Posts

muscle cells

Experimental model mimics early-stage myogenic deficit in boys with DMD

muscle cells

Muscle regeneration marked by incorporation of muscle stem cell nuclei (green) in the myofibers (red) in dystrophic muscles with low TGFβ level (upper image), but not with high TGFβ level (lower image). Inflammatory and other nuclei are labeled blue.

Boys with Duchenne muscular dystrophy (DMD) experience poor muscle regeneration, but the precise reasons for this remain under investigation. An experimental model of severe DMD that experiences a large spike in transforming growth factor-beta (TGFβ) activity after muscle injury shows that high TGFβ activity suppresses muscle regeneration and promotes fibroadipogenic progenitors (FAPs). This leads to replacement of the damaged muscle fibers by calcified and connective tissue, compromising muscle structure and function. While blocking FAP buildup provides a partial solution, a Children’s National Hospital study team identifies correcting the muscle micro-environment caused by high TGFβ as a ripe therapeutic target.

The team’s study was published online March 26, 2020, in JCI Insight.

DMD is a chronic muscle disease that affects 1 in 6,200 young men in the prime of their lives. The disorder, caused by genetic mutations leading to the inability to produce dystrophin protein, leads to ongoing muscle damage, chronic inflammation and poor regeneration of lost muscle tissue. The patients experience progressive muscle wasting, lose the ability to walk by the time they’re teenagers and die prematurely due to cardiorespiratory failure.

The Children’s National team finds for the first time that as early as preadolescence (3 to 4 weeks of age), their experimental model of severe DMD disease showed clear signs of the type of spontaneous muscle damage, regenerative failure and muscle fiber loss seen in preadolescent boys who have DMD.

“In boys, the challenge due to muscle loss exists from early in their lives, but had not been mimicked previously in experimental models,” says Jyoti K. Jaiswal, MSc, Ph.D., principal investigator in the Center for Genetic Medicine Research at Children’s National, and the study’s co-senior author. “TGFβ is widely associated with muscle fibrosis in DMD, when, in fact, our work shows its role in this disease process is far more significant.”

Research teams have searched for experimental models that replicate the sudden onset of symptoms in boys who have DMD as well as its complex progression.

“Our work not only offers insight into the delicate balance needed for regeneration of skeletal muscle, but it also provides quantitative information about muscle stem cell activity when this balanced is disturbed,” says Terence A. Partridge, Ph.D., principal investigator in the Center for Genetic Medicine Research at Children’s National, and the study’s co-senior author.

This schematic depicts the fate of injured myofibers in healthy or dystrophic muscle

This schematic depicts the fate of injured myofibers in healthy or dystrophic muscle (WT or mdx experimental models) that maintain low TGFβ level, compared with D2-mdx experimental models that experience a large increase in TGFβ level. As the legend shows, various cells are involved in this regenerative response.

“The D2-mdx experimental model is a relevant one to use to investigate the interplay between inflammation and muscle degeneration that is seen in humans with DMD,” adds Davi A.G. Mázala, co-lead study author.  “This model faithfully recapitulates many features of the complex disease process seen in humans.”

Between 3 to 4 weeks of age in the experimental models of severe DMD disease, the level of active TGFβ spiked up to 10-fold compared with models with milder disease. Intramuscular injections of an off-the-shelf drug that inhibits TGFβ signaling tamped down the number of FAPs, improving the muscle environment by lowering TGFβ activity.

“This work lays the foundation for studies that could lead to future therapeutic strategies to improve patients’ outcomes and lessen disease severity,” says James S. Novak, Ph.D., principal investigator in Children’s Center for Genetic Medicine Research, and co-lead study author. “Ultimately, our goal is to improve the ability of patients to continue to maintain muscle mass and regenerate muscle.”

In addition to Mázala, Novak, Jaiswal and Partridge, Children’s National study co-authors include Marshall W. Hogarth; Marie Nearing; Prabhat Adusumalli; Christopher B. Tully; Nayab F. Habib; Heather Gordish-Dressman, M.D.; and Yi-Wen Chen, Ph.D.

Financial support for the research described in this post was provided by the National Institutes of Health under award Nos. T32AR056993, R01AR055686 and U54HD090257; Foundation to Eradicate Duchenne; Muscular Dystrophy Association under award Nos. MDA295203, MDA480160 and MDA 477331; Parent Project Muscular Dystrophy; and Duchenne Parent Project – Netherlands.

Vote for STAT Madness

It’s a three-peat! Children’s National again competes in STAT Madness

Vote for STAT Madness

Children’s National Hospital collects patients’ blood, extracts T-cells and replicates them in the presence of specific proteins found on cancer cells which, in essence, teaches the T-cells to target specific tumor markers. Training the T-cells, growing them to sufficient quantities and ensuring they are safe for administration takes weeks. But when patients return to the outpatient clinic, their T-cell infusion lasts just a few minutes.

For the third consecutive year, Children’s National was selected to compete in STAT Madness, an annual bracket-style competition that chooses the year’s most impactful biomedical innovation by popular vote. Children’s entry, “Immunotherapy of relapsed and refractory solid tumors with ex vivo expanded multi-tumor associated antigen specific cytotoxic T lymphocytes,” uses the body’s own immune system to attack and eliminate cancer cells in pediatric and adult patients with solid tumor malignancies.

In 2018, Children’s first-ever STAT Madness entry advanced through five brackets in the national competition and, in the championship round, finished second. That innovation, which enables more timely diagnoses of rare diseases and common genetic disorders, helping to improve kids’ health outcomes around the world, also was among four “Editor’s Pick” finalists, entries that spanned a diverse range of scientific disciplines.

An estimated 11,000 new cases of pediatric cancer were diagnosed in children 14 and younger in the U.S. in 2019. And, when it comes to disease, cancer remains the leading cause of death among children, according to the National Institutes of Health. An enterprising research team led by Children’s National faculty leveraged T-cells – essential players in the body’s immune system – to treat pediatric and adult patients with relapsed or refractory solid tumors who had exhausted all other therapeutic options.

“We’re using the patient’s own immune system to fight their cancer, rather than more traditional chemotherapy drugs,” says Catherine M. Bollard, M.D., director of the Center for Cancer & Immunology Research at Children’s National and co-senior author of the study. “It’s more targeted and less toxic to the patient. These T-cells home in on any cancer cells that might be in the body, allowing healthy cells to continue to grow,” Dr. Bollard adds.

That means patients treated in the Phase I, first-in-human trial didn’t lose their hair and weren’t hospitalized for the treatment. After a quick clinical visit for their treatment, they returned to normal activities, like school, with good energy levels.

“With our specially trained T-cell therapy, many patients who previously had rapidly progressing disease experienced prolonged disease stabilization,” says Holly J. Meany, M.D., a Children’s National oncologist and the study’s co-senior author. “Patients treated at the highest dose level showed the best clinical outcomes, with a six-month, progression-free survival of 73% after tumor-associated antigen cytotoxic T-cell (TAA-T) infusion, compared with 38% with their immediate prior therapy.”

The multi-institutional team published their findings from the study online July 29, 2019, in the Journal of Clinical Oncology.

“Our research team and our parents are delighted that some patients treated in our study continue to do well following T-cell therapy without additional treatment. In some cases, two years after treatment, patients do not appear to have active disease and are maintaining an excellent quality of life,” says Amy B. Hont, M.D., the study’s lead author. “One of these was a patient whose parents were told his only other option was palliative care. Our innovation gives these families new hope,” Dr. Hont adds.

The 2020 STAT Madness #Core64 bracket opened March 2, and the champion will be announced April 6.

In addition to Drs. Hont, Meany and Bollard, Children’s National co-authors include C. Russell Cruz, M.D., Ph.D., Robert Ulrey, MS, Barbara O’Brien, BS, Maja Stanojevic, M.D., Anushree Datar, MS, Shuroug Albihani, MS, Devin Saunders, BA, Ryo Hanajiri, M.D., Ph.D., Karuna Panchapakesan, MS, Payal Banerjee, MS, Maria Fernanda Fortiz, BS, Fahmida Hoq, MBBS, MS, Haili Lang, M.D., Yunfei Wang, DrPH, Patrick J. Hanley, Ph.D., and Jeffrey S. Dome, M.D., Ph.D.; and Sam Darko, MS, National Institute of Allergy and Infectious Diseases.

Financial support for the research described in this post was provided by the Children’s National Hospital Heroes Gala, Alex’s Army Foundation, the Children’s National Board of Visitors and Hyundai Hope on Wheels Young Investigator Grant to Support Pediatric Cancer Research, the Children’s National Research Institute Bioinformatics Unit, the Clinical and Translational Science Institute and the National Institutes of Health under award No. UL1-TR001876.

DNA Molecule

Decoding cellular signals linked to hypospadias

DNA Molecule

“By advancing our understanding of the genetic causes and the anatomic differences among patients, the real goal of this research is to generate knowledge that will allow us to take better care of children with hypospadias,” Daniel Casella, M.D. says.

Daniel Casella, M.D., a urologist at Children’s National, was honored with an AUA Mid-Atlantic Section William D. Steers, M.D. Award, which provides two years of dedicated research funding that he will use to better understand the genetic causes for hypospadias.

With over 7,000 new cases a year in the U.S., hypospadias is a common birth defect that occurs when the urethra, the tube that transports urine out of the body, does not form completely in males.

Dr. Casella has identified a unique subset of cells in the developing urethra that have stopped dividing but remain metabolically active and are thought to represent a novel signaling center. He likens them to doing the work of a construction foreman. “If you’re constructing a building, you need to make sure that everyone follows the blueprints.  We believe that these developmentally senescent cells are sending important signals that define how the urethra is formed,” he says.

His project also will help to standardize the characterization of hypospadias. Hypospadias is classically associated with a downward bend to the penis, a urethra that does not extend to the head of the penis and incomplete formation of the foreskin. Still, there is significant variability among patients’ anatomy and to date, no standardized method for documenting hypospadias anatomy.

“Some surgeons take measurements in the operating room, but without a standardized classification system, there is no definitive way to compare measurements among providers or standardize diagnoses from measurements that every surgeon makes,” he adds. “What one surgeon may call ‘distal’ may be called ‘midshaft’ by another.” (With distal hypospadias, the urethra opening is near the penis head; with midshaft hypospadias, the urethra opening occurs along the penis shaft.)

“By advancing our understanding of the genetic causes and the anatomic differences among patients, the real goal of this research is to generate knowledge that will allow us to take better care of children with hypospadias,” he says.

Parents worry about lingering social stigma, since some boys with hypospadias are unable to urinate while standing, and in older children the condition can be associated with difficulties having sex. Surgical correction of hypospadias traditionally is performed when children are between 6 months to 1 year old.

When reviewing treatment options with family, “discussing the surgery and postoperative care is straight forward. The hard part of our discussion is not having good answers to questions about long-term outcomes,” he says.

Dr. Casella’s study hopes to build the framework to enable that basic research to be done.

“Say we wanted to do a study to see how patients are doing 15-20 years after their surgery.  If we go to their charts now, often we can’t accurately describe their anatomy prior to surgery.  By establishing uniform measurement baselines, we can accurately track long-term outcomes since we’ll know what condition that child started with and where they ended up,” he says.

Dr. Casella’s research project will be conducted at Children’s National under the mentorship of Eric Vilain, M.D., Ph.D., an international expert in sex and genitalia development; Dolores J. Lamb, Ph.D., HCLD, an established leader in urology based at Weill Cornell Medicine; and Marius George Linguraru, DPhil, MA, MSc, an expert in image processing and artificial intelligence.