A strongly adhesive hemostatic hydrogel for the repair of arterial and heart bleeds.

Uncontrollable bleeding is a major problem in surgical procedures and after major trauma. Existing hemostatic agents poorly control hemorrhaging from traumatic arterial and cardiac wounds because of their weak adhesion to wet and mobile tissues. Here we design a photo-reactive adhesive that mimics the extracellular matrix (ECM) composition. This biomacromolecule-based matrix hydrogel can undergo rapid gelling and fixation to adhere and seal bleeding arteries and cardiac walls after UV light irradiation. These repairs can withstand up to 290 mm Hg blood pressure, significantly higher than blood pressures in most clinical settings (systolic BP 60-160 mm Hg). Most importantly, the hydrogel can stop high-pressure bleeding from pig carotid arteries with 4~ 5 mm-long incision wounds and from pig hearts with 6 mm diameter cardiac penetration holes. Treated pigs survived after hemostatic treatments with this hydrogel, which is well-tolerated and appears to offer significant clinical advantage as a traumatic wound sealant.

Treatment of platelet concentrates with ultraviolet C light for pathogen reduction increases cytokine accumulation.

BACKGROUND: Pathogen reduction technologies use photoactive substances in combination with ultraviolet (UV) light to inactivate pathogens. A new method uses only UVC light for pathogen reduction. This study assesses the effects of UVC light treatment on cytokine release in platelet (PLT) concentrates (PCs). STUDY DESIGN AND METHODS: A PC with 35% plasma and 65% PLT additive solution (SSP+) was prepared from five buffy coats. Three such PCs were pooled and divided into 3 units. One unit was used as a nonirradiated control, the second was a gamma-irradiated control, and the third unit was treated with UVC light technology. Ten units of each type were investigated. Cytokine release was analyzed on Days 1, 5, and 7 of storage. Correlation between cytokines, PLT surface markers, and hemostatic properties was investigated. RESULTS: Swirling was well preserved and pH was above the reference limit of 6.4 during storage of PLTs in all groups. Cytokine levels increased during storage in all groups but to a larger degree in PCs treated with UVC light. Only weak correlation was found between cytokines and PLT surface markers (r < 0.5). However, several cytokines showed strong correlation (r > 0.6) with the PLTs' ability to promote clot retraction. CONCLUSION: UVC treatment resulted in increased release from PLT alpha granules as evident by a higher cytokine release compared to nonirradiated and gamma-irradiated PCs. The clinical relevance of these findings needs to be further evaluated.

A cardiovascular occlusion method based on the use of a smart hydrogel.

Smart hydrogels for biomedical applications are highly researched materials. However, integrating them into a device for implantation is difficult. This paper investigates an integrated delivery device designed to deliver an electro-responsive hydrogel to a target location inside a blood vessel with the purpose of creating an occlusion. The paper describes the synthesis and characterization of a Pluronic/methacrylic acid sodium salt electro-responsive hydrogel. Application of an electrical bias decelerates the expansion of the hydrogel. An integrated delivery system was manufactured to deliver the hydrogel to the target location in the body. Ex vivo and in vivo experiments in the carotid artery of sheep were used to validate the concept. The hydrogel was able to completely occlude the blood vessel reducing the blood flow from 245 to 0 ml/min after implantation. Ex vivo experiments showed that the hydrogel was able to withstand physiological blood pressures of > 270 mm·Hg without dislodgement. The results showed that the electro-responsive hydrogel used in this paper can be used to create a long-term occlusion in a blood vessel without any apparent side effects. The delivery system developed is a promising device for the delivery of electro-responsive hydrogels.

Development of a novel emergency hemostatic kit for severe hemorrhage.

Photocrosslinkable chitosan (Az-CH-LA) contains lactose moieties and photoreactive azide groups, and its viscous solution forms an insoluble hydrogel on exposure to UV irradiation. We previously developed an emergency hemostatic kit using the Az-CH-LA solution, calcium alginate, and a UV irradiation apparatus. However, a suitable UV irradiation apparatus is required to effectively convert the Az-CH-LA solution into a hydrogel, and power supply to use the UV irradiation apparatus may not always be available in a disaster area or battlefield. To address this problem, we produced a portable, battery-powered UV irradiation apparatus constituting a novel hemostatic kit for severe hemorrhage. When the hemostatic kit using the UV irradiation apparatus was examined using a rat model of severe hemorrhage, the survival rate increased up to 73%. Hematological values as markers of hemorrhage did not change significantly over the first 3 days. In this study, we describe the characteristics of a portable UV irradiation apparatus and its use in an emergency hemostatic kit prepared using Az-CH-LA and calcium alginate for severe hemorrhage.

Hemostasis for severe hemorrhage with photocrosslinkable chitosan hydrogel and calcium alginate.

In patients with severe hemorrhage, complications such as shock or death may occur if the patient is not treated appropriately and expeditiously. To create a hemostat kit for severe hemorrhage, ultraviolet light irradiation was applied to photocrosslinkable chitosan hydrogel and calcium alginate. As a hemorrhage model, the femoral arteries and veins of anesthetized rats were cut. Hemodynamics and hematological parameters including red blood cell (RBC) count, hemoglobin concentration, hematocrit, white blood cell (WBC) count, and platelet count, and serum parameters including aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were measured as a marker of hemostasis. In rats for which no procedure was used, death occurred within 30 min. By using the hydrogel hemostat, the survival rate rose to 75% or more. RBC count, hemoglobin, hematocrit, and platelet levels were not significantly changed for 3 days. WBC count increased 1 day after hemostasis. AST and ALT increased 1 day after hemostasis, but it decreased 3 days later. The photocrosslinkable chitosan hydrogel and calcium alginate were biodegraded at 3 and 28 days, respectively, by neutrophils and keratinocyte chemoattractant.

Photostabilization of menadione sodium bisulfite by glutathione.

Photodecomposition of solutions of menadione sodium bisulfite (MSB) in the presence and absence of glutathione (GSH) under artificial sunlight was investigated. In presence of 0.02% (GSH), an appreciable increase in photostability was observed when clear glass vials were used. The pH and the temperature of the solution significantly influenced the stability of MSB. Photodegradation of MSB appeared to follow first-order kinetics. Photostabilization of MSB was attributed in part to complex formation between MSB and GSH and the antioxidant property of the latter. Stability constants for the various solutions were determined at several temperatures. Thermodynamic parameters were calculated and were found to support complex formation.