Researchers flex new muscle in SMA drug development

By Paige Blankenbuehler

Lauren and Claire Gibbs share contagious laughter, ambition and a charismatic sarcasm.

Both are honor students at Shawnee Mission East High School in a Kansas City suburb.

They also share a neuromuscular disease called spinal muscular atrophy (SMA), designated as an “orphan disease” because it affects fewer than 200,000 people in the U.S.

However, the landscape for individuals with SMA is quickly changing with the development of new drugs.

More than 7 million people in the United States are carriers (approximately 1 in 40) of the so-called “rare” neurodegenerative disease, SMA.

 

Lauren,17 (left) and Claire, 16 (right), say their shared SMA diagnosis has strengthened their relationship and presented them with opportunities to travel and share their experiences. | Photo provided by the Gibbs family.

Lauren,17 (left) and Claire, 16 (right), say their shared SMA diagnosis has strengthened their relationship and presented them with opportunities to travel and share their experiences. | Photo provided by the Gibbs family.

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Faces of SMA

The success of therapeutics in lab experiments provides a new layer of hope for individuals and families living with the disease.

Lauren, now 17, fit the criteria for SMA Type III, while Claire, now 16, showed symptoms of a more severe manifestation of the disease, SMA Type II.

Lauren and Claire Gibbs were diagnosed on the same day.

Despite their numerous similarities, the biggest disparity between them is mobility.

Claire uses a power wheel chair while Lauren is able to use a manual chair. It’s not unusual to see Lauren being pulled along in her chair, playfully hanging onto the back of Claire’s motorized chair.

Lauren is participating in a clinical trial with ISIS-SMNRx a compound developed by Isis Pharmaceuticals, a leading company in the antisense drug discovery and development based in Carlsbad, Calif. Lauren feels that she has gained stamina and a greater ability to walk  — a feat that wasn’t routine just five years ago.

Prior to the trial, Lauren was able to walk only for short distances.

Time and Natalie Gibbs with their daughters Lauren, 17 (left) and Claire, 16 (right) in Washington D.C. The family have been visible advocates in the fight for a cure for spinal muscular atrophy. | Photo provided by the Gibbs family.

Tim and Natalie Gibbs with their daughters Lauren, 17 (left) and Claire, 16 (right) in Washington D.C. The Gibbs have been visible advocates in the fight for a cure for spinal muscular atrophy. | Photo provided by the Gibbs family.

 

Bringing New Hope

A new experimental drug developed by researchers at the Christopher S. Bond Life Sciences Center, is bringing hope to individuals with the orphan disease affecting one in 6,000 people.

Christian Lorson PhD, investigator in the Bond Life Sciences Center and Professor of Veterinary Pathobiology at the University of Missouri, has been researching SMA for seventeen years and has made a recent breakthrough with the development of a novel compound found to be highly efficacious in animal models of disease. In April, a patent was filed for Lorson’s compound for use in SMA.

Lorson’s therapeutic, an antisense oligonucleotide (a fancy name for a small molecule therapeutic that falls under the umbrella of gene therapy), repairs expression from the gene affected by the disease. The research was published May in in the Oxford University Press, Human Molecular Genetics.

The drug developed by Lorson’s lab is conceptually similar to ISIS-SMNRx already in clinical trial developed by Isis Pharmaceuticals and a team of investigators at Cold Spring Harbor Laboratory headed by Dr. Adrian Krainer.

Antisense drugs are not a new practice, but their wide-spread adoption seems to be on the cusp with recent success stories like the commercialization of an FDA-approved antisense compound produced by Isis in 2013 called Kynamro for the treatment of homozygous familial hypercholesterolemia, a high cholesterol disorder that is passed down through families.

 

Science behind success

The National Institutes of Health has listed SMA as the neurological disease closest to finding a cure. Discoveries made by the Lorson Lab have contributed significantly to current scientific understanding of the disease mechanisms and to the advances being made in finding an effective treatment for SMA.

These antisense therapies work because of the genetic makeup of SMA —the genetics are incredibly clear: a single, specific gene called Survival Motor Neuron 1  (SMN1) has been pinpointed as the cause of SMA.

SMA is a neurodegenerative disorder, meaning muscles become weaker over time due to sick or dying neurons.

These neurons become less functional because of low levels of the SMN.

Remarkably, the disease can be reversed in animal models of disease if the nearly identical duplicate gene, SMN2, can be “turned on” to compensate for low SMN levels.

Lorson’s antisense oligonucleotide therapeutic provides incredible specificity because it hones in on a specific genetic target sequence within SMN2 RNA and allows proper “editing” of the RNA encoding the SMN protein. The strategy is to “repress the repressor,” Lorson said.

The SMA-specific defect lies at the RNA step – the “cutting and splicing” of important RNA sequences does not happen efficiently in SMN2 RNAs because of a several “repressor” signals.

“The final chapter of the book — or the final exon — is omitted,” Lorson said. “But the exciting part is that the important chapter is still there – and can be tricked into being read correctly: if you know how.”

The new, antisense oligonucleotide seems to know how to get the job done.

The existence of such similar genes as SMN1 and SMN2 in humans creates a rare genetic landscape lending itself especially to a therapeutic development for SMA.

Humans are unique in this duplication — something Lorson calls a “genetic happenstance” that, on an evolutionary scale, may as well have happened yesterday.

Why humans have developed this redundant gene is unknown.

Thalia Sass, a University of Missouri biology major, genotypes samples in Christians Lorson's lab that conducts research on spinal spinal atrophy.

Thalia Sass, an MU biological sciences major, genotypes samples in the Lorson Lab where spinal muscular atrophy is researched.

 

Timing is everything

In addition to the developments of new SMA therapeutics, Lorson and his lab sought to answer an important biological question concerning the disease: When can a therapeutic be administered and still show some degree of efficacy?

Lorson’s research found that the earliest administration of a treatment provided the best outlook— extending the survival of laboratory mice by 500 to 700 percent, “a profound rescue,” according to his research published in April in the Oxford University Press, Human Molecular Genetics.

A near complete, 90 percent rescue was demonstrated in severe SMA mouse models. But even when the therapeutic was administered after the onset of SMA symptoms, there was still a significant impact on the severity of the disease.

“If you replace SMN early and get (a therapeutic) to cells that are important to the disease, you correct it,” Lorson said. “This provides hope that patients who have been diagnosed will still see some therapeutic benefit even if it is clear that the best results will likely come from early therapeutic administration.”

In Lorson’s study it’s definitive that the earlier a therapeutic can be administered, the better the outcome for individuals with SMA.

“This really points towards a strong push for neonatal screening,” Lorson said. “Infant screening would likely be incredibly beneficial for SMA and that’s something that the SMA community is really excited about.”

 

A breakthrough for families

On June 2, Lauren and Claire Gibbs attended a routine, annual rehab appointment with Dr. Robert Rinaldi, MD, division of pediatric rehabilitation medicine and attending physician at Children’s Mercy Hospital in Kansas City, Mo Dr. Rinaldi is not associated with the Isis clinical trial.

The appointment was like a reunion among close friends — Rinaldi began seeing Claire and Lauren Gibbs 16 years ago, the first year that he began working at the hospital and when the girls were one- and two-years-old, respectively.

The girls did all of the routine tests —measuring strength of grip and breathing, and assessing range of movement with the occupational and physical therapists.

A little later, Rinaldi sat with Natalie Gibbs, Lauren and Claire’s mother and a relentless advocate for advancement in SMA awareness.

Typically the muscles of individuals with SMA deteriorate over time, but together they inspected the definition of a new calf muscle on Lauren’s left leg.

For a young woman with Type III SMA — this means she can walk for short distances with little discomfort but still uses her wheel chair a majority of the time — Lauren’s new calf muscle is a remarkable achievement.

clinicaltrialinfoboxAs Lauren continues to participate in the ISIS antisense therapy clinical trial, her conditions continue to improve dramatically, even with the late administration of the therapy — in her case, 16 years after her diagnosis and onset of effects.

Lauren believes her ability and stamina for walking have increased significantly.

“Quite frankly my jaw almost hit the ground when she stood up — the change was that impressive to me,” Rinaldi said.

Rinaldi, also the co-director of the Nerve and Muscle Clinics at the hospital, had last seen Lauren two years ago. He said the Lauren he saw during a routine rehab appointment in June was like seeing a new person altogether.

“The way she stood up from the wheel chair — how quickly she did that with no support — her posture when she was standing up was more upright, her pelvis was in a much better position, her core was straighter,” Rinaldi said. “It struck me immediately how much better she looked.”

Lauren Gibbs is the first of Rinaldi’s patients to have participated in the ISIS clinical trial.

“It’s moving very fast in this field,” Rinaldi said. “I think the technology that’s evolving in research is opening up more avenues for investigation for us and there’s a big desire to find a cure for these types of diseases.”

The progress has rewarded the Gibbs family’s advocacy in SMA awareness and they’ve been able to set new goals they didn’t imagine were possible when the diagnoses for Lauren and Claire were made. Natalie Gibbs is a long-time member of Families of SMA and is currently on their Board of Directors.

The organization Families of SMA is currently providing funding to Lorson to advance this research area.

“We’re able to see first hand — and our physician who has been watching them for sixteen years has seen — that everything we’re doing in the clinical trials is really making a difference,” Natalie Gibbs said.

Over the course of their daughters’ lives, Natalie and her husband Tim Gibbs say a shift in momentum has accelerated the technology and research toward finding a cure for SMA.

“I am really impressed with the progress Lauren has made with the trial and how well Claire is doing overall,” Natalie Gibbs said. “Even though it’s a progressive and very devastating type of disease, I feel like we’re really conquering it.”

 

Link to publications:

Therapeutic window study:  http://www.ncbi.nlm.nih.gov/pubmed/24722206

University of Missouri ASO:  http://hmg.oxfordjournals.org/content/early/2014/04/29/hmg.ddu198.full.pdf+html

For more information on spinal muscular atrophy, visit FightSMA.org and fsma.org

 

At the Bond LSC, the wall wears the plants

The unusual red color of the Lobelias leaves stand out among 200 other species that thrive in the 20-foot plant wall at the Bond Life Sciences Center | Paige Blankenbuehler

The unusual red color of the Lobelias leaves make them stand out among 200 other species that thrive in the 20-foot plant wall at the Bond Life Sciences Center | Paige Blankenbuehler

Story by Madison Knapp | Bond Life Sciences summer intern

A hidden treasure on the University of Missouri’s campus is a living and breathing work of art.

In the Christopher S. Bond Life Sciences Center, a 20-foot plant wall stands as a towering tribute to the diversity of plant life and coexistence of species — a botanical landscape of more than 200 individual plants from 40 to 50 species including many ferns, vines, perennials, orchids and geraniums.

The display continues to be a visual reminder of the building’s interdisciplinary nature – much like the plants within the wall, the Bond Life Sciences Center facilitates the coexistence and collaboration between an array of researchers within its walls.

One plant cascades down the wall and stands out more than most — it looks more like a large insect than any type of plant typically seen in such displays.

Tillandsia is a genus of succulent plant native to Central America that can undergo long dry spells. The wiry plant thrives on the stone beside the plant wall without the help of a pot of soil, and is seemingly absent an essential, anatomical feature of most flora — roots.

With leaves more like Medusa's hair, Thallandsia are rootless plants mounted on stone  alongside the plant wall. | Paige Blankenbuehler

With leaves more like Medusa’s hair, Thallandsia are rootless plants mounted on stone alongside the plant wall. | Paige Blankenbuehler

They still have tiny root protrusions, but the mass is minuscule compared to the thick leaves, which take up and store water and nutrients, rather than the root system which handles that work in most plants.

Approximately 60 Tillandsias pepper the plant wall, including a few mounted directly onto the stone wall with a special kind of non-toxic rubber cement manufactured by Davis Farms based out of San Diego.

The strange plant was added to the green tapestry by Jason Fenton, an office support associate at the Bond Life Sciences Center. He first noticed the rootless plants in Belize while on a trip there in 2003 and had been growing them at his home.

“I think they’re really beautiful and distinctive,” Fenton said. “They help give variety to the wall.”

The rootless plants require special treatment — just a little extra attention from facilities manager, Jim Bixby, who waters the Tillandsias with a spray bottle once a week.

The wall started with a vision from Jack Schultz, director of the Bond Life Sciences Center. The execution and maintenance of the feature is credited to Bixby, who has honed the project since 2010.

After trying several watering systems, Bixby found one that worked. He hung rows of pots with modified flat sides and tailored a simple, drip irrigation system made for easy watering along a grid.

Within the diverse landscape and after additions of a variety of plants over the years, Bixby has seen competition between several of the species.

The wall favors the ferns, which have taken over much of the space, crowding out other plants for the eastern sunlight that flows through the windows, Bixby said.

Several long-stemmed species have found ways to cope, however; venturing out between the ferns’ curtain-like fronds to get their fair share of sunlight.

Supervising editor: Paige Blankenbuehler

The 20-foot tall plant wall outside of Monsanto Auditorium in the Bond Life Sciences Center is a nod to coexistence and diversity. | Paige Blankenbuehler

The 20-foot tall plant wall outside of Monsanto Auditorium in the Bond Life Sciences Center is a nod to coexistence and diversity. | Paige Blankenbuehler

A veterinarian abroad: Rwanda

While summer brings a slower pace for many researchers, others use it as an opportunity to learn for their profession and network with others in their field.

Bond LSC researcher Cheryl Rosenfeld recently traveled to Africa to further her learning as a veterinarian. This continuing education gives her the opportunity to learn the newest techniques in the field and network with others to learn what’s current and on the collective minds in veterinary medicine.  Through the North American Veterinary Community (NAVC), Rosenfeld has now gone on three expeditions where participants observe animals in their natural, exotic environments, attend nightly lectures and learn more about the humans near these animals. 

Previous expeditions led Rosenfeld to the Galapagos Islands and the Florida Keys, but her June 2014 trip started in Rwanda and ended in Tanzania. Here’s the first of two entries where Rosenfeld shares here experience. 

By Cheryl Rosenfeld

The fate of animal populations is generally intertwined with the predicament of humans in the area. Nowhere is this truer than in Rwanda. Most people know Rwanda for Dian Fossey’s work with the mountain gorillas and the genocide of more than 1 million Hutus and Tutsis that happened 20 years ago in 1994. In this 100-day period, an average of six individuals were killed per minute. Children that survived were often orphaned and many surviving women suffered being raped and exposed to HIV infection. In all, many still require extensive medical and psychological care. On our flight and checking into our hotel was a medical team from Harvard Medical Center that was there as part of the Clinton Foundation to assist in the medical needs.

We saw the history that continues to shape the country when we first visited a genocide memorial site just outside of Kigali where thousands of individuals were brutally murdered and the Kigali Genocide Museum that was partially funded by an English Jewish Holocaust survivor. The history of the conflict is rooted partially in Western influence that infused a social division. Prior to Europeans colonization, Hutus and Tutsis lived in relative peace and individuals could go back and forth between these two groups. The original difference was that Tutsi individuals owned more than 10 cows. The differential treatment and classification adopted by Europeans began to trigger conflict between the two groups. Prior indicators, including extensive propaganda, were ignored by the United States and United Nations. The museum includes two stained glass windows that depict the evidence that genocide was imminent and failure by other nations to prevent this tragedy. Genocide isn’t unique to Rwanda, though, and the displays describe the commonalities on their sad origins in other countries throughout history.  Outside the museum, there are several mass graves where fresh flowers are placed on a routine basis.

I was originally hesitant about traveling to Rwanda because of this history, but am very glad I took the chance. The Rwandan government has worked hard to turn around and instill pride in the country. Their economy is one of the fastest growing in Africa with construction of new businesses and hotels in Kigali. Moreover, the government has placed a ban on plastic bags and hired teams of individuals to keep the country clean. One Saturday a month, all Rwandans, including the President, are expected to participate in clean-up day, which becomes a convivial social event. While there is still sadness in the eyes of many individuals I met, I also saw hope of something better, which was inspiring to witness.

We were soon off to learn about the mountain gorillas that are now the pride of the country. During Dian Fossey’s time, she battled to prevent poaching of these magnificent and intelligent creatures. The country now realizes the worth of preserving and propagating the mountain gorilla populations. In a reasonable and safe way, they developed a tourist industry to view the various troops of gorillas. It currently costs $750 to spend one hour with the mountain gorillas. The government has restricted access to prevent gorilla habituation and stress from too many tourists.

We spent two days with different troops. While waiting in the morning to find out which troop we were responsible for trekking, we were entertained by local dancers. I regrettably made the mistake of indicating I felt fit to track the one of ten groups that was at the furthest distance.

The group that was involved in trekking the first day was called “Snow” in Kinyarwanda. I believe they received this name because they inevitably reside high in the mountains, which used to have snow. As we set off on our hike, many children came out to say “MooRahHoh”- hello in Kinyarwanda and asked for us to take their picture. We were informed that we should easily return before lunch, and therefore were only provided a package of peanuts. Unfortunately, it took us longer to hike through the forests that transitioned from bamboo to masses of stinging nettles and did not return to the hotel until 6:30 p.m. After more than three hours of hiking and our eyes finally fell upon our first mountain gorilla, the silverback of the group. Even knowing that this was the ultimate goal, we were not prepared for this amazing experience of being so close to a creature in the wild that resembled us.

We had the opportunity to meet the rest of the troop, including several 3 to 4 month old babies that were quite entertaining. The enclosed photos and videos only provide a sliver of the spectacle that we were privileged to be part of these two days of gorilla trekking that made our hunger and continued burning sensation on our face and legs from stinging nettles well worth it.

Hearing danger: predator vibrations trigger plant chemical defenses

Experiments show chewing vibrations, but not wind or insect song, cause response

As the cabbage butterfly caterpillar takes one crescent-shaped bite at a time from the edge of a leaf, it doesn’t go unnoticed.

This tiny Arabidopsis mustard plant hears its predator loud and clear as chewing vibrations reverberate through leaves and stems, and it reacts with chemical defenses. Plants have long been known to detect sound, but why they have this ability has remained a mystery.

University of Missouri experiments mark the first time scientists have shown that a plant responds to an ecologically relevant sound in its environment.

“What is surprising and cool is that these plants only create defense responses to feeding vibrations and not to wind or other vibrations in the same frequency as the chewing caterpillar,” said Heidi Appel, an investigator at MU’s Bond Life Sciences Center and senior research scientist in the Division of Plant Sciences in the College of Agriculture, Food and Natural Resources.

Heidi Appel, investigator at MU’s Bond Life Sciences Center and senior research scientist in the Division of Plant Sciences in the College of Agriculture, Food and Natural Resources, and Rex Cocroft, a professor of Biological Sciences in MU’s College of Arts and Science, found that plants create chemical responses specifically to predator chewing vibrations.

Heidi Appel, investigator at MU’s Bond Life Sciences Center and senior research scientist in the Division of Plant Sciences in the College of Agriculture, Food and Natural Resources, and Rex Cocroft, a professor of Biological Sciences in MU’s College of Arts and Science, found that plants create chemical responses specifically to predator chewing vibrations.

Appel partnered with Rex Cocroft, an MU animal communication expert who studies how plant-feeding insects produce and detect vibrations traveling through their host plants.

“It is an ideal collaboration, that grew out of conversations between two people working in different fields that turned out to have an important area of overlap,” said Cocroft, a professor of Biological Sciences in MU’s College of Arts and Science. “At one point we began to wonder whether plants might be able to monitor the mechanical vibrations produced by their herbivores.”

While Appel focused on quantifying “how plants care and in what ways,” Cocroft worked to capture inaudible caterpillar chewing vibrations, analyze them and play them back to plants in experiments that mimic the acoustic signature of insect feeding, but without any other cues such as leaf damage.

Cocroft used specialized lasers to listen to and record what the plant hears.

“Most methods of detecting vibrations use a contact microphone, but that wasn’t possible with these tiny leaves because the weight of the sensor would change the signal completely,” said Cocroft.

This cabbage butterfly caterpillar munches on an Arabidopsis leaf adjacent to  a leaf where a piece of reflective tape bounces back a laser beam used to detect the vibrations created by its chewing. Roger Meissen/Bond LSC

This cabbage butterfly caterpillar munches on an Arabidopsis leaf adjacent to a leaf where a piece of reflective tape bounces back a laser beam used to detect the vibrations created by its chewing. Roger Meissen/Bond LSC

The laser beam reflects off a small piece of reflective tape on the leaf’s surface to measure its deflection, minimizing contact with the plant. The laser’s output can also be played back through an audio speaker, allowing human ears to hear the vibrations produced by the caterpillar.

Moved by the sound

Recording the sound is just the start.

You can’t put headphones on a leaf, so tiny piezoelectric actuators – essentially a tiny speaker that plays back vibrations instead of airborne sound – is required.

“It’s a delicate process to vibrate leaves the way a caterpillar does while feeding, because the leaf surface is only vibrated up and down by about 1/10,000 of an inch,” Cocroft said. “But we can attach an actuator to the leaf with wax and very precisely play back a segment of caterpillar feeding to recreate a typical 2-hour feeding session.”

Appel and Cocroft tested whether these chewing sounds could create more chemical defenses in the plants and whether these feeding recordings primed defenses when played before an actual caterpillar ate part of a leaf.

“We looked at glucosinolates that make mustards spicy and have anticancer properties and anthocyanins that give red wine its color and provide some of the health benefits to chocolate,” Appel said. “When the levels of these are higher, the insects walk away or just don’t start feeding.”

The researchers played 2 hours of silence to some Arabidopsis plants and 2 hours of caterpillar-chewing noises to others. They then chose three leaves around the plant, and allowed caterpillars to eat about a third of each leaf.  After giving the plants 24 to 48 hours to respond to the caterpillar attack, they harvested the leaves for chemical analysis.

When they found higher levels of glucosinolates in the plants that were exposed to chewing vibrations, they knew they were on the right track.

A similar second experiment went further, testing whether the plants would simply respond to any vibration, or whether their response was specific to chewing vibrations. In this case Appel analyzed anthocyanins, which again were elevated – but only when plants had been exposed to chewing vibrations but not to vibrations created by wind or the sounds of a non-harmful insect.

Past echoes and future promise

While the past is littered with suggestions that people talk to their plants, Appel and Cocroft hope their work is shifting the focus on plant acoustics towards a better understanding of why plants can detect and respond to vibrations.

“The field is somewhat haunted by its history of playing music to plants. That sort of stimulus is so divorced from the natural ecology of plants that it’s very difficult to interpret any plant responses,” Cocroft said. “We’re trying to think about the plant’s acoustical environment and what it might be listening for, then use those vibrational sounds to figure out what makes a difference.”

The National Science Foundation seems to agree with the merit of their endeavor, awarding a grant to extend this project.

The next step includes looking at how other types of plants respond to insect predator sounds and pinpointing precisely what features of the sounds trigger the change in plant defenses.

These questions aim to further basic research understanding of how plants know what’s going on to respond appropriately to their environment. This could one day lead to ways to create better plants.

“Once you understand these things you can mess around with it in plant breeding through conventional methods or biotech approaches to modify plants so they are more responsive in the ways you want to make them more resistant against pests,” Appel said. “That’s the practical application one day.”

This research was published online in the journal Oecologia July 1, 2014 and will appear in print in its August issue.