Gene Therapy Treats Eye Disease whithout Surgery

A new gene therapy could eventually provide an alternative treatment for Fuchs’ endothelial corneal dystrophy, a genetic eye disease that affects roughly one in 2,000 people globally. Currently, the only treatment is corneal transplant, a major surgery with associated risks and potential complications.

When you do a transplant you make a huge difference for that person, but it’s a big deal for the patient with lots of visits, lots of eye drops, lots of co-pays, and if you had a medical treatment that did not require surgery, that would be great,” says Bala Ambati, a research professor at the University of Oregon who led an eight-year study involving the development of the gene therapy. “Not only could it help patients who need a transplant, but it could also help a lot of other people who could have used that (corneal) tissue.

For the study in the journal eLife, investigators focused on a rare, early-onset version of the disease and carried out the research in mice. They used CRISPR-Cas9, a powerful tool for editing genomes, to knock out a mutant form of a protein that is associated with the disease.

Fuchs’ dystrophy occurs when cells in the corneal layer called the endothelium gradually die off and stressed cells produce structures known as guttae. These cells normally pump fluid from the cornea to keep it clear, but when they die, fluid builds up, the cornea gets swollen, and vision becomes cloudy or hazy.

We were able to stop this toxic protein expression and study it in a mouse model,” says coauthor Hiro Uehara, a senior research associate in the Ambati lab. “We confirmed that (in mice who received it), our treatment was able to rescue loss of corneal endothelial cells, reduce guttata-like structures, and preserve the corneal endothelial cell pump function.

Corneal cells are non-reproducing, meaning you’re born with all of the cells you will ever have, Ambati says. One of the challenges of the study involved using CRISPR gene editing technology on such cells, a process that is technically difficult.

Uehara developed an innovative workaround that increases the utility of the CRISPR technology and could eventually lead to treatments for other diseases involving non-reproducing cells, including some neurologic diseases, immune diseases, and certain genetic disorders affecting the joints. The study marks the first time that researchers have applied the technique, called start codon disruption, to non-reproducing cells.

Source: https://accelerate.uoregon.edu/

Gene Therapy Offers Hope for Children with Rare, Incurable Disorder

Children with a devastating genetic disorder characterized by severe motor disability and developmental delay have experienced sometimes dramatic improvements in a gene therapy trial launched at UC San Francisco Benioff Children’s Hospitals. The trial includes seven children aged 4 to 9 born with deficiency of AADC, an enzyme involved in the synthesis of neurotransmitters, particularly dopamine, that leaves them unable to speak, feed themselves or hold up their head. Six of the children were treated at UCSF and one at Ohio State Wexner Medical Center.

Children in the study experienced improved motor function, better mood, and longer sleep, and were able to interact more fully with their parents and siblings. Oculogyric crisis, a hallmark of the disorder involving involuntary upward fixed gaze that may last for hours and may be accompanied by seizure-like episodes, ceased in all but one patient. Just 135 children worldwide are known to be missing the AADC enzyme, with the condition affecting more people of Asian descent.

The trial borrowed from gene delivery techniques used to treat Parkinson’s disease, pioneered by senior author Krystof Bankiewicz, MD, PhD, of the UCSF Department of Neurological Surgery and the Weill Institute for Neurosciences, and of the Department of Neurological Surgery at Ohio State University. Both conditions are associated with deficiencies of AADC, which converts levodopa into dopamine, a neurotransmitter involved in movement, mood, learning and concentration. In treating both conditions, Bankiewicz developed a viral vector containing the AADC gene. The vector is infused into the brain via a small hole in the skull, using real-time MR imaging to enable the neurosurgeon to map the target region and plan canula insertion and infusion.

Children with primary AADC deficiency lack a functional copy of the gene, but we had presumed that their actual neuronal pathway was intact,” said co-first author Nalin Gupta, MD, PhD, of the UCSF Department of Neurological Surgery and the surgical principal investigator. “This is unlike Parkinson’s disease, where the neurons that produce dopamine undergo degeneration.

While the Parkinson’s trial focused on the putamen, a part of the brain that plays a key role in this degeneration, Gupta said the AADC gene therapy trial targeted neurons in the substantia nigra and ventral tegmental area of the brainstem, sites that may have more therapeutic benefits.

The approach for treating AADC deficiency is much more straightforward than it is for Parkinson’s,” said Bankiewicz. “In AADC deficiency, the wiring of the brain is normal, it’s just the neurons don’t know how to produce dopamine because they lack AADC.”

Results appear in Nature Communications.

Source: https://www.ucsf.edu/

How To Regenerate Optic Nerve Cells

Scientists have found a new way to regenerate damaged optic nerve cells taken from mice and grown in a dish. This exciting development could lead to potential eye disease treatments in the future. Damage to full-grown nerve cells causes irreversible and life-altering consequences, because once nerve fibres mature, they lose their ability to regenerate after injury or disease. The new experiments show how activating part of a nerve cell’s regenerative machinery, a protein known as protrudin, could stimulate nerves in the eye to regrow after injury.

With more research, the achievement is a step towards future treatments for glaucoma, a group of eye diseases which cause vision loss by damaging the optic nerve (that links the eye to the brain).

What we’ve seen is the strongest regeneration of any technique we’ve used before,said ophthalmologist Keith Martin from the University of Melbourne in Australia. “In the past it seemed impossible we would be able to regenerate the optic nerve but this research shows the potential of gene therapy to do this.”

In this study, scientists stimulated nerve cells of the eye to produce more protrudin, to see if this would help protect the cells from damage and even repair after injury. First, in optical nerve cells cultured in a dish, the researchers showed that ramping up protrudin production stimulated regeneration of nerve cells that had been cut by a laser. Their spindly axons regenerated over longer distances, and in less time, than untreated cells.  Next, adult mice were administered gene therapy – an injection straight into the eye – carrying instructions for nerve cells to bump up protrudin production. As painful as that sounds, this procedure can actually be done safely in people (the injection, that is, not yet the gene therapy).

A few weeks and one optic nerve injury later, these mice had more surviving nerve cells in their retinas than the control group did. In one final experiment, the scientists used whole retinas from mice removed two weeks after giving them a protrudin boost, to see if this treatment could prevent nerve cells from dying in the first place. The researchers found, three days later, that stimulating protrudin production had been almost “entirely neuroprotective, with these retinas exhibiting no loss of [retinal] neurons,” the researchers wrote in their paper. Usually, about half of retinal neurons removed in this way die within a couple of days.

“Our strategy relies on using gene therapy – an approach already in clinical use – to deliver protrudin into the eye,” said Veselina Petrova, a neuroscience student at the University of Cambridge. “It’s possible our treatment could be further developed as a way of protecting retinal neurons from death, as well as stimulating their axons to regrow.”

Source: https://www.cam.ac.uk/

The Rising Of Gene Therapy

After false starts, drugs that manipulate the code of life are finally changing lives. The idea for gene therapy—a type of DNA-based medicine that inserts a healthy gene into cells to replace a mutated, disease-causing variant—was first published in 1972. After decades of disputed results, treatment failures and some deaths in experimental trials, the first gene therapy drug, for a type of skin cancer, was approved in China in 2003. The rest of the world was not easily convinced of the benefits, however, and it was not until 2017 that the U.S. approved one of these medicines. Since then, the pace of approvals has accelerated quickly. At least nine gene therapies have been approved for certain kinds of cancer, some viral infections and a few inherited disorders. A related drug type interferes with faulty genes by using stretches of DNA or RNA to hinder their workings. After nearly half a century, the concept of genetic medicine has become a reality.

These treatments use a harmless virus to carry a good gene into cells, where the virus inserts it into the existing genome, canceling the effects of harmful mutations in another gene.

GENDICINE: China’s regulatory agency approved the world’s first commercially available gene therapy in 2003 to treat head and neck squamous cell carcinoma, a form of skin cancer. Gendicine is a virus engineered to carry a gene that has instructions for making a tumor-fighting protein. The virus introduces the gene into tumor cells, causing them to increase the expression of tumor-suppressing genes and immune response factors.The drug is still awaiting FDA approval.

GLYBERA: The first gene therapy to be approved in the European Union treated lipoprotein lipase deficiency (LPLD), a rare inherited disorder that can cause severe pancreatitis. The drug inserted the gene for lipoprotein lipase into muscle cells. But because LPLD occurs in so few patients, the drug was unprofitable. By 2017 its manufacturer declined to renew its marketing authorization; Glybera is no longer on the market.

IMLYGIC: The drug was approved in China, the U.S. and the E.U. to treat melanoma in patients who have recurring skin lesions following initial surgery. Imlygic is a modified genetic therapy inserted directly into tumors with a viral vector, where the gene replicates and produces a protein that stimulates an immune response to kill cancer cells.

KYMRIAH: Developed for patients with B cell lymphoblastic leukemia, a type of cancer that affects white blood cells in children and young adults, Kymriah was approved by the FDA in 2017 and the E.U. in 2018. It works by introducing a new gene into a patient’s own T cells that enables them to find and kill cancer cells.

LUXTURNA: The drug was approved by the FDA in 2017 and in the E.U. in 2018 to treat patients with a rare form of inherited blindness called biallelic RPE65 mutation-associated retinal dystrophy. The disease affects between 1,000 and 2,000 patients in the U.S. who have a mutation in both copies of a particular gene, RPE65. Luxturna delivers a normal copy of RPE65 to patients’ retinal cells, allowing them to make a protein necessary for converting light to electrical signals and restoring their vision.

STRIMVELIS: About 15 patients are diagnosed in Europe every year with severe immunodeficiency from a rare inherited condition called adenosine deaminase deficiency (ADA-SCID). These patients’ bodies cannot make the ADA enzyme, which is vital for healthy white blood cells. Strimvelis, approved in the E.U. in 2016, works by introducing the gene responsible for producing ADA into stem cells taken from the patient’s own marrow. The cells are then reintroduced into the patient’s bloodstream, where they are transported to the bone marrow and begin producing normal white blood cells that can produce ADA.

YESCARTA: Developed to treat a cancer called large B cell lymphoma, Yescarta was approved by the FDA in 2017 and in the E.U. in 2018. It is in clinical trials in China. Large B cell lymphoma affects white blood cells called lymphocytes. The treatment, part of an approach known as CAR-T cell therapy, uses a virus to insert a gene that codes for proteins called chimeric antigen receptors (CARs) into a patient’s T cells. When these cells are reintroduced into the patient’s body, the CARs allow them to attach to and kill cancer cells in the bloodstream.

ZOLGENSMA: In May 2019 the FDA approved Zolgensma for children younger than two years with spinal muscular atrophy, a neuromuscular disorder that affects about one in 10,000 people worldwide. It is one of the leading genetic

causes of infant mortality. Zolgensma delivers a healthy copy of the human SMN gene to a patient’s motor neurons in a single treatment.

ZYNTEGLO: Granted approval in the E.U. in May 2019, Zynteglo treats a blood disorder called beta thalassemia that reduces a patient’s ability to produce hemoglobin, the protein in red blood cells that contains iron, leading to life-threatening anemia. The therapy has been approved for individuals 12 years and older who require regular blood transfusions. It employs a virus to introduce healthy copies of the gene for making hemoglobin into stem cells taken from the patient.The cells are then reintroduced into the bloodstream and transported to the bone marrow, where they begin producing healthy red blood cells that can manufacture hemoglobin.

The approach called ‘Gene Interference‘ uses a synthetic strand of RNA or DNA (called an oligonucleotide) that, when introduced into a patient’s cell, can attach to a specific gene or its messenger molecules, effectively inactivating them. Some treatments use an antisense method, named for one DNA strand, and others rely on small interfering RNA strands, which stop instruction molecules that go from the gene to the cell’s protein factories.

Source: https://www.nature.com/

Gene Therapy Combats Efficiently Age-related Diseases

As we age, our bodies tend to develop diseases like heart failure, kidney failure, diabetes, and obesity, and the presence of any one disease increases the risk of developing others. In traditional drug development, a drug usually only targets one condition, largely ignoring the interconnectedness of age-related diseases, such as obesity, diabetes, and heart failure, and requiring patients to take multiple drugs, which increases the risk of negative side effects.

A new study from the Wyss Institute for Biologically Inspired Engineering at Harvard University and Harvard Medical School (HMS) reports that a single administration of an adeno-associated virus (AAV)-based gene therapy delivering combinations of three longevity-associated genes to mice dramatically improved or completely reversed multiple age-related diseases, suggesting that a systems-level approach to treating such diseases could improve overall health and lifespan. The research is reported in PNAS.

The AAV-based gene therapy improved the function of the heart and other organs in mice with various age-related diseases, suggesting that such an approach could help maintain health during aging.

The results we saw were stunning, and suggest that holistically addressing aging via gene therapy could be more effective than the piecemeal approach that currently exists,” said first author Noah Davidsohn, Ph.D., a former Research Scientist at the Wyss Institute and HMS who is now the Chief Technology Officer of Rejuvenate Bio. “Everyone wants to stay as healthy as possible for as long as possible, and this study is a first step toward reducing the suffering caused by debilitating diseases.

The study was conducted in the lab of Wyss Core Faculty member George Church, Ph.D. as part of Davidsohn’s postdoctoral research into the genetics of aging. Davidsohn, Church, and their co-authors honed in on three genes that had previously been shown to confer increased health and lifespan benefits when their expression was modified in genetically engineered mice: FGF21, sTGFβR2, and αKlotho. They hypothesized that providing extra copies of those genes to non-engineered mice via gene therapy would similarly combat age-related diseases and confer health benefits.

The team created separate gene therapy constructs for each gene using the AAV8 serotype as a delivery vehicle, and injected them into mouse models of obesity, type II diabetes, heart failure, and renal failure both individually and in combination with the other genes to see if there was a synergistic beneficial effect.

Source; https://wyss.harvard.edu/

Gold Nanoparticles Ship With Efficiency CRISPR Cargo

Forget UPS and FedEx: Tiny golden delivery trucks created at Fred Hutchinson Cancer Research Center can ship CRISPR into human blood stem cells, offering a potential way to treat diseases like HIV and sickle cell anemia. And the researchers behind those trucks have even bigger distribution dreams. Gene therapy — the editing of our DNA to treat disease — is a clinical reality today, but only in a handful of rich countries. Fred Hutch scientists think their new CRISPR courier could help deliver gene therapy to patients around the world.

A new paper published in Nature Materials describes how the scientists loaded CRISPR onto spherical gold nanoparticles. These tiny shuttles then deposited the gene-editing tool into blood stem cells donated by healthy individuals and isolated in test tubes, where CRISPR altered genes related to HIV and certain blood disorders.   It is the first time that nanoparticles have successfully ferried CRISPR into blood stem cells to edit DNA, the researchers said. And it’s a promising step toward addressing CRISPR’s critical delivery problems. The first of these problems has vexed the field since the gene-editing technique was discovered. Scientists need to deliver CRISPR into the right spot in a cell. That is proving tricky enough. DNA represents the body’s crown jewels, and CRISPR must sneak past all sorts of security systems to gain access.

And then CRISPR must go global. Gene editing could benefit millions of people worldwide. But as the treatment process stands right now, the vast majority won’t. That process depends almost entirely on highly engineered viruses made in high-tech, multimillion-dollar facilities.
The researchers think their golden nanoparticles can solve both problems. As efficient couriers, they could reduce the need for engineered viruses and specialized research centers. And that could help make these emerging, high-tech treatments accessible and affordable, said senior scientist Dr. Jennifer Adair of Fred Hutch.

Gene therapy has a lot of potential across many diseases, but the process we have right now is just not feasible in every place in the world,” Adair said. “We want to end up delivering gene therapy in a syringe. This gold nanoparticle represents the first possibility we have to do that for blood stem cells.”

Source: https://www.fredhutch.org/

Nanomachines To Deliver Cancer Drugs to Hard-to-reach Areas

In a recent study in mice, researchers found a way to deliver specific drugs to parts of the body that are exceptionally difficult to access. Their Y-shaped block catiomer (YBC) binds with certain therapeutic materials forming a package 18 nanometers wide. The package is less than one-fifth the size of those produced in previous studies, so can pass through much smaller gaps. This allows YBCs to slip through tight barriers in cancers of the brain or pancreas.

The fight against cancer is fought on many fronts. One promising field is gene therapy, which targets genetic causes of diseases to reduce their effect. The idea is to inject a nucleic acid-based drug into the bloodstream — typically small interfering RNA (siRNA) — which binds to a specific problem-causing gene and deactivates it. However, siRNA is very fragile and needs to be protected within a nanoparticle or it breaks down before reaching its target.

siRNA can switch off specific gene expressions that may cause harm. They are the next generation of biopharmaceuticals that could treat various intractable diseases, including cancer,” explained Associate Professor Kanjiro Miyata of the University of Tokyo, who jointly supervised the study. “However, siRNA is easily eliminated from the body by enzymatic degradation or excretion. Clearly a new delivery method was called for.”

Presently, nanoparticles are about 100 nanometers wide, one-thousandth the thickness of paper. This is small enough to grant them access to the liver through the leaky blood vessel wall. However some cancers are harder to reach. Pancreatic cancer is surrounded by fibrous tissues and cancers in the brain by tightly connected vascular cells. In both cases the gaps available are much smaller than 100 nanometers. Miyata and colleagues created an siRNA carrier small enough to slip through these gaps in the tissues.

We used polymers to fabricate a small and stable nanomachine for the delivery of siRNA drugs to cancer tissues with a tight access barrier,” said Miyata. “The shape and length of component polymers is precisely adjusted to bind to specific siRNAs, so it is configurable.”

Source: https://www.u-tokyo.ac.jp/