Smart patch successfully monitors blood to release blood thinners as needed in animal model.

Thrombosis occurs when blood clots disrupt the normal flow of blood in the body, which can cause severe health problems such as pulmonary embolism, heart attack or stroke. Current treatments often rely on the use of blood thinners, such as Heparin, which require patients to have their blood tested on a regular basis in order to ensure proper dosages.  Therefore, the main goal of the global medical community is to develop a system which can monitor a patient’s blood and release additional drugs when necessary; effectively, a self-regulating system.  Now, a study from researchers led by North Carolina State University develops a smart patch designed to monitor a patient’s blood and release blood-thinning drugs as needed to prevent the occurrence of thrombosis. The team state that the patch was shown to be more effective in an animal model at preventing thrombosis than traditional methods of drug delivery. The study is published in the journal Advanced Materials.

Previous studies show that thrombosis, a pathological homeostatic condition, has become one of the leading causes of cardiovascular mortalities and morbidities worldwide.  As a first line of defense, anticoagulant drugs can prevent and delay the obstruction in blood flowUnfortunately, delivery of anticoagulants remains difficult for precise anticoagulant regulation, and incorrect dosages may lead to dangerous consequences.  Moreover, it is known that the timely delivery of drugs is critical for cardiovascular patients when an unpredictable attack happens. Therefore, a controlled and on-demand drug delivery system which enhances therapeutic efficacy while minimizing side effects and time–to–treatment, is urgently needed for the management of thrombotic diseases.  The current study develops a thrombin-responsive closed-loop patch for prolonged heparin delivery in a feedback-controlled manner.

The current study tested the Heparin smart patch in a mouse model injected with large doses of thrombin, which would result in fatal blood clotting of the lungs if left untreated.  In the first experiment, the mice were injected with thrombin 10 minutes later and were either left untreated, given a shot of Heparin, or given the Heparin smart patch.  Results show that 15 minutes after the thrombin injection, only the mice who received no treatment died.  In the second experiment, the thrombin was injected six hours after treatment. Data findings show that 15 minutes after the thrombin injection, all of the mice with the Heparin smart patch were fine, and around 80% of the mice that received the Heparin shot had died.

The lab explain that their smart patch incorporates microneedles made of a polymer that consists of hyaluronic acid and the drug Heparin. They go on to add that the polymer has been modified to be responsive to thrombin, an enzyme that initiates clotting in the blood; when elevated levels of thrombin enzymes in the bloodstream come into contact with the microneedle, the enzymes break the specific amino acid chains that bind the Heparin to the hyaluronic acid, releasing the Heparin into the blood stream.  The group state that the more thrombin there is in the bloodstream, the more Heparin is needed to reduce clotting.  They conclude that they have successfully developed a disposable patch in which the more thrombin there is in the blood stream, the more Heparin is released.

The team surmise that they have developed a closed-loop, self-regulating smart patch which successfully treats thrombosis in an animal model.  For the future, the researchers state they plan to further enhance the loading amount of drug in the patch, where the amount of Heparin in a patch can be tailored to a patient’s specific needs and replaced daily, or less often, as needed.

Source: North Carolina State University 

Schematic of thrombin-responsive patch that releases heparin in response to thrombin.  Credit: Yuqi Zhang.
Schematic of thrombin-responsive patch that releases heparin in response to thrombin. Credit: Yuqi Zhang.

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