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High-tech medicine

Scientists at the U of M's Faculties of Medicine and Engineering will soon be using artificial tissue to test a range of new drugs that could one day be used to treat diseases ranging from asthma to lung cancer

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It all starts with a little instrument called an electro-spin apparatus.

The gadget was built by Dr. Malcolm Xing, a Chinese-born, Harvard-trained, bio-mechanical engineer who works in the Biology of Breathing Group at the University of Manitoba's Faculty of Medicine. And an ingenious piece of technology it is.

Simply put, the device - which stands about a foot high and four feet long - combines electricity, polyhydroxybutyrate (or PHB) and gelatin to create a white, gauze-like tube.

Plug it in, flip the switch and watch it go to work. Within seconds, the device starts spewing a thread so thin it can barely be seen with the naked eye. As it winds its way around a spool on the machine, the thread starts to take the shape of a small straw.

To the casual observer, the material flowing from the instrument may not appear all that special - it could easily be mistaken for lining from a coat or a new kind of insulation.

But this is no ordinary cellulose, according to Dr. Andrew Halayko, Canada Research Chair in Airway Cell and Molecular Biology at the University of Manitoba, and Head of the Biology of Breathing Group. As he explains, the material in question shares some unique characteristics with the collagen and elastin found in human tissue. As such, it lends itself to certain medical applications, not least of which is the creation of artificial tissue.

"It's really a freaky-looking thing," says Halayko. "You can spin these nanofibres around and around and around a spinning tube, and eventually you get this matrix of nano-fibres where cells like to sit." And therein lies the secret.

Once the tube is completed, it can be populated with cells from a human lung. In time, these cells will transform the tube into something akin to a human airway, suitable for scientific research.

And that has Halayko and company extremely excited. Thanks to Xing's machine, the Biology of Breathing Group, created and funded by the Manitoba Institute of Child Health and the Children's Hospital Foundation, will soon find itself at the junction of two very important trends in research today: the growing interest in the use of nanoparticles to deliver prescription drugs, and the need to test those drugs more economically by using artificial tissue during the development process.

Nanoparticles are essentially tiny engineered molecules that can be used in a variety of ways. Sunscreen, for example, consists of nanoparticles containing titanium dioxide, the active ingredient that protects your skin from the sun's harmful rays.

In recent years, there has been growing interest in the use of nanoparticles to deliver prescription drugs. The thinking is that these little entities will make perfect vehicles for drug delivery because they are tiny, dissolve easily and can travel anywhere in the body.

Now that it has the ability to create artificial tissue, Halayko says the group expects to be in a position to test nanoparticle-based drugs within three years. If all goes to plan, the Biology of Breathing Group will be a leader in the field, testing and developing drugs that may one day be used to treat diseases ranging from asthma to lung cancer.

"The implications are really broad," says Halayko. "This is potentially a whole new realm of personalized medicine where we can test new drugs on a patient's tissues before we even test them out on the patients themselves."

Research in Winnipeg could help shave years off developing new life-saving drugs, or even provide a new medium for testing drugs that would otherwise never be developed because it would have been too costly. "Our goal is better drug development," says Halayko. "That's the concept of establishing this bio-engineering unit - to set up this conduit to do this kind of testing."

While other centres around the globe may be using similar methods, Halayko says much of the work done in Winnipeg is unique, employing technology in new ways to lead to new discoveries.

A case in point is the Bio-airway Research Offering New Concepts in Health partnership, or BRONCH for short. Funded by the National Sanatorium Association, it is a partnership of the Biology of Breathing Group of the Manitoba Institute of Child Health and University of Manitoba's Faculty of Medicine with the University of British Columbia. The project, which is being led locally by Halayko, brings together the new frontiers of science - stem cell research, gene therapy, bio-engineering and nanotechnology - to help find new treatments for asthma and other lung conditions such as chronic obstructive pulmonary disease (COPD), that are faster, safer and cost less.

That's no small thing. As Halayko explains, a major stumbling block for all drug research is cost. Bringing a drug to market can take up to $1 billion and years of research, a barrier that prevents drug companies from pursuing promising treatments. The process of moving a drug from lab bench to bedside is complicated. First, you have to test a drug on cells in a dish. That alone can take years. Then there's animal testing for toxicity and just figuring out whether the drug works. Then there are the human trials.

But just because it works on mice, doesn't mean it will on humans, says Halayko. "I might have the healthiest mouse in the world, but if I start giving you the same drug, it might do squat. This is a very common problem. We call this the second gap in translation of knowledge."

And it's why many drugs that could lead to cures for asthma, cancer or other diseases never see the light of day. Making that leap is so cost-prohibitive.

This is where Xing's electrospin apparatus comes into play. Although the technology for this machines is in use the world over, Xing's is a bit different. He has modified the design of his machine to create small tubes that lend themselves to creating simulated human airways. The fibrous material that it produces makes for a perfect bridge between drug trials on animals and clinical trials on people.

"The idea behind making this scaffold (tissue) is if you are a candidate for a drug and it's something to do with your lungs, we could test that drug on a scaffold populated with your airway's cells and see whether it actually works on your lung tissue without having to give you the drug," he says. "And the beauty of this technique is it could ultimately be used for any tubular organ - intestine, blood vessel, you name it." Adds Xing: "We have applied this not only for airways as a disease model for asthma. It can also be applied for cardiovascular graft and artificial skin."

But for the time being, the focus is on creating simulated airways using patients' stem cells to populate the scaffold with smooth muscle and epithelial (membrane) cells.

Eventually, Halayko hopes the research in this area will fund the entire group. "The idea would be, in the long-run, to establish a way that a drug company would come to us and say, 'Hey, we have compound X, and we think it might be a new cancer-fighting drug, but we're not sure everyone will respond well to it,'" he says. "It could allow us to bring more drugs forward, more effectively, instead of stopping at that first gap where drug companies get scared off because they don't know if they want to invest $750 million to get it through early clinical trials."

Some of the drugs that may end up being tested on this bio-engineered platform might actually be developed by the Biology of Breathing Group itself.

For example, Xing has been working with a pediatric surgeon in the group - Dr. Richard Keijzer - to develop a nanotechnology drug application for babies diagnosed while in-utero with a congenital lung defect.

Using ultrasound, doctors can diagnose a congenital diaphragmatic hernia (a hole in the diaphragm) in babies at about 20 weeks gestation in the womb. The diaphragm is the muscle at the bottom of the chest cavity that expands and contracts as we breathe. While babies are in the womb, they don't use their lungs. The mother provides oxygenated blood through the placenta.

During ultrasound - common practice for all women once they reach 20 weeks of pregnancy - doctors can diagnose the condition because they can see the intestines creeping up through the hole in the diaphragm into the chest.

"We know at 20 weeks this baby will have a problem after birth and we're just waiting for it to happen, and we deal with it when it happens," says Keijzer, who is originally from The Netherlands.

The hole can be repaired during surgery after birth. If the lungs are underdeveloped, they are unable to oxygenate the blood sufficiently so the body's cells do not get the energy they require for normal development. "They struggle with normal development, and we're trying to understand why these lungs develop abnormally," he says.

What starts out as an in-utero problem becomes a lifelong disability.

The other treatment available is to operate on the baby while in-utero. This involves laparoscopic surgery, using a camera to guide the surgeon. While invasive, it's similar to arthroscopic surgery. Only a small incision is made in the mother, and the surgeon then makes an incision in the womb to gain access to the baby.

"One of the things they're doing already is if you put a plug in the baby's trachea, the pressure that builds up during development makes the lungs grow," says Keijzer, who did his fellowship in laparoscopic surgery in Birmingham, Alabama, before arriving in Winnipeg two years ago to work with Xing and the others in the group.

The problem with this procedure is it helps make the lungs grow in size, but does little for the lungs' actual development. "It's not better lungs. It's just bigger lungs," he says. "If you could add something to that treatment to improve the lungs' development, then you might be able to fix things."

Keijzer took a position with the group two years ago because he wanted an opportunity to do research and clinical work in the same place. Working in Winnipeg offers him the chance to develop new treatments for lung development in newborns. But at the time, he didn't think he would be working with nanotechnology to potentially treat this in-utero lung disorder. That changed when he met Xing and started learning about his work with nanoparticles.

"He mentioned that he was doing this kind of stuff, and I always wanted to see if we could improve lung development prenatally, because after birth we're doing pretty well, but there's a lot of harm done to the babies because of all the things we need to do to keep them alive," Keijzer says.

In the typical way that many research ideas are born, one discussion led to another and soon Xing and Keijzer were working to determine how a new class of drug could be administered to a baby with this disorder while in-utero.

Xing's expertise with synthetic materials is playing an important role. In this case, Xing has created a polymer-type material that is essentially a form of carbohydrate that can bind to a nanoparticle-based drug, carry it to the targeted cells, and then release the drug into those cells.

"It's synthetic, but it's biodegradable and biocompatible," Xing says. "It's very novel. We developed them ourselves in the lab, but the idea comes from nature itself. It's nature's mechanisms we're using to develop these new materials."

The drug is a type of mico-RNA therapy that when delivered to a baby's lungs in-utero can help them develop faster. "Micro- RNAs are ways of regulating the products that your genes make," Halayko says. "You don't regulate the gene per se. You actually regulate how cells process what their genes are encoding."

Using this technology, the goal is to enhance the early development of the lungs of a baby diagnosed at 20 weeks with a hole in the diaphragm.

At this point, Keijzer says they have applied the micro- RNA enriched nanoparticles to the lung tissue cells in a petri dish. "You can sprinkle it on the cells, and then we know the nanoparticles get easily into the cells without any damage for now," Keijzer says.

The next step is testing it on the lungs of mice fetuses that are removed from the womb and put into culture. The lungs continue to develop while in culture, so the compound will be applied to the lungs to see if it enhances development, he says. The next step after that is to test the drugs on live mice, but that is still at least a few months away.

Keijzer says nanoparticles have great potential in advancing drug therapies because they can deliver a concentrated dose of a drug to a very specific area.

One of the bugaboos of all drug therapies is it's always been hard to target the treatment specifically to the region of the body that needs treatment. Halayko says one of the most obvious examples of this problem is chemotherapy in cancer patients. Take doxorubicin, for example. It is a common cancer drug, but while attacking the cancer cells, it also attacks other cells. And it can cause heart damage. "A lot of people who get chemotherapy from doxorubicin end up with heart failure because the drug damages heart tissue," says Halayko.

Researchers at other centres have been working with nanoparticles to deliver chemotherapy drugs to only cancer cells while leaving healthy cells unharmed. The difficulty, however, is figuring out just how that will be done. At the Biology of Breathing Group, Xing has been working on the same problem, only with respect to Keijzer's research on congenital lung development. "If you're using micro-RNA therapy, the problem that can happen is it could be absorbed by the wrong cells."

And because this drug treatment is a form of gene therapy, delivering it to the wrong part of the body could potentially cause dire outcomes. But Xing has a few tricks up his lab coat sleeve to ensure the nanoparticles will find the right location in the body. That way, the drug could be injected into the mother, but it will only affect the cells it's designed to treat.

One of those tricks has been to make a drug-carrying nanoparticle that reacts only to the specific pH value - or acidity level - of the targeted cell, such as tumor cells, for example. "It's a very smart material that can be made to be pH-sensitive because we know some of the organelles (subunits) of cells in our body have a pH value that is around five," Xing says.

When the nanoparticle encounters those cells, it reacts and is absorbed into the cell. Because it's also bio-degradable, it then decomposes and releases the drug inside the cell in a very concentrated dose.

This biotechnological treatment is also in its initial stages in another project at the Biology of Breathing Group, Halayko says.

He is working with a team at the Winnipeg Health Region's Cardiac Sciences Program at St. Boniface Hospital to create new coronary arteries using the scaffolding material created by Xing and populating it with the cells of a patient.

This technique could be used instead of removing a section of blood vessel from the patient's leg, as with most cardiac bypass surgery currently being done all over the world. It has already been performed at other centres; however, the trials have been unsuccessful because the artery closes up soon after being implanted in bypass surgery. "The concept we're doing is that the nanoparticles are embedded in the wall of the artery and they would release biological compounds or growth factors that would prevent the occlusion," he says. "It's almost like slow-release fertilizer that's embedded in the scaffold where the cells are going to be."

Xing says he's already found a method to control the degradation of the nanoparticles to create the slow-release effect. "Normally, we know that when we inject a drug it may have a quick release into the body, but then we have to inject it again after a period," says Xing, who also studied at Massachusetts Institute of Technology in Cambridge. "The use of nanoparticles allows us to modify the biopolymer's properties to degrade at a different rate."

But this research is still in its infancy and it will be a long time before the fruits of their labour can be used in actual clinical practice. Even Keijzer's work, now almost at the stage of testing in animals, is years away from human clinical trials. "To get it approved in humans will be really difficult," he says. "It has to be safe for both the mother and the baby. It's nice if you can fix the baby's lungs, but if the mother gets lung cancer or something, that's an obvious problem."

Adds Xing: "I'll be happy if I retire and this is finished."

And on the road to that goal, it may turn out that Halayko's research - culturing tissues to test new drugs - may intersect with Keijzer's work as it nears the human clinical trial stage. Yet already, the Biology of Breathing Group has been a success - even if those two projects never lead directly to usable human applications. It's more than likely that they would indirectly lead to other successes - maybe at the centre itself or some other research lab located half a world away.

None of it, however, would have been possible if it wasn't for that one unifying idea: to bring a wide breadth of expertise under one roof at the Manitoba Institute of Child Health and the University of Manitoba's Faculty of Medicine.

It's all about mixing together the ingredients to come up with new ideas, Keijzer says. "With the Biology of Breathing Group, I was adding lung development to the mix. Dr. Xing is adding nanotechnology," Keijzer says. "Now we're together and my bench is next to his bench in the lab and we talk and come up with these new ideas."

And he says he is thankful that Halayko took the initiative to foster recruitment of some of the world's leading medical experts on lung research and then see what comes out of it.

So far, the results have been promising. And it may be that one day, when histories are told of how a cure for a disease was discovered, the Biology of Breathing Group is acknowledged for its pivotal role. It started here, so the story might go. And it couldn't have begun any place else. "I could never do the nanoparticles on my own because I don't have that experience or knowledge, and Dr. Xing could never do the prenatal treatments," Keijzer says. "Together, we can now do something that maybe nobody else can do in the world."

Joel Schlesinger is a Winnipeg writer.

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