama believes this is the first lung-on-a-chip. It's the same size as the part of the lung it simulates, the smallest airway branches.

The researchers were able to recreate the sound of respiratory crackles on the chip. And they measured and watched the destruction associated with the crackling on the surrounding cells.

The crackling is the sound of a breath of air opening airways that are clogged with thick fluid plugs. The fluid plugs form more frequently in patients with lung diseases that block the production of a fluid-thinning protein or narrow the airways. The plugs burst when air expands the lungs during breathing.

Doctors have considered the crackling sound more as a symptom or red flag, explained Dr. James Grotberg, a co-author of the study who is a professor of biomedical engineering in the College of Engineering and the Medical School.

Now, the plugs that cause the crackles appear to be a cause in addition to an effect.

"We've shown that these liquid plugs are injurious, particularly when they rupture" Grotberg said. "The rupture sends a very strong stress wave onto the cells. What's interesting is that the forces from the rupture are large in one place and small in another and those two places are close to each other. So you have a very steep gradient in forces and that's what shreds the cells."

To the surrounding cells, the bursts are like little sticks of exploding dynamite, Grotberg said.

The lung-on-a-chip that allowed the scientists to demonstrate this is made of two rubber sheets with a groove etched across their length. Their grooved sides are stuck together, with a porous sheet of polyester between them. The polyester allows the device to function as two separate chambers.

Engineers flooded both chambers with nourishing liquid while they were growing the lung cells in the device. Then, they emptied the top chamber to simulate an airway. That's when the lung cells started to develop further than they do in a dish. They formed tighter tissue bonds and secreted airway proteins as if they were part of a real lung.

Once the cells were sufficiently developed on the chip, Takayama and his colleagues did the control part of the experiment. They ran liquid through the chip channels and then air before testing to see if the lung cells were still healthy. They were.

Then they turned on the "microfabricated plug generator," which was connected to the cell culture chamber on the same chip. The plug generator is a vial of liquid into which the scientists pump air in such a way that drops of liquid enter the mock airways of the chip and eventually burst. They tested for periods of 10 minutes and found that at least 24 percent of the cells had died after persistent exposure to bursting liquid plugs. They observed more cell damage with more frequent plug bursts.

Takayama is also an associate professor of macromolecular science and engineering. The paper is called "Acoustically detectable cellular-level lung injury induced by fluid mechanical stresses in microfluidic airway systems." Co-authors include Biomedical Engineering Research Fellow Dongeun Huh, Biomedical Engineering Senior Research Fellow Hideki Fujioka, Biomedical Engineering Research Fellow Yi-Chung Tung, Post-doctoral researcher Nobuyuki Futai, and Adjunct Professor of Internal Medicine Robert Paine III.

Drugs Encapsulated in Nanoparticles

Clinical trials using patients’ own immune cells to target tumors have yielded promising results. However, this approach usually works only if the patients also receive large doses of drugs designed to help immune cells multiply rapidly, and those drugs have life-threatening side effects.
MIT engineers have developed a way to attach drug-carrying pouches (yellow) to the surfaces of cells.
Image: Darrell Irvine and Matthias Stephan

Now a team of MIT engineers has devised a way to deliver the necessary drugs by smuggling them on the backs of the cells sent in to fight the tumor. That way, the drugs reach only their intended targets, greatly reducing the risk to the patient.

The new approach could dramatically improve the success rate of immune-cell therapies, which hold promise for treating many types of cancer, says Darrell Irvine, senior author of a paper describing the technique in the Aug. 15 issue of Nature Medicine.

“What we’re looking for is the extra nudge that could take immune-cell therapy from working in a subset of people to working in nearly all patients, and to take us closer to cures of disease rather than slowing progression,” says Irvine, associate professor of biological engineering and materials science and engineering and a member of MIT’s David H. Koch Institute for Integrative Cancer Research.

The new method could also be used to deliver other types of cancer drugs or to promote blood-cell maturation in bone-marrow transplant recipients, according to the researchers.

T-cell therapy

To perform immune-cell therapy, doctors remove a type of immune cells called T cells from the patient, engineer them to target the tumor, and inject them back into the patient. Those T cells then hunt down and destroy tumor cells. Clinical trials are under way for ovarian and prostate cancers, as well as melanoma.

Immune-cell therapy is a very promising approach to treating cancer, says Glenn Dranoff, associate professor of medicine at Harvard Medical School. However, getting it to work has proved challenging. “The major limitation right now is getting enough of the T cells that are specific to the cancer cell,” says Dranoff, who was not involved in this study. “Another problem is getting T cells to function properly in the patient.”

To overcome those obstacles, researchers have tried injecting patients with adjuvant drugs that stimulate T-cell growth and proliferation. One class of drugs that has been tested in clinical trials is interleukins — naturally occurring chemicals that help promote T-cell growth but have severe side effects, including heart and lung failure, when given in large doses.

Irvine and his colleagues took a new approach: To avoid toxic side effects, they designed drug-carrying pouches made of fatty membranes that can be attached to sulfur-containing molecules normally found on the T-cell surface.

In the Nature Medicine study, the researchers injected T cells, each carrying about 100 pouches loaded with the interleukins IL-15 and IL-21, into mice with lung and bone marrow tumors. Once the cells reached the tumors, the pouches gradually degraded and released the drug over a weeklong period. The drug molecules attached themselves to receptors on the surface of the same cells that carried them, stimulating them to grow and divide.

Within 16 days, all of the tumors in the mice treated with T cells carrying the drugs disappeared. Those mice survived until the end of the 100-day experiment, while mice that received no treatment died within 25 days, and mice that received either T cells alone or T cells with injections of interleukins died within 75 days.

The study was funded by the National Institutes of Health, the National Science Foundation, the National Cancer Institute and a gift to the Koch Institute from Curtis ’63 and Kathy Marble.

‘A much simpler procedure’

Irvine’s approach to delivering the adjuvant drugs is both simple and innovative, says Dranoff. “The idea of modifying T cells in the lab to make them work better is something many people are exploring through more complicated approaches such as gene modification,” he says. “But here, the possibility of just attaching a carefully engineered nanoparticle to the surface of cells could be a much simpler procedure.”

While he is now focusing on immune-cell therapy, Irvine believes his cell pouches could be useful for other applications, including targeted delivery of chemotherapy agents. “There are lots of people studying nanoparticles for drug delivery, especially in cancer therapy, but the vast majority of nanoparticles injected intravenously go into the liver or the spleen. Less than 5 percent reach the tumor,” says Irvine, who is also a Howard Hughes Medical Institute Investigator.

With a new way to carry drugs specifically to tumors, scientists may be able to resurrect promising drugs that failed in clinical trials because they were cleared from the bloodstream before they could reach their intended targets, or had to be given in doses so high they had toxic side effects.

Irvine and his colleagues also demonstrated that they could attach their pouches to the surface of immature blood cells found in the bone marrow, which are commonly used to treat leukemia. Patients who receive bone-marrow transplants must have their own bone marrow destroyed with radiation or chemotherapy before the transplant, which leaves them vulnerable to infection for about six months while the new bone marrow produces blood cells.

Delivering drugs that accelerate blood-cell production along with the bone-marrow transplant could shorten the period of immunosuppression, making the process safer for patients, says Irvine. In the Nature Medicine paper, his team reports successfully enhancing blood-cell maturation in mice by delivering one such drug along with the cells.

Irvine is now starting to work on making sure the manufacturing process will yield nanoparticles safe to test in humans. Once that is done, he hopes the particles could be used in clinical trials in cancer patients, possibly within the next two or three years.

Shedding Light on Blindness

Stem cells are at the forefront of medical research and incite some of the most controversial ethical and religious debates worldwide. While regarded by many top scientists as the Holy Grail of medicine, others consider embryonic stem-cell research sacrilegious.

http://thefutureofthings.com/upload/items_icons/ratine-eye.jpg

Recent advances in the field of stem-cell research are giving hope to millions. Are stem cells to become the future silver bullet of medical practice? Avant-garde approaches to stem-cell therapy may be the first stepping-stones to a bright new future of stem-cell medicine and are emerging in leading laboratories worldwide. A number of large biotech companies and scientists are looking toward stem cells as the basis for a therapeutic solution to cure such illnesses as blindness, diabetes and spinal cord injuries. In the future, embryonic stem cells may be able to restore sight to millions of people


Background on stem cells

The term stem cell can be defined by two very important qualities: the cell has the ability to self-renew and, in a more general sense, the cell has not completed differentiation into its final state. This general definition includes a wide variety of cells with varying degrees of differentiation potential. At the top of the list comes the zygote—a fertilized egg, which of course has the ability to divide and differentiate into all cell types in the body and create a new organism. Such a cell is considered omnipotent or totipotent; in other words, it has the potential to become any type of cell. The first three divisions of the zygote give birth to eight totipotent cells, each of which also has the ability to become an entire organism. As the embryonic cells divide and the daughter cells differentiate, they become increasingly specific.

Cell differentiation from zygote to three germ layers  Credit: NCBI
Cell differentiation from zygote to
three germ layers (Credit: NCBI)
The early mammalian embryo consists of the extra-embryonic cell layers—the trophoblast and a body of cells called the inner cell mass (ICM), which eventually become the embryo proper. The cells of the ICM are no longer omnipotent, because they no longer share the fate of the trophoblast, and they have committed themselves to an embryonic fate with the ability to become any cell in the body (but not the trophoblast). These cells are considered pluripotent. The ICM continues to differentiate into three germ layers—ectoderm, mesoderm and endoderm, each of which follows a specific developmental destiny that takes them along an ever-specifying path at which end the daughter cells will make up the different organs of the human body. Cells from the ICM are called embryonic stem cells; however, there are also stem cells in the adult body. These adult stem cells are considered multipotent, having the ability to differentiate into different cell types, albeit with a more limited repertoire than embryonic stem cells. They are found mainly in renewing tissues, such as the skin, the inner lining of the gastrointestinal tract and blood tissues. In addition to their ability to supply cells at the turnover rate of their respective tissues, they can be stimulated to repair injured tissue caused by liver damage, skin abrasions and blood loss.

The ability of our body to regenerate some of its tissues is largely owed to the reserves of adult stem cells. However, not all tissues possess the ability to regenerate. Injuries to most parts of the nervous system, for instance, are considered nearly impossible to heal naturally, if at all.

Adult stem-cell applications

Adult stem cells can be used to accelerate bone or tendon healing, and they can induce cartilage progenitor cells to produce a better matrix and repair cartilage damage. In rodents, and even in some preliminary trials in humans, human embryonic stem cells have been shown to bridge gaps in spinal cord injuries, allowing restoration of motor functions. Adult stem cells can be used to replace damaged heart-muscle cells and are used in practice today. The most common application of adult stem cells is probably the restoration of blood cells for patients with leukemia, and there are many more applications currently in practice.

Embryonic stem cells

The rest of this article will deal with embryonic stem (ES) cells and the future they hold for modern medicine.

ES cells and spinal cord injury (SCI)

On May 27, 1995, the world was shocked when actor Christopher Reeve, best known as “Superman,” became paralyzed from the neck down after falling from a horse. The damage to his spinal cord was so severe, it left him crippled until the end of his life. Christopher Reeve and his wife, Dana, started a foundation that continues to encourage research in the field of spinal injuries, the Christopher Reeve Foundation. A particular field encouraged by the foundation is stem-cell research, with the great hope that it will result in the ability to get cells to differentiate into neurons and support cells to bridge the gap of a spinal cord injury. Stem cells from a variety of sources have been effective in improving motor function after spinal cord injury in animals, making it an extremely promising field. It has been the hope of many that embryonic stem cells will be able to differentiate into neural cells and take the place of the damaged cells. So far, there has been limited success in achieving this goal in humans. Predifferentiated ES cells injected into mice with spinal cord injuries have been able to restore some of the sensory functions and prevent chronic pain behavior. However, this field has progressed further using adult stem cells rather than ES cells.

ES cells and diabetes

Normal function of pancreas  Credit: NIH
Normal function of pancreas (Credit: NIH)
Diabetes affects hundreds of millions of people worldwide. In Western countries, it has risen to pandemic proportions. The most common type of diabetes (type I) occurs usually in children or young adults and results when beta cells in the pancreas are destroyed for some reason. Beta cells are in charge of releasing insulin into the bloodstream when glucose levels are high, such as after a meal, to instruct the cells of the body to take up glucose. When these cells are destroyed, insulin is not released and the patient must take insulin artificially.

ES cells differentiated in culture and injected into mice can cure diabetes.  Credit: NIH
ES cells differentiated in
culture and injected into mice
can cure diabetes (Credit: NIH)
In mice with diabetes, adult stem cells from the bone marrow have been shown to be able to navigate to the pancreas and effectively restore function of damaged pancreatic cells that were damaged; and in humans, a risky trial of 15 patients was undertaken, in which hematopoietic stem cells were removed, treated in the laboratory and infused into patients. Fourteen of the 15 participants were cured (remained insulin free) for periods between 1 and 35 months. However, use of adult stem cells has its limits, they are very difficult to grow in culture, and obtaining sufficient amounts could prove difficult. By contrast, ES cells can be maintained indefinitely in culture and do not provoke a strong immune response when transplanted. In mice, embryonic stem cells can be differentiated in the lab to become beta cells and cure mice with diabetes. Several laboratories claim they have succeeded in turning Human Embryonic Stem (hES) cells into insulin-producing cells, raising the hopes that in the future, hES cells may be used to cure diabetes simply by giving back to patients the cells that were destroyed.

Stem cells and retina

Eye structure  Credit: University of Utah
Eye structure
(Credit: University of Utah)
The retina of the eye is the interface between the mechanical part of vision and the brain. The ability to pick up a light signal is bestowed upon us mainly by two special types of cells in the retina—cone and rod cells, generally termed photoreceptors. These cells obtain the ability to convert a photon into a cellular message that is conveyed to the brain through an electrical impulse. The photoreceptors are supported by a single layer of important cells that lie on the outermost layer of the retina, at the back of the eye: the retinal pigmented epithelium (RPE). The RPE both nourishes the photoreceptors and recycles the proteins needed for vision.

Rats treated with hES cells are saved from blindness
Rats treated with hES cells
are saved from blindness.
Without the RPE, photoreceptors die and patients become blind. RPE dysfunction is the most common cause of blindness in people over 60 in the United States, and it affects over 30 million people worldwide. While there are many pathologies of the eye that can be rectified mechanically or surgically, dead retinal cells cannot be replaced in this manner, leaving millions of people with a supposedly incurable form of blindness. However, new hope is emerging from the field of stem-cell therapy. Dr. Robert Lanza, vice-president of research and scientific development at Advanced Cell Technology, Inc., and his coworkers have been successful in culturing stem cells in petri dishes, making them differentiate into RPE cells, isolating them, and being able to passage them in vitro to generate sufficient numbers to replace the damaged retinal cells of rodents with macular degeneration. This model consists of rats with a genetic disorder where they do not have one of the enzymes needed for the RPE cell layer to function. As a result, the rats become blind due to deterioration of their photoreceptors. Following transplantation of human ES cells, injected into the sub-retinal area of the eye, rats displayed recovery of their photoreceptors and improved visual ability compared to the control rats, which were injected with a mock treatment and showed no significant improvement.

How are stem-cell lines established?

Extraction of hES cells from discarded embryos  Credit: Stanford University
Extraction of hES cells from
discarded embryos
(Credit: Stanford University)
As mentioned above, ES cells are obtained from the ICM of the blastocyst stage (before implantation of the embryo). At this stage the embryo consists of a mere few hundred cells and cannot even be seen by the naked eye. A major source of fertilized eggs is fertilization clinics. When patients have completed their treatment, they may leave behind up to several dozen embryos that were not used for conception. These fertilized eggs can be frozen for future use, or if the couple has no intention of using them, they are either discarded or donated for research. It is from these blastocysts that ES cells can be removed, plated and grown indefinitely in culture. These ES cells have the genetic makeup of the parents, and are therefore limited in clinical use for transplantation because a patient’s immune system would most likely reject them, perceiving them as foreign objects.

Somatic Cell Nuclear Transfer procedure.  Credit: KU Medical Center, University of Kansas.
Somatic Cell Nuclear
Transfer procedure
(Credit: KU Medical Center,
University of Kansas)
Therapeutic cloning: Human embryonic stem (hES) cell lines can also be “custom made” for the patient by a revolutionary process called “somatic cell nuclear transfer” (SCNT) or “therapeutic cloning.” In this process the nucleus of an ordinary differentiated cell from the patient is transferred using microscopic tools into a human oocyte (egg) instead of the oocyte’s original nucleus. There seems to be something in the egg’s cytoplasm that can reverse the differentiated status of the patient’s nucleus, and the cell will continue to divide to generate a blastocyst with ES cells with the exact genetic makeup of the patient. ES cells can be removed from the ICM and a cell line can be generated to match the patient’s genotype. These cells will not be rejected because they are exactly the same as the patient’s. The major drawback of this method is that it is still very inefficient, and many oocytes are needed to create just one cell line. This makes SCNT an extremely costly and complicated procedure and not likely to be a major method for producing therapeutic hES cells.

There are those who would argue that there is also an ethical problem with this method. SCNT is the procedure that has been used for cloning animals such as Dolly, the sheep who was the first mammal to be cloned. The blastocyst has the potential to develop into a fully grown organism, identical to the original donor. Reproductive cloning of humans is, of course, strictly forbidden, but concerns have been raised that should it become publicly accepted, it is only a matter of time before a renegade scientist follows the SCNT through to a cloned human baby.

Parthenogenesis  Credit: Imago Dei
Parthenogenesis illustration
(Credit: Imago Dei)
Parthenogenesis: This is the Greek term for reproduction from an unfertilized (usually female) gamete (egg), meaning the embryo produced is uniparental. This is a form of reproduction in some plants and lower invertebrates. In our context, it means the development of a blastocyst without the use of a sperm cell. An oocyte is derived before the second meiosis, meaning that it contains two nuclei that are almost genetically identical. In a normal zygote, half of the genes are from the oocyte (the mother) and the other half come from the sperm cell (the father). Each parent contributes their genetic makeup, doubling the complexity of the genes. In a parthenogenetic pseudo-zygote, which is made up only of the maternal genes, the complexity of the genes is only half. For most genes, this is unimportant, but for the genes that make up the proteins that contribute to tissue compatibility (the HLA complex) it makes an enormous difference. It’s a bit like a combination lock: with six numeric options you have nearly one million possible combinations, but with half the complexity—three numeric options—you have only 999 combinations. So ES cells derived from parthenogenetic blastocysts could be more readily introduced into patients without the trouble of immune rejection.

Blastomere removal

Removal of a single cell from an eight-cell embryo  Credit: Connecticut Fertility Associates
Removal of a single cell
from an eight-cell embryo
(Credit: Connecticut
Fertility Associates)
Dr. Lanza and his team have developed a method to produce ES cells from just one cell of the early embryo. Up to the eight-cell stage of the mammalian embryo, a cell can be removed without disturbing the normal development of the embryo. Blastomere (the omnipotent cell of the very early embryo) removal from the eight-cell stage is commonly used in fertility clinics for checking the embryos for potential genetic problems. The procedure is called preimplantation genetic diagnosis (PGD). A single cell is removed at the eight-cell stage, grown in culture and inspected for genetic makeup. In parents with potentially serious genetic diseases, only healthy embryos would be selected for implantation. Dr. Lanza and his team have shown that ES cells can be derived from this single cell. The great advantage of this method is that it circumvents any ethical issues regarding the destruction of a potential human life, because the embryo continues to develop normally. The ES cells can be kept frozen as a stock of “spare parts” for the person from whom they were derived or they can be used in hES cell research.

Ethical issues

The controversy over ES cells is, in essence, a religious and ethical debate. The definition of what is considered a human being differs between culture and religions. The most conservative view is the Christian Catholic belief that an embryo is considered a human being from the moment of fertilization of the egg, therefore destruction of a fertilized egg is essentially murder. Protestants have a more pluralistic view—and there are many others, such as that embryos gain personhood gradually, and therefore early embryos may not be considered human. Should the more conservative view be adopted, research of hES cells would essentially constitute the termination of potential human lives. According to Judaism, pregnancy is divided into six stages, during each of which the fetus’s rights as a human being change, and it is only considered a full human being when it is born. This does not mean that the embryo does not have rights. According to Jewish law, embryonic cells outside of the uterus are not considered to have any legal rights because they are not part of a human being. The embryo gains status as a fetus only after the first 40 days. Blastocysts are considered the same as sperm or eggs, but they cannot be “wasted” unless it is for the sake of saving human lives. Islamic law permits the use of early embryos for medical purposes as long as it is before the embryo “gets its soul,” which is around day 40 of pregnancy.

More information on hES ethical and religious issues can be found here.

Policies regarding hES cell research are largely related to the religious views of the people of that country, and there is no international policy regarding stem-cell research ethics. State policies divide into four main groups:

  1. Countries that completely ban any type of ES cell research: Austria, Brazil, Ireland, Norway and Poland, among others.
  1. Countries that allow research from old ES cell lines but do not permit the establishment of new cell lines (using public funding): Germany and the United States.
  1. Countries that allow ES cell research for medical purposes and the establishment of cell lines only from embryos that were conceived during fertility treatments and are no longer needed: Australia, Canada, Finland, Israel, Japan, Singapore and Sweden.
  1. Countries that allow research on ES cells that were derived from fertility clinics or for research purposes, meaning that ES cells can be created from blastocysts that were created specifically for research purposes: United Kingdom and United States (using private funding).

This is not just semantics. The Bush administration is blocking Federal funding for researchers who deal with stem cells, impeding stem-cell research from proceeding at the expected pace. President Bush has systematically vetoed bills that would fund stem-cell research. Currently the only hES cell lines that can be used with Federal funding are those that were established before August 9, 2001. Researchers say that these lines are of poor quality and have limited practical potential. The presidential veto has caused much aggravation and frustration in the scientific community and has borne the brunt of many criticizing editorials.

There is also the problem of intellectual property and legal rights over stem-cell lines. Producing and cultivating lines of hES cells is a complicated and expensive procedure. Some people argue that because stem-cell research in the U.S. is currently funded from mainly private money, ownership of the cell lines and any future benefits stemming from them should remain legal. Protocols for stem-cell cultivation are being developed and are being patented. The critics argue that stem-cell research should be available to the benefit of all, that success in cultivating a cell line could have been achieved anywhere with adequate funding. Researchers are claiming that protocols for cultivating hES cells are obvious, as they are the outcome of using already-known technology, and therefore unpatentable.

Where we stand

Dr. Robert Lanza
Dr. Robert Lanza
Embryonic stem cells constitute an exciting new emerging field of research, with enormous possibilities. The inherent ability of ES cells to differentiate into any type of cell in the body endows them with the potential to cure nearly any disease that is caused by the destruction of cells, including blindness; diabetes; Alzheimer’s; Huntington’s; leukemia; spinal cord injuries; heart, kidney or liver failures; and many more. Until we grasp how to grow and manipulate hES cells to mimic the intricate developmental pathways of an embryo to become the cell type needed, and to be able to safely use those cells clinically, there will be many hurdles to pass. However, these first bits of progress show there is a bright, promising future ahead. Never before has it been more appropriate to mention the cliché, “Even a journey of a thousand miles begins with a small step.”

Interview with Dr. Robert Lanza

To acquire more insight into the potential of hES cell technology, TFOT recently interviewed Dr. Robert Lanza, vice-president of research and scientific development at Advanced Cell Technology.


Q: Of the many possible applications of human stem-cell therapy, why did you choose to focus on RPE cell replacement?
A:
We believe these cells could be used to treat blindness and degenerative eye diseases, such as macular degeneration and retinitis pigmentosa. We choose this application for several reasons. First, the eye is an immune privileged site—which means transplanted cells won’t be rejected as aggressively as the rest of the body. Second, many of these diseases are quite serious. For instance, macular degeneration alone affects more than 30 million people worldwide and is the leading cause of blindness in patients over 55 in the United States. And finally, it turns out that except for neurons, very few replacement cell types can be reliably generated from human embryonic stem cells. For clinical therapies, you need to be able to generate them in sufficient number and purity for them to be of therapeutic value. The RPE cells we generated have been extensively characterized and have all the markers and behavior of normal retinal cells. We have demonstrated that these cells can rescue visual function in animals that otherwise would have gone blind. There was a 100% improvement in visual acuity over untreated controls without any apparent adverse effects.


Q: In the rat model, you injected the cells into the retina at post-natal day 21, before photoreceptor deterioration had occurred. Patients that are to be treated will already have lost many of their photoreceptors. Have you observed photoreceptor cell recovery following RPE cell transfusion?
A:
Of course, the goal of the therapy is to attenuate visual loss—that is, to maintain vision in patients who—if untreated—would continue to lose the rest of their photoreceptors and eventually go blind. Our tests clearly show that RPE cell transfusions were capable of extensive rescue of photoreceptors. That is, the cones and rods we see with were preserved by transplantation of the cells. To give you an idea of just how impressive the results were, in untreated animals, the layer of cells the animals see with was only one layer deep after 100 days. However, in the treated animals, the cells were a healthy five to seven cells deep. We also have work underway using earlier progenitors that have the ability to generate the photoreceptors themselves, as well as most of the other components that may allow us someday to actually reverse blindness after it has already occurred. Stay tuned.


Q: What advantages do you see in using stem-cell therapy over standard RPE cell transplantation?
A:
There are numerous advantages of using cells derived from embryonic stem cells as a source of RPE for clinical studies. Primary RPE tissue (usually from fetuses) cannot be obtained in large enough quantities for wide-scale clinical use. Furthermore, practical restrictions prevent full safety testing from being performed on every fetal or adult donor source, nor can the functional parameters of graft efficacy be systematically assessed. In contrast, unlimited quantities of embryonic-stem-cell-derived RPE can be derived and maintained under well-defined and reproducible conditions using traceable reagents, including specific lots of media, sera, growth factors, and other culture materials. New and additional banks of RPE can be created to test and further optimize yields and functionality.


Q: How do you propose to overcome the problem of tissue immunocompatibility?
A:
It has been found that despite the immunoprivileged status of the eye, RPE cells can still be rejected, albeit less floridly than a typical tissue mismatch. With the further development of somatic cell nuclear transfer (therapeutic cloning), parthenogenesis (just recently reported), or the creation of banks of reduced-complexity human leukocyte antigen (HLA) embryonic stem cells, RPE lines could be generated to overcome the problem of immune rejection and the need for immunoprotective regimens. In the meantime, local immunosuppression (in just the eye) could be administered if it proves necessary.


Q: Where do we stand in terms of clinical trials in human patients?
A:
We’re hoping to file an IND (Investigational New Drug) application with the Food and Drug Administration (FDA) for human clinical trials in patients by early next year.


Q: Sustaining hES cells indefinitely in culture for future differentiation and clinical use raises concerns about the genetic integrity of these cells after long-term passaging in vitro. How can you reassure people that the differentiated cells will be safe to use and will not develop into tumors?
A:
First of all, there is never any need to passage hES cells long-term. We freeze down large banks of early passage hES cells that can periodically be thawed to start the process anew, which can also be expanded and frozen down early on. Importantly, once you have RPE cell lines, they undergo dedifferentiation and expansion—over 30 population doublings—just like the primary RPE tissue in the eye. As far as safety, in compliance with FDA standards, we are of course carrying out very extensive—and long-term—safety and dosage studies in animals to ensure the cells won’t cause tumors or any other unwanted pathology. A range of scientists, clinicians, safety experts and, of course, the FDA, will carefully scrutinize these results.


Q: What are the advantages of using embryonic stem cells over adult stem cells?
A:
Embryonic stem cells are the body’s master cells—they are undifferentiated and immortal—and can become virtually every type of cell in the body. In contrast, adult stem cells don’t have as much versatility—they can only become this or that specific cell type. Thus, most scientists think that embryonic stem cells have the potential to treat a much broader range of human diseases. For instance, we’re unaware of any usable adult stem-cell source for generating the RPE cells.


Q: The political setbacks of stem-cell research are well known, but what, in your view, are the major scientific setbacks or difficulties in this field?
A:
Aside from politics, the lack of funding is the major problem. Without money there’s no research—it’s as simple as that. Of course many private groups such as the JDF and Christopher Reeve Foundation have stepped forward with millions of dollars in grants—and they are to be applauded for this. However, even a generous private sector will be hard pressed to fill the government’s role. Overcoming the remaining scientific challenges will require a large and sustained investment in this research. The Federal government—and individual states—are the only realistic sources for such an infusion of funds, and remain the greatest hope for moving ES cell research in this country (U.S.) into the clinic in the next five to ten years.


Q: There are several methods to generate an embryonic stem-cell line: blastocyst donations from fertility clinics, therapeutic cloning (SCNT), parthenogenesis or even a method you have recently published a paper on—blastomere removal at the eight-cell stage. Which of these methods do you envision to be the most practical for widespread use in the future?
A:
Embryonic stem-cell lines generated from either blastocysts, which destroy the embryo, or from single-cell biopsy, which doesn’t harm the embryo, are the most immediate and practical methods for wide-scale use in the future. Theoretically, parthenogenesis and therapeutic cloning (SCNT) could be used to provide an exact match for a small number of egg donors. But this would be of little value to the public health at large. It’s hard to even obtain a handful of human eggs for research, let alone the millions of eggs that would be necessary to match all the patients who could potentially benefit from this technology. On the other hand, it might be possible to use these two technologies to produce a stem-cell bank with reduced HLA complexity. For instance, a small bank of approximately a hundred parthenogenetic or SCNT lines could theoretically furnish a complete haplotype match (of all the major MHC types) for half (50%) of the U.S. population. Without parthenogenesis or cloning, it could take tens of thousands of stem-cell lines to achieve this same goal—clearly it’s an impractical task.


Q: There has been recent criticism of universities such as the University of Wisconsin for patenting hES and primate cell lines. What is your stand on this matter?
A:
I have very mixed feelings about this. Certainly I’m against anything that interferes with moving this technology into the clinic and helping people. In that regard, these patents have slowed progress in the field. But in the larger picture, it’s going to require hundreds of millions of dollars to get stem-cell therapies into the clinic. Without patents, biotechnology and pharmaceutical companies will not invest the money needed to make it happen. As far as the University of Wisconsin, like many other scientists, I wonder whether these patents should have ever been allowed to begin with. Embryonic stem cells were around long before the “WiCell” patents were filed.


Q: What is your vision for the future of stem-cell therapy over the next 10 years?
A:
Of course, there are still many scientific challenges that need to be overcome, but in the next ten years, I think we’ll be well into the next great medical revolution. Hopefully, we’ll be in human clinical trials for a range of human diseases, such as blindness, spinal cord injuries and cardiovascular disease. I also think we’ll be able to reconstitute stem-cell derivatives into more complex tissues and structures, such as bone, blood vessels and even whole organs. We may not be able to grow an entire heart or kidney by then, but the basic science should be well underway.

 
Design by sudhanshu. Converted To Web By SUDHANSHU RATNA THAKUR