Property and contrast-enhancement effects of lipid ultrasound contrast agent: a preliminary experimental study

Sonophoresis Using Ultrasound Contrast Agents: Dependence on Concentration

Sonophoresis can increase skin permeability to various drugs in transdermal drug delivery. Cavitation is recognized as the predominant mechanism of sonophoresis. Recently, a new logical approach to enhance the efficiency of transdermal drug delivery was tried. It is to utilize the engineered microbubble and its resonant frequency for increase of cavitation activity. Actively-induced cavitation with low-intensity ultrasound (less than ~1 MPa) causes disordering of the lipid bilayers and the formation of aqueous channels by stable cavitation which indicates a continuous oscillation of bubbles. Furthermore, the mutual interactions of microbubble determined by concentration of added bubble are also thought to be an important factor for activity of stable cavitation, even in different characteristics of drug. In the present study, we addressed the dependence of ultrasound contrast agent concentration using two types of drug on the efficiency of transdermal drug delivery. Two types of experiment were designed to quantitatively evaluate the efficiency of transdermal drug delivery according to ultrasound contrast agent concentration. First, an experiment of optical clearing using a tissue optical clearing agent was designed to assess the efficiency of sonophoresis with ultrasound contrast agents. Second, a Franz diffusion cell with ferulic acid was used to quantitatively determine the amount of drug delivered to the skin sample by sonophoresis with ultrasound contrast agents. The maximum enhancement ratio of sonophoresis with a concentration of 1:1,000 was approximately 3.1 times greater than that in the ultrasound group without ultrasound contrast agent and approximately 7.5 times greater than that in the control group. These results support our hypothesis that sonophoresis becomes more effective in transdermal drug delivery due to the presence of engineered bubbles, and that the efficiency of transdermal drug delivery using sonophoresis with microbubbles depends on the concentration of microbubbles in case stable cavitation is predominant.

Contrast-enhanced ultrasonography with contrast-tuned imaging technology for the detection of prostate cancer: comparison with conventional ultrasonography

Study Type - Diagnostic (exploratory cohort) Level of Evidence 2b What's known on the subject? and What does the study add? The present study was to perform contrast-tuned imaging (CnTI) technology to detect prostate cancer and compare the use of CnTI technology for the detection of prostate cancer with conventional ultrasonography. The preliminary data from our study suggested that targeted biopsy of the prostate with CnTI technology could improve the cancer detection and detect higher grade prostate cancers.

OBJECTIVES

To perform contrast-enhanced ultrasonography (CEUS) using contrast-tuned imaging (CnTI) technology to detect prostate cancer. To evaluate the detection of prostate cancer with CnTI compared with conventional grey-scale and power Doppler ultrasonography.

PATIENTS AND METHODS

In all, 150 patients referred for prostate biopsy were evaluated using transrectal grey-scale, power Doppler and CnTI ultrasonography. Biopsy was performed at 10 sites in each patient. If an abnormality was found at any of these three ultrasonography examinations, a biopsy specimen was targeted towards from the corresponding site. The performances of the three ultrasonography techniques for prostate cancer detection were compared.

RESULTS

Prostate cancer was detected at 383 sites from 73 patients. The combination of these three examinations detected more patients with prostate cancer than grey-scale (P= 0.002), power Doppler (P= 0.001) or baseline imaging (the combination of grey-scale and power Doppler; P= 0.031) alone. By biopsy site, CnTI had higher sensitivity and accuracy (73.1% and 83.7%) than grey-scale (50.9%; P < 0.001 and 78.8%; P < 0.001) or power Doppler (48.3%; P < 0.001 and 77.7%; P < 0.001), while the specificity was similar for grey-scale (88.4%), power Doppler (87.8%) and CnTI (87.3%; P > 0.05 in each case). CnTI had higher sensitivity (73.1% vs 62.9%; P < 0.001), specificity (87.3% vs 82.1%; P < 0.001) and accuracy (83.7% vs 77.2%; P < 0.001) than baseline imaging. The mean Gleason score of CnTI-positive cases was significantly higher than CnTI-negative cases (7.1 vs 6.3; P= 0.002).

CONCLUSIONS

CEUS using CnTI technology enables a visualization of the microvasculature associated with prostate cancer. CnTI technology could be used to guide biopsy and improve the detection rate of prostate cancer. CnTI technology was able to detect higher grade prostate cancers.

Ultrasound-targeted microbubble destruction mediated herpes simplex virus-thymidine kinase gene treats hepatoma in mice

Objective

The purpose of the study was to explore the anti-tumor effect of ultrasound -targeted microbubble destruction mediated herpes simplex virus thymidine kinase (HSV-TK) suicide gene system on mice hepatoma.

Methods

Forty mice were randomly divided into four groups after the models of subcutaneous transplantation tumors were estabilished: (1) PBS; (2) HSV-TK (3) HSV-TK+ ultrasound (HSV-TK+US); (4) HSV-TK+ultrasound+microbubbles (HSV-TK+US+MB). The TK protein expression in liver cancer was detected by western-blot. Applying TUNEL staining detected tumor cell apoptosis. At last, the inhibition rates and survival time of the animals were compared among all groups.

Results

The TK protein expression of HSV-TK+MB+US group in tumor-bearing mice tissues were significantly higher than those in other groups. The tumor inhibitory effect of ultrasound-targeted microbubble destruction mediated HSV-TK on mice transplantable tumor was significantly higher than those in other groups (p < 0.05), and can significantly improve the survival time of tumor-bearing mice.

Conclusion

Ultrasound-targeted microbubble destruction can effectively transfect HSV-TK gene into target tissues and play a significant inhibition effect on tumors, which provides a new strategy for gene therapy in liver cancer.

Phospholipid-based ultrasonic microbubbles for loading protein and ultrasound-triggered release

BACKGROUND

Ultrasonic microbubbles are used as ultrasound-triggered delivery carriers for protein drugs.

AIM

This work was to prepare stabilized protein-loaded phospholipid-based ultrasonic microbubbles (PUM) and to determine its value as a protein delivery system.

METHOD

Bovine serum albumin (BSA) was used as a model protein drug. BSA-containing PUM were prepared by dissolving lyophilized PUM powder in BSA solution. The particle size and microbubble concentration of BSA-containing PUM were measured. The BSA encapsulation efficiency as a function of BSA concentration was determined. Contrast enhancement of BSA-containing PUM in vivo was detected. The release profile of BSA from PUM was also investigated.

RESULTS

The mean particle size and microbubble concentration of PUM were unchanged by the presence of BSA for at least 30 minutes after preparation. The net amount of BSA entrapped in PUM was maintained unchanged with increasing BSA concentration. BSA-containing PUM were shown easily to be visible in in vivo rabbit kidney. There was no difference in echogenicity between the loaded and unloaded PUM. Ultrasound duration had a positive relationship with BSA release. Ultrasound of 30 seconds stimulated 94.1% and 93.3% of BSA release from PUM solutions containing 0.3% and 1.5% BSA, respectively.

CONCLUSIONS

Protein-loaded PUM exhibited satisfactory physical characteristics and were potent for using in ultrasound-triggered delivery.

Application of ultrasonic gas-filled liposomes in enhancing transfer for breast cancer-related antisense oligonucleotides: an experimental study

The aim of this study was to investigate the application of ultrasonic gas-filled liposomes in enhancing transfer for breast cancer-related antisense oligonucleotides in vitro. An antisense oligodeoxynucleotide (AS-ODN) sequence, HA2741, modified with luciferase reporter plasmid, was used in evaluating the enhancing effect of gas-filled liposomes for gene transfer in breast cancer cells. Some important factors on HA 2741 transfection efficiency, such as wave intensity, ultrasound duration, gas-filled liposome concentration, and HA2741 concentration, were tested, respectively. Transfection efficiency was detected by fluorescence microscopy. Cell viability was verified by propidium iodide assay. Reverse-transcriptase polymerase chain reaction and immunocytochemistry were used to detect the inhibitory effect of HA2741 on HER-2 expression. All the four factors (wave intensity, ultrasound duration, gas-filled liposome concentration, and HA2741 concentration) showed a positive effect on AS-ODN transfection efficiency. However, these factors had a negative effect on cell viability. Considering all the factors investigated, the maximum transfection efficiency with minimum cell viability achieved under 2% gas-filled liposome mixed with 80 nmol/L HA2741 for 30-second ultrasound exposure at -3.0 dB wave intensity, which gave an overall transfection efficiency exceeding 90% and a cell viability near 90%. Under controlled conditions, ultrasound-mediated AS-ODN transfer, enhanced by gas-filled liposomes, may represent an effective, safe avenue for cancer-related gene delivery.

Microvascular architecture of breast lesions: evaluation with contrast-enhanced ultrasonographic micro flow imaging

OBJECTIVE

The purpose of this study was to evaluate the effectiveness of micro flow imaging (MFI) of the microvascular architecture with contrast-enhanced ultrasonography for classification of breast lesions as benign or malignant and the microvascular architectural patterns.

METHODS

Contrast-enhanced ultrasonography and MFI were performed in 61 women with breast lesions. The microvascular morphologic and distribution features of the breast tumors were evaluated with MFI. Receiver operating characteristic curve analysis was used to evaluate the diagnostic value of MFI, and the microvascular architectural patterns were analyzed.

RESULTS

Surgical pathologic analysis showed 29 benign and 32 malignant lesions. For MFI, the area under the receiver operating characteristic curve (A(z)) value for the overall features of the blood vessels for classification of breast lesions was 0.94. The accuracy, sensitivity, and specificity were 90.2% (55/61), 93.8% (30/32), and 86.2% (25/29), respectively. The A(z) value for the morphologic and distribution features of peripheral blood vessels was 0.91, which was significantly higher than the A(z) value for the morphologic and distribution features of interior vessels (P= .019). The microvascular architecture of the 61 lesions was categorized into 3 patterns: treelike, root hair-like, and crab claw-like. Benign lesions mainly displayed the treelike pattern (17 [58.6%]); malignant lesions tended to display the crab claw-like pattern (20 [62.5%]); and the root hair-like pattern was shown in both benign and malignant lesions (11 [37.9%] and 8 [25%], respectively). The microvascular architecture showed significant differences between benign and malignant lesions (P< .001).

CONCLUSIONS

Micro flow imaging can clearly delineate the microvascular architecture of breast lesions and can aid in discrimination between benign and malignant breast lesions.

Phospholipids-based microbubbles sonoporation pore size and reseal of cell membrane cultured in vitro

OBJECTIVE

To investigate phospholipids-based microbubbles induced sonoporation and cell membrane reseal in vitro under various conditions.

METHODS

A breast cancer cell line SK-BR-3 was used to investigate ultrasonic sonoporation under various conditions. Atomic force microscopy (AFM) scanning techniques were employed to observe the change of membrane pores.

RESULTS

Normal SK-BR-3 cells membrane pores were evenly distributed and less than 1 microm. After ultrasound exposure, membrane pores were enlarged at different degree depending on ultrasound exposure durations, filling gas species and microbubble suspension concentration. With microbubble suspension concentration being increased to 5% or ultrasound exposure reached 30 s, membrane pores in fluorocarbon (C(3)F(8) or SF(6))-filled microbubble groups exceeded 1 microm, which were significantly larger than that of air-filled microbubble group. Membrane pores were about 2-3 microm under ultrasound 60 s with 5% fluorocarbon-filled microbubble suspension. After 24 h of incubation, most of the enlarged membrane pores could reseal to normal size, which corresponded to cell viability.

CONCLUSIONS

Membrane pores can be obviously enlarged by ultrasonic sonoporation of fluorocarbon-filled microbubbles, whose reseal time depended on ultrasound exposure duration and microbubble suspension concentration.

Contrast-enhanced ultrasound characterization of the vascularity of the rotator cuff tendon: age- and activity-related changes in the intact asymptomatic rotator cuff

The natural history of the blood supply to the rotator cuff and its role in the etiology of rotator cuff disease has not been definitively established. To date, there has not been an in-vivo dynamic assessment of the baseline vascularity of the asymptomatic rotator cuff. This study was designed to test the hypothesis that regional variations in supraspinatus tendon vascularity exist with an age-dependent decrease in asymptomatic individuals with intact rotator cuffs. Lipid microsphere, contrast-enhanced ultrasound shoulder examinations were done in 31 patients with a mean age of 41.5 years (range, 22-65 years). Images were obtained at baseline, after contrast administration at rest, and after contrast administration following exercise to visualize the intratendinous blood flow to the supraspinatus tendon. Qualitative and quantitative analysis was performed by determining 4 regions of interest (bursal medial, articular medial, bursal lateral, and articular lateral) with quantification and analysis software (QLAB Philips, Andover, MA) to examine each region of interest and normalize data for interpretation of the mean intensity per pixel. A statistically significant decrease in blood flow to the supraspinatus tendon with age was observed in a comparative analysis of patients aged younger than 40 and older than 40, (P < .05 for all 4 zones after exercise and for the bursal medial, articular medial, and bursal lateral zones after exercise; P = .07 for the articular lateral zone after exercise). A statistically significant increase in blood flow with exercise was observed in an analysis of all patients (P < .001). The age-related decrease in the vascular supply of the tendon observed in this study is consistent with published reports demonstrating an increasing prevalence of rotator cuff pathology with age and may predispose to the development of rotator cuff tendinopathy and, ultimately, attritional tears.

Comparing transfection efficiency and safety for antisense oligodeoxyribonucleotide between phospholipids-based microbubbles and liposomes

OBJECTIVE

To compare transfection efficiency and safety for antisense oligodeoxynucleotides (AS-ODNs) between two type of phospholipids-based vectors.

METHODS

An AS-ODNs sequence HA824 combined with luciferase reporter plasmid was used. Under low intensity ultrasound (US), a breast cancer cell line SK-BR-3 was exposed to different concentration of microbubbles and liposomes. Transfection efficiency was detected by fluorescence microscopy. Cell viability was verified by propidium iodide assay. Reverse transcription-polymerase chain reaction (RT-PCR) was used to detect the inhibitory effect of HA824 on HER-2 expression at mRNA level. Atomic force microscopy (AFM) scanning techniques was employed to observe the change of membrane pore size.

RESULTS

AS-ODNs transfection efficiency showed an increasing tend with microbubble concentration, but not with liposome concentration. Maximum transfection efficiency with minimum cell viability was achieved under 2% microbubble concentration. Too strong sonoporation activity would enlarge membrane pores significantly and cause low cell viability.

CONCLUSION

US-mediated AS-ODNs transfection enhanced by phospholipids-based microbubbles represents an effective and safe avenue.