Model of a sticky situation

Here’s an example of how 3D printing can be applied to pediatric cardiology. It’s also an example of how Georgia Tech, Emory and Children’s Healthcare of Atlanta all work together.

Biomedical engineers used a modified form of gelatin to create a model of pulmonary arteries in newborn and adolescent patients with a complex (and serious) congenital heart defect: tetralogy of Fallot with pulmonary atresia. The model allowed the researchers to simulate surgical catheter-based intervention in vitro.

The results were recently published in Journal of the American Heart Association. Biomedical engineer Vahid Serpooshan and his lab collaborated with Sibley Heart Center pediatric cardiologist Holly Bauser-Heaton; both are part of the Children’s Heart Research and Outcomes Center.

“This is a patient-specific platform, created with state-of-the-art 3D bioprinting technology, allowing us to optimize various interventions,” Serpooshan says.

Model of an adolescent patient’s pulmonary arteries, created by 3D printing. From Tomov et al JAHA (2019) via Creative Commons

Posted on January 7, 2020 by Quinn Eastman in Heart Leave a comment

Powerful opioids + kids: bad combo

New research demonstrates the dangers of having powerful opioids such as fentanyl around children and adolescents. National Poison Data System reports show that many are ingesting the drugs unintentionally, but particularly concerning is a rise in the proportion of suspected suicides.

Among children, the proportion of opioid poisonings resulting in admission to a hospital critical care unit has increased since 2005, according to an analysis by Emory and Children’s Healthcare of Atlanta doctors.

Megan Land, MD, Jocelyn Grunwell, MD, PhD and colleagues in the Division of Critical Care in the Department of Pediatrics conducted the research, which is published in the journal Clinical Toxicology.

In a December 20 broadcast, critical care fellow Land told NPR’s Rhitu Chatterjee about her encounter with a child with severe respiratory distress as a result of consuming a fentanyl patch. Grunwell has previous experience studying pediatric intensive care admissions procedures and poisonings.

Posted on January 2, 2020 by Quinn Eastman in Uncategorized Leave a comment

Sifting through signs of inflammation to analyze causes of Crohn’s disease

When studying Crohn’s disease – an inflammatory disorder of the gastrointestinal tract, a challenge is separating out potential causes from the flood of systemic inflammation inherent in the condition. Researchers led by Subra Kugathasan, MD recently published an analysis that digs under signs of inflammation, in an effort to assess possible causes.

Graduate student Hari Somineni, in Kugathasan’s lab, teamed up with Emory and Georgia Tech geneticists for a sophisticated approach that may have found some gold nuggets in the inflammatory gravel. The results were published in the journal Gastroenterology.

In studying Crohn’s disease, Emory + Georgia Tech researchers may have found some gold nuggets in the inflammatory gravel.

The group looked at DNA methylation in blood samples from pediatric patients with Crohn’s disease, both at diagnosis and after treatment and follow-up. The information came from blood samples from 164 children with Crohn’s disease and 74 controls, as part of the RISK study, which is supported by the Crohn’s & Colitis Foundation and Kugathasan leads.

DNA methylation is a dynamic process that can influence molecular phenotypes of complex diseases by turning the gene(s) on or off. The researchers observed that disrupted methylation patterns at the time of diagnosis in pediatric Crohn’s disease patients returned to those resembling controls following treatment of inflammation

“Our study emphasized how important it is to do longitudinal profiling – to look at the patients before and after treatment, rather than just taking a cross section,” Somineni says.

Posted on March 6, 2019 by Quinn Eastman in Immunology Leave a comment

Where it hurts matters in the gut

What part of the intestine is problematic matters more than inflammatory bowel disease subtype (Crohn’s disease vs ulcerative colitis), when it comes to genetic activity signatures in pediatric IBD.

Suresh Venkateswaran and Subra Kugathasan in the lab

That’s the takeaway message for a recent paper in Cellular and Molecular Gastroenterology and Hepatology (the PDF is open access) from gastroenterologist Subra Kugathasan and colleagues. His team has been studying risk factors in pediatric IBD that could predict whether a child will experience complications requiring surgery.

Kugathasan is professor of pediatrics and human genetics at Emory University School of Medicine and scientific director of the pediatric IBD program at Children’s Healthcare of Atlanta. He is also director of the Children’s Center for Transplantation and Immune-mediated Disorders.

“This study has demonstrated that tissue samples from the ileum and rectum of CD patients show higher molecular level differences, whereas in tissue samples from two different patients with the same type of disease, the molecular differences are low,” Kugathasan says. “This was an important question to answer, since IBD can be localized to one area, and the treatment responses can vary and can be tailored to a localized area if this knowledge is well known.”

Research associate Suresh Venkateswaran, PhD, is the first author on the CMGH paper.

“We see that the differences are not connected to genomic variations,” he says. “Instead, they may be caused by non-genetic factors which are specific to each location and disease sub-type of the patient.”

These findings have implications for other study designs involving molecular profiling of IBD patients. The authors believe the findings will be important for future design of locally acting drugs.

Posted on July 26, 2018 by Quinn Eastman in Immunology Leave a comment

Blood vessels and cardiac muscle cells off the shelf

Tube-forming ability of purified CD31+ endothelial cells derived from induced pluripotent stem cells after VEGF treatment.

Chunhui Xu’s lab in the Department of Pediatrics recently published a paper in Stem Cell Reports on the differentiation of endothelial cells, which line and maintain blood vessels. Her lab is part of the Emory-Children’s-Georgia Tech Pediatric Research Alliance. The first author was postdoc Rajneesh Jha.

This line of investigation could eventually lead to artificial blood vessels, grown with patients’ own cells or “off the shelf,” or biological/pharmaceutical treatments that promote the regeneration of damaged blood vessels. These treatments could be applied to peripheral artery disease and/or coronary artery disease.

Xu’s paper concerns the protein LGR5, part of the Wnt signaling pathway. The authors report that inhibiting LGR5 steers differentiating pluripotent stem cells toward endothelial cells and away from cardiac muscle cells. The source iPSCs were a widely used IMR90 line.

Young-sup Yoon’s lab at Emory has also been developing methods for the generation of endothelial cells via “direct reprogramming.”

Posted on August 15, 2017 by Quinn Eastman in Heart Leave a comment

Excellent exosomes harvest cardiac regenerative capacity

Thanks to biomedical engineer Mike Davis for writing an explanation of “Exosomes: what do we love so much about them?” for Circulation Research, a companion to his lab’s November 2016 publication analyzing exosomes secreted by human cardiac progenitor cells.

We can think of exosomes as tiny packages that cells send each other. They’re secreted bubbles containing proteins and regulatory RNAs. Thus, they may be a way to harvest the regenerative capacity of pediatric heart tissue without delivering the cells themselves.

Mike Davis, PhD is director of the Children’s Heart Research and Outcomes Center (HeRO), part of the Emory/Children’s/Georgia Tech Pediatric Research Alliance

Davis’ lab studied cardiac tissue derived from children of different ages undergoing surgery for congenital heart defects. The scientists isolated exosomes from the cardiac progenitor cells, and tested their regenerative activity in rats with injured hearts.

They found that exosomes derived from older children’s cells were only reparative if they were subjected to hypoxic conditions (lack of oxygen), while exosomes from newborns’ cells improved rats’ cardiac function with or without hypoxia. Read more

Posted on March 13, 2017 by Quinn Eastman in Heart Leave a comment

Double vision: seeing viruses by both light and electron microscopy

Advances in both light and electron microscopy are improving scientists’ ability to visualize viruses such as HIV, respiratory syncytial virus (RSV), measles, influenza, and Zika in their native states.

Researchers from Emory University School of Medicine and Children’s Healthcare of Atlanta developed workflows for cryo-correlative light and electron microscopy (cryo-CLEM), which were published in the January 2017 issue of Nature Protocols.

An example of the images of viruses obtainable with cryo-CLEM. Pseudotyped HIV-1 particles undergoing endocytosis. Viral membrane = light blue. Mature core = yellow. Clathrin cages = purple. From Hampton et al Nat. Protocols (2016)

Previously, many electron microscopy images of well-known viruses were obtained by studying purified virus preparations. Yet the process of purification can distort the structure of enveloped viruses, says Elizabeth R. Wright, PhD, associate professor of pediatrics at Emory University School of Medicine.

Wright and her colleagues have refined techniques for studying viruses in the context of the cells they infect. That way, they can see in detail how viruses enter and are assembled in cells, or how genetic modifications alter viral structures or processing.

“Much of what is known about how some viruses replicate in cells is really a black box at the ultrastructural level,” she says. “We see ourselves as forming bridges between light and electron microscopy, and opening up new realms of biological questions.”

Wright is director of Emory’s Robert P. Apkarian Integrated Electron Microscopy Core and a Georgia Research Alliance Distinguished Investigator. The co-first authors of the Nature Protocols paper are postdoctoral fellows Cheri Hampton, PhD. and Joshua Strauss, PhD, and graduate students Zunlong Ke and Rebecca Dillard.

The Wright lab’s work on cryo-CLEM includes collaborations with Gregory Melikyan in Emory’s Department of Pediatrics, Phil Santangelo in the Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory, and Paul Spearman, now at Cincinnati Children’s.

For this technique, virus-infected or transfected cells are grown on fragile carbon-coated gold grids and then “vitrified,” meaning that they are cooled rapidly so that ice crystals do not form. Once cooled, the cells are examined by cryo-fluorescent light microscopy and cryo-electron tomography. Read more

Posted on January 4, 2017 by Quinn Eastman in Immunology Leave a comment

Threading the RSV needle: live attenuated vaccine effective in animals

Crafting a vaccine against RSV (respiratory syncytial virus) has been a minefield for 50 years, but scientists believe they have found the right balance.

A 3-D rendering of a live-attenuated respiratory syncytial virus (RSV) particle, captured in a near-to-native state by cryo-electron tomography. Surface glycoproteins (yellow) are anchored on the viral membrane (cyan), with ribonucleoprotein complexes inside (red). Image courtesy of Zunlong Ke and Elizabeth Wright.

Researchers at Emory University School of Medicine and Children’s Healthcare of Atlanta have engineered a version of RSV that is highly attenuated – weakened in its ability to cause disease – yet potent in its ability to induce protective antibodies.

The researchers examined the engineered virus using cryo-electron microscopy and cryo-electron tomography techniques, and showed that it is structurally very similar to wild type virus. When used as a vaccine, it can protect mice and cotton rats from RSV infection.

The results were published this morning in Nature Communications.

“Our paper shows that it’s possible to attenuate RSV without losing any immunogenicity,” says senior author Martin Moore, PhD, associate professor of pediatrics at Emory University School of Medicine and a Children’s Healthcare of Atlanta Research Scholar. “This is a promising live-attenuated vaccine candidate that merits further investigation clinically.”

The next steps for this vaccine are to produce a clinical grade lot and conduct a phase 1 study of safety and immunogenicity in infants, Moore says. Read more

Posted on December 21, 2016 by Quinn Eastman in Immunology Leave a comment

Bad neighbors cause bad blood -> cancer

Certain DNA mutations in bone cells that support blood development can drive leukemia formation in nearby blood stem cells, cancer researchers have found.

Many cancer-driving mutations are “cell-autonomous,” meaning the change in a cell’s DNA makes that same cell grow more rapidly. In contrast, an indirect neighbor cell effect was observed in a mouse model of Noonan syndrome, an inherited disorder that increases the risk of developing leukemia.

In mouse bone marrow, mesenchymal stem cells (red), which normally nurture blood stem cells, produce a signal that is attractive for monocytes. The monocytes (green) prod nearby blood stem cells to proliferate, leading to leukemia. From Dong et al Nature (2016).

The findings were published Wednesday, October 26 in Nature.

The neighbor cell effect could be frustrating efforts to treat leukemias in patients with Noonan syndrome and a related condition, juvenile myelomonocytic leukemia (JMML). That’s because bone marrow transplant may remove the cancerous cells, but not the cause of the problem, leading to disease recurrence. However, the researchers show that a class of drugs can dampen the cancer-driving neighbor effect in mice. One of the drugs, maraviroc, is already FDA-approved against HIV infection.

“Our research highlights the importance of the bone marrow microenvironment,” says Cheng-Kui Qu, MD, PhD, professor of pediatrics at Emory University School of Medicine, Winship Cancer Institute and Aflac Cancer and Blood Disorders Center, Children’s Healthcare of Atlanta. “We found that a disease-associated mutation, which disturbs the niches where blood stem cell development occurs, can lead to leukemia formation.”

Editorial note: This Nature News + Views, aptly titled “Bad neighbors cause bad blood,” explains JMML, and how the relapse rate after bone marrow transplant is high (about 50 percent). It also notes that a variety of genetic alterations provoke leukemia when engineered into bone marrow stromal cells in mice (like this), but Qu and his colleagues described one that is associated with a known human disease.

Noonan syndrome often involves short stature, distinctive facial features, congenital heart defects and bleeding problems. It occurs in between one in 1000 to one in 2500 people, and can be caused by mutations in several genes. The most common cause is mutations in the gene PTPN11. Children with Noonan syndrome are estimated to have a risk of developing leukemia or other cancers that is eight times higher than their peers.
Read more

Posted on November 8, 2016 by Quinn Eastman in Cancer, Immunology Leave a comment

Strength tests for platelets

Bleeding disorders could one day be diagnosed by putting platelets through strength tests, researchers have proposed.

Biomedical engineers from Emory and Georgia Tech have devised a microfluidic testing ground where platelets can demonstrate their strength by squeezing two protein dots together. Imagine rows and rows of strength testing machines from a carnival, but very tiny. Platelets are capable of exerting forces that are several times larger, in relation to their size, in comparison with muscle cells.

After a blood clot forms, it contracts, promoting wound closure and restoration of normal blood flow. This process can be deficient in a variety of blood clotting disorders. Previously, it was difficult to measure individual platelet’s contributions to contraction, because clots’ various components got in the way.

The prototype diagnostic tools are described in Nature Materials.

Top: platelets exert their strength. Bottom left: red = platelets, green = fibrinogen dots. Bottom right: size of actual device.

“We discovered that platelets from some patients with bleeding disorders are ‘wimpier’ than platelets from healthy people,” says Wilbur Lam, MD, PhD, assistant professor in the Department of Pediatrics at Emory University School of Medicine and in the Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory University. “Our device may function as a new physics-based method to test for bleeding disorders, complementary to current methods.”

The first author of the paper is instructor David Myers, PhD. Lam is also a physician in the Aflac Cancer and Blood Disorders Center, Children’s Healthcare of Atlanta. Collaborators at North Carolina State University led by Ashley Brown, PhD, contributed to testing the device.

The scientists infer how strong or wimpy someone’s platelets are by measuring how far the protein dots move, taking a picture of the rows of dots, and then analyzing the picture on a computer. The dots are made of fibrinogen, a sticky protein that is the precursor for fibrin, which forms a mesh of insoluble strands in a blood clot.

In addition to detecting problems with platelet contraction in patients with known inherited disorders such as Wiskott Aldrich syndrome, Myers, Lam and colleagues could also see differences in some patients who had bleeding symptoms, but who performed normally on standard diagnostic tests. Read more

Posted on October 11, 2016 by Quinn Eastman in Heart, Uncategorized Leave a comment

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