scholarly journals In-vitro sonothrombolysis using thick-shelled polymer microbubbles - a comparison with thin-shelled microbubbles

2020 ◽  
Vol 18 (1) ◽  
Author(s):  
Jovana Janjic ◽  
Malin K Larsson ◽  
Anna Bjällmark
Keyword(s):  
Drug Delivery ◽  
Mass Loss ◽  
Low Pressure ◽  
Clot Lysis ◽  
Ultrasound Exposure ◽  
Blood Clots ◽  
Upstream Pressure ◽  
Set Up ◽  
Partially Occluded

Abstract Background Vascular thrombosis can be treated pharmacologically, however, serious shortcomings such as bleeding may occur. Several studies suggest that sonothrombolysis can induce lysis of the clots using ultrasound. Moreover, intravenously injected thin-shelled microbubbles (MBs) combined with ultrasound can further improve clot lysis. Thick-shelled MBs have been used for drug delivery, targeting and multimodal imaging. However, their capability to enhance sonothrombolysis is unknown. In this study, using an in-vitro set-up, the enhancement of clot lysis using ultrasound and thick-shelled MBs was investigated. Thin-shelled MBs was used for comparison. Method The main components in the in-vitro set-up was a vessel mimicking phantom, a pressure mearing system and programmable ultrasound machine. Blood clots were injected and entrapped on a pore mesh in the vessel phantom. Four different protocols for ultrasound transmission and MB exposure (7 blood clots/protocol) were considered together with a control test were no MBs and ultrasound were used. For each protocol, ultrasound exposure of 20 min was used. The upstream pressure of the partially occluded mesh was continuously measured to assess clot burden. At the end of each protocol blood clots were removed from the phantom and the clot mass loss was computed. Results For the thick-shelled MBs no difference in clot mass loss compared with the control tests was found. A 10% increase in the clot mass loss compared with the control tests was found when using thin-shelled MBs and low pressure/long pulses ultrasound exposure. Similarly, in terms of upstream pressure over exposure time, no differences were found when using the thick-shelled MBs, whereas thin-shelled MBs showed a 15% decrease achieved within the first 4 min of ultrasound exposure. Conclusion No increase in clot lysis was achieved using thick-shelled MBs as demonstrated by no significant change in clot mass or upstream pressure. Although thick-shelled MBs are promising for targeting and drug delivery, they do not enhance clot lysis when considering the ultrasound sequences used in this study. On the other hand, ultrasound in combination with thin-shelled MBs can facilitate thrombolysis when applying long ultrasound pulses with low pressure.

scholarly journals Nanodroplet-mediated catheter-directed sonothrombolysis of retracted blood clots

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Leela Goel ◽  
Huaiyu Wu ◽  
Bohua Zhang ◽  
Jinwook Kim ◽  
Paul A. Dayton ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Negative Pressure ◽  
Boiling Point ◽  
Clot Lysis ◽  
Control Group ◽  
Peak Negative Pressure ◽  
Blood Clots ◽  
Tissue Plasminogen ◽  
First Time

AbstractOne major challenge in current microbubble (MB) and tissue plasminogen activator (tPA)-mediated sonothrombolysis techniques is effectively treating retracted blood clots, owing to the high density and low porosity of retracted clots. Nanodroplets (NDs) have the potential to enhance retracted clot lysis owing to their small size and ability to penetrate into retracted clots to enhance drug delivery. For the first time, we demonstrate that a sub-megahertz, forward-viewing intravascular (FVI) transducer can be used for ND-mediated sonothrombolysis, in vitro. In this study, we determined the minimum peak negative pressure to induce cavitation with low-boiling point phase change nanodroplets and clot lysis. We then compared nanodroplet mediated sonothrombolysis to MB and tPA mediate techniques. The clot lysis as a percent mass decrease in retracted clots was 9 ± 8%, 9 ± 5%, 16 ± 5%, 14 ± 9%, 17 ± 9%, 30 ± 8%, and 40 ± 9% for the control group, tPA alone, tPA + US, MB + US, MB + tPA + US, ND + US, and ND + tPA + US groups, respectively. In retracted blood clots, combined ND- and tPA-mediated sonothrombolysis was able to significantly enhance retracted clot lysis compared with traditional MB and tPA-mediated sonothrombolysis techniques. Combined nanodroplet with tPA-mediated sonothrombolysis may provide a feasible strategy for safely treating retracted clots.

In Vitro Clot Lysis as a Potential Indicator of Thrombus Resistance to Fibrinolysis – Study in Healthy Subjects and Correlation with Blood Fibrinolytic Parameters

1997 ◽  
Vol 77 (04) ◽  
pp. 725-729 ◽  
Author(s):  
Mario Colucci ◽  
Silvia Scopece ◽  
Antonio V Gelato ◽  
Donato Dimonte ◽  
Nicola Semeraro
Keyword(s):  
Plasminogen Activator ◽  
Clot Lysis ◽  
Individual Response ◽  
Plasminogen Activator Inhibitor 1 ◽  
Autologous Plasma ◽  
Wide Range ◽  
Blood Clots ◽  
Physiological Variations ◽  
Pai 1

SummaryUsing an in vitro model of clot lysis, the individual response to a pharmacological concentration of recombinant tissue plasminogen activator (rt-PA) and the influence on this response of the physiological variations of blood parameters known to interfere with the fibrinolytic/thrombolytic process were investigated in 103 healthy donors. 125I-fibrin labelled blood clots were submersed in autologous plasma, supplemented with 500 ng/ml of rt-PA or solvent, and the degree of lysis was determined after 3 h of incubation at 37° C. Baseline plasma levels of t-PA, plasminogen activator inhibitor 1 (PAI-1), plasminogen, α2-anti-plasmin, fibrinogen, lipoprotein (a), thrombomodulin and von Willebrand factor as well as platelet and leukocyte count and clot retraction were also determined in each donor. rt-PA-induced clot lysis varied over a wide range (28-75%) and was significantly related to endogenous t-PA, PAI-1, plasminogen (p <0.001) and age (p <0.01). Multivariate analysis indicated that both PAI-1 antigen and plasminogen independently predicted low response to rt-PA. Surprisingly, however, not only PAI-1 but also plasminogen was negatively correlated with rt-PA-ginduced clot lysis. The observation that neutralization of PAI-1 by specific antibodies, both in plasma and within the clot, did not potentiate clot lysis indicates that the inhibitor, including the platelet-derived form, is insufficient to attenuate the thrombolytic activity of a pharmacological concentration of rt-PA and that its elevation, similarly to the elevation of plasminogen, is not the cause of clot resistance but rather a coincident finding. It is concluded that the in vitro response of blood clots to rt-PA is poorly influenced by the physiological variations of the examined parameters and that factors other than those evaluated in this study interfere with clot dissolution by rt-PA. In vitro clot lysis test might help to identify patients who may be resistant to thrombolytic therapy.

scholarly journals Ultrasound-Mediated Drug Delivery With a Clinical Ultrasound System: In Vitro Evaluation

2021 ◽  
Vol 12 ◽  
Author(s):  
Josanne S. de Maar ◽  
Charis Rousou ◽  
Benjamin van Elburg ◽  
Hendrik J. Vos ◽  
Guillaume P.R. Lajoinie ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Clinical Translation ◽  
Drug Uptake ◽  
Single Element ◽  
Hydrophilic Drug ◽  
Ultrasound System ◽  
Fadu Cells ◽  
Set Up

Chemotherapy efficacy is often reduced by insufficient drug uptake in tumor cells. The combination of ultrasound and microbubbles (USMB) has been shown to improve drug delivery and to enhance the efficacy of several drugs in vitro and in vivo, through effects collectively known as sonopermeation. However, clinical translation of USMB therapy is hampered by the large variety of (non-clinical) US set-ups and US parameters that are used in these studies, which are not easily translated to clinical practice. In order to facilitate clinical translation, the aim of this study was to prove that USMB therapy using a clinical ultrasound system (Philips iU22) in combination with clinically approved microbubbles (SonoVue) leads to efficient in vitro sonopermeation. To this end, we measured the efficacy of USMB therapy for different US probes (S5-1, C5-1 and C9-4) and US parameters in FaDu cells. The US probe with the lowest central frequency (i.e. 1.6 MHz for S5-1) showed the highest USMB-induced intracellular uptake of the fluorescent dye SYTOX™ Green (SG). These SG uptake levels were comparable to or even higher than those obtained with a custom-built US system with optimized US parameters. Moreover, USMB therapy with both the clinical and the custom-built US system increased the cytotoxicity of the hydrophilic drug bleomycin. Our results demonstrate that a clinical US system can be used to perform USMB therapy as efficiently as a single-element transducer set-up with optimized US parameters. Therefore, future trials could be based on these clinical US systems, including validated US parameters, in order to accelerate successful translation of USMB therapy.

Charge-conversion and ultrasound-responsive O-carboxymethyl chitosan nanodroplets for controlled drug delivery

Nanomedicine ◽  
2019 ◽  
Vol 14 (19) ◽  
pp. 2549-2565 ◽  
Author(s):  
Dong Meng ◽  
Lu Guo ◽  
Dandan Shi ◽  
Xiao Sun ◽  
Mengmeng Shang ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Tumor Cells ◽  
Drug Delivery System ◽  
Ultrasound Imaging ◽  
Delivery System ◽  
Cell Interaction ◽  
Carboxymethyl Chitosan ◽  
Ultrasound Exposure ◽  
Interaction Efficiency

Aim: O-carboxymethyl chitosan/perfluorohexane nanodroplets (O-CS NDs) and doxorubicin-loading O-carboxymethyl chitosan nanodroplets were synthesized and functionally tested as drug delivery system in vitro. Materials & methods: The characteristics, charge conversion, stability, cytotoxicity, ultrasound imaging ability, interaction with tumor cells of the nanodroplets and eradication on tumor cells of the doxorubicin-loaded nanodroplets were investigated. Results: O-CS NDs (below 200 nm) achieved higher tumor cellular associations at acidic pH, with great serum stability, pH-dependent charge conversion and good ultrasound imaging ability. Doxorubicin-loading O-carboxymethyl chitosan nanodroplets exhibited strong cytotoxicity on PC-3 cells with ultrasound exposure. Conclusion: These stable, safe and smart O-CS NDs may be a promising approach to improve cell interaction efficiency as an ultrasound imaging and cancer-targeting drug delivery system.

scholarly journals Understanding nanoparticle flow with a new in vitro experimental and computational approach using hydrogel channels

2020 ◽  
Vol 11 ◽  
pp. 296-309
Author(s):  
Armel Boutchuen ◽  
Dell Zimmerman ◽  
Abdollah Arabshahi ◽  
John Melnyczuk ◽  
Soubantika Palchoudhury
Keyword(s):  
Drug Delivery ◽  
Mass Loss ◽  
Flow Velocity ◽  
Brownian Dynamics ◽  
Drug Delivery Systems ◽  
Delivery Systems ◽  
Preclinical Stage ◽  
Flow Channels ◽  
Mass Concentrations

Nanoparticles (NPs) are considered as one of the most promising drug delivery vehicles and a next-generation solution for current medical challenges. In this context, variables related to flow of NPs such as the quantity of NPs lost during transport and flow trajectory greatly affect the clinical efficiency of NP drug delivery systems. Currently, there is little knowledge of the physical mechanisms dominating NP flow inside the human body due to the limitations of available experimental tools for mimicking complex physiological environments at the preclinical stage. Here, we report a coupled experimental and computational fluid dynamics (CFD)-based novel in vitro approach to predict the flow velocity and binding of NP drug delivery systems during transport through vasculature. Poly(hydroxyethyl)methacrylate hydrogels were used to form soft cylindrical constructs mimicking vascular sections as flow channels for synthesized iron oxide NPs in these first-of-its-kind transport experiments. Brownian dynamics and material of the flow channels played key roles in NP flow, based on the measurements of NP flow velocity over seven different mass concentrations. A fully developed laminar flow of the NPs under these conditions was simultaneously predicted using CFD. Results from the mass loss of NPs during flow indicated a diffusion-dominated flow at higher particle concentrations but a flow controlled by the surrounding fluid and Brownian dynamics at the lowest NP concentrations. The CFD model predicted a mass loss of 1.341% and 6.253% for the 4.12 g·mL−1 and 2.008 g·mL−1 inlet mass concentrations of the NPs, in close confirmation with the experimental results. This further highlights the reliability of our new in vitro technique in providing mechanistic insights of NP flow for potential preclinical stage applications.

Studies on Thrombolysis with Streptokinase

1968 ◽  
Vol 19 (01/02) ◽  
pp. 094-098 ◽  
Author(s):  
R Gottlob ◽  
G Blümel
Keyword(s):  
Whole Blood ◽  
Ringer Solution ◽  
Clot Lysis ◽  
Blood Clots ◽  
Free Environment

SummaryIn vitro whole blood clots were incubated in SK, washed several times in Ringer-solution and then introduced into plasminogen solution. These clots showed marked signs of lysis surpassing those observed in clots that had only been incubated in SK. There was a correlation between the duration of the SK incubation and the clot lysis in the plasminogen solution. We deduce from these findings that SK enters the clots by diffusion and that this process lasts several hours.If SK-incubated clots are placed into an SK-free environment, the SK slowly diffuses out of the thrombi.Even in contact with very slight plasminogen concentrations, SK-incubated clots undergo distinct degrees of lysis.

Thrombin Activatable Fibrinolysis Inhibitor (TAFI) Does not Inhibit In Vitro Thrombolysis by Pharmacological Concentrations of t-PA

2001 ◽  
Vol 85 (04) ◽  
pp. 661-666 ◽  
Author(s):  
Anna D’Aprile ◽  
Alessandra Italia ◽  
Paolo Gresele ◽  
John Morser ◽  
Nicola Semeraro ◽  
...  
Keyword(s):  
Specific Inhibitor ◽  
Clot Lysis ◽  
Thrombin Activatable Fibrinolysis Inhibitor ◽  
Experimental Conditions ◽  
Soluble Thrombomodulin ◽  
Blood Clots ◽  
Fibrinolysis Inhibitor ◽  
Vitro Model

SummaryTAFI (thrombin activatable fibrinolysis inhibitor) is a plasma procarboxypeptidase that upon activation inhibits the fibrinolytic process by removing the C-terminal lysines from partially degraded fibrin. The generation of activated TAFI (TAFIa) has been suggested to represent a mechanism of thrombus resistance to thrombolytic therapy. However, the ability of TAFI to inhibit fibrinolysis by pharmacological concentrations of t-PA has not been properly investigated. We used an in vitro model consisting of 125I-fibrin blood clots submerged in auto-logous defibrinated plasma. Upon addition of t-PA (125-5000 ng/ml) and CaCl2 (25 mM), samples were incubated at 37° C, and clot lysis was measured at intervals from the radioactivity released into solution. The role of TAFI was assessed either by neutralizing the generated TAFIa with the specific inhibitor PTI (50 g/ml) or by enhancing TAFI activation through the addition of recombinant soluble thrombomodulin (solulin, 1 μg/ml). In our clot lysis model, activation of TAFI amounted to about 20% of inducible carboxypeptidase activity. Addition of PTI, however, produced a significant increase in the extent of lysis only at concentrations of t-PA equal to or lower than 250 ng/ml. When solulin was added to the plasma surrounding the clot, about 70% of TAFI was activated within 15 min. Under these conditions, inhibition of clot lysis was very marked in samples containing 125 or 250 ng/ml of t-PA, but negligible in those containing pharmacological concentrations of the activator (1000 and 5000 ng/ml). Additional experiments suggest that loss of fibrin-dependence by elevated concentrations of t-PA may be one of the mechanisms explaining the lack of effect of TAFIa. Our data indicate that, under our experimental conditions, clot lysis by pharmacological concentrations of t-PA is not influenced by TAFIa even after maximal activation of this procarboxypeptidase.

Preparation and analysis of human medication tablets in drug delivery system

2020 ◽  
Vol 10 (3) ◽  
pp. 59-62
Author(s):  
Soujanya H ◽  
Purushothaman M ◽  
Jagadeeshwari S ◽  
Shiva Kumar K
Keyword(s):  
Drug Delivery ◽  
Drug Delivery System ◽  
Delivery System ◽  
Innovative Drug ◽  
Significant Deterioration ◽  
R And D ◽  
Assessment Tests ◽  
Medication Delivery ◽  
Set Up

Presently days, a significant objective medication conveyance study is twisted to the improvement of robust medication conveyance frameworks with previously existing dynamic fixings in the event of new medication disclosure. A considerable lot of remedial drug operators are generally viable when made accessible at steady rates close to assimilation locales. Much exertion has been proceeding to create advanced medication conveyance frameworks, for example, osmotic gadgets for oral request. Oral medication conveyance framework is more preferred on famous measured medication conveyance framework in innovative drug work (R and D) business because of increment in attention to clinical and drug network about the significance of sheltered and viable utilization of medication. In the current examination work, pulsatile drug conveyance arrangement of Zileuton tablets was planned by utilizing pressure covering innovation. At first, the centre tablets were set up by 30% groupings of wonderful crumbles; the figured centre tablets were covered with the polymers by utilizing pressure covering innovation. All the centre and press covered tablet details were exposed to different corporeal and concoction assessment tests for centre and press covered tablets. The hardness, thickness and weight variety appeared by all the tablet definitions were originate inside the authorized pharmacopoeias bounds. In-vitro arrival of Zileuton of centre tablet details F1 demonstrated quicker medication discharge after 15 min. Quicker medication delivery can be connected with significant deterioration, and friability saw in this examination. The enteric covered plans C1, C3 indicated the most significant medication discharge following 4 hours. Time subordinate pulsatile drug conveyance framework has been accomplished from the tablet of definition C3, C6 and C9 with 95.5%, 94.76% and 97.48% separately.

Abstract 334: An Echogenic Clot Method for Thrombolysis Monitoring of Directed Lytics in Thrombotic Stroke

2016 ◽  
Vol 36 (suppl_1) ◽  
Author(s):  
Dalton E Carter ◽  
Tao Peng ◽  
Melanie R Moody ◽  
Shao-Ling Huang ◽  
David D McPherson ◽  
...  
Keyword(s):  
Mass Loss ◽  
Dissolution Rate ◽  
Microcrystalline Cellulose ◽  
Quantitative Assessment ◽  
Imaging Techniques ◽  
Ultrasound Contrast Agent ◽  
Rabbit Blood ◽  
Blood Clots

Background: We have previously demonstrated thrombolytic efficacy of tissue plasminogen activator (tPA)-loaded echogenic liposomes (TELIP), a directed therapeutic construct that features exposed tPA fibrin-binding sites, in a rabbit abdominal aorta thrombosis model. The most relevant animal model for evaluation of directed thrombolytic therapy for ischemic stroke is the rabbit thrombotic stroke model previously used to validate recombinant tPA (rtPA; Alteplase). The ability to precisely monitor tPA-mediated thrombus dissolution in vivo is important for quantitative assessment of directed TELIP efficacy. Hypothesis: A gas-free ultrasound contrast agent can be incorporated into blood clots at a concentration that does not affect the tPA-mediated clot dissolution rate, while enabling quantitative assessment of the clot dissolution rate. Methods: In 1.5-ml Eppendorf tubes, 0.2-ml clots were formed from a mixture of whole rabbit blood, 1 M calcium chloride, human thrombin and various amounts of microcrystalline cellulose. At 0-time, 50 μg rtPA in 0.5 ml porcine plasma was added to each tube. Washed clots in tubes were weighed with an analytical balance at 30, 60 and 90 minutes. Clot echogenicity at each time point was assessed with a Philips HDI 5000 ultrasound system using an L12-5 linear array probe positioned laterally to tubes placed in an anechoic chamber. Recorded Images were subjected to videodensitometric analysis that converted image reflectivity to mean gray scale values (MGSV). Results: We found that 1.12 mg/ml of microcrystalline cellulose in rabbit blood clots (0.2 ml) provided optimal echogenicity without affecting the clot dissolution rates (0.3-0.6 mg/min.) caused by 100 μg/ml of rtPA. The clot dissolution rate measured by videodensitometric analysis of serial sonograms of the echogenic clots agreed well with that determined by mass loss measurements (0.28% 0-time value/minute). Conclusions: We have developed a method for monitoring rtPA-mediated clot mass loss by ultrasound imaging techniques and validated it in vitro. This method will be important for demonstrating the enhanced efficacy and decreased hemorrhagic effects provided by directed tPA vehicles relative to systemic administration of the free thrombolytic.

Abstract 12419: Preclinical Safety and Efficacy of a Novel Thrombolytic Agent Administered by Rapid Bolus Injection: Clot Specific Streptokinase (CSSK/SMRX-11)

Circulation ◽  
2015 ◽  
Vol 132 (suppl_3) ◽  
Author(s):  
Ronald J Shebuski ◽  
Kishore Joshi ◽  
Abhay Pande ◽  
Ravinder Sharma ◽  
Yatindra Prashar ◽  
...  
Keyword(s):  
In Vitro Studies ◽  
Plasma Fibrinogen ◽  
Clot Lysis ◽  
Repeat Dose ◽  
Safety And Efficacy ◽  
Cynomolgus Monkeys ◽  
Binding Domains ◽  
Blood Clots ◽  
Preclinical Safety

Introduction: Clot specific Streptokinase (CSSK), also known as SMRX-11, is a novel recombinant protein, produced and purified from a yeast system (Pichia pastoris). Novel fibrin binding domains attached to each end of streptokinase mask the ability of the streptokinase component of SMRX-11 to interact with blood plasminogen. As a result, SMRX-11 remains inactive in the blood circulation and does not convert blood plasminogen into plasmin until the fibrin binding domains are cleaved by clot-bound plasmin. This is in contrast to native Streptokinase (SK), which indiscriminately converts plasminogen into plasmin. The molecular weight of the glycosylated SMRX-11 protein is approximately 80kD, with a specific activity of 80,000 Units/mg of protein. Results. In vitro experiments comparing SMRX-11 to other fibrinolytics (SK and tPA), demonstrated that SMRX-11 lyses experimentally-preformed human blood clots without reducing residual plasma fibrinogen levels. Initial in vitro studies compared the activity of SMRX-11 to lyse human whole blood clots to native Streptokinase (SK) and tissue Plasminogen Activator (tPA). SMRX-11 had comparable clot lysis activity to SK, with tPA eliciting a slightly greater percent clot lysis. Additional in vitro studies determined the relative fibrinogenolytic effects of SMRX-11 versus tPA. SMRX-11 demonstrated superior fibrinogen sparing compared to tPA with minimal consumption of alpha-2 antiplasmin relative to native SK. In vivo, SMRX-11 (0.7-1.4 mg/kg as an iv bolus), lysed experimentally-induced femoral arterial thrombi in cynomolgus monkeys with relatively minor fluctuation in plasma fibrinogen, forearm bleeding time or hemodynamics. In GLP safety studies, treatment with SMRX-11 at doses of 1, 3 and 10 mg/kg/day for 5 consecutive days was generally well-tolerated in male and female cynomolgus monkeys. Thus, the low dose of 1 mg/kg was considered the No-Observed Adverse Effect Level (NOAEL) for daily repeat-dose administration of SMRX-11 administered via bolus i.v. injection in cynomolgus monkeys. Conclusion. SMRX-11 represents a novel pharmacophore with the appropriate preclinical safety and efficacy profile to warrant clinical investigation for acute treatment of myocardial infarction and stroke.

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