Vascular Biology Program

Head of Westport, MA, United States

Vascular Biology Program

Head of Westport, MA, United States
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News Article | May 18, 2017
Site: www.eurekalert.org

(BOSTON) --The human heart beats approximately 35 million times every year, effectively pumping blood into the circulation via four different heart valves. Unfortunately, in over four million people each year, these delicate tissues malfunction due to birth defects, age-related deteriorations, and infections, causing cardiac valve disease. Today, clinicians use either artificial prostheses or fixed animal and cadaver-sourced tissues to replace defective valves. While these prostheses can restore the function of the heart for a while, they are associated with adverse comorbidity and wear down and need to be replaced during invasive and expensive surgeries. Moreover, in children, implanted heart valve prostheses need to be replaced even more often as they cannot grow with the child. A team lead by Kevin Kit Parker, Ph.D. at Harvard University's Wyss Institute for Biologically Inspired Engineering recently developed a nanofiber fabrication technique to rapidly manufacture heart valves with regenerative and growth potential. In a paper published in Biomaterials, Andrew Capulli, Ph.D. and colleagues fabricated a valve-shaped nanofiber network that mimics the mechanical and chemical properties of the native valve extracellular matrix (ECM). To achieve this, the team used the Parker lab's proprietary rotary jet spinning technology - in which a rotating nozzle extrudes an ECM solution into nanofibers that wrap themselves around heart valve-shaped mandrels. "Our setup is like a very fast cotton candy machine that can spin a range of synthetic and natural occurring materials. In this study, we used a combination of synthetic polymers and ECM proteins to fabricate biocompatible JetValves that are hemodynamically competent upon implantation and support cell migration and re-population in vitro. Importantly, we can make human-sized JetValves in minutes - much faster than possible for other regenerative prostheses," said Parker. To further develop and test the clinical potential of JetValves, Parker's team collaborated with the translational team of Simon P. Hoerstrup, M.D., Ph.D., at the University of Zurich in Switzerland, which is a partner institution with the Wyss Institute. As a leader in regenerative heart prostheses, Hoerstrup and his team in Zurich have previously developed regenerative, tissue-engineered heart valves to replace mechanical and fixed-tissue heart valves. In Hoerstrup's approach, human cells directly deposit a regenerative layer of complex ECM on biodegradable scaffolds shaped as heart valves and vessels. The living cells are then eliminated from the scaffolds resulting in an "off-the-shelf" human matrix-based prostheses ready for implantation. In the paper, the cross-disciplinary team successfully implanted JetValves in sheep using a minimally invasive technique and demonstrated that the valves functioned properly in the circulation and regenerated new tissue. "In our previous studies, the cell-derived ECM-coated scaffolds could recruit cells from the receiving animal's heart and support cell proliferation, matrix remodeling, tissue regeneration, and even animal growth. While these valves are safe and effective, their manufacturing remains complex and expensive as human cells must be cultured for a long time under heavily regulated conditions. The JetValve's much faster manufacturing process can be a game-changer in this respect. If we can replicate these results in humans, this technology could have invaluable benefits in minimizing the number of pediatric re-operations," said Hoerstrup. In support of these translational efforts, the Wyss Institute for Biologically Inspired Engineering and the University of Zurich announced today a cross-institutional team effort to generate a functional heart valve replacement with the capacity for repair, regeneration, and growth. The team is also working towards a GMP-grade version of their customizable, scalable, and cost-effective manufacturing process that would enable deployment to a large patient population. In addition, the new heart valve would be compatible with minimally invasive procedures to serve both pediatric and adult patients. The project will be led jointly by Parker and Hoerstrup. Parker is a Core Faculty member of the Wyss Institute and the Tarr Family Professor of Bioengineering and Applied Physics at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS). Hoerstrup is Chair and Director of the University of Zurich's Institute for Regenerative Medicine (IREM), Co-Director of the recently founded Wyss Translational Center Zurich and a Wyss Institute Associate Faculty member. Since JetValves can be manufactured in all desired shapes and sizes, and take seconds to minutes to produce, the team's goal is to provide customized, ready-to-use, regenerative heart valves much faster and at much lower cost than currently possible. "Achieving the goal of minimally invasive, low-cost regenerating heart valves could have tremendous impact on patients' lives across age-, social- and geographical boundaries. Once again, our collaborative team structure that combines unique and leading expertise in bioengineering, regenerative medicine, surgical innovation and business development across the Wyss Institute and our partner institutions, makes it possible for us to advance technology development in ways not possible in a conventional academic laboratory," said 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 SEAS. The Wyss Institute for Biologically Inspired Engineering at Harvard University(http://wyss. ) uses Nature's design principles to develop bioinspired materials and devices that will transform medicine and create a more sustainable world. Wyss researchers are developing innovative new engineering solutions for healthcare, energy, architecture, robotics, and manufacturing that are translated into commercial products and therapies through collaborations with clinical investigators, corporate alliances, and formation of new startups. The Wyss Institute creates transformative technological breakthroughs by engaging in high risk research, and crosses disciplinary and institutional barriers, working as an alliance that includes Harvard's Schools of Medicine, Engineering, Arts & Sciences and Design, and in partnership with Beth Israel Deaconess Medical Center, Brigham and Women's Hospital, Boston Children's Hospital, Dana-Farber Cancer Institute, Massachusetts General Hospital, the University of Massachusetts Medical School, Spaulding Rehabilitation Hospital, Boston University, Tufts University, Charité - Universitätsmedizin Berlin, University of Zurich and Massachusetts Institute of Technology. The University of Zurich (UZH) is a member of the League of European Research Universities and numbers among Europe's most prestigious research institutions. UZH's international standing is reflected in the many renowned academic distinctions conferred upon its members, including twelve Nobel Prizes. As Switzerland's largest university, UZH has a current enrollment of over 25,000 students and offers the most comprehensive academic program in the country. Nearly 5,000 excellent members of staff teach and perform research at one of the University's 150 departments, including over 600 professors. UZH also looks back on a rich history, having been founded in 1833 as Europe's first university to be established by a democratic political system. The mission of the Institute for Regenerative Medicine * IREM is advancing molecular life sciences into next generation bio-inspired therapy at the interface of degeneration and regeneration with a major focus on the most relevant human diseases, including neurodegeneration and cardiovascular disease. The Harvard John A. Paulson School of Engineering and Applied Sciences(http://seas. ) serves as the connector and integrator of Harvard's teaching and research efforts in engineering, applied sciences, and technology. Through collaboration with researchers from all parts of Harvard, other universities, and corporate and foundational partners, we bring discovery and innovation directly to bear on improving human life and society.


News Article | May 18, 2017
Site: www.prnewswire.com

A team lead by Kevin Kit Parker, Ph.D. at Harvard University's Wyss Institute for Biologically Inspired Engineering recently developed a nanofiber fabrication technique to rapidly manufacture heart valves with regenerative and growth potential. In a paper published in Biomaterials, Andrew Capulli, Ph.D. and colleagues fabricated a valve-shaped nanofiber network that mimics the mechanical and chemical properties of the native valve extracellular matrix (ECM). To achieve this, the team used the Parker lab's proprietary rotary jet spinning technology – in which a rotating nozzle extrudes an ECM solution into nanofibers that wrap themselves around heart valve-shaped mandrels. "Our setup is like a very fast cotton candy machine that can spin a range of synthetic and natural occurring materials. In this study, we used a combination of synthetic polymers and ECM proteins to fabricate biocompatible JetValves that are hemodynamically competent upon implantation and support cell migration and re-population in vitro. Importantly, we can make human-sized JetValves in minutes – much faster than possible for other regenerative prostheses," said Parker. To further develop and test the clinical potential of JetValves, Parker's team collaborated with the translational team of Simon P. Hoerstrup, M.D., Ph.D., at the University of Zurich in Switzerland, which is a partner institution with the Wyss Institute. As a leader in regenerative heart prostheses, Hoerstrup and his team in Zurich have previously developed regenerative, tissue-engineered heart valves to replace mechanical and fixed-tissue heart valves. In Hoerstrup's approach, human cells directly deposit a regenerative layer of complex ECM on biodegradable scaffolds shaped as heart valves and vessels. The living cells are then eliminated from the scaffolds resulting in an "off-the-shelf" human matrix-based prostheses ready for implantation. In the paper, the cross-disciplinary team successfully implanted JetValves in sheep using a minimally invasive technique and demonstrated that the valves functioned properly in the circulation and regenerated new tissue. "In our previous studies, the cell-derived ECM-coated scaffolds could recruit cells from the receiving animal's heart and support cell proliferation, matrix remodeling, tissue regeneration, and even animal growth. While these valves are safe and effective, their manufacturing remains complex and expensive as human cells must be cultured for a long time under heavily regulated conditions. The JetValve's much faster manufacturing process can be a game-changer in this respect. If we can replicate these results in humans, this technology could have invaluable benefits in minimizing the number of pediatric re-operations," said Hoerstrup. In support of these translational efforts, the Wyss Institute for Biologically Inspired Engineering and the University of Zurich announced today a cross-institutional team effort to generate a functional heart valve replacement with the capacity for repair, regeneration, and growth. The team is also working towards a GMP-grade version of their customizable, scalable, and cost-effective manufacturing process that would enable deployment to a large patient population. In addition, the new heart valve would be compatible with minimally invasive procedures to serve both pediatric and adult patients. The project will be led jointly by Parker and Hoerstrup. Parker is a Core Faculty member of the Wyss Institute and the Tarr Family Professor of Bioengineering and Applied Physics at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS). Hoerstrup is Chair and Director of the University of Zurich's Institute for Regenerative Medicine (IREM), Co-Director of the recently founded Wyss Translational Center Zurich and a Wyss Institute Associate Faculty member. Since JetValves can be manufactured in all desired shapes and sizes, and take seconds to minutes to produce, the team's goal is to provide customized, ready-to-use, regenerative heart valves much faster and at much lower cost than currently possible. "Achieving the goal of minimally invasive, low-cost regenerating heart valves could have tremendous impact on patients' lives across age-, social- and geographical boundaries. Once again, our collaborative team structure that combines unique and leading expertise in bioengineering, regenerative medicine, surgical innovation and business development across the Wyss Institute and our partner institutions, makes it possible for us to advance technology development in ways not possible in a conventional academic laboratory," said 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 SEAS. The Wyss Institute for Biologically Inspired Engineering at Harvard University(http://wyss.harvard.edu) uses Nature's design principles to develop bioinspired materials and devices that will transform medicine and create a more sustainable world. Wyss researchers are developing innovative new engineering solutions for healthcare, energy, architecture, robotics, and manufacturing that are translated into commercial products and therapies through collaborations with clinical investigators, corporate alliances, and formation of new startups. The Wyss Institute creates transformative technological breakthroughs by engaging in high risk research, and crosses disciplinary and institutional barriers, working as an alliance that includes Harvard's Schools of Medicine, Engineering, Arts & Sciences and Design, and in partnership with Beth Israel Deaconess Medical Center, Brigham and Women's Hospital, Boston Children's Hospital, Dana–Farber Cancer Institute, Massachusetts General Hospital, the University of Massachusetts Medical School, Spaulding Rehabilitation Hospital, Boston University, Tufts University, Charité – Universitätsmedizin Berlin, University of Zurich and Massachusetts Institute of Technology. University of Zurich The University of Zurich (UZH) is a member of the League of European Research Universities and numbers among Europe's most prestigious research institutions. UZH's international standing is reflected in the many renowned academic distinctions conferred upon its members, including twelve Nobel Prizes. As Switzerland's largest university, UZH has a current enrollment of over 25,000 students and offers the most comprehensive academic program in the country. Nearly 5,000 excellent members of staff teach and perform research at one of the University's 150 departments, including over 600 professors. UZH also looks back on a rich history, having been founded in 1833 as Europe's first university to be established by a democratic political system. The mission of the Institute for Regenerative Medicine • IREM is advancing molecular life sciences into next generation bio-inspired therapy at the interface of degeneration and regeneration with a major focus on the most relevant human diseases, including neurodegeneration and cardiovascular disease. The Harvard John A. Paulson School of Engineering and Applied Sciences(http://seas.harvard.edu) serves as the connector and integrator of Harvard's teaching and research efforts in engineering, applied sciences, and technology. Through collaboration with researchers from all parts of Harvard, other universities, and corporate and foundational partners, we bring discovery and innovation directly to bear on improving human life and society. To view the original version on PR Newswire, visit:http://www.prnewswire.com/news-releases/engineering-heart-valves-for-the-many-300459641.html


News Article | May 18, 2017
Site: phys.org

Today, clinicians use either artificial prostheses or fixed animal and cadaver-sourced tissues to replace defective valves. While these prostheses can restore the function of the heart for a while, they are associated with adverse comorbidity and wear down and need to be replaced during invasive and expensive surgeries. Moreover, in children, implanted heart valve prostheses need to be replaced even more often as they cannot grow with the child. A team lead by Kevin Kit Parker, Ph.D. at Harvard University's Wyss Institute for Biologically Inspired Engineering recently developed a nanofiber fabrication technique to rapidly manufacture heart valves with regenerative and growth potential. In a paper published in Biomaterials, Andrew Capulli, Ph.D. and colleagues fabricated a valve-shaped nanofiber network that mimics the mechanical and chemical properties of the native valve extracellular matrix (ECM). To achieve this, the team used the Parker lab's proprietary rotary jet spinning technology - in which a rotating nozzle extrudes an ECM solution into nanofibers that wrap themselves around heart valve-shaped mandrels. "Our setup is like a very fast cotton candy machine that can spin a range of synthetic and natural occurring materials. In this study, we used a combination of synthetic polymers and ECM proteins to fabricate biocompatible JetValves that are hemodynamically competent upon implantation and support cell migration and re-population in vitro. Importantly, we can make human-sized JetValves in minutes - much faster than possible for other regenerative prostheses," said Parker. To further develop and test the clinical potential of JetValves, Parker's team collaborated with the translational team of Simon P. Hoerstrup, M.D., Ph.D., at the University of Zurich in Switzerland, which is a partner institution with the Wyss Institute. As a leader in regenerative heart prostheses, Hoerstrup and his team in Zurich have previously developed regenerative, tissue-engineered heart valves to replace mechanical and fixed-tissue heart valves. In Hoerstrup's approach, human cells directly deposit a regenerative layer of complex ECM on biodegradable scaffolds shaped as heart valves and vessels. The living cells are then eliminated from the scaffolds resulting in an "off-the-shelf" human matrix-based prostheses ready for implantation. In the paper, the cross-disciplinary team successfully implanted JetValves in sheep using a minimally invasive technique and demonstrated that the valves functioned properly in the circulation and regenerated new tissue. "In our previous studies, the cell-derived ECM-coated scaffolds could recruit cells from the receiving animal's heart and support cell proliferation, matrix remodeling, tissue regeneration, and even animal growth. While these valves are safe and effective, their manufacturing remains complex and expensive as human cells must be cultured for a long time under heavily regulated conditions. The JetValve's much faster manufacturing process can be a game-changer in this respect. If we can replicate these results in humans, this technology could have invaluable benefits in minimizing the number of pediatric re-operations," said Hoerstrup. In support of these translational efforts, the Wyss Institute for Biologically Inspired Engineering and the University of Zurich announced today a cross-institutional team effort to generate a functional heart valve replacement with the capacity for repair, regeneration, and growth. The team is also working towards a GMP-grade version of their customizable, scalable, and cost-effective manufacturing process that would enable deployment to a large patient population. In addition, the new heart valve would be compatible with minimally invasive procedures to serve both pediatric and adult patients. The project will be led jointly by Parker and Hoerstrup. Parker is a Core Faculty member of the Wyss Institute and the Tarr Family Professor of Bioengineering and Applied Physics at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS). Hoerstrup is Chair and Director of the University of Zurich's Institute for Regenerative Medicine (IREM), Co-Director of the recently founded Wyss Translational Center Zurich and a Wyss Institute Associate Faculty member. Since JetValves can be manufactured in all desired shapes and sizes, and take seconds to minutes to produce, the team's goal is to provide customized, ready-to-use, regenerative heart valves much faster and at much lower cost than currently possible. "Achieving the goal of minimally invasive, low-cost regenerating heart valves could have tremendous impact on patients' lives across age-, social- and geographical boundaries. Once again, our collaborative team structure that combines unique and leading expertise in bioengineering, regenerative medicine, surgical innovation and business development across the Wyss Institute and our partner institutions, makes it possible for us to advance technology development in ways not possible in a conventional academic laboratory," said 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 SEAS. Explore further: Clinical study offers new hope for patients with congenital heart disease More information: Andrew K. Capulli et al, JetValve: Rapid manufacturing of biohybrid scaffolds for biomimetic heart valve replacement, Biomaterials (2017). DOI: 10.1016/j.biomaterials.2017.04.033


News Article | May 23, 2017
Site: www.eurekalert.org

(BOSTON) The average human pair of lungs is permeated by a network of about 164 feet of blood vessels (roughly the width of a football field), including microscopic blood capillaries, which facilitate the diffusion of oxygen into the bloodstream in exchange for carbon dioxide. Damage to any of those vessels can cause a blood clot, or thrombus, to form, which can cause or exacerbate a number of lung diseases, including pneumonia, acute lung injury and acute chest syndrome. The use of some drugs is also limited by their propensity to promote clot formation in lung vessels. Developing and testing drugs to treat or prevent pulmonary thrombosis is difficult because the complex interplay between the many different cell types in the lung hampers efforts to tease out the exact causes of clot formation. A new study conducted by members of the Wyss Institute at Harvard University, Emulate Inc., and Janssen Pharmaceutical Research and Development, published today in the journal Clinical Pharmacology and Therapeutics, is the first to successfully recreate a human pulmonary thrombosis within an organ-level model of the lung in vitro. "It's very difficult to distill out specific mechanisms inside an animal, and a lot of work in toxicology or drug discovery fails when it goes to human clinical trials," says co-first author Abhishek Jain, Ph.D., former Wyss Institute Postdoctoral Fellow and current Assistant Professor of Biomedical Engineering at Texas A&M University. "In vitro models like our Thrombosis-on-a-Chip are made from the ground-up, so you can build them to be exactly as complex as you need for the problem you want to study." To meet this challenge, the team used Organ-on-a-Chip (Organ Chip) technology developed at the Wyss Institute, which involves engineering microfluidic culture devices with two parallel channels separated by a porous extracellular-matrix-coated membrane. The key innovation in this new design relative to a previously described Lung-on-a-Chip is that the upper surface of the porous membrane is lined by primary human alveolar epithelial cells, and all sides of the lower vascular channel are coated with a layer of lung microvascular endothelium to accurately mimic human lung capillaries. Because thrombosis is perpetrated by platelets and other cells, the team perfused whole human blood through the lower endothelium-lined channel of the chip for the first time, while air was introduced into the upper channel. When an inflammatory stimulus was applied to the endothelial cells followed by perfusing whole blood, platelets clumped and formed blood clots on the surface of the endothelium in a characteristic teardrop shape that has been observed in living animals, but never before in vitro. "This is the first time we're seeing clots form with the same dynamics and morphology that you see in vivo, which is a major step forward in studying and eventually treating blood clots that cause many life-threatening diseases." says Donald Ingber, M.D., Ph.D., senior author of the study and the Judah Folkman Professor of Vascular Biology at Harvard Medical School (HMS) and the Vascular Biology Program at Boston Children's Hospital, as well as Professor of Bioengineering at Harvard's School of Engineering and Applied Sciences (SEAS). The team further tested the chip's functionality by replicating an inflammatory lung injury that originates in the lung's airways - the most likely source of a pathogen or other damaging substance. They introduced lipopolysaccharide endotoxin (LPS), an inflammatory chemical found on the surface of certain types of bacteria and is known to induce clot formation in vivo, into both the upper and lower channels of the chip. They were surprised to find that LPS had no effect on blood clot formation when they added it directly to the endothelium-lined blood channel; but, when added to the air channel, it induced the air-facing epithelium to trigger a cascade of cytokines, a class of inflammatory signaling molecules that initiate blood clot formation, in the underlying endothelium. "Epithelial cells are the guardians of the airways - they need to be sensitive to airborne pathogens and then signal the danger to the rest of the body," says co-author Riccardo Barrile, Ph.D., also a former Wyss Institute Postdoctoral Fellow and current principal investigator at Emulate, Inc. "This study demonstrated that information travels from the epithelium to the endothelium, but I was surprised to see that the entire system is so well-connected." In addition to facilitating the discovery of crucial insights into the mechanism of how lung injury promotes blood clot formation, the Thrombosis-on-a-Chip allows for the testing of potential drugs on an organ-level system in vitro, an approach that has become highly attractive to pharmaceutical companies. Working with Robert Flaumenhaft, M.D., Ph.D., Associate Professor of Hematology at HMS and Beth Israel Deaconess Medical Center, the team introduced parmodulin-2 (PM2), an inflammation inhibitor, into the vascular channel of the device, and found that it significantly decreased the number of clots on the vessel wall following the addition of LPS to the airway channel. This confirmation of drug activity, as well as the insight that LPS causes thrombosis only by acting directly on the epithelium, would have been very difficult to achieve in vivo, as blood flow and individual cellular compartments cannot be controlled individually as they can in Organ Chips. The team plans to continue their pulmonary thrombosis work by introducing mechanical forces that imitate breathing to the Chip and analyzing the role that immune cells such as neutrophils play in blood clot formation. "By including whole blood, we're reaching a new standard of complexity and precision for mimicking a human body in both health and disease," says Barrile. "This study affirms that we are recapitulating organ-level responses to lung injury, emphasizing that this is a true Organ-on-a-Chip, not just a tissue-on-a-chip," adds Ingber. Andries D. van der Meer, Ph.D., former Senior Research Fellow at the Wyss Institute and current Assistant Professor at the MIRA Institute for Biomedical Technology and Technical Medicine, was the third co-author of this study. Additional authors include Akiko Mammoto, M.D., Ph.D., Instructor in the Vascular Biology Program at Boston Children's Hospital and HMS; Tadanori Mammoto, M.D., Ph.D., Instructor in Surgery at Boston Children's Hospital and HMS; Karen De Ceunynck, Ph.D., Postdoctoral Research Fellow at Beth Israel Deaconess Medical Center and HMS; Omozuanvbo Aisiku, Ph.D., former Postdoctoral Research Fellow at Beth Israel Deaconess Medical Center and HMS, currently a Scientist at Instrumentation Laboratory; Monicah A. Otieno, Ph.D., Senior Research Investigator at Bristol-Myers Squibb; Calvert S. Louden, D.V.M., Ph.D., Senior Director at Johnson & Johnson Pharmaceuticals; and Geraldine A. Hamilton, Ph.D., President and Chief Scientific Officer of Emulate, Inc. This work was funded by DARPA contract N66001-11-1-4180, HR0011-13-C-0025, Janssen Pharmaceuticals, and the Wyss Institute for Biologically Inspired Engineering at Harvard University. Ingber and Hamilton are founders and hold equity in Emulate, Inc, and Ingber chairs its scientific advisory board; van der Meer serves as a scientific consultant to the company. The Wyss Institute for Biologically Inspired Engineering at Harvard University (http://wyss. ) uses Nature's design principles to develop bioinspired materials and devices that will transform medicine and create a more sustainable world. Wyss researchers are developing innovative new engineering solutions for healthcare, energy, architecture, robotics, and manufacturing that are translated into commercial products and therapies through collaborations with clinical investigators, corporate alliances, and formation of new startups. The Wyss Institute creates transformative technological breakthroughs by engaging in high risk research, and crosses disciplinary and institutional barriers, working as an alliance that includes Harvard's Schools of Medicine, Engineering, Arts & Sciences and Design, and in partnership with Beth Israel Deaconess Medical Center, Brigham and Women's Hospital, Boston Children's Hospital, Dana-Farber Cancer Institute, Massachusetts General Hospital, the University of Massachusetts Medical School, Spaulding Rehabilitation Hospital, Boston University, Tufts University, Charité - Universitätsmedizin Berlin, University of Zurich and Massachusetts Institute of Technology.


News Article | May 29, 2017
Site: www.eurekalert.org

(BOSTON) - The microbiome, or the collections of microorganisms present in the body, is known to affect human health and disease and researchers are thinking about new ways to use them as next-generation diagnostics and therapeutics. Today bacteria from the normal microbiome are already being used in their modified or attenuated form in probiotics and cancer therapy. Scientists exploit the microorganisms' natural ability to sense and respond to environmental- and disease-related stimuli and the ease of engineering new functions into them. This is particularly beneficial in chronic inflammatory diseases like inflammatory bowel disease (IBD) that remain difficult to monitor non-invasively. However, there are several challenges associated with developing living diagnostics and therapeutics including generating robust sensors that do not crash and are capable of long-term monitoring of biomolecules. In order to use bacteria of the microbiome as biomarker sensors, their genome needs to be modified with synthetic genetic circuits, or a set of genes that work together to achieve a sensory or response function. Some of these genetic alterations may weaken or break normal signaling circuits and be toxic to these bacteria. Even in cases where the probiotic microbes tolerate the changes, the engineered cells can have growth delays and be outcompeted by other components of the microbiome. As a result, probiotic bacteria and engineered therapeutic microbes are rapidly cleared from the body, which makes them inadequate for long period monitoring and modulation of the organism's tissue environment. A team at the Wyss Institute of Biologically Inspired Engineering led by Pamela Silver, Ph.D., designed a powerful bacterial sensor with a stable gene circuit in a colonizing bacterial strain that can record gut inflammation for six months in mice. This study offers a solution to previous challenges associated with living diagnostics and may bring them closer to use in human patients. The findings are reported in Nature Biotechnology. Silver, who is a Core Faculty member at the Wyss Institute and also the Elliot T. and Onie H. Adams Professor of Biochemistry and Systems Biology at Harvard Medical School, thought of the gut as a first application for this system due to its inaccessibility by non-invasive means and its susceptibility to inflammation in patients suffering from chronic diseases like IBD. "We think about the gut as a black box where it is hard to see, but we can use bacteria to illuminate these dark places. There is great interest from patients and doctors that push us to build sensors for biomarkers of gut conditions like IBD and colon cancer," said Silver, "We believe that our work opens up enormous possibilities that can exploit the flexibility and modularity of our diagnostic tool and expand the use of engineered organisms to a wide variety of applications." Key to the team's work is the introduction of a memory module to the circuit that is able to detect a molecule of interest and respond to this exposure long after the stimulus is gone. As bacteria can be rapidly cleared from the intestinal tract, the team used a strain of bacteria that is part of the microbiome of mice, and engineered it to contain the sensory and memory elements capable of detecting tetrathionate. Tetrathionate is a transient metabolic molecule produced in the inflamed mouse intestine as a result of either infection with pathogenic bacteria like Salmonella typhimurium and Yersinia enterocolitica or genetic defects affecting inflammation. The synthetic genetic circuit designed by the Wyss team contains a "trigger element" that is adopted from the natural system specifically recognizing the biomarker (in this case tetrathionate) in cells, or that can be developed using synthetic approaches when no prior sensor exists. The second element in the circuit is the "memory element" that resembles a toggle switch and has been adapted from a virus that attacks bacteria. It consists of two genes (A and B for simplicity) that regulate each other depending on whether the stimulus is present. In the tetrathionate sensor, the product of gene A blocks expression of gene B when tetrathionate is absent. When tetrathionate is produced during inflammation and is sensed by the trigger element, levels of A decrease and the gene B is induced and begins to shut off expression of gene A. The expression of the B gene is also coupled to a reporter gene which turns bacteria from colorless to blue only when they have switched the memory element on. The switch can be maintained in the on state long after the first tetrathionate exposure. After verifying the functionality of the sensor in a liquid culture of bacteria, David Riglar, Ph.D., the study's first author, was able to show that it detected tetrathionate in a mouse model of gut inflammation caused by infection with S. typhimurium up to six months after administration of the sensor-containing probiotic bacteria. Through simple analysis of fecal matter, the synthetic circuit's memory state was confirmed to be on and its DNA unchanged and stable. "Our approach is to use the bacteria's sensing ability to monitor the environment in unhealthy tissue or organs. By adding gene circuits that retain memory, we envision giving humans probiotics that record disease progression by a simple and non-invasive fecal test," said Riglar. Silver's team plans to extend this work to sensing inflammation in the human gut and also to develop new sensors detecting signs of a variety of other conditions. "Pam's work demonstrates the power of synthetic biology for advancing medicine as it provides a way to rationally and rapidly design sophisticated sensors for virtually any molecule. If successful in humans, their technology would offer a much less expensive and more specific way to monitor gut function at home than sophisticated imaging instruments used today", said Donald Ingber, M.D., Ph.D., Founding Director of the Wyss Institute, the Judah Folkman Professor of Vascular Biology at Harvard Medical School and the Vascular Biology Program at Boston Children's Hospital, as well as Professor of Bioengineering at the Harvard John A. Paulson School of Engineering and Applied Sciences. Other authors contributing to this study are Tobias Giessen, Ph.D., Michael Baym Ph.D., S Jordan Kerns, Ph.D., Matthew Niederhuber, Roderick Bronson Ph.D., Jonathan Kotula, Ph.D., Georg Gerber, Ph.D., and Jeffrey Way, Ph.D. The research was funded by the Defense Advanced Research Projects Agency (DARPA) and the Wyss Institute for Biologically Inspired Engineering. David Riglar is supported by the Human Frontier Science Program Long-Term Fellowship and an NHMRC/RG Menzies Early Career Fellowship from the Menzies Foundation and the Australian National Health and Medical Research Council. The Wyss Institute for Biologically Inspired Engineering at Harvard University uses Nature's design principles to develop bioinspired materials and devices that will transform medicine and create a more sustainable world. Wyss researchers are developing innovative new engineering solutions for healthcare, energy, architecture, robotics, and manufacturing that are translated into commercial products and therapies through collaborations with clinical investigators, corporate alliances, and formation of new startups. The Wyss Institute creates transformative technological breakthroughs by engaging in high risk research, and crosses disciplinary and institutional barriers, working as an alliance that includes Harvard's Schools of Medicine, Engineering, Arts & Sciences and Design, and in partnership with Beth Israel Deaconess Medical Center, Brigham and Women's Hospital, Boston Children's Hospital, Dana-Farber Cancer Institute, Massachusetts General Hospital, the University of Massachusetts Medical School, Spaulding Rehabilitation Hospital, Boston University, Tufts University, Charité - Universitätsmedizin Berlin, University of Zurich and Massachusetts Institute of Technology.


News Article | May 29, 2017
Site: phys.org

Engineered bacteria not exposed to inflammatory signals do not turn on the memory circuit and thus remain colorless. In the presence of the inflammatory chemical tetrathionate, the memory circuit switches on and colors the engineered bacteria blue. Credit: Wyss Institute and Harvard Medical School. The microbiome, or the collections of microorganisms present in the body, is known to affect human health and disease and researchers are thinking about new ways to use them as next-generation diagnostics and therapeutics. Today bacteria from the normal microbiome are already being used in their modified or attenuated form in probiotics and cancer therapy. Scientists exploit the microorganisms' natural ability to sense and respond to environmental- and disease-related stimuli and the ease of engineering new functions into them. This is particularly beneficial in chronic inflammatory diseases like inflammatory bowel disease (IBD) that remain difficult to monitor non-invasively. However, there are several challenges associated with developing living diagnostics and therapeutics including generating robust sensors that do not crash and are capable of long-term monitoring of biomolecules. In order to use bacteria of the microbiome as biomarker sensors, their genome needs to be modified with synthetic genetic circuits, or a set of genes that work together to achieve a sensory or response function. Some of these genetic alterations may weaken or break normal signaling circuits and be toxic to these bacteria. Even in cases where the probiotic microbes tolerate the changes, the engineered cells can have growth delays and be outcompeted by other components of the microbiome. As a result, probiotic bacteria and engineered therapeutic microbes are rapidly cleared from the body, which makes them inadequate for long period monitoring and modulation of the organism's tissue environment. A team at the Wyss Institute of Biologically Inspired Engineering led by Pamela Silver, Ph.D., designed a powerful bacterial sensor with a stable gene circuit in a colonizing bacterial strain that can record gut inflammation for six months in mice. This study offers a solution to previous challenges associated with living diagnostics and may bring them closer to use in human patients. The findings are reported in Nature Biotechnology. Silver, who is a Core Faculty member at the Wyss Institute and also the Elliot T. and Onie H. Adams Professor of Biochemistry and Systems Biology at Harvard Medical School, thought of the gut as a first application for this system due to its inaccessibility by non-invasive means and its susceptibility to inflammation in patients suffering from chronic diseases like IBD. "We think about the gut as a black box where it is hard to see, but we can use bacteria to illuminate these dark places. There is great interest from patients and doctors that push us to build sensors for biomarkers of gut conditions like IBD and colon cancer," said Silver, "We believe that our work opens up enormous possibilities that can exploit the flexibility and modularity of our diagnostic tool and expand the use of engineered organisms to a wide variety of applications." Key to the team's work is the introduction of a memory module to the circuit that is able to detect a molecule of interest and respond to this exposure long after the stimulus is gone. As bacteria can be rapidly cleared from the intestinal tract, the team used a strain of bacteria that is part of the microbiome of mice, and engineered it to contain the sensory and memory elements capable of detecting tetrathionate. Tetrathionate is a transient metabolic molecule produced in the inflamed mouse intestine as a result of either infection with pathogenic bacteria like Salmonella typhimurium and Yersinia enterocolitica or genetic defects affecting inflammation. The synthetic genetic circuit designed by the Wyss team contains a "trigger element" that is adopted from the natural system specifically recognizing the biomarker (in this case tetrathionate) in cells, or that can be developed using synthetic approaches when no prior sensor exists. The second element in the circuit is the "memory element" that resembles a toggle switch and has been adapted from a virus that attacks bacteria. It consists of two genes (A and B for simplicity) that regulate each other depending on whether the stimulus is present. In the tetrathionate sensor, the product of gene A blocks expression of gene B when tetrathionate is absent. When tetrathionate is produced during inflammation and is sensed by the trigger element, levels of A decrease and the gene B is induced and begins to shut off expression of gene A. The expression of the B gene is also coupled to a reporter gene which turns bacteria from colorless to blue only when they have switched the memory element on. The switch can be maintained in the on state long after the first tetrathionate exposure. After verifying the functionality of the sensor in a liquid culture of bacteria, David Riglar, Ph.D., the study's first author, was able to show that it detected tetrathionate in a mouse model of gut inflammation caused by infection with S. typhimurium up to six months after administration of the sensor-containing probiotic bacteria. Through simple analysis of fecal matter, the synthetic circuit's memory state was confirmed to be on and its DNA unchanged and stable. "Our approach is to use the bacteria's sensing ability to monitor the environment in unhealthy tissue or organs. By adding gene circuits that retain memory, we envision giving humans probiotics that record disease progression by a simple and non-invasive fecal test," said Riglar. Silver's team plans to extend this work to sensing inflammation in the human gut and also to develop new sensors detecting signs of a variety of other conditions. "Pam's work demonstrates the power of synthetic biology for advancing medicine as it provides a way to rationally and rapidly design sophisticated sensors for virtually any molecule. If successful in humans, their technology would offer a much less expensive and more specific way to monitor gut function at home than sophisticated imaging instruments used today", said Donald Ingber, M.D., Ph.D., Founding Director of the Wyss Institute, the Judah Folkman Professor of Vascular Biology at Harvard Medical School and the Vascular Biology Program at Boston Children's Hospital, as well as Professor of Bioengineering at the Harvard John A. Paulson School of Engineering and Applied Sciences. More information: Engineered bacteria can function in the mammalian gut long-term as live diagnostics of inflammation, Nature Biotechnology (2017). nature.com/articles/doi:10.1038/nbt.3879

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