Heart surgery

New anticoagulant platform, offering hope for advances in cardiac surgery, dialysis and other procedures

Although blood clotting is important for preventing blood loss and for our immunity, clotting can also lead to health problems and even death. Currently, one in four people worldwide die of diseases and conditions caused by blood clots. Meanwhile, blood thinners used to reduce risk can also cause significant problems, such as uncontrolled bleeding.

Now, a new biomolecular anticoagulant platform invented by a team led by UNC researcher Charlotte Kirill Afonin holds promise as a breakthrough advance over anticoagulants currently used in surgeries and other procedures. The team’s findings are reported in the journal Nano-lettersfirst available online July 5th.

“We anticipate uses for our new anticoagulant platform to be during coronary bypass surgeries, kidney dialysis and a variety of vascular, surgical and coronary procedures,” said Afonin. “We are currently investigating whether there are potential future applications with cancer treatments to prevent metastasis and also to address the needs of malaria, which can cause clotting problems.”

The article shares the most recent results of three years of collaboration between researchers from the Frederick National Laboratory for Cancer Research (Nanotechnology Characterization Laboratory), the University of São Paulo in Brazil, Pennsylvania State University and from the Uniformed Services University of the Health Sciences.

“All of this culminated in a massive international and interdisciplinary effort to develop entirely new technology that we believe could revolutionize the field and be taken up by other areas of health research,” Afonin said.

The team’s technology looks to programmable RNA-DNA anticoagulant fibers that, when injected into the bloodstream, form modular structures that communicate with thrombin, which are the enzymes in blood plasma that cause blood clotting. The technology allows the structures to prevent blood from clotting when needed, then to be quickly cleared from the body by the renal system once the work is done.

The fibrous structures use aptamers, short DNA or RNA sequences designed to specifically bind and inactivate thrombin.

“Instead of having a single small molecule that deactivates thrombin,” Afonin said, “we now have a relatively large structure that has hundreds of aptamers on its surface that can bind to thrombin and deactivate them. And because the structure becomes larger, it will circulate in the bloodstream for a significantly longer time than traditional options.”

The extended circulation in the bloodstream allows for a single injection, instead of multiple doses. The design also decreases the concentration of anticoagulants in the blood, which leads to less stress on the kidney and other systems in the body, Afonin said.

This technology also introduces a new “kill-switch” mechanism. A second injection reverses the anticoagulant function of the fibrous structure, allowing the fibers to metabolize into tiny, harmless, inactive materials that are easily excreted through the renal system.

The whole process takes place outside the cell, through extracellular communication with thrombin. The researchers note that this is important because immunological reactions do not appear to occur, based on their extensive studies.

The team tested and validated the platform using computer models, human blood and various animal models. “We conducted proof-of-concept studies using freshly collected human blood from donors in the United States and Brazil to address potential between-donor variability,” Afonin said.

The technology can provide a foundation for other biomedical applications that require communication through the extracellular environment in patients, he said. “Thombin is just one potential application,” he said. “Anything you want to deactivate extracellularly, without entering cells, we think you can. That means potentially any blood protein, any cell surface receptor, maybe antibodies and toxins, are possible.”

The technique allows the design of structures of any desired shape, with the circuit breaker mechanism intact. “By changing the shape, we can get them into different parts of the body, so we can change the distribution,” Afonin said. “He gets an extra layer of sophistication from what he can do.”

While the application is sophisticated, producing the structures is relatively easy. “The shelf life is incredibly good for these formulations,” Afonin said. “They’re very stable, so you can dry them out, and we expect them to stay for years at room temperature, making them very accessible to economically disadvantaged parts of the world.”

Although the researchers’ work so far is relevant to short-term applications, such as surgeries, they eventually hope to extend their research to maintenance situations, such as the medications that patients with heart disease take.

The potential to save lives and improve health care drives the team, as does inventing something new, Afonin said. “We can learn from nature, but we’ve built something that’s never been introduced before,” he said. “So we develop and build all of these platforms de novo – from scratch. And then we can explain through our platforms what we want nature – or our bodies – to do and our bodies understand us.”

UNC Charlotte’s Office of Commercialization and Research Development is working closely with Penn State to patent and bring this new technology to market.

Afonin, a professor in the nanoscale science doctoral program in the Department of Chemistry at UNC Charlotte, is the corresponding author of the paper. Other authors are: Weina Ke from UNC Charlotte, Morgan Chandler from UNC Charlotte, Edward Cedrone from Frederick National Laboratory for Cancer Research, Renata F. Saito from University of São Paulo, Maria Cristina Rangel from University from São Paulo, Mara de Souza Junqueira from the University of São Paulo, Jian Wang from Penn State, Da Shi from the Frederick National Laboratory for Cancer Research, Nguyen Truong from UNC Charlotte, Melina Richardson from UNC Charlotte, Lewis A. Rolband from UNC Charlotte, Didier Dréau from UNC Charlotte, Peter Bedocs from Uniformed Services University of the Health Sciences, Roger Chammas from UNC Charlotte, Nikolay V. Dokholyan from Penn State and Marina A. Dobrovolskaia from the Frederick National Laboratory for Cancer Research.