Breaking News
February 21, 2018 - Postnatal depression impacts mother-child relationships for longer time frame
February 21, 2018 - Study describes new protection mechanisms to fight neurodegeneration in Parkinson’s and Alzheimer’s
February 21, 2018 - Tiny ‘brains on chips’ reveal mechanisms underlying brain’s wrinkling process
February 21, 2018 - Bedfont Scientific makes FDA 510(k) submission for clearance of ToxCO monitor
February 21, 2018 - ‘Grey’s Anatomy’ Traumas Lack Realism
February 21, 2018 - Sleep quality improves with help of incontinence drug
February 21, 2018 - Scientists uncover genetic cause behind typhoid’s antibiotic resistance
February 21, 2018 - Study reveals a significant link between heavy alcohol use and dementia
February 21, 2018 - French scientists develop new wearable laser that eradicates skin conditions
February 21, 2018 - People with major depressive disorder have reduced arginine levels, study shows
February 21, 2018 - National Health Spending at $3.5 Trillion in 2017, CMS Says
February 21, 2018 - Substantial inequalities in cesarean births persist in many countries
February 21, 2018 - Early childhood immune signature predicts risk of developing asthma later on
February 21, 2018 - Stanford researchers explore how gut bacteria respond to common changes in habitat
February 21, 2018 - Household Products May Pollute the Air as Much as Your Car Does: Study
February 21, 2018 - Combo Bests Targeted Agent in mRCC
February 21, 2018 - Researchers discover brain pathway that dissociates opioid addiction from analgesia
February 21, 2018 - Scientists uncover how newly discovered gene helps grow blood vessels
February 21, 2018 - Brain’s quality control process holds clues to obesity’s roots
February 21, 2018 - Researchers to study whether menstrual cups can help prevent vaginal infections
February 21, 2018 - MS patients who feel stigmatized more likely to suffer from depression
February 21, 2018 - Vitamin D supplementation during pregnancy could protect against childhood obesity
February 21, 2018 - Lower-Quality Medical Tx Might Have Skewed Key PCI vs CABG Trials
February 21, 2018 - Love and fear are visible across the brain instead of being restricted to any brain region
February 21, 2018 - Researchers discover potential new antimalarial treatment targets
February 21, 2018 - Adults with congenital heart disease have increased risk for dementia, study finds
February 21, 2018 - Clinical trial studying type 1 diabetes reaches full enrollment
February 21, 2018 - Father’s stress affects the brain development of offspring, mice study shows
February 21, 2018 - ESRD Death Declines in Vasculitis Patients
February 21, 2018 - Taking ibuprofen for long periods found to alter human testicular physiology
February 21, 2018 - Google AI device could predict a person’s risk of a heart attack
February 20, 2018 - FDA Approves Domestic Source for Tc-99m Isotopes
February 20, 2018 - Sanofi rejects refund demand faces Philippine suit over dengue vaccine (Update)
February 20, 2018 - Researchers discover that activation of specific enzyme may help suppress tumor metastasis
February 20, 2018 - Blood or marrow transplantation survivors have higher risk of cognitive impairment
February 20, 2018 - Booze Beats Pot at Being Unhealthy: Oregon Poll
February 20, 2018 - Morning Break: ’20 Years Late’; Drugs in the Dirt; Catching Flu in the Dorm
February 20, 2018 - Another piece to the puzzle in naked mole rats’ long, cancer-free life
February 20, 2018 - Scientists identify four viruses that can produce insulin-like hormones
February 20, 2018 - New e-Health solution developed to prevent cardiovascular disease, dementia in senior citizens
February 20, 2018 - New genetic risk score could help guide screening decisions for prostate cancer
February 20, 2018 - Study finds higher risk of stroke among blacks with atrial fibrillation than whites
February 20, 2018 - Physical activity could be used as strategy for diabetes prevention
February 20, 2018 - Researchers develop sensing method for early detection of cancer and diabetes
February 20, 2018 - New wearable electronics could be game-changer for stroke rehabilitation
February 20, 2018 - Immune history influences person’s response to flu vaccine
February 20, 2018 - Research findings could help develop new drugs to prevent, treat dry eye disease
February 20, 2018 - Serenity Now! Learn to Have Patience with Patients
February 20, 2018 - Computer simulation addresses the problem of blood clotting
February 20, 2018 - Women with type 1 diabetes not protected against coronary artery disease
February 20, 2018 - Persistent bloating can be a sign of ovarian cancer, warns charity
February 20, 2018 - Trump administration proposes rule to loosen curbs on short-term health plans
February 20, 2018 - Key protein involved in epigenetic regulation of gene expression guides skin cell renewal
February 20, 2018 - Heart attack symptoms often missed in women
February 20, 2018 - Diagnosis of celiac disease takes 3.5 years for patients who do not report GI symptoms
February 20, 2018 - Study reveals functional dynamics of ion channels
February 20, 2018 - Study explores link between mortality risk and combustible tobacco use
February 20, 2018 - ‘She Trusted Me, and I’d Turned Her Away’
February 20, 2018 - AbbVie and Voyager Therapeutics collaborate to develop new treatments for tauopathies
February 20, 2018 - Fast food makes the immune system more aggressive in the long term
February 20, 2018 - Therapeutic target for glaucoma could have treatment ramifications for Alzheimer’s and Parkinson’s
February 20, 2018 - Overcoming Negative Reviews | Medpage Today
February 20, 2018 - MyD88—villain of allergies and asthma
February 20, 2018 - Food scientists develop rapid screening technique to detect pesticide residue in vegetables
February 20, 2018 - Lab-grown cerebellar cells may help explain how ASD develops at molecular level
February 20, 2018 - Scientists explore connection between bad sleep habits and stiff blood vessels
February 20, 2018 - New Treatment Apalutamide (Erleada) Approved for Prostate Cancer That Resists Hormone Therapy
February 20, 2018 - Do You Really Need My Signature on That?
February 20, 2018 - HIV-1 genetic diversity is higher in vaginal tract than in blood during early infection
February 20, 2018 - Diabetes does not increase work-loss years due to early retirement
February 20, 2018 - Researchers aim to find out how PTSD affects decisions of police
February 20, 2018 - UH Cleveland Medical Center explores novel treatments for uterine fibroids
February 20, 2018 - Flu Vax Efficacy 25% Against Predominant H3N2 Strain So Far
February 20, 2018 - HIV screening most optimal at 25 years of age if no risk factors
February 20, 2018 - Loyola Medicine primary care physician offers advice to minimize risk of flu
February 20, 2018 - Safe sleep recommendations for parents that may help reduce child’s risk of SUID
February 20, 2018 - Why Do So Few Docs Have Buprenorphine Waivers?
February 20, 2018 - Low levels of alcohol good for the brain
February 20, 2018 - Experimental treatment improves invisible symptoms of a man with spinal cord injury
February 20, 2018 - Myriad’s EndoPredict offers better prediction of breast cancer recurrence, analysis shows
Blood-vessel-on-a-chip provides insight into new anti-inflammatory drug candidate

Blood-vessel-on-a-chip provides insight into new anti-inflammatory drug candidate

image_pdfDownload PDFimage_print
Credit: Wyss Institute at Harvard University

One of the most important and fraught processes in the human body is inflammation. Inflammatory responses to injury or disease are crucial for recruiting the immune system to help the body heal, but inflammation can also cause an increase in the production of thrombin, which can lead to dangerous blood clots and other conditions. Activated protein C (APC) is a naturally occurring anti-coagulant protein with anti-inflammatory and other protective effects that has been used medically to treat severe blood infections and wounds; however, its use is limited because its inhibition of thrombin also impacts the blood’s ability to clot, increasing bleeding risk.

Now, a collaborative team of researchers from the Division of Hemostasis and Thrombosis at Beth Israel Deaconess Medical Center (BIDMC) and the Wyss Institute at Harvard University have discovered that synthetic APC-mimicking small molecules called “parmodulins” provide anti-inflammatory and anti-thrombotic protection to endothelial cells on par with APC’s without interfering with blood clotting, making them attractive new drug candidates. This work was enabled by leveraging the Institute’s Organ-on-a-Chip technology to model coagulation within a human blood vessel in vitro. The results are reported in this week’s issue of Proceedings of the National Academy of Sciences.

“We essentially performed a mini pre-clinical trial of parmodulins’ effect on the endothelium, and not only determined the pathway through which parmodulins function, but also demonstrated that they help protect endothelial cells from inflammatory damage,” says former Wyss postdoc Abhishek Jain, Ph.D., who is now an Assistant Professor and director of the the Bioinspired Translational Microsystems lab at Texas A&M University.

The target protein on which both APC and parmodulins act is the transmembrane protein protease-activated receptor 1 (PAR1), which is present on both endothelial cells that line blood vessels and platelets that circulate through the blood and promote clotting, making mechanistic analysis difficult. PAR1 was originally identified as a receptor for thrombin, which is a crucial part of the inflammatory process. However, when PAR1 is activated by APC on endothelium, it triggers anti-inflammatory, anti-apoptotic, and barrier-fortifying pathways, all of which help protect cells from the negative effects of inflammation.

In addition to activating PAR1, APC also independently inhibits the generation of thrombin, which is an essential component of healthy blood clotting – but inhibiting thrombin too much leads to uncontrolled bleeding. Knowing that parmodulins bind to PAR1, the team of scientists and clinicians set out to find a way to activate endothelial PAR1 and reduce thrombic responses without thinning the blood, and thus provide a better alternative to APC.

To evaluate the activity of parmodulins on endothelium, Karen De Ceunynck, Ph.D., postdoctoral research fellow at BIDMC and first author of the paper, incubated human endothelial cells with parmodulin 2 in vitro for 4 hours and then exposed them to the thrombin-inducing inflammatory agents lipopolysaccharide (LPS) or tumor necrosis factor-α (TNF-α). In the parmodulin-exposed cells, both agents’ ability to generate thrombin was reduced by over 50% compared with non-parmodulin-exposed cells. However, parmodulin 2 did not inhibit the activity of factor V or factor X, proteins that function in blood coagulation. “We were intrigued by the notion that parmodulin 2 inhibited LPS- and TNF-mediated prothrombotic effects on the endothelial surface without impairing blood clotting” says De Ceunynck.

Credit: Wyss Institute at Harvard University

To confirm this theory, the team used a Wyss-developed blood-vessel-on-a-chip consisting of microfluidic channels embedded in a clear polymer chip, coated with collagen, and lined by human endothelial cells. Whole blood was perfused through the chip to simulate the flow conditions within human blood vessels, to which were added different pro- and anti-inflammatory compounds to evaluate the response of the endothelium.

When the endothelial cells were exposed to TNF-α before being perfused with whole blood, platelets accumulated on the endothelium in a typical inflammatory response; if the cells were first exposed to parmodulin 2 and then TNF-α, platelet accumulation was inhibited and the endothelium resumed its normal function. These results indicated that parmodulin exposure blocks the thrombotic response of endothelium to inflammatory stimuli without affecting blood coagulation in humans – a significant improvement over APC.

A series of tests in vitro performed by co-first author Christian Peters, Ph.D. at BIDMC, confirmed that parmodulin 2’s activation of PAR1 also induces cytoprotective responses in endothelial cells by inhibiting apoptosis (programmed cell death) induced by thrombin, TNF-α, and the apoptotic alkaloid staurosporine through a signaling pathway that begins with parmodulin 2’s binding to a specific site on the cytoplasmic side of PAR1. “We observed that the cytoprotective response induced by parmodulin 2 happened very quickly, and confirmed its rapid onset in time course and gene expression assays,” says Peters.

Furthermore, in vivo studies in mice showed that parmodulin 2 reduces the binding of white blood cells to blood vessels and impairs platelet and fibrin accumulation at injury sites during the inflammatory response, confirming the anti-thrombotic and anti-coagulant activity of parmodulin 2 observed in vitro. Additionally, parmodulins do not interact with many of APC’s other binding partners, making it much more targeted to PAR1 and reducing other side effects.

“The discovery of an anti-inflammatory molecule that prevents endothelial thrombosis but also preserves normal blood coagulation is a major step toward an alternative and better approach to treating inflammatory disease,” says Rob Flaumenhaft, M.D., Ph.D., Professor of Medicine at Harvard Medical School, Chief of the Division of Hemostasis and Thrombosis at BIDMC, and corresponding author of the paper. “Furthermore, nearly all other pharmaceuticals that target G-protein coupled receptors like PAR1 bind to the exterior of the receptor; parmodulin 2 represents a paradigm shift for compounds targeting GPCRs because it acts on internal domains. We are excited to see if we can advance it to clinical trials.”

“This work provides another example of how organ-on-a-chip technology can enable faster and safer development and evaluation of drugs that could help patients around the world,” says co-author and Wyss Institute Founding Director Donald Ingber, M.D., Ph.D., who is also the Judah Folkman Professor of Vascular Biology at HMS and the Vascular Biology Program at Boston Children’s Hospital, as well as Professor of Bioengineering at Harvard’s John A. Paulson School of Engineering and Applied Sciences (SEAS).


Explore further:
Pulmonary Thrombosis-on-a-Chip provides new avenue for drug development

More information:
Karen De Ceunynck el al., “PAR1 agonists stimulate APC-like endothelial cytoprotection and confer resistance to thromboinflammatory injury,” PNAS (2018). www.pnas.org/cgi/doi/10.1073/pnas.1718600115

Journal reference:
Proceedings of the National Academy of Sciences

Provided by:
Harvard University

Tagged with:

About author

Related Articles