Intravenous release of NO from lipidic microbubbles accelerates deep vein thrombosis resolution in a rat model

Targeted Microbubbles for Drug, Gene, and Cell Delivery in Therapy and Immunotherapy

Microbubbles are 1-10 μm diameter gas-filled acoustically-active particles, typically stabilized by a phospholipid monolayer shell. Microbubbles can be engineered through bioconjugation of a ligand, drug and/or cell. Since their inception a few decades ago, several targeted microbubble (tMB) formulations have been developed as ultrasound imaging probes and ultrasound-responsive carriers to promote the local delivery and uptake of a wide variety of drugs, genes, and cells in different therapeutic applications. The aim of this review is to summarize the state-of-the-art of current tMB formulations and their ultrasound-targeted delivery applications. We provide an overview of different carriers used to increase drug loading capacity and different targeting strategies that can be used to enhance local delivery, potentiate therapeutic efficacy, and minimize side effects. Additionally, future directions are proposed to improve the tMB performance in diagnostic and therapeutic applications.

Microbubbles for human diagnosis and therapy

Microbubbles (MBs) were observed for the first time in vivo as a curious consequence of quick saline injection during ultrasound (US) imaging of the aortic root, more than 50 years ago. From this serendipitous event, MBs are now widely used as contrast enhancers for US imaging. Their intrinsic properties described in this review, allow a multitude of designs, from shell to gas composition but also from grafting targeting agents to drug payload encapsulation. Indeed, the versatile MBs are deeply studied for their dual potential in imaging and therapy. As presented in this paper, new generations of MBs now opens perspectives for targeted molecular imaging along with the development of new US imaging systems. This review also presents an overview of the different therapeutic strategies with US and MBs for cancer, cardiovascular diseases, and inflammation. The overall aim is to overlap those fields in order to find similarities in the MBs application for treatment enhancement associated with US. To conclude, this review explores the new scales of MBs technologies with nanobubbles development, and along concurrent advances in the US imaging field. This review ends by discussing perspectives for the booming future uses of MBs.

The combination of EGCG with warfarin reduces deep vein thrombosis in rabbits through modulating HIF-1α and VEGF via the PI3K/AKT and ERK1/2 signaling pathways

Deep venous thrombosis (DVT) poses a major challenge to public health worldwide. Endothelial cell injury evokes inflammatory and oxidative responses that contribute to thrombus formation. Tea polyphenol (TP) in the form of epigallocatechin-3-gallate (EGCG) has anti-inflammatory and oxidative effect that may ameliorate DVT. However, the precise mechanism remains incompletely understood. The current study was designed to investigate the anti-DVT mechanism of EGCG in combination with warfarin (an oral anticoagulant). Rabbits were randomly divided into five groups. A DVT model of rats was established through ligation of the inferior vena cava (IVC) and left common iliac vein, and the animals were orally administered with EGCG, warfarin, or vehicle for seven days. In vitro studies included pretreatment of human umbilical vein endothelial cells (HUVECs) with different concentrations of EGCG for 2 h before exposure to hydrogen peroxide. Thrombus weight and length were examined. Histopathological changes were observed by hematoxylin-eosin staining. Blood samples were collected for detecting coagulation function, including thrombin and prothrombin times, activated partial thromboplastin time, and fibrinogen levels. Protein expression in thrombosed IVCs and HUVECs was evaluated by Western blot, immunohistochemical analysis, and/or immunofluorescence staining. RT-qPCR was used to determine the levels of AGTR-1 and VEGF mRNA in IVCs and HUVECs. The viability of HUVECs was examined by CCK-8 assay. Flow cytometry was performed to detect cell apoptosis and ROS generation was assessed by 2',7'-dichlorofluorescein diacetate reagent. In vitro and invivo studies showed that EGCG combined with warfarin significantly reduced thrombus weight and length, and apoptosis in HUVECs. Our findings indicated that the combination of EGCG and warfarin protects HUVECs from oxidative stress and prevents apoptosis. However, HIF-1α silencing weakened these effects, which indicated that HIF-1α may participate in DVT. Furthermore, HIF-1α silencing significantly up-regulated cell apoptosis and ROS generation, and enhanced VEGF expression and the activation of the PI3K/AKT and ERK1/2 signaling pathways. In conclusion, our results indicate that EGCG combined with warfarin modifies HIF-1α and VEGF to prevent DVT in rabbits through anti-inflammation via the PI3K/AKT and ERK1/2 signaling pathways.

Localized Delivery of Caveolin-1 Peptide Assisted by Ultrasound-Mediated Microbubble Destruction Potentiates the Inhibition of Nitric Oxide-Dependent Vasodilation Response

In the endothelium, nitric oxide synthase (eNOS) is the enzyme that generates nitric oxide, a key molecule involved in a variety of biological functions and cancer-related events. Therefore, selective inhibition of eNOS represents an attractive therapeutic approach for NO-related diseases and anticancer therapy. Ultrasound-mediated microbubble destruction (UMMD) conjugated with cell-permeable peptides has been investigated as a drug delivery system for effective delivery of anticancer molecules. We investigated the feasibility of loading antennapedia-caveolin-1 peptide (AP-Cav), a specific eNOS inhibitor, onto microbubbles to be delivered by UMMD in rat aortic endothelium. AP-Cav-loaded microbubbles (AP-Cav-MBs) and US parameters were characterized. Aortas were treated with UMMD for 30 s with 1.3 × 10⁸ MBs/mL AP-Cav (8 μM)-MBs at 100-Hz pulse repetition frequency, 0.5-MPa acoustic pressure, 0.5 mechanical index and 10% duty cycle. NO-dependent vascular responses were assessed using an isolated organ system, 21 h post-treatment. Maximal relaxation response was inhibited 61.8% ± 1.6% in aortas treated with UMMD-AP-Cav-MBs, while in aortas treated with previously disrupted AP-Cav-MBs and then US, the inhibition was 31.6% ± 1.6%. The vascular contractile response was not affected. The impact of UMMD was evaluated in aortas treated with free AP-Cav; 30 μM of free AP-Cav was necessary to reach an inhibition response similar to that obtained with UMMD-AP-Cav-MBs. In conclusion, UMMD enhances the delivery and potentiates the effect of AP-Cav in the endothelial layer of rat aorta segments.

Cotinine inhibits TLR4/NF-κB signaling pathway and improves deep vein thrombosis in rats

Background: The present study was designed to explore the regulatory mechanisms and influences of cotinine on deep vein thrombosis (DVT) in rats via the toll-like receptor 4/nuclear factor κ binding (TLR-4/NF-κB) pathway. Methods: In this experimental study, 30 SD rats were randomly assigned to control group, sham operation group, model group, cotinine (10 μg/kg) group, and model + cotinine (10 μg/kg) group. The thromboxane B2 (TXB2), 6-keto-PGF_1α, plasminogen activator inhibitor (PAI), tissue plasminogen activator (t-PA), TLR4, NF-κB, and p65 mRNA and protein expression and tissue changes were analyzed by ELISA, Hematoxylin–Eosin (HE) staining, RT-PCR, and Western blot. Results: There was no significant difference between the control and sham operation groups (P>0.05). The model and cotinine groups showed significantly higher mRNA and protein levels of TXB2, interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α), PAI, TLR-4, and NF-κB, and significantly lower levels of 6-keto-PGF_1α and t-PA than the control and sham operation groups (P<0.05), and the model + cotinine group showed significantly higher mRNA and protein levels of TXB2, IL-6 and TNF-α, PAI, TLR-4, and NF-κB and significantly lower levels of 6-keto-PGF_1α and t-PA than the model group (P<0.05). Conclusion: Cotinine can aggravate thrombus and inflammation in rats with DVT, and the mechanism may be associated with the activation of the TLR-4/NF-κB inflammatory signaling pathway.

Ultrasound-mediated therapies for the treatment of biofilms in chronic wounds: a review of present knowledge

Bacterial biofilms are an ever-growing concern for public health, featuring both inherited genetic resistance and a conferred innate tolerance to traditional antibiotic therapies. Consequently, there is a growing interest in novel methods of drug delivery, in order to increase the efficacy of antimicrobial agents. One such method is the use of acoustically activated microbubbles, which undergo volumetric oscillations and collapse upon exposure to an ultrasound field. This facilitates physical perturbation of the biofilm and provides the means to control drug delivery both temporally and spatially. In line with current literature in this area, this review offers a rounded argument for why ultrasound-responsive agents could be an integral part of advancing wound care. To achieve this, we will outline the development and clinical significance of biofilms in the context of chronic infections. We will then discuss current practices used in combating biofilms in chronic wounds and then critically evaluate the use of acoustically activated gas microbubbles as an emerging treatment modality. Moreover, we will introduce the novel concept of microbubbles carrying biologically active gases that may facilitate biofilm dispersal.

Precise treatment of acute antibody-mediated cardiac allograft rejection in rats using C4d-targeted microbubbles loaded with nitric oxide

BACKGROUND

Antibody-mediated rejection (AMR) constitutes an important cause of cardiac allograft loss; however, all current therapeutic strategies represent systemic applications with unsatisfactory efficacy. Previously, we successfully non-invasively detected C4d, a specific marker for AMR diagnosis, in allografts using C4d-targeted microbubbles (MB_C4d). In this study, we extended this approach by incorporating nitric oxide (NO), as high NO levels manifest immunosuppressive and anti-thrombotic effects.

METHODS

We designed novel MB_C4d loaded with NO (NO-MB_C4d). A rat model of AMR was established by pre-sensitization with skin transplantation. Contrast-enhanced ultrasound (CEUS) images were obtained and quantitatively analyzed following NO-MB_C4d injection. Allograft survival and histologic features were analyzed to evaluate the therapeutic effect and underlying mechanism of NO-MB_C4d toward AMR.

RESULTS

We successfully obtained CEUS images following NO-MB_C4d injection and demonstrated that the ultrasound signal intensity of the myocardial area and clearance time of NO-MB_C4d both increased with increased C4d grade, thereby realizing non-invasive diagnosis of AMR. Furthermore, allograft survival was significantly prolonged, and rejection was obviously attenuated following NO-MB_C4d injection through significant suppression of thrombosis and reduction of inflammatory cell infiltrates. Overall, the therapeutic efficacy was significantly improved in the NO-MB_C4d group compared with the control NO-MB group, demonstrating that precise treatment could significantly improve the therapeutic efficacy compared with that afforded by systemic applications.

CONCLUSIONS

This study presented a novel tool to provide simultaneous non-invasive diagnosis and precise treatment of AMR using NO-MB_C4d CEUS imaging, which may be expected to provide a better option for recipients with AMR in clinic.

Bactericidal Activity of Lipid-Shelled Nitric Oxide-Loaded Microbubbles

The global pandemic of antibiotic resistance is an ever-burgeoning public health challenge, motivating the development of adjunct bactericidal therapies. Nitric oxide (NO) is a potent bioactive gas that induces a variety of therapeutic effects, including bactericidal and biofilm dispersion properties. The short half-life, high reactivity, and rapid diffusivity of NO make therapeutic delivery challenging. The goal of this work was to characterize NO-loaded microbubbles (MB) stabilized with a lipid shell and to assess the feasibility of antibacterial therapy in vitro. MB were loaded with either NO alone (NO-MB) or with NO and octafluoropropane (NO-OFP-MB) (9:1 v/v and 1:1 v/v). The size distribution and acoustic attenuation coefficient of NO-MB and NO-OFP-MB were measured. Ultrasound-triggered release of the encapsulated gas payload was demonstrated with 3-MHz pulsed Doppler ultrasound. An amperometric microelectrode sensor was used to measure NO concentration released from the MB and compared to an NO-OFP-saturated solution. The effect of NO delivery on the viability of planktonic (free living) Staphylococcus aureus (SA) USA 300, a methicillin-resistant strain, was evaluated in a 96 well-plate format. The co-encapsulation of NO with OFP increased the total volume and attenuation coefficient of MB. The NO-OFP-MB were destroyed with a clinical ultrasound scanner with an output of 2.48 MPa peak negative pressure (in situ MI of 1.34) but maintained their echogenicity when exposed to 0.02 MPa peak negative pressure (in situ MI of 0.01. The NO dose in NO-MB and NO-OFP-MB was more than 2-fold higher than the NO-OFP-saturated solution. Delivery of NO-OFP-MB increased bactericidal efficacy compared to the NO-OFP-saturated solution or air and OFP-loaded MB. These results suggest that encapsulation of NO with OFP in lipid-shelled MB enhances payload delivery. Furthermore, these studies demonstrate the feasibility and limitations of NO-OFP-MB for antibacterial applications.

Characterization and Imaging of Lipid-Shelled Microbubbles for Ultrasound-Triggered Release of Xenon

Xenon (Xe) is a bioactive gas capable of reducing and stabilizing neurologic injury in stroke. The goal of this work was to develop lipid-shelled microbubbles for xenon loading and ultrasound-triggered release. Microbubbles loaded with either xenon (Xe-MB) or xenon and octafluoropropane (Xe-OFP-MB) (9:1 v/v) were synthesized by high-shear mixing. The size distribution and the frequency-dependent attenuation coefficient of Xe-MB and Xe-OFP-MB were measured using a Coulter counter and a broadband acoustic attenuation spectroscopy system, respectively. The Xe dose was evaluated using gas chromatography/mass spectrometry. The total Xe doses in Xe-MB and Xe-OFP-MB were 113.1 ± 13.5 and 145.6 ± 25.5 μl per mg of lipid, respectively. Co-encapsulation of OFP increased the total xenon dose, attenuation coefficient, microbubble stability (in an undersaturated solution), and shelf life of the agent. Triggered release of gas payload was demonstrated with 6-MHz duplex Doppler and 220-kHz pulsed ultrasound. These results constitute the first step toward the use of lipid-shelled microbubbles for applications such as neuroprotection in stroke.

Novel microspheres reduce the formation of deep venous thrombosis and repair the vascular wall in a rat model

L-Arginine (L-arg), widely known as a substrate for endogenous nitric oxide synthesis, can improve endothelial function associated with the vasculature, inhibit platelet aggregation, and alter the activity of vascular smooth muscle cells. P-selectin is a membrane component of the platelet alpha-granule and the endothelial cell-specific Wiebel–Palade body that plays a central role in mediating interactions between platelets and both leukocytes and the endothelium. The experiment was designed to evaluate the effect of novel microspheres with L-arg targeting P-selectin on the formation of deep vein thrombosis and repair of vascular wall in a rat model. Thrombosis of the inferior vena cava was induced by applying a piece of filter paper (5 mm × 10 mm) saturated with 10% FeCl₃ solution for 5 min. Targeted microspheres with L-arg, targeted microspheres with water, and saline were injected into the tail veins of the rats after 30 min of applying the filter paper saturated with 10% FeCl₃ solution. The dry weight and length of the thrombus isolated from the inferior vena cava were significantly decreased in the group with L-arg in microsphere after 24 h. No significant differences in prothrombin time, activated partial thromboplastin time, thrombin time, and fibrinogen among the groups were indicated. Images revealed that apoptosis in the vascular wall was less in the group injected with targeted microspheres with L-arg than in the other two groups at 1 and 8 d postsurgery. Meanwhile, cell proliferation was considerably excessive in the group injected with L-arg wrapped in targeted microspheres. Therefore, these novel microspheres could decrease the formation of thrombus in the early stages and in the subsequent periods of thrombosis. The microspheres can also enhance the vitality of impaired endothelial cells and reduce cell apoptosis.

Recent advances in thromboresistant and antimicrobial polymers for biomedical applications: just say yes to nitric oxide (NO)

Biomedical devices are essential for patient diagnosis and treatment; however, when blood comes in contact with foreign surfaces or homeostasis is disrupted, complications including thrombus formation and bacterial infections can interrupt device functionality, causing false readings and/or shorten device lifetime. Here, we review some of the current approaches for developing antithrombotic and antibacterial materials for biomedical applications. Special emphasis is given to materials that release or generate low levels of nitric oxide (NO). Nitric oxide is an endogenous gas molecule that can inhibit platelet activation as well as bacterial proliferation and adhesion. Various NO delivery vehicles have been developed to improve NO's therapeutic potential. In this review, we provide a summary of the NO releasing and NO generating polymeric materials developed to date, with a focus on the chemistry of different NO donors, the polymer preparation processes, and in vitro and in vivo applications of the two most promising types of NO donors studied thus far, N-diazeniumdiolates (NONOates) and S-nitrosothiols (RSNOs).

S-Nitrosothiols as Platforms for Topical Nitric Oxide Delivery

Nitric oxide (NO) is a small radical species involved in several fundamental physiological processes, including the control of vascular tone, the immune response and neuronal signalling. Endothelial dysfunction with the decreased NO bioavailability is the underlying cause of several diseases and has led to the development of a wide range of systemic NO donor compounds to lower the blood pressure and control hypertensive crises. However, several potential therapeutic actions of NO, not related to the cardiovascular system, demand exclusively local actions. Primary S-nitrosothiols (RSNOs) are endogenously found NO carriers and donors and have emerged as platforms for the localized delivery of NO in topical applications. Formulations for this purpose have evolved from low molecular weight RSNOs incorporated in polymeric films, hydrogels and viscous vehicles, to polymeric RSNOs where the SNO moiety is covalently bound to the polymer backbone. The biological actions displayed by these formulations include the increase in dermal vasodilation, the acceleration of wound healing, the killing of infectious microorganisms and an analgesic action against inflammatory pain. This MiniReview focuses on the state of the art of experimental topical formulations for NO delivery based on S-nitrosothiols and their potential therapeutic applications.

Danhong huayu koufuye prevents deep vein thrombosis through anti-inflammation in rats

BACKGROUND

Danhong huayu koufuye (DHK) has traditionally been used clinically for a long time in China. This study was to evaluate the effect of DHK in treating deep vein thrombosis (DVT) in rats and explore its possible mechanism.

METHODS

Forty-eight Sprague-Dawley rats were divided into four groups, performed with incomplete inferior vena cava ligation to induce DVT, and orally administered with DHK (3.20 mg/kg/d), warfarin (2.00 mg/kg/d), or vehicle for 7 days. The involved inferior vena cava and thrombi were collected and measured in size. The tissue specimens were performed for routine histopathologic evaluation and immunohistochemical staining with tissue factor and matrix metalloproteinases-9. Blood samples were collected for detecting coagulation function, blood cell count, and the levels of interleukin-6 and tumor necrosis factor-α.

RESULTS

The treatment of DHK markedly reduced the size of thrombi by 49.26%, and the vein wall thickness by 47.86%. The recanalization rate was significant higher in the DHK-treated group than the vehicle-treated group (26.34 ± 6.53% versus 15.91 ± 3.93%, P < 0.01). Comparing to vehicle control, DHK significantly reduced neutrophils (P < 0.05) and lymphocytes (P < 0.05), serum tumor necrosis factor-α level (4.90 ± 1.14 pg/mL versus 6.60 ± 1.62 pg/mL, P < 0.01), and the expression of matrix metalloproteinases-9 and tissue factor (P < 0.05) in thrombi.

CONCLUSIONS

DHK effectively prevented DVT through anti-inflammatory action in rats.

Deep venous thrombosis in the nonoperated leg after primary major lower extremity arthroplasty: a retrospective study based on diagnosis using venography

Venous thromboembolism (VTE) is a common complication after major orthopedic surgery. However, the reported rates of deep venous thrombosis (DVT) vary widely. Our aim was to study the incidence of DVT in the nonoperated leg after primary major lower extremity arthroplasty using bilateral venography. The records of patients who underwent total hip arthroplasty (THA) or total knee arthroplasty (TKA) at our institution between August 2013 and August 2014 were reviewed. We examined the records for a total of 380 patients, of which 244 had undergone bilateral venography 3-5 days after THA or TKA. A total of 244 patients undergoing TKA (n = 119) or THA (n = 125) were recruited for this study. DVT was diagnosed in 42 (17.2%) of the 244 patients; nine patients developed DVT in both legs, and four developed DVT only in the nonoperated leg. All of the DVTs were located in calf veins. DVT occurred more frequently after TKA than THA, especially in muscular veins. Female sex and older age were found to be positive risk factors for DVT after THA. The incidence of DVT after major lower arthroplasty is high. DVT in nonoperated legs should be carefully considered because of its potential risks, especially in left. Distal DVT also has a high risk to develop pulmonary embolism (PE). The combination of anticoagulant and pneumatic compression is a good measure to avoid proximal DVT, and it is well tolerated to stop anticoagulant if the patients were diagnosed as having no DVT.

Inhibitory effect of epirubicin-loaded lipid microbubbles with conjugated anti-ABCG2 antibody combined with therapeutic ultrasound on multiple myeloma cancer stem cells

Ultrasound-targeted microbubble destruction (UTMD) technique is thought to improve the chemotherapeutic agent delivery from microbubbles (MBs) in tumor tissues and reduce the side effects in non-tumor tissues. Multiple myeloma (MM) is a bone marrow cancer and remains to be an incurable disease. In this study, we used the UTMD technique to investigate the inhibitory effect of our developed novel reagent on MM cancer stem cells (CD138(-)CD34(-)MM CSCs) that are MM cells with CD138(-)CD34(-) phenotypes, responsible for MM-initiating potential, drug resistance and eventual relapse. The preparatory steps of novel reagent was first epirubicin (EPI)-loaded in the lipid MBs that was consisted of 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)-2000]-biotin, dipalmitoyl-phosphatidylglycerol and 25-NBD-cholesterol, then anti-ABCG2 monoclonal antibody (mAb) was conjugated onto the MB surface to form EPI-MBs+mAb. CD138(-)CD34(-)MM CSCs were isolated from human MM RPMI 8226 cell line by the magnetic associated cell sorting method. The results showed that the attenuated proliferation, migration and invasion ability, and increased apoptosis were observed when MM CSCs were incubated with a various agents. EPI-MBs+mAb combined with therapeutic ultrasound significantly promoted the MM CSC apoptosis compared with EPI, EPI-MBs alone or EPI-MBs+mAb without ultrasound exposure. These results suggest that the developed EPI-MBs+mAb combined with therapeutic ultrasound remarkably induced MM CSC apoptosis in vitro.

The anti-thrombotic effect of hydrogen sulfide is partly mediated by an upregulation of nitric oxide synthases

INTRODUCTION

Hydrogen sulfide (H2S) known as a gasotransmitter is increasingly recognized for its anti-adhesive, anti-inflammatory and vasoactive properties. Due to these properties, we analysed anti-thrombotic effects of H2S and the participation of the nitric oxide synthase (NOS)-pathway.

MATERIALS AND METHODS

In individual venules of the ear of hairless SKH1-hr mice, thrombus formation was induced using a phototoxic light/dye-injury model and intravital fluorescence microscopy. Animals were treated intravenously with the H2S donor Na2S or NaCl as control. In a second setting, the NOS inhibitor L-NAME was applied intraperitoneally as a bolus 12h prior to Na2S treatment and thrombus induction. Blood and ear tissue were sampled after microscopy for assessment of plasma concentrations of soluble (s)P-selectin, sE-selectin, sVCAM-1 and sICAM-1 and expression of endothelial (e)NOS and inducible (i)NOS, respectively.

RESULTS

When mice were treated with Na2S, venular thrombus formation was significantly delayed versus that in animals of the NaCl-treated control group. While plasma levels of pro-thrombotic adhesion molecules were not affected by Na2S, immunohistochemistry of the vessel walls showed a significant up-regulation of eNOS and iNOS expression within the Na2S-treated group. The delay of thrombus formation in the Na2S-group was partly but significantly reverted by application of L-NAME.

CONCLUSIONS

The anti-thrombotic efficacy of H2S involves the NOS-pathway and may be of preventive and therapeutic value for clinical disorders with increased risk of thrombotic events.