gene therapy

Kevin Kaifer #IAmScience

Kevin Kaifer

Kevin Kaifer, a Ph.D candidate who works in Dr. Christian Lorson’s lab. | Photo by Mary Jane Rogers, Bond LSC

By Mary Jane Rogers | Bond LSC

“#IAmScience because there are people suffering all over the world and this is where I’m most likely to make any kind of an impact.”

When he came to MU three years ago, Kevin Kaifer knew he wanted to work in Bond LSC. He felt it was where the best science and collaborations were happening on campus, and everything that he needed for his research – a vivarium, a DNA core, and proteomics core – were all conveniently housed here.

“I entered research because I thought the complexity of cellular life is the most fascinating topic in the world,” said Kaifer. “I wanted to be a part of it.”

He completed his undergraduate degree in biology at Truman State University and is currently part of Dr. Christian Lorson’s lab. There, Kaifer is learning transferable skills – everything from communication skills to the production of recombinant gene therapy vectors – all of which will give him a strong foundation for a career in industry.

“The growing promise of gene therapy as a safe and realistic treatment option has led to the start up of many biotech companies that are making really exciting progress,” he said. “This is where I think I will be best able to contribute to science and therapy.”

For undergraduate students who are just getting started in a science field, Kaifer emphasizes that success in science comes and goes.

“In my own personal experience, success in science only comes after a significant set of hurdles,” he said. “You have to be okay with feeling stupid, because part of your job description is to answer questions to which you do not know the answer. I would actually be concerned if you were not struggling to feel successful.”

One step closer from mice to men

Gene therapy treating the neurodegenerative disease, SMARD1, shows promising results in mice studies.

Shababi uses an instrument to measure grip strength in the forelimbs of mice. Healthy mice are able to cling to the rack with a stronger grip than SMARD1 mice. | photo by Jennifer Lu, Bond LSC .

Shababi uses an instrument to measure grip strength in the forelimbs of mice. Healthy mice are able to cling on with a stronger grip than SMARD1 mice. | photo by Jennifer Lu, Bond LSC

Monir Shababi was confident her experiments treating a rare genetic disease would yield positive results before she even ran them.

Scientists had success with a similar degenerative neuromuscular disease, so she had every expectation their strategy would work just as well in her mice.

Monir Shababi, assistant research professor in the Department of Veterinary Pathobiology, studies SMARD1 in mice. | photo courtesy of the Department of Veterinary Pathobiology

Monir Shababi, an assistant research professor in the Department of Veterinary Pathobiology, studies SMARD1 in mice. | photo courtesy of the Department of Veterinary Pathobiology

“I was expecting to get the same results,” said Shababi, an assistant research profession in Christian Lorson’s lab at the University of Missouri Bond Life Sciences Center. Shababi studies spinal muscular atrophy with respiratory disease type 1, or SMARD1.

The treatment worked, but not without a few surprises.

Her findings, published in Molecular Therapy, a journal by Nature Publishing Group, are one of the first to show how gene therapy can effectively reverse SMARD1 symptoms in mice.

In patients, SMARD1 is considered such a rare genetic disorder by the U.S. National Library of Medicine that no one knows how frequently the disease occurs. It’s only when babies develop the first symptom—trouble breathing–that pediatricians screen for SMARD1.

Shortly after diagnosis, muscle weakness appears in the hands and feet before spreading inwards to the rest of the body. The average life expectancy for a child diagnosed with SMARD1 is 13 months. There is currently no effective treatment.

Since the neuromuscular disease is caused by a recessive gene, SMARD1 comes as a shock to the parents, who are carriers but do not show signs of the illness, Shababi said. This genetic defect prevents cells from making a particular protein that scientists suspect is vital to replication and protein production.

The hereditary nature of the disease has a silver lining, though. Because SMARD1 is a caused by a single pair of faulty genes and not multiple ones, it is a prime candidate for gene therapy that could restore the missing protein and reverse the disease.

To do that, Shababi set up a dose-response study using a tiny virus to carry the genetic instructions for making the missing protein. She injected newborn mice with a low dose of the virus, a high dose, or a placebo with no virus at all.

Injecting at different doses allowed her to ask which dose worked better, Shababi said.

According to the previous research, a higher dose should have resulted in a more effective treatment.

“So I thought a higher dose was going to work better,” Shababi said.

Instead, the high dose had a toxic effect. Mice given more of the virus died sooner than untreated mice. Meanwhile, mice given a low dose of the gene therapy lived longest. They regained muscle function and strength in both the forearms and the hind limbs and became more active.

In fact, some of them survived long enough to mate and produce offspring.

Initially, Shababi housed her SMARD1 mice in the same cage as their mothers so that the moms could intervene if the sick pups become too feeble to feed themselves. When the male pups became well, their moms became pregnant.

“That was another surprise,” Shababi said. “That was when I knew I had to separate them.”

Shababi marks a pup, only a few days old, with permanent marker so she can identify each mouse in her study. | photo by Jennifer Lu, Bond LSC .

Shababi marks a pup, only a few days old, with permanent marker so each mouse in her study can be identified. | photo by Jennifer Lu, Bond LSC .

In another twist, Shababi discovered that the route of injection also mattered.

To get the treatment across the blood-brain barrier and to the spinal cord, Shababi used a special type of injection that passes through the skull and the ventricles of the brain, and into the spine.

This was no easy task.

The newborn mice were no larger than a gummy bear. To perform the delicate work, Shababi — who has written a chapter in a gene delivery textbook about this procedure — had to craft special needles with tips fine enough for this injection. She added food coloring to the injection solution so she could tell when it had reached its intended destination.

“After half an hour, you will see it in the spinal cord,” Shababi said. “The blue line in the spine: that’s how you can monitor the accuracy of the injection.”

Unfortunately, repeated injections in the mice caused hydrocephaly, or swelling in the brain.

“They get a dome-shaped head,” Shababi explained.

The swelling happened in all three treatment groups, but most frequently in the group that received a high dose of viral gene therapy. This reinforced the finding that while a low dose was beneficial, a high dose was even more harmful than no treatment at all. It’s unclear why.

Christian Lorson is a professor of veterinary pathobiology at the Bond LSC. His research focuses on spinal muscular atrophy and more recently, SMARD1. | photo by Hannah Baldwin, Bond LSC .

Christian Lorson is a professor of veterinary pathobiology at the Bond LSC. His research focuses on spinal muscular atrophy and more recently, SMARD1. | photo by Hannah Baldwin, Bond LSC .

The Lorson lab plans to continue studying SMARD1 and this treatment, in particular, how changing the delivery routes for gene therapy can improve outcomes in treating SMARD1.

“It’s not as simple as replacing the gene,” Lorson said. “It comes down to the delivery.”

Injections in the brains of mice are meant to mimic spinal cord injections in humans, but intravenous delivery could be another option. However, intravenous injections, which travel through the blood stream and to the entire body, might cause off-target effects that could interfere with the effectiveness of the treatment.

Once researchers better understand how to optimize dosing and delivery on the cellular and organismal level, the therapy can move closer to clinical trials, Lorson said.

Even though gene therapy for SMARD1 is still in its early stages, he said he was optimistic that developing treatments for rare genetic diseases is no longer the impossible task it seemed even ten years ago.

Spinal muscular atrophy (SMA) is a prime example of a recent success, Lorson pointed out. In the last six years, gene therapy for that disease has moved from the research lab to Phase I clinical trials.

“While it feels like a long time for any patient and their families,” Lorson reassured, “things are moving at a breakneck pace.”

 

The study, “Rescue of a Mouse Model of Spinal Muscular Atrophy With Respiratory Distress Type 1 by AAV9-IGHMBP2 Is Dose Dependent,” was published in Molecular Therapy, a journal published by Nature Publishing Group. This work was supported by a MU Research Board Grant (C.L.L.); MU College of Veterinary Medicine Faculty Research Grant (M.S.); the SMA Foundation (C.P.K.); National Institute of Health/National Institute of Neurological Disorders and Stroke grants; and the Missouri Spinal Cord Injury Research Program (M.L.G.).

Viruses as Vehicles: Finding what drives

Graduate students Yuleam Song and Dan Salamango inoculate a bacteria culture in Johnson's lab. The inoculation takes a small portion of a virus and multiplies the sample, allowing researchers to custom-make viruses.

Graduate students Yuleam Song and Dan Salamango inoculate a bacteria culture in Johnson’s lab. The inoculation takes a small portion of a virus and multiplies the sample, allowing researchers to custom-make viruses.

By Madison Knapp | Bond Life Sciences Center summer intern

Modern science has found a way to turn viruses —tiny, dangerous weapons responsible for runny noses, crippling stomach pains and worldwide epidemics such as AIDS— into a tool.

Gene therapy centers on the idea that scientists can hijack viruses and use them as vehicles to deliver DNA to organs in the body that are missing important genes, but the understanding of virus behavior is far from exhaustive.

Marc Johnson, researcher at the Christopher S. Bond Life Sciences Center and associate professor of molecular microbiology and immunology in the MU School of Medicine, has been building an understanding of viral navigation mechanisms which allow a virus to recognize the kind of cell it can infect.

Johnson’s research specifically explores the intricacies of the viral navigation system and could improve future direction of gene therapy, he said.

 

Marc Johnson (left) with a post doctoral student that works in his lab. The lab does important research on the basic function and mechanisms of viral navigation and transport.

Marc Johnson (left) with Dan Salamango, a graduate student that works in his lab. The lab does important research on the basic function and mechanisms of viral navigation and transport.

Turning a virus into a tool

Conceptualized in the 1970s, gene therapy was developed to treat patients for a variety of diseases, including Parkinson’s, leukemia and hemophilia (a genetic condition that stops blood from clotting).

To treat disease using gene therapy, a customized virus is prepared. A virus can be thought of as a missile with a navigation system and two other basic subunits: A capsule that holds the ammunition and the ammunition itself.

The viral genetic material can be thought of as the missile’s ammunition. When a cell is infected, this genetic material is deployed and incorporated into the cell’s DNA. The host cell then becomes a factory producing parts of the virus. Those parts assemble inside the cell to make a new virus, which then leaves the cell to infect another.

The capsule is made of structural protein that contains the genetic material, and the navigation system is a protein that allows the virus to recognize the kind of cell it can infect.

 

Viral navigation

Gene therapy uses viruses to solve many problems by utilizing a virus’ ability to integrate itself into a host cell’s DNA; to do this successfully, researchers need to provide a compatible navigation component.

In the body, viruses speed around as if on a busy highway. Each virus has a navigation system telling it which cells to infect. But sometimes if a virus picks up the wrong type of navigation system, it doesn’t know where to go at all.

“What you can do is find a virus that infects the liver already, steal its navigation protein and use that to assemble the virus you want to deliver the gene the liver needs,” Johnson said. “You can basically take the guidance system off of one and stick it onto another to custom design your virus.”

But this doesn’t always work because of incompatibility among certain viruses, he said.

Johnson and his lab are working to understand what makes switching out navigation proteins possible and why some viruses’ navigation systems are incompatible with other viruses.

“I’m trying to understand what makes it compatible so that hopefully down the road we can intelligently make others compatible,” Johnson said.

 

The right map, the right destination

Johnson creates custom viruses by introducing the three viral components—structural protein, genetic material, and navigation protein—to a cell culture. The structural protein and genetic material match, but the navigation component is the wild card. It could either take to the other parts to produce an infectious virus, or it could be incompatible.

Johnson uses a special fluorescent microscope to identify which viruses assembled correctly and which didn’t.

A successful pairing is like making a match. If a navigation protein is programmed to target liver cells, it’s considered a successful pairing when the virus arrives at the liver cell target location.

The scope of gene therapy continues to widen. Improved mechanisms for gene therapy, and greater knowledge of how a navigation protein drives a virus could help more people benefit from the vehicles viruses can become.

Johnson uses several high-profile model retroviruses, including human immunodeficiency virus (HIV), which affects an estimated 35 million people worldwide each year, according to the World Health Organization.

Understanding nuances of HIV in comparison to other viruses allows Johnson to pick out which behaviors might be common to all retroviruses and others behaviors that might be specific to each virus.

Johnson said his more general approach makes it easier to understand more complex viral features.

“If there are multiple mechanisms at work, it gets a little trickier,” Johnson said. “My angle is more generic, which makes it easier to tease them apart.”

Supervising editor is Paige Blankenbuehler

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.

SMA-sidebar

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