Mighty Mussel Glue for Surgery

 

Thu, 07/23/2015 - 4:30pm Greg Watry, Digital Reporter Image: MarumInspired by biological functions seen in mussels and insects, Korean scientists have manufactured a nontoxic surgical glue, which seals surgical openings within one minute, and may become a viable replacement for sutures and staples. Mussels, according to Live Science, use silky fibers known as byssus threads to attach themselves to underwater surfaces. Researchers later determined a part of the “mussel ‘glue’ molecule, called catechol, pushes water molecules out of the way to bind directly to (a) wide variety of surfaces,” according to the American Chemical Society. The researchers said the discovery could lead to developing adhesives that work underwater and in the body. Pohang Univ. of Science and Technology Prof. Hyung Joon Cha and his student Eun Young Jeon report their light-activated, mussel-based bioadhesive, called LAMBA, is compatible with the human body and strong in wet conditions. “LAMBA opens numerous doors for medical practices, ranging from blocking air leaks and suture-less wound closures of delicate organs (to) tissues beyond surgeons’ reach,” Cha said. The scientists’ findings were reported in Biomaterials. Unlike previous attempts utilizing mussel adhesive proteins (MAP), Cha and Jeon’s method, through a photochemical reaction, uses blue visible light to activate the adhesive. The idea came from dityrosine crosslinks found in dragonfly wings and insect cuticles. An illustration from the university shows MAP strands dotted with tyrosine. When blue visible light is applied, neighboring tyrosine are coupled into the aforementioned dityrosine crosslinks. According to the university, “the invasive nature of traditional methods,” such as sutures and staples, is a drawback due to severe tissue damage, complicated post-treatment management and scars. According to the university, biologically derived adhesives, such as LAMPA, have an advantage over chemically derived adhesives, such as cyanoacrylates. According to Medscape.org, cyanoacrylates are only used externally, as they cause an “intense inflammatory response” when in contact with surfaces other than skin.   The paper is based on tests performed on animals. source: http://www.rdmag.com

Researchers design tailored tissue adhesives

 

Thu, 01/29/2015 - 8:17am Anne Trafton, MIT News Office   MIT researchers have created a tissue adhesive (pictured here in red) that could be used to repair surgical incisions following colon surgery. Image: Jose-Luis Olivares/MITAfter undergoing surgery to remove diseased sections of the colon, up to 30% of patients experience leakage from their sutures, which can cause life-threatening complications. Many efforts are under way to create new tissue glues that can help seal surgical incisions and prevent such complications; now, a new study from Massachusetts Institute of Technology (MIT) reveals that the effectiveness of such glues hinges on the state of the tissue in which they are being used. The researchers found that a sealant they had previously developed worked much differently in cancerous colon tissue than in colon tissue inflamed with colitis. The finding suggests that for this sealant or any other kind of biomaterial designed to work inside the human body, scientists must take into account the environment in which the material will be used, instead of using a “one-size fits all” approach, according to the researchers. “This paper shows why that mentality is risky,” says Natalie Artzi, a research scientist at MIT’s Institute for Medical Science and Engineering (IMES) and senior author of a paper describing the findings in Science Translational Medicine. “We present a new paradigm by which to design and examine materials. Detailed study of tissue and biomaterial interactions can open a new chapter in precision medicine, where biomaterials are chosen and rationally designed to match specific tissue types and disease states.” After characterizing the adhesive material’s performance in different diseased tissues, the researchers created a model that allows them to predict how it will work in different environments, opening the door to a more personalized approach to treating individual patients. Elazer Edelman, the Thomas D. and Virginia W. Cabot Professor of Health Sciences and Technology and a member of IMES, is also a senior author of the paper. The paper’s lead authors are graduate student Nuria Oliva and former graduate student Maria Carcole. Exploring material properties Artzi and Edelman originally developed this tissue glue several years ago by combining two polymers—dextran (a polysaccharide) and a highly branched chain called dendrimer. In a 2009 paper, the researchers demonstrated that such adhesives work better when tailored to specific organs. In their new paper, they explored what happens when an adhesive is used in the same organ but under different disease conditions. They show that the adhesive actually performed better in cancerous colon tissue than in healthy tissue. However, it performed worse in tissue inflamed with colitis than in healthy tissue. Further studies of the molecular interactions between the adhesive and tissue explained those differences in behavior. The tissue glue works through a system where molecules in the adhesive serve as “keys” that interact with “locks”—chemical structures called amines found in abundance in structural tissue known as collagen. When enough of these locks and keys bind each other, the adhesive forms a tight seal. This system is disrupted in colitic tissue because the inflammation breaks down collagen. The more severe the inflammation, the less adhesion occurs. However, cancerous tissue tends to have excess collagen, so the adhesive ends up working better than in healthy tissue. “Now we show that adhesive-material performance is not organ-dependent, but rather, disease type and state-dependent,” says Artzi, who is also an assistant professor at Harvard Medical School. Predicting adhesion Using this data, the researchers created a model to help them alter the composition of the material depending on the circumstances. By changing the materials’ molecular weight, the number of keys attached to each polymer, and the ratio of the two polymers, the researchers can tune it to perform best in different types and states of tissue. An inherent property of the adhesive is that any unused keys are absorbed back into the polymer, preventing them from causing any undesired side effects. This would allow the researchers to create two or three different versions that could cover a wide range of tissues. “We can take a biopsy from a patient for a quick readout of disease state that would serve as an input for our model, and the output is the precise material composition that should be used to attain adequate adhesion,” Artzi says. “This exercise can be done in a clinical setting.” Doctors have begun using this kind of personalized approach when choosing drugs that match individual patients’ genetic profiles, but it has not yet spread to the selection of biomaterials such as tissue glue. The MIT team now hopes to move the sealant into clinical trials and has founded a company to help that process along. “It’s something that we want to do as rapidly as possible,” Edelman says. “We’re excited. It’s not often that you have a technology that is this close to clinical introduction.” Source: Massachusetts Institute of Technology

Shutting off blood supply to extremity to protect heart

 

October 24, 2014

The Norwegian University of Science and Technology (NTNU)

Shutting off the blood supply to an arm or leg before cardiac surgery protects the heart during the operation, a study shows. "The heart muscle of the patients who had restricted blood flow to their arm before surgery were able to maintain the same level of energy production during the whole operation, while heart muscle from the other patients' hearts was not. This may be important because heart tissue is dependent on energy to survive, as well as to repair injuries the cells may have endured during surgery," an investigator says.

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In a study just published in the International Journal of Cardiology, researchers from the K.G. Jebsen Center for Exercise in Medicine -- Cardiac Exercise Research Group (CERG) at the Norwegian University of Science and Technology (NTNU) and the Department of Cardiothoracic Surgery at the St. Olavs Hospital in Trondheim, Norway have shown that shutting off the blood supply to an arm or leg before cardiac surgery protects the heart during the operation.

The research group wanted to see how the muscle of the left chamber of the heart was affected by a technique, called RIPC (remote ischemic preconditioning), during cardiac surgery.

RIPC works by shutting off the blood supply to an arm or a leg before heart surgery. The goal is to reduce risk during cardiac surgery in the future. The technique is not new, but its effects have never before been tested directly on the left chamber of the heart.

"During heart surgery we have to stop the blood supply to the heart to be able to operate on it. After some time without fresh blood, the heart will reduce its ability to produce energy because it doesn't get oxygen. When we shut off the bloodflow to another large muscle, such as an arm or a leg, the body prepares for an upcoming challenge by mobilizing its defense system," says the first author of the study, Katrine Hordnes Slagsvold, a PhD candidate at NTNU and medical doctor at St. Olavs Hospital.

The researchers investigated cardiac tissue from 60 patients who had coronary bypass surgery at St. Olavs Hospital in Trondheim. The patients were randomized to either undergo RIPC, or to a control group. Patients who were treated with RIPC underwent brief periods without blood supply to the arm before surgery, by inflating a blood pressure cuff for five minutes three times.

"The heart muscle of the patients who had restricted blood flow to their arm before surgery were able to maintain the same level of energy production during the whole operation, while heart muscle from the other patients' hearts was not. This may be important because heart tissue is dependent on energy to survive, as well as to repair injuries the cells may have endured during surgery," Slagsvold says.

The researchers also found that a protein called Akt was activated after RIPC, and believe that activation of this protein may be key in inducing the protective effect on the heart.

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Story Source:

The above story is based on materials provided by The Norwegian University of Science and Technology (NTNU). Note: Materials may be edited for content and length.

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Journal Reference:

1. Katrine H. Slagsvold, Jose B.N. Moreira, Øivind Rognmo, Morten Høydal, Anja Bye, Ulrik Wisløff, Alexander Wahba. Remote ischemic preconditioning preserves mitochondrial function and activates pro-survival protein kinase Akt in the left ventricle during cardiac surgery: A randomized trial. International Journal of Cardiology, 2014; DOI: 10.1016/j.ijcard.2014.09.206

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