Poly(lactide-co-glycolide) ultrasonographic microbubbles carrying sudan black for preoperative and intraoperative localization of lymph nodes

Lymph node (LN) examination plays a critical role in the staging and treatment of several kinds of cancer such as lesions of the breast. However current strategies have limitations. This study aimed to develop a novel imaging agent, a polymeric ultrasonographic contrast agent carrying Sudan black (SB), for ultrasonographic imaging of the regional LNs before surgery and to directly localize the LNs during surgery. The poly(lactide-co-glycolide) (PLGA) ultrasonographic microbubbles carrying Sudan black B (SB) (SB-PLGA microbubbles) were prepared by the double emulsion method. The SB-PLGA microbubbles had a diameter of 1.5 ± 0.5 μm and the SB encapsulation efficiency was (86.2 ± 1.56%). Results from MTT assays suggested that these bubbles have little cytotoxicity to mouse macrophages after incubation. Confocal laser scanning microscopy showed that the PLGA microbubbles carrying the fluorescent dye rhodamine 6G were taken up by macrophages after 2-hour incubation. In addition, these SB-PLGA microbubbles were able to enhance ultrasonographic contrast of 12 popliteal LNs of 6 rabbits. Furthermore, the LNs were easily identifiable by the naked eye during surgery because of the blue color of the SB-PLGA microbubbles inside the LNs. By cryosectioning and hematoxylin and eosin (H&E) staining of LN tissue, our results showed that these SB-PLGA microbubbles were internalized inside the macrophages of the LNs. To conclude, the SB-PLGA microbubbles could be a suitable imaging agent for preoperative and intraoperative localization of LNs as well as for a preoperative ultrasonographically guided core needle biopsy of suspicious sentinel lymph nodes (SLNs) in cancer patients, hence enhancing treatment outcome

Liquid-solid phase-inversion PLGA implant for the treatment of residual tumor tissue after HIFU ablation.

HIFU has been shown to be a more suitable alternative for the treatment of primary solid tumors and metastatic diseases than other focal heat ablation techniques due to its noninvasive and extracorporeal nature. However, similar to other focal heat ablation techniques, HIFU is still in need of refinements due to tumor recurrence.In this work, we investigated the effectiveness of an adjunct treatment regimen using doxorubicin (DOX)-loaded, injectable, in situ-forming, and phase-inverting PLGA as the second line of defense after HIFU ablation to destroy detrimental residual tumors and to prevent tumor recurrence. All of the statistical analyses were performed using the Statistical Package for the Social Sciences 18.0 (SPSS, Inc., Chicago, IL, USA), and p<0.05 was considered statistically significant. All of the results are presented as the means ± STDEV (standard deviation). For multiple comparisons, ANOVA (differences in tumor volumes, growth rates, apoptosis, proliferation indexes, and Bcl-2 and Bax protein levels) was used when the data were normally distributed with homogenous variance, and rank sum tests were used otherwise. Once significant differences were detected, Student-t tests were used for comparisons between two groups.Our results revealed that DOX diffused beyond the ablated tissue regions and entered tumor cells that were not affected by the HIFU ablation. Our results also show that HIFU in concert with DOX-loaded PLGA led to a significantly higher rate of tumor cell apoptosis and a lower rate of tumor cell proliferation in the areas beyond the HIFU-ablated tissues and consequently caused significant tumor volume shrinkage (tumor volumes:0.26±0.1,1.09±0.76, and 1.42±0.9 cm3 for treatment, sham, and no treatment control, respectively).From these results, we concluded that the intralesional injection of DOX-loaded PLGA after HIFU ablation is significantly more effective than HIFU alone for the treatment of solid tumors

Distribution of Doxorubicin in HIFU-ablated Tumor Tissue.

<p>Zero signifies the center of the implants, and the other numerical values refer to the radial distances from the center of the implants. A: Light microscopy image of cryosectioned tumor tissue. B: Fluorescence microscopy image of the same tumor tissue section. C: High-power image of the area in the white box shown in B. D: Fluorescent intensity. The asterisk (*) indicates the PLGA implant, the white arrow indicates the edge of the PLGA implant, and the yellow arrow indicates the distance from the edge. The scale bar represents 100μm.</p

Contrast-Enhanced HIFU Ablation Imaging.

<p>Representative ultrasound tumor images with and without intentionally incomplete HIFU ablation. A: Without HIFU ablation and without contrast enhancement. B: TTC-stained tumor that was not subjected to HIFU ablation. C: Contrast-enhanced ultrasound image of tumor without HIFU ablation. D: HIFU-ablated tumor without contrast enhancement. E: TTC-stained tumor that received HIFU ablation. F: Contrast-enhanced ultrasound image of tumor with HIFU ablation. The arrows indicate the ablated area. The scale bars represent 1cm.</p

In vitro Cumulative DOX Release (%).

<p>The data are presented as the means ± STDEV (the standard deviation, n = 3).</p