Release date: 2016-11-30

Recently, a team from Professors of the University of North Carolina at Chapel Hill and North Carolina State University, Professor Gu Yong, and Professor Caterina Gallippi developed a team. A "smart anti-thrombosis" patch provides a new strategy for the prevention and treatment of thrombosis. This achievement has also recently been published online in the leading academic journal "Advanced Materials" in the field of materials science.

Thrombosis is the world's top three lethal vascular diseases caused by clots produced in the body, and 1-3 out of every 1,000 people are sick. When the clot is formed, it will block the normal blood circulation of the human body, leading to a series of serious consequences such as pulmonary embolism, heart disease or stroke. According to statistics, China is the country with the most cases of thrombosis; in the United States, between 100,000 and 300,000 people die of venous thrombosis each year, and the number of hospitalizations exceeds 500,000.

Currently, conventional treatments rely on blood thinners such as heparin and warfarin. Although these drugs are effective, they are quite cumbersome in the actual use process - in order to ensure that the amount of heparin is in the proper range, patients need to regularly detect coagulation. If the concentration of heparin in the body is too high, the patient will have a risk of spontaneous bleeding; and if the concentration of heparin is too low, it may not be able to prevent the recurrence of thrombosis.

“We wanted to develop a patch that automatically monitors the patient's blood. It automatically releases the drug when the patient needs it,” said Professor Gu Yu, one of the co-authors of this paper. “This will be a physiological signal. Responsive, thus achieving a system of self-regulation." In recent years, Professor Gu Yu's research group has innovatively proposed the design of transdermal microneedle patches that can respond biologically, and realizes intelligent subcutaneous delivery of dose-controllable drugs. Related inventions include a smart insulin patch that responds to blood glucose, an islet cell patch, and a patch that responds to a tumor microenvironment in response to a sustained release immunological checkpoint (PD-1/CTLA4) antibody.

If you want to achieve self-regulation, the key step is how to know if the patient is at risk of blood clotting. To achieve this, researchers turned their attention to thrombin, an enzyme that initiates a blood clotting reaction. The researchers looked for a system that responded to thrombin—a system that cuts off specific polypeptide chains when thrombin is activated. If we add heparin to this system, can we cut the polypeptide chain and release heparin in the case of thrombin activation, and play a therapeutic role?

To test this idea, researchers used the system to create a patch of "microneedles". These microneedles are composed of a hyaluronic acid polymer which binds heparin via a specific polypeptide. Researchers hope that these polymers will release heparin after exposure to thrombin in the blood.

"The more thrombin in the blood, the more heparin needs to reduce the risk of blood clotting," said Zhang Yuqi, a Ph.D. student who is one of the co-first authors of this paper. "So we designed a one-off patch that would More heparin is released as thrombin increases in the blood."

In mice, the research team tested the effects of this smart patch. In the first trial, mice in the experimental group received heparin injection or a smart patch; mice in the control group did not use any effective preventive measures. Ten minutes after receiving prophylactic treatment, these mice received a thrombin injection sufficient to kill. The researchers found that only mice in the control group died, while mice in the experimental group survived. The results of this trial indicate that there is no significant difference in the ability of smart patches to prevent thrombosis in the short-term and heparin injection.

In the second trial, a lethal dose of thrombin was injected into the mice 6 hours after receiving heparin or smart patches. In just 15 minutes, mice receiving heparin alone had a mortality rate of up to 80%, while mice using smart patches were asymptomatic. In other words, smart patches are superior to ordinary heparin injections in long-term preventive effects.

â–²This smart patch is expected to bring the gospel to patients with thrombosis (Source: Reference [2])
"These test results are expected to bring a self-regulating closed-circuit smart patch to treat patients affected by thrombosis. Thrombosis affects thousands of patients every year, and our patches are expected to be administered more accurately. Treatment, and potentially reduce the cost of treatment." Professor Gu Yu said.
“We are trying to further increase the drug loading of the patch so that the drug content in the patch can be adjusted to the different needs of each patient. Our goal is that patients can change one tablet per day or change one tablet every few days,” Yu Jicheng, another co-first author of this thesis, added: "But the level of heparin released in patients can be regulated by the thrombin content in the patient's own blood."

Researchers believe that this work heralds a good start. More preclinical trials are also expected in the near future. We look forward to the early transformation of this smart patch to benefit more patients living at risk of thrombosis.
Reference materials:
[1] Smart Patch Releases Blood Thinners As Needed, Prevents Thrombosis in Animal Model
[2] Thrombin-Responsive Transcutaneous Patch for Auto-Anticoagulant Regulation
[3] Professor Gu Yu's laboratory official website

Source: WuXi PharmaTech

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