Synthetic platelets helps clot blood faster

New York: Taking a cue from the human body’s own blood-clotting process, researchers at University of California, Santa Barbara have developed synthetic platelets that can do more than clot blood.
By creating nanoparticles that mimic the shape, flexibility and surface biology of the body’s own platelets, the team was able to accelerate natural healing processes while opening the door to therapies and treatments that can be customised to specific patient needs.
“This is a significant milestone in the development of synthetic platelets, as well as in targeted drug delivery,” said Samir Mitragotri, director of Center for Bioengineering (CBE) who specialises in targeted therapy technologies.
In case of blood loss due to minor injury, platelets release chemicals that “call” other platelets to the site, eventually plugging the wound.
But what happens when the injury is too severe or the patient is on anti-coagulation medication or is otherwise impaired in his or her ability to form a clot, even for a modest or minor injury?
That’s where platelet-like nanoparticles (PLNs) come in.
“These tiny, platelet-shaped particles that behave just like their human counterparts can be added to the blood flow to supply or augment the patient’s own natural platelet supply, stemming the flow of blood and initiating the healing process,” researchers emphasised.
“We were actually able to render a 65 percent decrease in bleeding time compared to no treatment,” said graduate student researcher Aaron Anselmo, lead author of the study.
With PLNs, emergency situations can be brought under control faster, injuries can heal more quickly and patients can recover with fewer complications, he added.
The results appeared in the journal ACS Nano.

Clot-building nanoparticles raise survival rate following blast trauma Read more: Clot-building nanoparticles raise survival rate following blast trauma

A type of artificial platelet being developed to help natural blood platelets form clots faster offers promise for saving the lives of soldiers, as well as victims of car crashes and other severe trauma.

In preclinical tests led by a Case Western Reserve University researcher, the artificial platelets, called "hemostatic nanoparticles," when injected after blast trauma dramatically increased survival rates and showed no signs of interfering with healing or causing other complications weeks afterward.

"The nanoparticles have a huge impact on survival—not just in the short term, but in the long term," said Erin Lavik, an associate professor of biomedical engineering at Case Western Reserve. Other researchers had raised concerns that the foreign matter would interfere with healing, or form free-floating clots, but "we saw none of that."

The research, published in the Proceedings of the National Academy of Sciences this week ("Intravenously administered nanoparticles increase survival following blast trauma"), show the survival rate of mice models of blast trauma treated with the nanoparticles increased to 95, compared to 60 percent for those untreated.

Spherical hemostatic nanoparticles accumulate on a clot-stabilizing mesh of fibrin the body produces. (Image: Andrew Shoffstall)

Also, no unwanted side effects, such as accumulation of the nanoparticles, clot formation or aberrant healing, were found during examinations one ands three weeks after the injection.

Lavik worked with Margaret M. Lashof-Sullivan, Erin Shoffstall and Kristyn T. Atkins, of Case Western Reserve; Nickolas Keane and Cynthia Bir of Wayne State University and Pamela VandeVord of Virginia Tech.

Explosions account for 79 percent of combat-related injuries and are the leading cause of battlefield deaths, according to researchers at Veterans Affairs hospitals and the federally run Uniformed Services University of the Health Sciences.

The primary blast wave, flying shrapnel and being thrown to the ground cause the lungs, liver, kidneys and other organs to hemorrhage and bleed uncontrollably.

Such uncontrolled bleeding from collisions, blows and falls is also the leading cause of death among victims age 5 to 44 in the United States.

Natural blood platelets are the key ingredient to stopping bleeding, a process called hemostasis. The process works well for typical cuts and scrapes, but can be overwhelmed with serious injuries.

This is a schematic of hemostatic nanoparticles linking with blood platelets. The nanoparticles significantly increased survival rate from blast trauma in preclinical testing. (Image: Erin Lavik)

Hospitals try to stem internal bleeding by giving trauma patients blood products or the hemophilia medicine called recombinant factor VIIa, but there isn't a good option for the battlefield or accident scenes. Recombinant factor VIIa must be refrigerated, costs up to tens of thousands of dollars per treatment and can cause clots in brain and spinal cord injuries, which are common from explosions.

Lavik's team has fine-tuned the nanoparticles to increase clotting efficiency. "They are incredibly simple… spheres with arms of peptides that react with activated blood platelets in damaged tissues to help clots form more quickly," she said.

The particles are made from short polymer chains already approved for other uses by the U.S. Food and Drug Administration. In earlier testing, rat models injected with the nanoparticles stopped bleeding faster than untreated models.

The dry particles remained viable after two weeks on a shelf. A medic in the field or an ambulance crew would add saline, shake and inject them, the researchers say.

Further research and testing are underway. Clinical trials on humans are likely at least five years out, Lavik said.

Scientists Develop Communicating Nanoparticles that Boost Targeted Drug Delivery to Tumors

Scientists have developed a two-stage communicating nanoparticle approach to tissue targeting and drug delivery that they claim can target 40 times higher doses of chemotherapeutics to tumors than traditional nanoparticles. Basing the new approach on communications systems found in nature such as insect swarming, immune-cell trafficking, and platelet self-assembly, the collaborative team led by Massachusetts Institute of Technology professor Sangeeta Bhatia, M.D., has devised a system that combines signaling nanoparticles or engineered proteins with receiving nanoparticles that carry the diagnostic or therapeutic agents.
Essentially, the signaling molecules home in on the tumor and activate the coagulation cascade, which results in recruitment of the clot-targeting receiving nanoparticles to the tumor site to deliver their cargo. Reporting in Nature Materials, the researchers claim their work provides the groundwork for a systems nanotechnology approach to targeting that could lead to more sensitive location, diagnosis, and treatment of tissue- or cell-specific diseases. Their paper is titled “Nanoparticles that communicate in vivo to amplify tumour targeting.”
Current approaches for targeting nanomaterials in vivo have focused on tuning the properties of individual nanoparticles (NPs) including their geometry, surface chemistry, ligand type, and ligand density, Dr. Bhatia and team notes. In contrast, the two-stage approach led by the MITresearchers and their collaborators uses two types of nanoparticles that work in concert.
They hypothesized that two signaling modules could selectively activate the coagulation cascade in tumors: NPs (gold nanorods, NRs) that target tumors and convert external electromagnetic energy into heat to locally disrupt tumor vessels, and engineered human proteins—more specifically tumor-targeted tissue factor, tTF—which autonomously survey host vessels for angiogenic tumor receptors and, in their presence, activate the extrinsic coagulation pathway. The receiving modules were constructed using a prototype imaging agent (magnetofluorescent iron oxide nanoworms, NWs) and a prototypical therapeutic agent comprising doxorubicin-loaded liposomes (LPs).
The first step was to test the capacity of the signaling modules to induce coagulation in tumors. Previous work had confirmed that PEG-coated gold NRs have a circulation half-life of over 17 hours in mice and can passively target tumors. The researchers intravenously administered PEG-NRs into tumor-bearing mice, and subsequently irradiated the treated tumors with near-infrared (NIR) light to increase focal tumor surface temperatures. After 24 hours the irradiated tumors in NR-treated mice demonstrated evidence that tumor blood vessel disruption had activated extravascular coagulation.
The researchers then moved on to investigate the potential for a biological signaling module to autonomously survey the host vasculature for angiogenic tumor receptors and, in their presence, engage the extrinsic coagulation cascade. This type of system would operate without the need for any external electromagnetic inputs (such as NIR energy) and could potentially amplify NP targeting to deep-seated and disseminated cancers, they note. For this the team used a truncated, tumor-targeted version of the human protein tissue factor (tTF-RGD), which harnesses an RGD peptide motif to induce coagulation on binding to angiogenic αvβ3 receptors. As occurred following PEG-NR administration, the tumors of mice injected with t-TF-RGD proteins also demonstrated vascular coagulation.
The next step was to construct receiving NPs that could efficiently target regions of coagulation and deliver therapeutics or imaging agents. To this end, a peptide substrate for the coagulation transglutaminase FXIII was tagged to magnetofluorescent iron oxide nanoworm imaging agents to act as an FXIII-NW imaging receiver.
Having verified the coagulation-targeting properties of the receiving FXIII-NW NPs in isolation, the researchers evaluated the two-stage signaling-receiving approach in combination. PEG-NRs were intravenously injected into mice bearing bilateral tumors. After NR clearance from circulation mixtures of active and inactive receiving NPs (FXIII-NWs and FXIIIControl-NWs) labelled with distinct NIR fluorochromes were co-injected intravenously, followed by NIR irradiation of just the right flank of the mouse.
Ninety-six hours later, imaging studies revealed pronounced homing of FXIII-NWs to the NR-heated tumors on the right flank, when compared both with the unirradiated tumor-bearing left flank, and with control, saline-injected mice. Histological examination showed that integrated NP generated intense regions of FXIII-NW fluorescence relative to controls, particularly in tumor boundaries where blood vessels were well perfused. Equivalent results were confirmed in different xengraft tumor models, which also demonstrated a several-fold amplification in the homing of targeted receiving NPs compared with untargeted controls.
In a separate set of experiments, the researchers evaluated the ability of autonomous communication between tTF-RGD signaling modules and FXIII-NW receiving modules to amplify tumor targeting. When co-injected alongside FXIII-NW receivers, the tTF-RGD signaling modules where shown to amplify the receiver targeting response several-fold compared with both noncommunicating controls and with NWs that are directly targeted by RGD-targeting ligands. Closer examination demonstrated that FXIII-NW receivers injected alongside tTF-RGD proteins produced a dendritic pattern of accumulation in tumors, corresponding to abundant intravascular localization immunohistochemically, the authors note. This amplified vascular targeting was found to be specific for tumors and was absent when the coagulation inhibitor heparin was administered alongside signaling and receiving modules.
To demonstrate proof of principal that the approach could improve tumor drug delivery and therapy, the researchers evaluated the efficacy of a therapeutic communicating nanosystem in which the receiver comprised doxorubicin-loaded LPs with tethered active FXIII. When these therapeutic receivers were used in place of the imaging receivers, the team was able to show that communication between NR signaling modules and FXIII-LP receivers amplified the accumulation of doxorubicin in NR-heated tumors by over 40-fold compared with LPs alone, and more than sixfold when compared with an optimized LP formulation that targeted endogenous vascular receptors (αvβ3 for high-affinity cyclic-RGD peptide-targeted LPs).
This amplification of drug delivery probably has at least two components, the authors suggest. Heat-dependent increases in passive accumulation due to improved extravasation in tumors, and specific biochemical recognition of the coagulation process by the peptide coating.
In a final set of studies the team evaluated the therapeutic efficacy of the communicating strategy using PEG-NRs as the signaling molecules and an intravenous dose of FXII-LPs in mice bearing a single human tumor. The PEG-NRs were injected into mice, and once cleared from the circulation, a single intravenous dose of FXIII-LP was given followed immediately by irradiation with NIR energy. The treatment resulted in prolonged inhibition of tumor growth that was significantly more effective than system components in isolation, without any detectable weight loss due to system toxicity.
“Given the diverse NP and synthetic biological 'building blocks' under development, coupled with the plethora of robust biological cascades that could be repurposed to enable communication between synthetic components, we believe that a wide array of nanosystems could be engineered to more sensitively locate, diagnose, and treat a diversity of focal human diseases,” the authors conclude. “We believe that this work motivates a paradigm of systems nanotechnology directed toward the construction of communicative diagnostic and therapeutic agents with sophisticated in vivo behaviors.”

Cotton candy-like glass nanofibers appear to speed healing in initial venous stasis wound trial

Imagine a battlefield medic or emergency medical technician providing first aid with a special wad of cottony glass fibers that simultaneously slows bleeding, fights bacteria (and other sources of infection), stimulates the body's natural healing mechanisms, resists scarring, and-because it is quickly absorbed by surrounding tissue - may never have to be removed in follow-up care.Or, imagine diabetics with hard-to-heal wounds finding a source of relief from the battle against infections and limb amputation.Those scenarios are the hope of the developers of a revolutionary borate glass nanofiber material, which appears have sped and helped the final of healing long-term wounds in eight out of 12 venous stasis wound sufferers in a recent clinical trial held at a medical center in Rolla, Mo.Details about the trials and the glass fiber material were published today in the May issue of the American Ceramic Society's Bulletin magazine.The story reports on the discovery of the fibers and on an empirical study that began late in the fall of 2010 supervised by the internal review board of the Phelps County Regional Medical Center. The trial groups originally had 13 volunteer members, but one dropped out during the early stages.According to Peggy Taylor, the PCRMC registered nurse who administered the treatments, all of the volunteers in the trial are enthusiastic about the use of the glass fiber product, which she says "looks like cotton candy.""All of the participants had diabetes and several of them had wounds that had been unhealed for more than a year," says Taylor, a specialist in wound care. "One patient had the same wound for three years. After using the glass fiber product for a few months, we were able to repair the skin in eight of the patients. Remarkably, the other four have made a lot of progress and all of their wounds should be healed soon, too."All of the patients suffered from problems associated with venous stasis, a condition where blood circulation in extremities is poor. As the blood pools, typically in lower legs, fluids accumulate causing unusual pressure on skin tissues. Sores and wounds can then develop when the fluid "weeps" from skin cracks, cuts or abrasions.Because of an enzyme in the weeping fluid, the skin surrounding small venous stasis injuries can quickly erode and turn into large and deep wounds. Even small bruises can eventually develop into bone-deep openings.The goal of the PCRMC trial was to provide an initial evaluation of the effects of the novel fibrous glass material produced by the Mo-Sci Corporation, a Rolla company already known for creating glass-based materials for medical applications."Bioglass" materials aren't particularly new to the medical field, but thus far all bioglass has been formed from a silica-based glass composition, and these primarily have been used in hard-tissue regeneration, such as bone repair.Glass scientist Steve Jung, who helped develop the new material, says he and co-developer Delbert Day had wondered whether a different type of bioactive glass material could be used for soft-tissue regeneration. "We felt from our in-vitro studies that bioactive glasses containing boron would react to body fluids much faster than silicate glasses," says Jung, who obtained his Ph.D from Missouri University of Science and Technology, where he conducted his research with Day, a professor at the university. "We also knew that an in-vitro study of lithium borate glasses had showed it to have beneficial effects against bacteria, such as E. coli, salmonella and staphylococcus microbes."Lastly, Jung and Day recall they were interested in a composition that was rich in calcium. "Previously, investigators have reported that calcium is important for wound healing. It appears to assist the migration of epidermal cells and help the body regulate the healing process of open wounds," says Jung.Besides composition, Jung and Day thought the structure of the material may be important to consider, too, and suspected that providing a healing "scaffold" might be beneficial. "We thought it might be advantageous to have a material that could mimic the microstructure of fibrin that forms the basis of a blood clot. We reasoned that if the structure could imitate fibrin, it might trap blood platelets and allow the formation of a wound cover that could support the healing process."Jung and Day finally settled on a particular borate glass composition - called 13-93B3 glass - one that Mo-Sci, a company founded by Day, already knew how to form into cottony glass fibers, 300 nanometers to 5 micrometers in diameter.

Excessive use of toxic materials in medical nanotechnology could be avoided

(Nanowerk Spotlight) Metal nanomaterials are often synthesized using the toxic reagent formaldehydeat concentrations thousands of times higher than necessary. Many of these same nanomaterials are being investigated for use in cancer treatment – however, there is a risk that they could do more harm than good. The large excess of formaldehyde that is used originates from methods developed 100 years ago. Because these methods work well, they have stood the test of time. By better understanding the role that formaldehyde plays in nanomaterial synthesis it will become possible to reduce or eliminate this toxic reagent. By eliminating formaldehyde it will become safer to prepare these nanomaterials and safer to use them in cancer treatment.

"The observation that previous synthetic routes for nanoshell and core-shell nanoparticles utilize a large excess of formaldehyde suggested an opportunity for minimizing the quantity of formaldehyde used,"Scott Reed, an assistant professor of chemistry at the University of Colorado at Denver, tells Nanowerk. "However, the synthesis of gold-core, silver-shell nanoparticles that are active in the near-infrared requires the polymer that forms by reaction of formaldehyde and ammonium hydroxide. Until a replacement polymer is found, formaldehyde is required to obtain the desired optical properties."

In a recent paper in the May 19, 2010 online edition of Chemistry of Materials ("Minimizing Formaldehyde Use in the Synthesis of Gold-Silver Core-Shell Nanoparticles"), Reed's team and colleagues from Portland State University describe an effort to minimize the amount of formaldehyde used for coating silver onto gold nanoparticles. They describe a strategy where formaldehyde use can be reduced 100-fold from prior routes and this minimization strategy can be applied to other nanoparticle syntheses.

"We discovered that most of the formaldehyde used in preparing silver nanomaterials is consumed by formation of a polymer" Reed explains. "Formaldehyde reacts with ammonium hydroxide to form a previously unnoticed polymer. When we decreased the ammonium hydroxide concentration it became possible to decrease the formaldehyde concentration, too."

At the same time, these materials maintain optical activity in the near-infrared, the property that makes them attractive for treating cancer with light.

The excessive use of toxic formaldehyde in fabrication processes for nanomaterials is particularly worrisome in the area of nanomedicine where these materials are deliberately injected into the body for diagnostic or therapeutic purposes. Many of the synthetic routes to nanoshells and core-shell metal nanoparticles use a large excess of the toxic reagent formaldehyde as a reducing agent.

Reed notes that one of the early methods reported for coating silver on silica spheres made use of 1 mmol of formaldehyde for reduction of a 0.15 mM solution of silver ("Silver Nanoshells: Variations in Morphologies and Optical Properties").

He estimates that a 3000-fold more formaldehyde is used to prepare silver nanoshells than necessary.

"This large excess is based on Zsigmondy's original silver nanoparticle synthesis reported in 1927 and is typical of coating procedures" he continues. "Other reports have used a 1000-fold excess for coating silver on polystyrene beads or gold nanoparticles, up to 320-fold excess for coating silver on silica nanowires, a 346-fold excess to coat silver onto latex spheres, and a 24000-fold excess for layering silver onto tin-coated silica nanoparticles."

Representative TEM image of core-shell nanoparticles prepared using a mixture of formaldehyde and ascorbic acid. One-half a microliter of formaldehyde was incubated with 4.5 mL water for 15 min prior to addition of 0.5 mL of gold nanoparticles and 0.2 mL of 1.1 mM silver nitrate followed by 21.2 µL ammonium hydroxide after a 5 min incubation and 0.1 mL of 0.534Mascorbic acid after an additional 5 min incubation. Scale bar=20 nm. (Reprinted with permission from American Chemical Society)

Demonstrating an approach to developing greener synthesis methods, Reed and his team fabricated silver-coated gold nanoparticles suitable for phototherapy. Although formaldehyde still is an essential component of this process, they were able to reduce its amount 100-fold compared to previous processes. Part of this minimization resulted from the discovery that ascorbic acid (vitamin C) can be used as a reducing agent in combination with formaldehyde.

"Understanding this previously overlooked polymer formation is a good starting point for minimizing formaldehyde use in the synthesis of nanoshells and other core-shell nanomaterials" says Reed. "We expect that this will result in greener syntheses and more biocompatible nanomaterials suitable for medical applications."

In previous Nanowerk Spotlights we have raised the issue that today's nanomanufacturing processes actually are quite dirty and polluting activities ("Not so 'green' nanotechnology manufacturing"). As Reed and his collaborators show, by designing greener synthetic routes it will become possible to more safely prepare metal nanoparticles without creating hazardous waste. An issue that is particularly important for applications in nonomedicine.

As this particular example shows, this new understanding of formaldehyde will allow for changes in how many types of nanomaterials are synthesized. Nanoparticles prepared using green methods are more likely make it through the regulatory hurdles associated with medical applications.

Researchers Study Molecular Architecture of Fibrin Networks

The research, published by Cell Press in Biophysical Journal on May 18th, provides insight into how the molecular architecture of a fibrin network contributes to its resilience and may help to explain what causes the failure of a clot, which can lead to a stroke or heart attack.

Fibrin is a fibrous protein which assembles into a remarkably strong spider web-like gel that forms the structural framework of blood clots. Previous work has shown that fibrin networks, thought to be among the most resilient proteins in the natural world, stiffen when deformed and become increasingly resistant to further strain. Although this extraordinary resilience appears to be crucial for the biological function of blood clots, the molecular basis of this resilience is not well understood.

"To better understand the superior elasticity of fibrin networks, we measured the mechanical behavior of purified fibrin gels on multiple scales," says senior study author, Dr. Gijsje H. Koenderink from the Biological Soft Matter Group at the FOM Institute AMOLF in The Netherlands. "We found that the fibrin has a series of molecular domains that are stretched out sequentially, on smaller and smaller scales, when clots are deformed. This stretching leads to gel stiffening, which protects the clots from damage"

Specifically, Dr. Koenderink's group made the surprising discovery that the fibrin fibers are very porous loose bundles of thin filaments that are connected by flexible crosslinkers. This open structure (containing 80% water) makes the fibers 100-fold more flexible than previously thought, and enables sequential stiffening due to straightening out of the bundles between network crosslinks followed by straightening out of flexible protein domains inside the bundles. "We found that it is this bundle-like structure of fibrin fibers that is ultimately responsible for the superior mechanical properties of fibrin gels," explains Dr. Koenderink.

The researchers presented a theoretical model that explained their observations in terms of this unique hierarchical architecture of the fibers. "Our data reveal molecular design principles that allow blood clots to recover from large forces, such as shear forces from blood flow, furthering our understanding of how pathological alterations in fibrin cause clot rupture and bleeding or thrombosis," concludes Dr. Koenderink. "Moreover, our findings suggest a new design concept for resilient bio-inspired materials with potential applications in drug delivery and tissue repair."

Nanoscale features patterned on surfaces of polymer biomaterials can prevent blood clots

(Nanowerk News) Implanting artificial materials or devices in patients can cause adverse reactions when contacting natural tissue and blood. In blood-related defense mechanisms, plasma proteins quickly adsorb on the biomaterial surfaces and trigger a series of biochemical events that lead to platelet adhesion and aggregation into blood clots. The clotting can hinder the performance of an artificial device and can be life-threatening in some instances.

Now, Isabel Rodriguez from the Institute of Materials Research and Engineering of A*STAR, Singapore, and co-workers have discovered that adding miniature topographical features to polymer surfaces can reduce blood coagulation and improve the ‘hemocompatibility’, or blood compatibility, of biomaterials ("The effect of topography of polymer surfaces on platelet adhesion").

Using chemical modifications, many researchers have tried to coat or graft a secondary material to the surface of biomaterials to enhance their biocompatibility. Attempts to date, however, have met with limited success.

In many circumstances, secondary materials can leach out from the modified surfaces, which may have toxic effects, according to Rodriguez. “Hence, a biocompatible surface without additional chemical modifications is most desirable,” she says.

Fig. 1: Scanning electron micrograph showing that platelets adhere more to a planar surface (far left) than a nanostructured polymer surface (center, right).
To achieve this goal, Rodriguez and her team prepared various nano- and micro-structured surfaces from the biocompatible polymer poly(lactic-co-glycolic acid) (PLGA). They used alumina and silica templates prepared using nano- and micro-fabrication techniques to create nano- and micrometer-sized cavities. They then deposited PLGA solutions into these templates and cured them under vacuum to produce the structured polymer films.Next, the researchers incubated the surface-structured PLGA films with human fibrinogen—blood protein that mediates platelet adhesion and activation—and then with platelet-rich plasma. Finally, by quantifying fibrinogen, platelet adhesion and platelet activation, they assessed the ability of the films to promote blood clotting. Significantly fewer platelets adhered to surfaces covered with dense, high aspect ratio, nanometer-sized features than to planar surfaces (Fig. 1).From a comparison between a featureless PLGA film and an inert carbon surface, the researchers found that surface chemistry had an important role in the initial adsorption of proteins and platelets. However, appropriated surface features can overcome or complement the effect of chemistry and indeed reduce the tendency of blood clotting on an artificial surface, notes Rodriguez.“Surfaces with [a] high level of hemocompatibility will have important applications in surgical tools such as catheters and implantable medical devices like heart valves, stents or vascular grafts,” says Rodriguez. The team is currently planning to perform in vitro tests using whole blood samples, instead of just plasma, to assess clot size formation and clotting rate before moving on to in vivo tests.

Individual Fibrin Fibers Distribute Strain Across A Network

A new study shows that when it comes to networks of protein fibers, individual fibers play a substantial role in effectively strengthening an entire network of fibers. The research, published by Cell Press in the April 20th issue of the Biophysical Journal,describes a mechanism that explains how individual fibrin fibers subjected to significant strain can respond by stiffening to resist stretch and helping to equitably distribute the strain load across the network.

Fibrin is a fibrous protein that assembles into a remarkably strong mesh-like network and forms the structural framework of a blood clot. Failure of a clot can have fatal consequences. For example, if a portion of the clot breaks away and is carried downstream by the flowing blood, it can cause a stroke or heart attack. Although previous research has characterized the mechanical properties and behavior of fibrin networks on a macroscopic level, much less is known about the behavior of individual fibrin fibers and the distribution of strain from one fiber to the next.

"We know that network strength is determined in part by the maximum strain individual fibers can withstand, so it is of particular interest to determine how the high strain and failure characteristics of single fibrin fibers affect the overall strength of the network," says senior study author Dr. Michael R. Falvo from the Department of Physics and Astronomy at the University of North Carolina at Chapel Hill. "Further, determining how strain is shared among the constituent fiber segments in a network under imposed stress is crucial to understanding failure modes of networks and their strength."

Dr. Falvo and colleagues used a combined fluorescence/atomic force microscope nanomanipulation system to stretch two dimensional fibrin networks to the point of failure while recording the strain of individual fibers. "Specifically, we observed that as fibers were stretched, they became stiffer than the surrounding fibers at lower strains; this allowed the more strained, stiffer fibers, to distribute the strain load to the less strained fibers and reduce strain concentrations," explains Dr. Falvo. "So in effect, strain stiffening in the individual fibers acts to distribute strain equitably throughout the network and thereby strengthen it."

The strain concentration reduction effect described in this study may be part of an important physiological mechanism to strengthen blood clots under high shear conditions in the blood stream. The authors note that along with this physiological insight, their findings bring about a better understanding of this remarkable strengthening mechanism and may help to guide new design strategies for engineered materials

US researchers develop intravenous blood-clotting agent

New York (Dec 28, 2009) : Whether in war-torn Iraq and Afghanistan or on the world's roads, many thousands of people bleed to death each year as a result of traffic accidents, gunshot wounds and bombs.
Traumatic injury is the leading cause of death for people aged 4 to 44, US researchers wrote this month in the journal Science Translational Medicine. But they think they have found a way to halt
internal bleeding with the help of nanotechnology.
A team led by Erin Lavik, a biomedical engineer at Case Western Reserve University in Cleveland, Ohio, has developed synthetic blood platelets from biodegradable polymers already used in treatments approved by the US Food and Drug Administration (FDA), whose regulatory purview includes biologics and blood products.
If injected into a trauma patient, the synthetic nanoparticles could bind at the site of injury with natural blood platelets, thereby hastening clotting. In tests, the synthetic platelets halved
bleeding time in wounded rats. Lavik and her colleagues said that injecting the nanoparticles was like adding sand bags to a levee along a flooding river.
When blood starts to flow from a wound, the researchers explained, natural platelets try to staunch it by binding together using fibrous protein molecules. The synthetic platelets augment this process by binding to the natural ones.
To prevent the synthetic platelets from clumping into dangerous clots, each one is built with a surrounding "shield" of water. In the test animals, surplus synthetic platelets were flushed out of the body within 24 hours.
The researchers said they had been looking for a means to stem internal bleeding that medics could carry in their field packs. "The military has been phenomenal at developing technology to halt bleeding from external or compressible injuries," Lavik remarked, pointing out that the nanoparticles could complement existing therapies

Synthetic Blood Platelets Are Twice As Effective

Scientists working with small particles at the nanoscale have recently revealed that they have developed a new type of synthetic blood platelets, which have twice the clotting capabilities of the standard variety. In the experiments they conducted on lab mice, the science group, which are based at the Case Western University (CWU), in Cleveland, managed to obtain an increased efficiency using their innovation than they could squeeze out of traditional clotting methods.
Technology Review reports that the nanoparticles could be the next major innovation in this field, considering that the regular drugs were so significantly exceeded in terms of performance. “We're helping to form the clot,” CWU bioengineer Erin Lavik, who has also been the leader of the new investigation, explains briefly. The scientist reveals that plans are to create blood clotting particles that are so effective that they could be used by paramedics right at an accident site, or by doctors working on injured soldiers in battlefields around the globe.
Early safety tests turned out to be very promising, but the CWU team admits that there is still a lot of work to be done until the new nanoparticles are ready to be mass-produced, and administered to patients. Speaking about the challenges associated with the development of a good blood clotting method, University of Pennsylvania Medical School physician Mortimer Poncz said, “There's a balance between the two edges of the sword--bleeding too much and clotting too much. You don't want to stop bleeding in the leg but die of a heart attack or have stroke.” He has not been involved in the new study.
The new nanoparticles are about one third the size of normal platelets. They can run through the bloodstream without experiencing obstacles, but also have the same stickiness that makes their natural counterparts so effective at stopping bleeding. While existing drugs can indeed boost the immune system's proprietary response to injury, they can also be terribly expensive, so a cheaper, more effective method was very high up on researchers' priority lists.

Gecko Stitches

Unlocking the gecko's ability to walk on walls is leading researchers to find a way to replace surgical stitches with sticky tape. As this ScienCentral News video explains, the challenge is to make a surgical tape that works in the wet conditions inside your body.

Laser-activated tissue repair trumps standard surgical closure

Boston — Photochemical tissue bonding, or laser-assisted nanosuturing, is a new cutting-edge technology that may rewrite the surgical books in terms of standard surgical closure procedures.This novel technique allows the surgeon to close the epidermal defect with laser following the application of a light-sensitive dye to the wound edges eliminating the need for epidermal suture placement. Led by Sandy Tsao, M.D., the human clinical trial is based on novel photochemical concepts developed at Massachusetts General Hospital, Boston, by scientists Min Yao, M.D., Robert W. Redmond, Ph.D., and Irene E. Kochevar, Ph.D."Traditional closure techniques work well, but there is always an issue of scarring. Dermabond adhesive liquid techniques also work, but these closure methods do not necessarily have the tensile strength to close wounds when compared to the laser-assisted nanosuturing technique, particularly in areas which may be more prone to keloid formation or unattractive scars," Dr. Tsao says.
Photosensitizing dyesPhotosensitizing dyes have already been utilized in conjunction with lasers in other therapies. Rose Bengal (RB), the ophthalmological dye used in this procedure, is approved by the Food and Drug Administration (FDA).When applied to the skin, RB is activated by light and cross-links proteins such as collagen and epidermal keratins. This non-thermal "stitching" of molecules restores the normal collagenous cross-links that are disrupted during surgery.
Clinical trialIn a recent trial, Dr. Tsao set out to determine the efficacy of wound closure using the photosensitizing dye coupled with laser irradiation and compared it to standard epidermal-interrupted suture closure.In the 28-patient study, Dr. Tsao performed 31 excisions of skin lesions that clinically needed to be removed including dysplastic nevi, SCC and BCC.All defects were closed with vicryl dermal sutures. Half of each epidermal wound was closed using standard interrupted epidermal sutures. The other wound half was closed with laser assisted nanosuturing by applying the rosebengal dye for one minute just to the incision edges of the wound followed by irradiation of this epidermal wound edge with a 308 nm KTP laser for 200 seconds. This way, each patient served as a built-in control in which the quality of closure of each part could be compared.
Results showed that a vast majority of the patients preferred the laser-assisted approach. In all cases, the tensile strength was comparable if not better than the traditional closure technique, and the scar appearance of the laser-treated side in many of the patients was near imperceptible.Though in a few cases, the scar was not clinically and aesthetically attractive, Dr. Tsao says, the laser-treated side was always the better appearing side. There were no complications, infections or dehiscence associated with either the traditional or the laser-assisted treated wound edges.Patients were evaluated at two weeks, three months and at six months. Study endpoints included efficacy of wound closure, vascularity, pigmentation, elevation, atrophy and scar appearance. The surgical sites were evaluated by two blinded physicians and patients were also asked to make an evaluation based on the same attributes."This novel technique provides a very effective means of providing epidermal wound closure with comparable if not markedly better clinical outcome compared to suture closure when evaluating scar erythema, pigmentation, atrophy, keloid formation and track mark formation," Dr. Tsao says.The excisions were attained from non-facial multiple body sites, including the shoulders, chest, back, abdomen, thighs and arms including keloid-prone areas such as the deltoid and sternal regions.Dr. Tsao says that one patient had an SCC in situ on the sternal region requiring a larger excision margin, and on the laser assisted treated side, there is simply no perceptible scar.
‘Next frontier’"With the current technology and knowledge, we still do not have the ability to close the deep dermis yet using this technique which is our next frontier. Eventually, suturing all together may become unnecessary and be a relic of the past."I think the utility beyond the necessity of removing the lesion is in areas where cosmesis is a really critical aspect of the outcome such as the face," Dr. Tsao says.According to Dr. Tsao, this revolutionary technique will save patients, as well as physicians, a lot of valuable time, because there are no sutures to be removed translating into less follow-up, a greater ease for the patient to take care of the area as well as less use of surgical materials.

Scar-free surgery with nanotechnology sealant

(Nanowerk Spotlight) Much attention of nanotechnology researchers has recently been paid to the fabrication of free-standing, ultra-thin films. These systems have been developed for use in a wide variety of fields such as nano-separation membranes or nanosensors for electrochemical and photochemical applications. In a first report on the fabrication of free-standing nanosheets for biomedical applications, scientists in Japan have developed a biodegradable thin film of only about 20 nanometers thickness that could replace surgical stitches.

"We have developed a free-standing PLLA nanosheet with a thickness of 20nm and an area in centimeter order, fabricated by a simple combination of a spin-coating method and a peeling technique with PVA as a supporting film,"

Shinji Takeoka tells Nanowerk. "We found that our ultra-thin nanosheet has an excellent sealing efficacy for gastric incision as a novel wound dressing that does not require adhesive agents. Furthermore, the sealing operation repaired the incision completely without scars and tissue adhesion. This approach would constitute an ideal candidate for an alternative to conventional suture/ligation procedures, from the perspective not only of a minimally invasive surgical technique but also reduction of operation times."Takeoka is a professor in the Department of Department of Life Science and Medical Bioscience at Waseda University in Tokyo. With collaborators from the National Defense Medical College and members of his group he reports his findings in a recent paper in "Free-Standing Biodegradable Poly(lactic acid) Nanosheet for Sealing Operations in Surgery"

Macroscopic and microscopic observations of the stomach seven days after treatments. Sealing with the PLLA nanosheet (a,c). Conventional suture/ligation (b,d). Letters F, M, and S show fibroblasts, mucosa, and submucosa, respectively. Sealing surgical incisions with this nanosheet instead of performing the traditional suture and ligation procedures is more than just a godsend for Hollywood's plastic surgeons. In cases where internal organs or other tissue has been severely damaged, repair by suture and ligation may become technically difficult and unreliable. Also, internal scarring can lead to sometimes dangerous adhesions, with areas of tissue that should remain separate become joined by scar tissue.Researchers have already been working on novel glue-type (see for instance: Gel-based glue fastens snails to wet surfaces, model for surgical adhesive and sheet-type biomaterials for wound dressing. "Ideally" explains Takeoka, "desirable properties of a novel wound dressing material should incorporate the advantages of both types, that is, not only sufficient adhesive strength to cover the wound site as with a sheet-type structure, but also compatibility with the site as with a glue-type structure."The nanosheet developed by the Japanese team fits that bill – it has very interesting features such as high adhesiveness, high flexibility, and high transparency at the same time. PLLA and other polyesters have been clinically applied in drug delivery and as degradable stitches before, but not as nano-thin sheets. Interestingly, the mechanical properties of the nanosheets are very different from the conventional thin film of the same components.

tPreparation of PLLA nanosheets and appearance. (Image: Dr. Shinji Takeoka, Waseda University)

Takeoka explains that his and his team's scientific backgrounds are bio-related macromolecular chemistry and molecular assembling science and engineering." We have studied platelet substitutes, which are biodegradable nanoparticles such as phospholipid vesicles and polymerized albumin particles carrying platelet membrane proteins and peptides for ten years" he says. "We noticed that the nanoparticles specifically accumulated at sites of vascular injury and had hemostatic ability. Moreover, in order to enhance their hemostatic abilities, we proposed the idea of sheet-shaped carriers having a larger contact area for a targeting site than spherical nanoparticles." To demonstrate the suitability of their nanosheets as a novel wound dressing material that lacks adhesive reagents, the researchers repaired incisions on mouse stomachs with them instead of sutures. They found that the PLLA nanosheet has an excellent sealing efficacy and the healed wound showed neither scar nor tissue adhesion. Although it will be several years before this material is developed enough to enter clinical trials, Takeoka expects that the nanosheet will be applied not only in the field of surgery as a wound dressing instead of conventional suturing operation but also in the field of plastic surgery, endoscopic surgery, regeneration medicine, and external use (skin etc.). He also sees applications in the fields of material science, material engineering, and surface science.

New Ultra-Thin Surgical Patch Has Endless Possibilities

Throughout the decades, surgeons have typically used stitches and staples to close up wounds. They may even use sheets several millimeters thick coated with fibrin, a protein that makes blood clot and is glue-like but which can cause unwanted sticking to nearby tissue.

Now, Japanese scientists have revealed a new, cutting edge surgical ‘nano-sheet’ they have developed that is one thousand times thinner than Cellophane that can patch up internal wounds before dissolving inside the body.

This transparent adhesive sheeting is made from a substance derived from crab shells and a viscous gum from algae and is only 75 nanometers thick. A nanometer is one-billionth of one meter.

"This is the world's thinnest adhesive plaster," said Toshinori Fujie, a researcher involved in the joint project by Tokyo's private Waseda University and the National Defense Medical College.


"We know food Cellophane clings on to the surface of various objects. We have made a sheet ultimately thin... so that it is highly flexible and can stick to organs well with no glue," he told AFP.

The experiment, which was repeated several times, consisted of using the new nano-sheet to patch a six-millimeter-wide hole in a dog’s lung.

The sheet proved to have the strength to stand up under the pressure of the dog’s respiration and allow the wounds to heal within a month without a visible trace, according to Fujie.

Researchers hope to launch human clinical trials in three years.

The sheets might also prove to be useful in treating external wounds in the future as well.

"Organs repaired with this sheet do not have scars, unlike after stitches," Fujie said. "We believe this could also be true on the skin."

If the tests show that it is effective externally, it could open up a world of applications such as being applied to wounds from surgery in breast cancer patients, he said.

"Some people also want to use this for treating bed sores. The next application will definitely be on the skin," he said.

Fujie says that the inventors have been exploring all possibilities, even cosmetic uses such as stretching out wrinkles or holding skin conditioners in place.

"As this is transparent on the skin, you could be wearing a face pack while working in the office," he said.

Nanotech in the O.R.

Arch Therapeutics CEO Terry Norchi talks about the company's technology and the challenges of bringing a new product for surgeons to the market.

Iran invents extremely sticky nanoglue

Iranian scientists have employed nanoparticles in an innovative way, inventing a new generation of tension-resistant tissue glue.
The 'nanoglue' made of branched biopolymer is characterized by its high adhesive and tension-resistant quality. Its effect becomes apparent in less than a minute.
Scientists say because it is rich in fibrinogen, extracted from the patients own blood, allergic reactions are rarely reported when used.
The glue also contains high amounts of fibronectin, which facilitates the conjunction of biological agents to a cellular scaffold, improving the tissue repair process.
Shahid Beheshti University scientists claim the glue has been successfully tested in repairing intestines, trachea, fallopian tubes and brachial plexus on dogs.
They add that the intestinal repair process, considered as one of the most sophisticated operations, can be simplified using the new glue.
According to the scientists, the glue has also shown promising results in repairing fallopian tubes, helping the treatment of infertile couples.
source: presstv

Clottocytes: Artificial Mechanical Platelets

While to some Robert A. Freitas Jr.'s clottocyte technology may resemble science-fiction recent developments in the hemostasis field lend his ideas more credibility.............The artificial mechanical platelet or clottocyte may allow complete hemostasis in as little as ~1 second, even in moderately large wounds. This response time is on the order of 100-1000 times faster than the natural system. Our baseline clottocyte is conceived as a serum oxyglucose-powered spherical nanorobot ~2 microns in diameter (~4 micron3 volume) containing a fiber mesh that is compactly folded onboard. Upon command from its control computer, the device promptly unfurls its mesh packet in the immediate vicinity of an injured blood vessel — following, say, a cut through the skin. Soluble thin films coating certain parts of the mesh dissolve upon contact with plasma water, revealing sticky sections (e.g., complementary to blood group antigens unique to red cell surfaces) in desired patterns. Blood cells are immediately trapped in the overlapping artificial nettings released by multiple neighboring activated clottocytes, and bleeding halts at once.......................................Read more HERE

Who else is interested in Nanotech? ........Hemcon, Alltracel

HemCon's acquisition of Alltracel gives access to Alltracel's joint venture with Elmarco and its proprietary nanotechnology manufacturing process called Nanospider®. HemCon will seek to leverage this process to aggressively grow its market share in acute wound care products developed from chitosan.

Elmarco is a specialist R&D and manufacturing company that has developed, in conjunction with the Technical University of Liberic, a novel proprietary & patented process for spinning polymers into nano-scale fibres for a range of industrial, chemical, micro-electronic and bio-medical applications. This proprietary technology branded Nanospider", represents a major breakthrough in the mass production of nanofibre materials and is now deployed in a number of markets including medical products.
NANOPEUTICS headquartered in Liberic in the Czech Republic and operating internationally has been assigned the relevant woundcare and Nanospider(TM) intellectual property and patents and has already been in advanced discussions including successful product testing with a number of existing consumer and professional woundcare companies.

Nanoparticle Laden High-Tech Gauze Looks To Save Lives

Nanoparticles are one of the hottest fields of studies. These tiny molecules promise to revolutionize everything from medicine, to computing, to power, to water purification. The diverse uses being discovered are only limited by the difficulties in bringing this incredibly promising technology to market.
Now the scientific community is enthralled by a perhaps unexpected new use of the particles -- high-tech gauze. By using a special gauze fabric, permeated with Kaolin clay which is rich in aluminosilicate nanoparticles, scientists have discovered they can dramatically inducing clotting that is nothing short of a medical miracle.
The gauze bandage is easy to apply and greatly improves clotting in hard to apply regions such as the neck or groin. This makes it ideal for the battlefield. In recent conflicts, such as the Iraq war, many of the casualties have been due to blood loss. The new gauze could soon be saving lives.
Richard McCarron, head of trauma and resuscitative medicine at the Naval Medical Research Center in Maryland stated, "We are currently testing bandages because hemorrhage is a leading cause of death in military trauma patients. The recent tests with Combat Gauze indicate that it decreased blood loss and improved survival."
Z-Medica, a medical products company located in Connecticut, manufactures the high tech gauze. Z-Medica CEO Ray Huey says the new gauze has already saved two lives. Huey describes his company's start, stating, "In 2002, following the September 11 attacks, the military was looking at new technologies to stop bleeding."
The company easily won the Navy's test of high-tech medical products, according to Huey, when Z-Medica debuted its first product, QuikClot, a special powder dumped on wounds to induce clotting. The powder is currently in use in Afghanistan and Iraq. However, despite saving lives QuikClot had some nasty side effects. During the clotting process, the powder heated up enough to cause burns, which many of the soldiers complained of. While burns were better than dying, Z-Medica went back to work looking for a better solution.
A leading materials researcher Galen Stucky led a team of several graduate students and collaborated with Z-Medica to solve the problem. Stucky's solution was to instead use a material frequently used in medical testing -- Kaolin Clay. The clay's nanoparticles trigger clotting.
Graduate student April Sawvel explains, "Kaolin clay has been used since the 1950s as an activating agent for a clotting test that medical doctors routinely perform. We tested it against the original granular QuikClot and discovered that it worked just as well, but without the large heat release associated with the original QuikClot formulation."
While some nanoparticles are thought to possibly be hazardous, there is little known risk from aluminosilicate nanoparticles, which have been frequently which mankind has been in contact with since its early days. Further, the nanoparticles are trapped by the clot at the site of the injury, so should have little chance of traveling into the body.
Having found the new material the team found that it was much easier to use it, when it was added to gauze, instead of a powder. Huey describes, "We immediately started looking at ways to impregnate gauze with this material. We very quickly prototyped some material. When I say very quickly, I mean within less than two weeks."

The video below shows the original Quikclot.

Wound-Sealing, Self-Assembling, Nanoscale Technology

A super-stealthy MIT (Massachusetts Institute of Technology) spinoff is poking its head out today to announce that it has finalized a licensing agreement with the Institute. The pact gives Arch Therapeutics rights to a family of clear liquids developed by research scientist Rutledge Ellis-Behnke that stanch or prevent bleeding after an injury or during surgery.

Ellis-Behnke and his colleagues had started out working with the liquids, which are packed with tiny protein fragments, or peptides, as potential aids to the regeneration of damaged neural tissue; they discovered in the course of brain surgeries on lab animals that some of the peptides stopped bleeding—within just 15 seconds. It turned out that what was happening was the nanoscale peptides were self-assembling into a biodegradable gel that sealed the wound on contact.

Around the same time as that work was published in 2006, Ellis-Behnke founded Arch—which then went by the perhaps-too-literal Clear Nano Solutions—with healthcare investment veteran Terrence Norchi and Steve Kelly, a serial entrepreneur and founding CEO of Myomo, another MIT spinoff. (Both Myomo’s founders and Ellis-Behnke have received grants from MIT’s Deshpande Center for Technological Innovation.) The company still has yet to ink any venture financing deals; in an article in Mass High Tech written shortly after the company’s founding, Kelly was identified as the sole investor in the firm.

It’s still early days, but Arch materials might eventually be used in the operating room, on the battle field, or even in first-aid kits. Says former Cleveland Clinic head and Arch advisor Floyd D. Loop in a press release: “Discovering ways to control something so fundamental as bleeding has potentially huge implications for the medical field.”
I had trouble viewing the 2006 Pdf full description at its web location so I have made it public hosting it at http://www.adrive.com/ and it is available HERE.