PLGA Microspheres for Sustained Protease Inhibitor Release
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Solution Overview
Problem
Current treatments for delaying fibrin clot degradation, such as those using aprotinin and tranexamic acid, face challenges in providing a sustained and uniform release mechanism, often resulting in initial bursts followed by slow release, which is inadequate for lengthy wound treatment therapies.
Innovation Solution
The development of biodegradable PLGA microspheres encapsulating protease inhibitors like tranexamic acid (TA) or its calcium salt, which are designed for sustained release in proteolytic environments, ensuring prolonged fibrin sealant longevity by releasing the inhibitor uniformly over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If traditional protease inhibitors (aprotinin, tranexamic acid) are used to delay fibrin clot degradation, then fibrin sealant longevity is improved, but the release mechanism results in initial bursts followed by slow release rather than sustained uniform delivery
Solution Approach 1:
The patent modifies the physical and chemical parameters of the protease inhibitor delivery system by incorporating it into PLGA microspheres with controlled size (5-100 microns), surface charge, and porosity. These parameter changes enable sustained uniform release by controlling diffusion rates and preventing initial bursts, while maintaining adequate fibrin sealant longevity.
Solution Approach 2:
The patent utilizes porous PLGA microspheres as the delivery vehicle, where the porous structure controls the release rate of the protease inhibitor through diffusion and capillary action. The pore size and porosity are engineered to provide sustained uniform release over time, avoiding both initial bursts and premature depletion, thereby resolving the contradiction between longevity and release uniformity.
2Duration of action of stationary object
If protease inhibitors are delivered to provide sustained fibrin sealant longevity, then clot stability is improved, but the device complexity increases due to microsphere encapsulation requirements
Solution Approach 1:
The PLGA microspheres are designed to be self-degrading through hydrolysis of their polymer chains, releasing the encapsulated protease inhibitor automatically without requiring external control mechanisms. This self-service approach simplifies the delivery system by eliminating the need for complex pumping, actuation, or control systems, while still achieving sustained release and improved fibrin sealant longevity.
Solution Approach 2:
The patent employs disposable PLGA microspheres that are biodegradable and do not require recovery or reuse. The microspheres are designed to degrade completely in the body over the treatment period, simplifying the overall system by avoiding issues related to device removal, sterilization, or long-term durability. This approach reduces device complexity while maintaining adequate longevity for the therapeutic effect.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively delays fibrin clot degradation, providing sustained protease inhibition and extending the longevity of fibrin sealants in vivo, with a prolonged release profile that maintains clot stability for several days to months, compared to traditional methods.
Implementation Method 1
biodegradable PLGA microspheres encapsulating protease inhibitors like tranexamic acid (TA) or its calcium salt, which are designed for sustained release in proteolytic environments
Implementation Method 2
PLGA microspheres...designed for sustained release in proteolytic environments
Implementation Method 3
TA, often recommended for cardiac surgery, reversibly blocks lysine-binding sites on plasminogen, a plasmin proenzyme present in blood. By blocking lysine-binding sites on plasminogen, TA delays the conversion of plasminogen to plasmin, effectively slowly fibrinolysis
Implementation Method 4
The diffusion properties and behavior of protease inhibitors from a fibrin sealant is further discussed in a paper by C. Buchta et al., Biomaterials, Vol. 26, Iss. 31, pp 6233-6241, November 2005
Data Source
AI summary
The disclosed invention provides a system and method of artificially retarding fibrin-based blood clot degradation via the sustained release of a protease inhibitor, such as, for example, aprotinin or tranexamic acid (“TA”). The sustained release of the protease inhibitor is accomplished through incorporation within a biodegradable polymer microsphere to produce a protease inhibitor formulation. Next, the formulation along with fibrinogen and thrombin is applied to a wound site where an outer surface of the polymer microsphere degrades in a proteolytic environment to expose and release the incorporated protease inhibitor to the surrounding hydrogel or sealant or clot matrix at the wound site.