Inhibition of prostate cancer growth using doxorubicin assisted by ultrasound-targeted nanobubble destruction

Progress in the treatment of drug-loaded nanomaterials in renal cell carcinoma

Renal cell carcinoma (RCC) is a common urinary tract tumor that arises from the highly heterogeneous epithelium of the renal tubules. The incidence of kidney cancer is second only to the incidence of bladder cancer, and has shown an upward trend over time. Although surgery is the preferred treatment for localized RCC, treatment decisions should be customized to individual patients considering their overall health status and the risk of developing or worsening chronic kidney disease postoperatively. Anticancer drugs are preferred to prevent perioperative and long-term postoperative complications; however, resistance to chemotherapy remains a considerable problem during the treatment process. To overcome this challenge, nanocarriers have emerged as a promising strategy for targeted drug delivery for cancer treatment. Nanocarriers can transport anticancer agents, achieving several-fold higher cytotoxic concentrations in tumors and minimizing toxicity to the remaining parts of the body. This article reviews the use of nanomaterials, such as liposomes, polymeric nanoparticles, nanocomposites, carbon nanomaterials, nanobubbles, nanomicelles, and mesoporous silica nanoparticles, for RCC treatment, and discusses their advantages and disadvantages.

Nanobubble technologies: Applications in therapy from molecular to cellular level

Nanobubbles are gaseous entities suspended in bulk liquids that have widespread beneficial usage in many industries. Nanobubbles are already proving to be versatile in furthering the effectiveness of disease treatment on cellular and molecular levels. They are functionalized with biocompatible and stealth surfaces to aid in the delivery of drugs. At the same time, nanobubbles serve as imaging agents due to the echogenic properties of the gas core, which can also be utilized for controlled and targeted delivery. This review provides an overview of the biomedical applications of nanobubbles, covering their preparation and characterization methods, discussing where the research is currently focused, and how they will help shape the future of biomedicine.

Development of an Antibody Delivery Method for Cancer Treatment by Combining Ultrasound with Therapeutic Antibody-Modified Nanobubbles Using Fc-Binding Polypeptide

A key challenge in treating solid tumors is that the tumor microenvironment often inhibits the penetration of therapeutic antibodies into the tumor, leading to reduced therapeutic efficiency. It has been reported that the combination of ultrasound-responsive micro/nanobubble and therapeutic ultrasound (TUS) enhances the tissue permeability and increases the efficiency of delivery of macromolecular drugs to target tissues. In this study, to facilitate efficient therapeutic antibody delivery to tumors using this combination system, we developed therapeutic antibody-modified nanobubble (NBs) using an Fc-binding polypeptide that can quickly load antibodies to nanocarriers; since the polypeptide was derived from Protein G. TUS exposure to this Herceptin^®-modified NBs (Her-NBs) was followed by evaluation of the antibody's own ADCC activity, resulting the retained activity. Moreover, the utility of combining therapeutic antibody-modified NBs and TUS exposure as an antibody delivery system for cancer therapy was assessed in vivo. The Her-NBs + TUS group had a higher inhibitory effect than the Herceptin and Her-NBs groups. Overall, these results suggest that the combination of therapeutic antibody-modified NBs and TUS exposure can enable efficient antibody drug delivery to tumors, while retaining the original antibody activity. Hence, this system has the potential to maximize the therapeutic effects in antibody therapy for solid cancers.

Construction and validation of a prognostic marker and risk model for HCC ultrasound therapy combined with WGCNA identification

Background: Hepatocellular carcinoma (HCC) is a malignant tumor with a highly aggressive and metastatic nature. Ultrasound remains a routine monitoring tool for screening, treatment and post-treatment recheck of HCC. Therefore, it is of great significance to explore the role of ultrasound therapy and related genes in prognosis prediction and clinical diagnosis and treatment of HCC.

Methods: Gene co-expression networks were developed utilizing the R package WGCNA as per the expression profiles and clinical features of TCGA HCC samples, key modules were identified by the correlation coefficients between clinical features and modules, and hub genes of modules were determined as per the GS and MM values. Ultrasound treatment differential expression genes were identified using R package limma, and univariate Cox analysis was conducted on the intersection genes of ultrasound differential expression genes and hub genes of key HCC modules to screen the signatures linked with HCC prognosis and construct a risk model. The median risk score was used as the threshold point to classify tumor samples into high- and low-risk groups, and the R package IOBR was used to assess the proportion of immune cells in high- and low-risk groups, R package maftools to assess the genomic mutation differences in high- and low-risk groups, R package GSVA’s ssgsea algorithm to assess the HALLMARK pathway enrichment analysis, and R package pRRophetic to analyze drug sensitivity in patients with HCC.

Results: WGCNA analysis based on the expression profiles and clinical data of the TCGA LIHC cohort identified three key modules with two major clinical features associated with HCC. The intersection of ultrasound-related differential genes and module hub genes was selected for univariate Cox analysis to identify prognostic factors significantly associated with HCC, and a risk score model consisting of six signatures was finally developed to analyze the prognosis of individuals with HCC. The risk model showed strength in the training set, overall set, and external validation set. The percentage of immune cell infiltration, genomic mutations, pathway enrichment scores, and chemotherapy drug resistance were significantly different between high- and low-risk groups according to the risk scores. Expression of model genes correlated with tumor immune microenvironment and clinical tumor characteristics while generally differentially expressed in pan-cancer tumor and healthy samples. In the immunotherapy dataset, patients in the high-risk group had a worse prognosis with immunotherapy, indicating that subjects in the low-risk group are more responsive to immunotherapy.

Conclusion: The 6-gene signature constructed by ultrasound treatment of HCC combined with WGCNA analysis can be used for prognosis prediction of HCC patients and may become a marker for immune response.

Highlights in ultrasound-targeted microbubble destruction-mediated gene/drug delivery strategy for treatment of malignancies

Ultrasound is one of the safest and most advanced medical imaging technologies that is widely used in clinical practice. Ultrasound microbubbles, traditionally used for contrast-enhanced imaging, are increasingly applied in Ultrasound-targeted Microbubble Destruction (UTMD) technology which enhances tissue and cell membrane permeability through cavitation and sonoporation, to result in a promising therapeutic gene/drug delivery strategy. Here, we review recent developments in the application of UTMD-mediated gene and drug delivery in the diagnosis and treatment of tumors, including the concept, mechanism of action, clinical application status, and advantages of UTMD. Furthermore, the future perspectives that should be paid more attention to in this field are prospected.

Development and application of ultrasound contrast agents in biomedicine

With the rapid development of molecular imaging, ultrasound (US) medicine has evolved from traditional imaging diagnosis to integrated diagnosis and treatment at the molecular level. Ultrasound contrast agents (UCAs) play a crucial role in the integration of US diagnosis and treatment. As the micro-bubbles (MBs) in UCAs can enhance the cavitation effect and promote the biological effect of US, UCAs have also been studied in the fields of US thrombolysis, mediated gene transfer, drug delivery, and high intensity focused US. The application range of UCAs is expanding, and the value of their applications is improving. This paper reviews the development and application of UCAs in biomedicine in recent years, and the existing problems and prospects are pointed out.

ICAM-1-carrying targeted nano contrast agent for evaluating inflammatory injury in rabbits with atherosclerosis

To investigate the feasibility of using ICAM-1-targeted nano ultrasonic contrast to evaluate the degree of inflammatory injury at different stages in the abdominal aorta of rabbits with atherosclerosis (AS). Twenty-five experimental rabbits were assigned to five groups: the control group (A); the week-4 after modeling group (B); the week-8 after modeling group (C); the week-12 after modeling group (D); the week-16 after modeling group (E). All groups were given 2D ultrasonography, conventional ultrasonic contrast (SonoVue), and ICAM-1-targeted nano ultrasonic contrast, respectively. Signal intensity of vascular perfusion was evaluated. Signal intensity of ICAM-1-targeted nano ultrasonic contrast was substantially enhanced and prolonged in the vascular wall of the abdominal bubble aorta increased in B, C, D, and E groups (all P < 0.05). A positive linear correlation between intensity and the expression of ICAM-1 (r = 0.895, P < 0.001). The intensity of outer membrane was enhanced from week 4 to week 12, and both the intima-media membrane and outer membrane were enhanced with double-layer parallel echo at week 16, which was in line with the progression of atherosclerotic plaque inflammatory injury. ICAM-1-targeted nano contrast agent would be possibly a novel non-invasive molecular imaging method for plaque inflammatory injury and site high expression of specific adhesion molecules in early atherosclerotic lesions.

Therapeutic oxygen delivery by perfluorocarbon-based colloids

After the protocol-related indecisive clinical trial of Oxygent, a perfluorooctylbromide/phospholipid nanoemulsion, in cardiac surgery, that often unduly assigned the observed untoward effects to the product, the development of perfluorocarbon (PFC)-based O₂ nanoemulsions ("blood substitutes") has come to a low. Yet, significant further demonstrations of PFC O₂-delivery efficacy have continuously been reported, such as relief of hypoxia after myocardial infarction or stroke; protection of vital organs during surgery; potentiation of O₂-dependent cancer therapies, including radio-, photodynamic-, chemo- and immunotherapies; regeneration of damaged nerve, bone or cartilage; preservation of organ grafts destined for transplantation; and control of gas supply in tissue engineering and biotechnological productions. PFC colloids capable of augmenting O₂ delivery include primarily injectable PFC nanoemulsions, microbubbles and phase-shift nanoemulsions. Careful selection of PFC and other colloid components is critical. The basics of O₂ delivery by PFC nanoemulsions will be briefly reminded. Improved knowledge of O₂ delivery mechanisms has been acquired. Advanced, size-adjustable O₂-delivering nanoemulsions have been designed that have extended room-temperature shelf-stability. Alternate O₂ delivery options are being investigated that rely on injectable PFC-stabilized microbubbles or phase-shift PFC nanoemulsions. The latter combine prolonged circulation in the vasculature, capacity for penetrating tumor tissues, and acute responsiveness to ultrasound and other external stimuli. Progress in microbubble and phase-shift emulsion engineering, control of phase-shift activation (vaporization), understanding and control of bubble/ultrasound/tissue interactions is discussed. Control of the phase-shift event and of microbubble size require utmost attention. Further PFC-based colloidal systems, including polymeric micelles, PFC-loaded organic or inorganic nanoparticles and scaffolds, have been devised that also carry substantial amounts of O₂. Local, on-demand O₂ delivery can be triggered by external stimuli, including focused ultrasound irradiation or tumor microenvironment. PFC colloid functionalization and targeting can help adjust their properties for specific indications, augment their efficacy, improve safety profiles, and expand the range of their indications. Many new medical and biotechnological applications involving fluorinated colloids are being assessed, including in the clinic. Further uses of PFC-based colloidal nanotherapeutics will be briefly mentioned that concern contrast diagnostic imaging, including molecular imaging and immune cell tracking; controlled delivery of therapeutic energy, as for noninvasive surgical ablation and sonothrombolysis; and delivery of drugs and genes, including across the blood-brain barrier. Even when the fluorinated colloids investigated are designed for other purposes than O₂ supply, they will inevitably also carry and deliver a certain amount of O₂, and may thus be considered for O₂ delivery or co-delivery applications. Conversely, O₂-carrying PFC nanoemulsions possess by nature a unique aptitude for ¹⁹F MR imaging, and hence, cell tracking, while PFC-stabilized microbubbles are ideal resonators for ultrasound contrast imaging and can undergo precise manipulation and on-demand destruction by ultrasound waves, thereby opening multiple theranostic opportunities.

Nanovectorization of Prostate Cancer Treatment Strategies: A New Approach to Improved Outcomes

Prostate cancer (PC) is the most frequent male cancer in the Western world. Progression to Castration Resistant Prostate Cancer (CRPC) is a known consequence of androgen withdrawal therapy, making CRPC an end-stage disease. Combination of cytotoxic drugs and hormonal therapy/or genotherapy is a recognized modality for the treatment of advanced PC. However, this strategy is limited by poor bio-accessibility of the chemotherapy to tumor sites, resulting in an increased rate of collateral toxicity and incidence of multidrug resistance (MDR). Nanovectorization of these strategies has evolved to an effective approach to efficacious therapeutic outcomes. It offers the possibility to consolidate their antitumor activity through enhanced specific and less toxic active or passive targeting mechanisms, as well as enabling diagnostic imaging through theranostics. While studies on nanomedicine are common in other cancer types, only a few have focused on prostate cancer. This review provides an in-depth knowledge of the principles of nanotherapeutics and nanotheranostics, and how the application of this rapidly evolving technology can clinically impact CRPC treatment. With particular reference to respective nanovectors, we draw clinical and preclinical evidence, demonstrating the potentials and prospects of homing nanovectorization into CRPC treatment strategies.

Ultrasound-Responsive Nanocarriers in Cancer Treatment: A Review

The safe and effective delivery of anticancer agents to diseased tissues is one of the significant challenges in cancer therapy. Conventional anticancer agents are generally cytotoxins with poor pharmacokinetics and bioavailability. Nanocarriers are nanosized particles designed for the selectivity of anticancer drugs and gene transport to tumors. They are small enough to extravasate into solid tumors, where they slowly release their therapeutic load by passive leakage or biodegradation. Using smart nanocarriers, the rate of release of the entrapped therapeutic(s) can be increased, and greater exposure of the tumor cells to the therapeutics can be achieved when the nanocarriers are exposed to certain internally (enzymes, pH, and temperature) or externally (light, magnetic field, and ultrasound) applied stimuli that trigger the release of their load in a safe and controlled manner, spatially and temporally. This review gives a comprehensive overview of recent research findings on the different types of stimuli-responsive nanocarriers and their application in cancer treatment with a particular focus on ultrasound.

Targeted drug delivery using an aptamer against shared tumor-specific peptide antigen of MAGE-A3

We developed a DNA aptamer, Ap52, against the shared tumor-specific MAGE-A3_111-125 peptide antigen that was used to target multiple types of cancer cells. Here we report the in vivo study of mice implanted with pancreatic tumor cells AsPC-1, which demonstrates accumulation of phosphorothioate-modified Ap52 (ThioAp52) at the xenograft tumor following either intravenous or in situ injection. When complexed with antitumor drug doxorubicin (Dox), ThioAp52 achieves targeted delivery to four types of cancer cells, including breast, oral, pancreatic, and skin. Image analysis shows that ThioAp52-Dox complex selectively enters cancer cells, while free Dox is taken up by all cell lines. The cytotoxicity of ThioAp52-Dox for cancer cells is enhanced as compared to that for the corresponding normal/noncancerous cells. These results indicate that this aptamer against shared tumor-specific antigen can be a potential delivery vehicle for therapeutics to treat multiple cancers.

Multifunctional nanobubbles carrying indocyanine green and paclitaxel for molecular imaging and the treatment of prostate cancer

BACKGROUND

Combining ultrasound imaging with photoacoustic imaging provides tissue imaging with high contrast and resolution, thereby enabling rapid, direct measurements and the tracking of tumour growth and metastasis. Moreover, ultrasound-targeted nanobubble destruction (UTND) provides an effective way to deliver drugs, effectively increasing the content of the drug in the tumour area and reducing potential side effects, thereby successfully contributing to the treatment of tumours.

RESULTS

In this study, we prepared multifunctional nanobubbles (NBs) carrying indocyanine green (ICG) and paclitaxel (PTX) (ICG-PTX NBs) and studied their applications in ultrasound imaging of prostate cancer as well as their therapeutic effects on prostate cancer when combined with UTND. ICG-PTX NBs were prepared by the mechanical oscillation method. The particle size and zeta potential of the ICG-PTX NBs were 469.5 ± 32.87 nm and - 21.70 ± 1.22 mV, respectively. The encapsulation efficiency and drug loading efficiency of ICG were 68% and 2.52%, respectively. In vitro imaging experiments showed that ICG-PTX NBs were highly amenable to multimodal imaging, including ultrasound, photoacoustic and fluorescence imaging, and the imaging effect was positively correlated with their concentration. The imaging effects of tumour xenografts also indicated that ICG-PTX NBs were of good use for multimodal imaging. In experiments testing the growth of PC-3 cells in vitro and tumour xenografts in vivo, the ICG-PTX NBs + US group showed more significant inhibition of cell proliferation and the promotion of cell apoptosis compared to the other groups (P < 0.05). Blood biochemical analysis of the six groups showed that the levels of aspartate aminotransferase (AST), phenylalanine aminotransferase (ALT), serum creatinine (CRE) and blood urea nitrogen (BUN) in the ICG-PTX NBs and the ICG-PTX NBs + US groups were significantly lower than those in the PTX group (P < 0.05). Moreover, H&E staining of tissue sections from vital organs showed no obvious abnormalities in the ICG-PTX NBs and the ICG-PTX NBs + US groups.

CONCLUSIONS

ICG-PTX NBs can be used as a non-invasive, pro-apoptotic contrast agent that can achieve multimodal imaging, including ultrasound, fluorescence and photoacoustic imaging, and can succeed in the local treatment of prostate cancer providing a potential novel method for integrated research on prostate cancer diagnosis and treatment.

Targeted Nanobubbles Carrying Indocyanine Green for Ultrasound, Photoacoustic and Fluorescence Imaging of Prostate Cancer

Objective

To construct prostate-specific membrane antigen (PSMA)-targeting, indocyanine green (ICG)-loaded nanobubbles (NBs) for multimodal (ultrasound, photoacoustic and fluorescence) imaging of prostate cancer.

Methods

The mechanical oscillation method was used to prepare ICG-loaded photoacoustic NBs (ICG NBs). Then, PSMA-binding peptides were connected to the surface of ICG NBs using the biotin–avidin method to make targeted photoacoustic NBs, namely, PSMAP/ICG NBs. Their particle sizes, zeta potentials, and in vitro ultrasound, photoacoustic and fluorescence imaging were examined. Confocal laser scanning microscopy and flow cytometry were used to detect the binding ability of the PSMAP/ICG NBs to PSMA-positive LNCaP cells, C4-2 cells, and PSMA-negative PC-3 cells. The multimodal imaging effects of PSMAP/ICG NBs and ICG NBs were compared in nude mouse tumor xenografts.

Results

The particle size of the PSMAP/ICG NBs was approximately 457.7 nm, and the zeta potential was approximately −23.5 mV. Both confocal laser scanning microscopy and flow cytometry confirmed that the PSMAP/ICG NBs could specifically bind to both LNCaP and C4-2 cells, but they rarely bound to PC-3 cells. The ultrasound, photoacoustic and fluorescence imaging intensities of the PSMAP/ICG NBs in vitro positively correlated with their concentrations. The ultrasound and photoacoustic imaging effects of the PSMAP/ICG NBs in LNCaP and C4-2 tumor xenografts were significantly enhanced compared with those in PC-3 tumor xenografts, which were characterized by a significantly increased duration of ultrasound enhancement and heightened photoacoustic signal intensity (P < 0.05). Fluorescence imaging showed that PSMAP/ICG NBs could accumulate in LNCaP and C4-2 tumor xenografts for a relatively long period.

Conclusion

The targeted photoacoustic nanobubbles prepared in this study can specifically bind to PSMA-positive prostate cancer cells and have the ability to enhance ultrasound, photoacoustic and fluorescence imaging of PSMA-positive tumor xenografts. Photoacoustic imaging could visually display the intensity of the red photoacoustic signal in the tumor region, providing a more intuitive imaging modality for targeted molecular imaging. This study presents a potential multimodal contrast agent for the accurate diagnosis and assessment of prostate cancer.

Active targeting nano-scale bubbles enhanced ultrasound cavitation chemotherapy in Y1 receptor-overexpressed breast cancer

Ultrasound cavitation therapy has attracted much attention in recent years because the cavitation of microbubbles can be leveraged to boost the infiltration of chemotherapeutic drugs into cancer tissues. For breast cancer therapy, most of the previously reported microbubbles lack specific targeting capacity and permeability. In this study, we have successfully fabricated Y₁ receptor ligand (NPY)-modified bubbles, and examined their therapeutic efficacies as size-dependent functions with or without NPY targeting. To achieve this, four types of micro-scale bubbles (MBs or MBs-NPY) and nano-scale bubbles (NBs or NBs-NPY) were comprehensively evaluated. In vivo results indicated that the NBs-NPY group with doxorubicin (DOX) under ultrasound irradiation showed a high tumor suppression effect and a prolonged survival time. Furthermore, the NBs-NPY with DOX group exhibited minimal damage to mouse vital organs, which points to the considerable tolerance of the proposed nanosystem for efficacious breast cancer therapy. In summary, these findings suggest that the developed NPY-targeted NBs could have a broad application prospect in ultrasound cavitation chemotherapy of Y₁ receptor-overexpressed breast cancer.

Anti-G250 nanobody-functionalized nanobubbles targeting renal cell carcinoma cells for ultrasound molecular imaging

Traditional imaging examinations have difficulty in identifying benign and malignant changes in renal masses. This difficulty may be solved by ultrasound molecular imaging based on targeted nanobubbles, which could specifically enhance the ultrasound imaging of renal cell carcinomas (RCC) so as to discriminate benign and malignant renal masses. In this study, we aimed to prepare anti-G250 nanobody-functionalized targeted nanobubbles (anti-G250 NTNs) by coupling anti-G250 nanobodies to lipid nanobubbles and to verify their target specificity and binding ability to RCC cells that express G250 antigen and their capacity to enhance ultrasound imaging of RCC xenografts. Anti-G250 nanobodies were coupled to the lipid nanobubbles using the biotin-streptavidin bridge method. The average particle diameter of the prepared anti-G250 NTNs was 446 nm. Immunofluorescence confirmed that anti-G250 nanobodies were uniformly distributed on the surfaces of nanobubbles. In vitro experiments showed that the anti-G250 NTNs specifically bound to G250-positive 786-O cells and HeLa cells with affinities of 88.13% ± 4.37% and 71.8% ± 5.7%, respectively, and that they did not bind to G250-negative ACHN cells. The anti-G250 NTNs could significantly enhance the ultrasound imaging of xenograft tumors arising from 786-O cells and HeLa cells compared with blank nanobubbles, while the enhancement was not significant for xenograft tumors arising from ACHN cells. Immunofluorescence of tumor tissue slices confirmed that the anti-G250 NTNs could enter the tissue space through tumor blood vessels and bind to tumor cells specifically. In conclusion, anti-G250 nanobody-functionalized targeted nanobubbles could specifically bind to G250-positive RCC cells and enhance the ultrasound imaging of G250-positive RCC xenografts. This study has high-potential clinical application value for the diagnosis and differential diagnosis of renal tumors.

Development of stimuli-responsive intelligent polymer micelles for the delivery of doxorubicin

Doxorubicin is still used as a first-line drug in current therapeutics for numerous types of malignant tumours (including lymphoma, transplantable leukaemia and solid tumour). Nevertheless, to overcome the serious side effects like cardiotoxicity and myelosuppression caused by effective doses of doxorubicin remains as a world-class puzzle. In recent years, the usage of biocompatible polymeric nanomaterials to form an intelligently sensitive carrier for the targeted release in tumour microenvironment has attracted wide attention. These different intelligent polymeric micelles (PMs) could change the pharmacokinetics process of drugs or respond in the special microenvironment of tumour site to maximise the efficacy and reduce the toxicity of doxorubicin in other tissues and organs. Several intelligent PMs have already been in the clinical research stage and planned for market. Therefore, related research remains active, and the latest nanotechnology approaches for doxorubicin delivery are always in the spotlight. Centring on the model drugs doxorubicin, this review summarised the mechanisms of PMs, classified the polymers used in the application of doxorubicin delivery and discussed some interesting and imaginative smart PMs in recent years.

Impact of pH and cell medium on the interaction of doxorubicin with lipoic acid cyclodextrin conjugate as the drug carrier

Lipoic acid derivative of cyclodextrin, βCDLip, was used as the drug carrier for doxorubicin (DOX) and the stability constants of the DOX–βCDLip were determined in the environment of the cell medium. The experiments were performed in neutral (pH 7.6) and acidified (pH 6.3) cell media containing more than forty interferences including: amino acids, vitamins, lipids and proteins. We proved that the pH of the medium has a noticeable impact on the affinity of the drug towards the carrier. At neutral pH, the formation constants of the complex are higher than at pH 6.3, what is characteristic for the cancer cells microenvironment. Furthermore, the values obtained in both cell media are twice smaller than the values obtained previously for the same complex but in the absence of common cell media components indicating that there is a competition between DOX and some hydrophobic medium components for the complex formation with βCDLip. On the other hand at pH 7.6, the amount of free DOX is highly limited due to the fact that most of DOX is still in the complexed form, while at pH 6.3 the cell media ingredients become strong interferences in the formation of the complex between DOX and the drug carrier. The observed behaviour is due to partial protonation of DOX and to competition between the drug and the lipoic side arm of cyclodextrin for the cyclodextrin cavity. The stability constants of the DOX–βCDLip complex in acidic pH are similar to the values for DOX with native β-cyclodextrin, demonstrating that the strengthening effect of DOX–CD complex resulting from the presence of cyclodextrin’s aromatic substituent (Lip) occurs only in the case of neutral pH. The high value of the stability constant of the DOX–βCDLip complex in cell medium at pH 7.6 indicates high selectivity of βCDLip ligand which would be of importance both for the effective drug delivery and for its application in DOX sensing devices.

Efficacy evaluation and mechanism study on inhibition of breast cancer cell growth by multimodal targeted nanobubbles carrying AMD070 and ICG

To construct targeted nanobubbles carrying both small-molecule CXCR4 antagonist AMD070 and light-absorbing material indocyanine green (ICG), and to study their in vitro multimodal imaging, as well as their mechanism and efficacy of inhibition of breast cancer cell growth. Nanobubbles carrying AMD070 and ICG (ICG-TNBs) were constructed by carbodiimide reaction and mechanical oscillation. The physical characteristics and in vitro multimodal imaging were determined. The binding potential of ICG-TNBs to human breast cancer cells were observed by laser confocal microscopy. CCK-8 and flow cytometry were used to analyze the role of ICG-TNBs + US in inhibiting proliferation and inducing apoptosis of tumor cells. Flow cytometry and Western blotting are used to analyse the ROS generation and molecular mechanisms. ICG-TNBs had a particle size of 497.0 ± 29.2 nm and a Zeta potential of -8.05 ± 0.73 mV. In vitro multimodal imaging showed that the image signal intensity of ICG-TNBs increased with concentration. Targeted binding assay confirmed that ICG-TNBs could specifically bind to MCF-7 cells (CXCR4 positive), but not to MDA-MB-468 cells (CXCR4 negative). CCK-8 assay and flow cytometry analysis showed that ICG-TNBs + US could significantly inhibit the growth of MCF-7 breast cancer cells and promote their apoptosis. Flow cytometry and Western blotting showed that ICG-TNBs + US could significantly raise generation of ROS, reduce the expression of CXCR4, inhibit phosphorylation of Akt, and increase the expression of Caspase3 and Cleaved-caspase3. This indicated that ICG-TNBs could effectively inhibit and block the SDF-1/CXCR4 pathway, thus leading to the apoptosis of MCF-7 cells. ICG-TNBs can specifically bind to CXCR4 positive breast cancer cells, furthermore inhibit growth and promote apoptosis of breast cancer cells combined with ultrasonic irradiation by blocking the SDF-1/CXCR4 pathway. This study introduces a novel concept, method and mechanism for integration of targeted diagnosis and treatment of breast cancer.

Ultrasound-Targeted Microbubble Destruction Enhances the Antitumor Efficacy of Doxorubicin in a Mouse Hepatocellular Carcinoma Model

The aim of the study described here was to investigate whether ultrasound-mediated microbubble destruction (UTMD) of targeted microbubbles conjugated with an anti-vascular endothelial growth factor receptor 2 (anti-VEGFR2) antibody can enhance the therapeutic effect of doxorubicin (DOX) on a mouse hepatocellular carcinoma (HCC) model bearing HEP-G2-RFP tumors. The growth of liver tumors in mice was inhibited by using Visistar VEGFR2 plus ultrasound irradiation and by DOX alone. DOX plus UTMD had an inhibitory effect on tumor growth beginning on the seventh day of treatment, while Visistar VEGFR2 alone and DOX alone had inhibitory effects beginning on the 11th day. DOX + UTMD significantly decreased tumor volume and tumor weight compared with DOX alone (p < 0.05) and Visistar VEGFR2 alone (p < 0.05). Compared with DOX alone and Visistar VEGFR2 alone, DOX + UTMD had the highest inhibitory effect on tumor angiogenesis and the highest apoptosis index. UTMD-targeted microbubbles can significantly enhance the antitumor effect of DOX on a mouse HCC model, inhibit angiogenesis and induce apoptosis in tumor cells.

G250 Antigen-Targeting Drug-Loaded Nanobubbles Combined with Ultrasound Targeted Nanobubble Destruction: A Potential Novel Treatment for Renal Cell Carcinoma

Purpose

We intended to design G250 antigen-targeting temsirolimus-loaded nanobubbles (G250-TNBs) based on the targeted drug delivery system and to combine G250-TNBs with ultrasound targeted nanobubble destruction (UTND) to achieve a synergistic treatment for renal cell carcinoma (RCC).

Methods

The filming-rehydration method was combined with mechanical shock and electrostatic interactions to prepare temsirolimus-loaded nanobubbles (TNBs). G250-TNBs were prepared by attaching anti-G250 nanobodies to the surface of TNBs using the biotin-streptavidin-bridge method. The ability of G250-TNBs to target the G250 antigen of RCC cells and the synergistic efficacy of G250-TNBs and UTND in the treatment of RCC were assessed.

Results

The average diameter of the prepared G250-TNBs was 368.7 ± 43.4 nm, the encapsulation efficiency was 68.59% ± 5.43%, and the loading efficiency was 5.23% ± 0.91%. In vitro experiments showed that the affinity of G250-TNBs to the human RCC 786-O cells was significantly higher than that of TNBs (P <0.05), and the inhibitory effect on 786-O cell proliferation and the induction of 786-O cell apoptosis was significantly enhanced in the group treated with G250-TNBs and UTND (G250-TNBs+ UTND group) compared with the other groups (P <0.05). In a nude mouse xenograft model, compared with TNBs, G250-TNBs could target the transplanted tumors and thus significantly enhance the ultrasound imaging of the tumors. Compared with all other groups, the G250-TNBs+UTND group exhibited a significantly lower tumor volume, a higher tumor growth inhibition rate, and a higher apoptosis index (P <0.05).

Conclusion

The combined G250-TNBs and UTND treatment can deliver anti-tumor drugs to local areas of RCC, increase the local effective drug concentration, and enhance anti-tumor efficacy, thus providing a potential novel method for targeted therapy of RCC.

Carbon Nanotubes Having Haeckelite Defects as Potential Drug Carriers. Molecular Dynamics Simulation

Carbon nanotubes (CNTs) are valuable drug carriers since when properly functionalized they transport drugs and anchor directly to cancerous tumors whose more acidic pH causes the drug release. Herein, we study the so-called zigzag and armchair CNTs with haeckelite defects to rank their ability to adsorb doxorubicin (DOX) by determining the DOX-CNT binding free energies using the MM/PBSA and MM/GBSA methods implemented in AMBER. Our results reveal stronger DOX-CNT interactions for encapsulation of the drug inside the nanotube compared to its adsorption onto the defective nanotube external surface. Armchair CNTs with one and two defects exhibit better results compared with those with four and fifteen defects. Each haeckelite defect consists of a pair of square and octagonal rings. DOX-CNT binding free energies are predicted to be dependent on: (i) nanotube chirality and diameter, (ii) the number of defects, (iii) nitrogen doping and (iv) the position of the encapsulated DOX inside the nanotube. Armchair (10,10) nanotubes with two haeckelite defects, doped with nitrogen, exhibit the best drug-nanotube binding free energies compared with zigzag and fully hydrogenated nanotubes and, also previously reported ones with bumpy defects. These results contribute to further understanding drug-nanotube interactions and their potential application to the design of new drug delivery systems.

Ultrasound microbubble-mediated CRISPR/Cas9 knockout of C-erbB-2 in HEC-1A cells

OBJECTIVE

Epidermal growth factor receptor 2 (C-erbB-2) is one of the most frequently mutated oncogenes in human tumors. We aimed to evaluate the knockout efficiency of clustered regularly interspaced short palindromic repeat (CRISPR) technology using ultrasound microbubble transfection to target C-erbB-2 in human endometrial cancer (HEC)-1A cells.

METHODS

Three single guide RNAs (sgRNAs) targeting C-erbB-2 were designed and used to construct CRISPR/CRISPR-associated (Cas)9-C-erbB-2 plasmids. The constructed plasmids were transfected into HEC-1A cells using ultrasound microbubbles. C-erbB-2 knockout cloned cells were identified by green fluorescence. C-erbB-2 mRNA and protein expression was measured by reverse transcription (RT)-PCR and western blotting, respectively.

RESULTS

RT-PCR showed that C-erbB-2 mRNA expression was significantly lower in sgRNA1-transfected cells (0.57 ± 0.06) than in blank (1.00 ± 0.09) and negative-control groups (1.02 ± 0.12). Western blotting revealed C-erbB-2 protein expression to be significantly lower in sgRNA1-transfected cells (0.269 ± 0.033) than in blank (0.495 ± 0.059) and negative-control groups (1.243 ± 0.281). However, there was no significant difference in C-erbB-2 protein and mRNA expression in sgRNA2- and sgRNA3-transfected cells compared with controls.

CONCLUSION

Ultrasound microbubbles can mediate plasmid transfer into HEC-1A cells to interfere with gene expression and knockout C-erbB-2.

GSH-sensitive Pt(IV) prodrug-loaded phase-transitional nanoparticles with a hybrid lipid-polymer shell for precise theranostics against ovarian cancer

Background: Platinum (II) (Pt(II))-based anticancer drugs dominate the chemotherapy field of ovarian cancer. However, the patient's quality of life has severely limited owing to dose-limiting toxicities and the advanced disease at the time of diagnosis. Multifunctional tumor-targeted nanosized ultrasound contrast agents (glutathione (GSH)-sensitive platinum (IV) (Pt(IV)) prodrug-loaded phase-transitional nanoparticles, Pt(IV) NP-cRGD) were developed for precise theranostics against ovarian cancer.

Methods: Pt(IV) NP-cRGD were composed of a perfluorohexane (PFH) liquid core, a hybrid lipid-polymer shell with PLGA_12k-PEG_2k and DSPE-PEG_1k-Pt(IV), and an active targeting ligand, the cRGD peptide (PLGA: poly(lactic-co-glycolic acid), PEG: polyethylene glycol, DSPE: 1,2-distearoyl-sn-glycero-3-phosphoethanolamine, cRGD: cyclic Arg-Gly-Asp). Pt(IV), a popular alternative to Pt(II), was covalently attached to DSPE-PEG_1k to form the prodrug, which fine-tuned lipophilicity and improved cellular uptake. The potential of Pt(IV) NP-cRGD as contrast agents for ultrasound (US) imaging was assessed in vitro and in vivo. Moreover, studies on the antitumor efficiency and antitumor mechanism of Pt(IV) NP-cRGD assisted by US were carried out.

Results: Pt(IV) NP-cRGD exhibited strong echogenic signals and excellent echo persistence under an US field. In addition, the GSH-sensitive and US-triggered drug delivery system maximized the therapeutic effect while reducing the toxicity of chemotherapy. The mechanistic studies confirmed that Pt(IV) NP-cRGD with US consumed GSH and enhanced reactive oxy gen species (ROS) levels, which further causes mitochondria-mediated apoptosis.

Conclusion: A multifunctional nanoplatform based on phase-transitional Pt(IV) NP-cRGD with US exhibited excellent echogenic signals, brilliant therapeutic efficacy and limited side effect, suggesting precise theranostics against ovarian cancer.

CAIX aptamer-functionalized targeted nanobubbles for ultrasound molecular imaging of various tumors

Purpose

Targeted nanobubbles can penetrate the tumor vasculature and achieve ultrasound molecular imaging (USMI) of tumor parenchymal cells. However, most targeted nanobubbles only achieve USMI of tumor parenchymal cells from one organ, and their distribution, loading ability, and binding ability in tumors are not clear. Therefore, targeted nanobubbles loaded with carbonic anhydrase IX (CAIX) aptamer were fabricated for USMI of various tumors, and the morphological basis of USMI with targeted nanobubbles was investigated.

Materials and methods

The specificity of CAIX aptamer at the cellular level was measured by immunofluorescence and flow cytometry. Targeted nanobubbles loaded with CAIX aptamer were prepared by a maleimidethiol coupling reaction, and their binding ability to CAIX-positive tumor cells was analyzed in vitro. USMI of targeted and non-targeted nanobubbles was performed in tumor-bearing nude mice. The distribution, loading ability, and binding ability of targeted nanobubbles in xenograft tumor tissues were demonstrated by immunofluorescence.

Results

CAIX aptamer could specifically bind to CAIX-positive 786-O and Hela cells, rather than CAIX-negative BxPC-3 cells. Targeted nanobubbles loaded with CAIX aptamer had the advantages of small size, uniform distribution, regular shape, and high safety, and they could specifically accumulate around 786-O and Hela cells, while not binding to BxPC-3 cells in vitro. Targeted nanobubbles had significantly higher peak intensity and larger area under the curve than non-targeted nanobubbles in 786-O and Hela xenograft tumor tissues, while there was no significant difference in the imaging effects of targeted and non-targeted nanobubbles in BxPC-3 xenograft tumor tissues. Immunofluorescence demonstrated targeted nanobubbles could still load CAIX aptamer after penetrating the tumor vasculature and specifically binding to CAIX-positive tumor cells in xenograft tumor tissues.

Conclusion

Targeted nanobubbles loaded with CAIX aptamer have a good imaging effect in USMI of tumor parenchymal cells, and can improve the accuracy of early diagnosis of malignant tumors from various organs.

Cavitation-threshold Determination and Rheological-parameters Estimation of Albumin-stabilized Nanobubbles

Nanobubbles (NBs) are of high interest for ultrasound (US) imaging as contrast agents and therapy as cavitation nuclei. Because of their instability (Laplace pressure bubble catastrophe) and low sensitivity to US, reducing the size of commonly used microbubbles to submicron-size is not trivial. We introduce stabilized NBs in the 100-250-nm size range, manufactured by agitating human serum albumin and perfluoro-propane. These NBs were exposed to 3.34- and 5.39-MHz US, and their sensitivity to US was proven by detecting inertial cavitation. The cavitation-threshold information was used to run a numerical parametric study based on a modified Rayleigh-Plesset equation (with a Newtonian rheology model). The determined values of surface tension ranged from 0 N/m to 0.06 N/m. The corresponding values of dilatational viscosity ranged from 5.10-10 Ns/m to 1.10-9 Ns/m. These parameters were reported to be 0.6 N/m and 1.10-8 Ns/m for the reference microbubble contrast agent. This result suggests the possibility of using albumin as a stabilizer for the nanobubbles that could be maintained in circulation and presenting satisfying US sensitivity, even in the 3-5-MHz range.

Organic Semiconducting Photoacoustic Nanodroplets for Laser-Activatable Ultrasound Imaging and Combinational Cancer Therapy

Combination of photoacoustic (PA) and ultrasound (US) imaging offers high spatial resolution images with deep tissue penetration, which shows great potential in applications in medical imaging. Development of PA/US dual-contrast agents with high contrast and excellent biocompatibility is of great interest. Herein, an organic semiconducting photoacoustic nanodroplet, PS-PDI-PAnD, is developed by stabilizing low-boiling-point perfluorocarbon (PFC) droplet with a photoabsorber and photoacoustic agent of perylene diimide (PDI) molecules and coencapsulating the droplet with photosensitizers of ZnF₁₆Pc molecules. Upon irradiation, the PDI acts as an efficient photoabsorber to trigger the liquid-to-gas phase transition of the PFC, resulting in dual-modal PA/US imaging contrast as well as photothermal heating. On the other hand, PFC can serve as an O₂ reservoir to overcome the hypoxia-associated resistance in cancer therapies, especially in photodynamic therapy. The encapsulated photosensitizers will benefit from the sustained oxygen release from the PFC, leading to promoted photodynamic efficacy regardless of pre-existing hypoxia in the tumors. When intravenously injected into tumor-bearing mice, the PS-PDI-PAnDs show a high tumor accumulation via EPR effect. With a single 671 nm laser irradiation, the PS-PDI-PAnDs exhibit a dual-modal PA/US imaging-guided synergistic photothermal and oxygen self-enriched photodynamic treatment, resulting in complete tumor eradication and minimal side effects. The PS-PDI-PAnDs represents a type of PFC nanodroplets for synergistic PDT/PTT treatment upon a single laser irradiation, which is expected to hold great potential in the clinical translation in dual-modal PA/US imaging-guided combinational cancer therapy.

Epidermal growth factor receptor-targeted sonoporation with microbubbles enhances therapeutic efficacy in a squamous cell carcinoma model

Sonoporation is a drug and gene delivery system using ultrasonication that allows the intracellular delivery of foreign molecules that cannot enter cells under normal conditions. We previously reported that sonoporation with microbubbles (MBs) could achieve effective intracellular drug delivery to human gingival squamous carcinoma Ca9-22 cells. In this study, we developed anti-epidermal growth factor receptor (EGFR) antibody-conjugated MBs (EGFR-MBs) and evaluated their capacity to enhance anti-cancer drug toxicity in vitro and in vivo. We first assessed the effect of sonoporation with EGFR-MBs on Ca9-22 cells by the WST-8 assay, flow cytometry and Hoechst's staining in vitro. Sonoporation and EGFR-MB had a strong cytotoxic effect on Ca9-22 cells with low-dose bleomycin. Furthermore, bleomycin delivery using sonoporation with EGFR-MBs remarkably increased the number of apoptotic cells. We next examined the effect of EGFR-MBs in a murine squamous cell carcinoma model. Bleomycin delivery by sonoporation with EGFR-MBs exhibited remarkable antitumor activity. Together, our results show that EGFR-MBs and ultrasound treatment increases the efficacy and specificity of intracellular drug uptake, suggesting this could be a novel drug-targeting modality for oral squamous cell carcinoma chemotherapy treatment.

Combining doxorubicin-nanobubbles and shockwaves for anaplastic thyroid cancer treatment: preclinical study in a xenograft mouse model

Anaplastic thyroid cancer is one of the most lethal diseases, and a curative therapy does not exist. Doxorubicin, the only drug approved for anaplastic thyroid cancer treatment, has a very low response rate and causes numerous side effects among which cardiotoxicity is the most prominent. Thus, doxorubicin delivery to the tumor site could be an import goal aimed to improve the drug efficacy and to reduce its systemic side effects. We recently reported that, in human anaplastic thyroid cancer cell lines, combining doxorubicin-loaded nanobubbles with extracorporeal shock waves, acoustic waves used in lithotripsy and orthopedics without side effects, increased the intracellular drug content and in vitro cytotoxicity. In the present study, we tested the efficacy of this treatment on a human anaplastic thyroid cancer xenograft mouse model. After 21 days, the combined treatment determined the greatest drug accumulation in tumors with consequent reduction of tumor volume and weight, and an extension of the tumor doubling time. Mechanistically, the treatment induced tumor apoptosis and decreased cell proliferation. Finally, although doxorubicin caused the increase of fibrosis markers and oxidative stress in animal hearts, loading doxorubicin into nanobubbles avoided these effects preventing heart damage. The improvement of doxorubicin anti-tumor effects together with the prevention of heart damage suggests that the combination of doxorubicin-loaded nanobubbles with extracorporeal shock waves might be a promising drug delivery system for anaplastic thyroid cancer treatment.

Targeting Taxanes to Castration-Resistant Prostate Cancer Cells by Nanobubbles and Extracorporeal Shock Waves

To target taxanes to castration-resistant prostate cancer cells, glycol-chitosan nanobubbles loaded with paclitaxel and docetaxel were constructed. The loaded nanobubbles were then combined with Extracorporeal Shock Waves, acoustic waves widely used in urology and orthopedics, with no side effects. Nanobubbles, with an average diameter of 353.3 ± 15.5 nm, entered two different castration-resistant prostate cancer cells (PC3 and DU145) as demonstrated by flow cytometry and immunofluorescence. The shock waves applied increased the amount of intracellular nanobubbles. Loading nanobubbles with paclitaxel and docetaxel and combining them with shock waves generated the highest cytotoxic effects, resulting in a paclitaxel GI₅₀ reduction of about 55% and in a docetaxel GI₅₀ reduction of about 45% respectively. Combined treatment also affected cell migration. Paclitaxel-loaded nanobubbles and shock waves reduced cell migration by more than 85% with respect to paclitaxel alone; whereas docetaxel-loaded nanobubbles and shock waves reduced cell migration by more than 82% with respect to docetaxel alone. The present data suggest that nanobubbles can act as a stable taxane reservoir in castration-resistant prostate cancer cells and shock waves can further increase drug release from nanobubbles leading to higher cytotoxic and anti-migration effect.