Spatial Control of Gene Expression by Nanocarriers Using Heparin Masking and Ultrasound-Targeted Microbubble Destruction

Biomedical applications of engineered heparin-based materials

Heparin is a negatively charged polysaccharide with various chain lengths and a hydrophilic backbone. Due to its fascinating chemical and physical properties, nontoxicity, biocompatibility, and biodegradability, heparin has been extensively used in different fields of medicine, such as cardiovascular and hematology. This review highlights recent and future advancements in designing materials based on heparin for various biomedical applications. The physicochemical and mechanical properties, biocompatibility, toxicity, and biodegradability of heparin are discussed. In addition, the applications of heparin-based materials in various biomedical fields, such as drug/gene delivery, tissue engineering, cancer therapy, and biosensors, are reviewed. Finally, challenges, opportunities, and future perspectives in preparing heparin-based materials are summarized.

Major Strategies for Spatial Control of Ultrasound-Driven Gene Expression to Enhance Therapeutic Specificity

A major challenge of gene therapy is to achieve highly specific transgene expression in tissues of interest with minimized off-target expression. Ultrasound in combination with microbubbles can transiently increase permeability of desired cells or tissues and thereby facilitate gene transfer. This kind of ultrasound-driven transgene expression has gained increasing attention due to its deep tissue penetration and high spatiotemporal resolution. However, successful genetic manipulation in vivo with ultrasound need to well optimize various aspects involved in this process. Ultrasound parameters, microbubble dose, and gene vectors need to be optimized for highly increased transgene expression in the cells of interest. Conversely, the potential off-target transgene expression and toxicities need to be reduced by modification of gene vectors and/or promoter sequence. This review will discuss some major strategies for enhanced specificity of the ultrasound-mediated gene transfer in vivo. Five major strategies will be discussed, including the integration of real-time imaging methods, local injection, targeted microbubbles loaded with nucleic acids, stealth nanocarriers, and cell-specific promoter. The advantages and limitations of each strategy were outlined, hoping to provide a guideline for researchers in achieving high specific ultrasound-driven gene expression.

Drug Release from Gelsolin-Targeted Phase-Transition Nanoparticles Triggered by Low-Intensity Focused Ultrasound

Purpose

Current strategies for tumour-induced sentinel lymph node detection and metastasis therapy have limitations. It is essential to identify and provide warnings earlier for tumour metastasis to carry out effective clinical interventions. In addition, traditional cancer chemotherapy encounters drastic limitations due to the nonspecific delivery of antitumour drugs and severe side effects. We aimed to exploit the potential of gelsolin (GSN) monoclonal antibody as a targeting agent and perfluorohexane (PFH) as a phase-transition agent to maximize the cytotoxic effect of poly(lactic-co-glycolic acid) (PLGA) nanoparticle-based drug controllable release systems for Hca-F cells.

Methods

We co-encapsulated PFH and doxorubicin (DOX) into PLGA nanoparticles (NPs) and further conjugated GSN monoclonal antibody onto the surface of NPs to form GSN-targeted phase transition polymer NPs (GSN-PLGA-PFH-DOX) for both imaging and therapy of tumours and metastatic lymph nodes. To promote and trigger drug release on demand, low-intensity focused ultrasound (LIFU) was applied to achieve a controllable release of the encapsulated drug.

Results

GSN-PLGA-PFH-DOX NPs exhibited characteristics such as a narrow size distribution and smooth surface. GSN-PLGA-PFH-DOX NPs could also specifically bind to Hca-F cells and increase the ultrasound contrast agent (UCA) image contrast intensity. GSN-PLGA-PFH-DOX NPs enable GSN-mediated targeting and biotherapeutic effects as well as LIFU-responsive drug release, resulting in synergistic cytotoxic effects in GSN-overexpressing cells in vitro.

Conclusion

Our work might provide a strategy for the imaging and chemotherapy of primary tumours and their metastases.

Mitochondria-Targeted Nanocarriers Promote Highly Efficient Cancer Therapy: A Review

Mitochondria are the primary organelles which can produce adenosine triphosphate (ATP). They play vital roles in maintaining normal functions. They also regulated apoptotic pathways of cancer cells. Given that, designing therapeutic agents that precisely target mitochondria is of great importance for cancer treatment. Nanocarriers can combine the mitochondria with other therapeutic modalities in cancer treatment, thus showing great potential to cancer therapy in the past few years. Herein, we summarized lipophilic cation- and peptide-based nanosystems for mitochondria targeting. This review described how mitochondria-targeted nanocarriers promoted highly efficient cancer treatment in photodynamic therapy (PDT), chemotherapy, combined immunotherapy, and sonodynamic therapy (SDT). We further discussed mitochondria-targeted nanocarriers’ major challenges and future prospects in clinical cancer treatment.

Synergic fabrication of pembrolizumab loaded doxorubicin incorporating microbubbles delivery for ultrasound contrast agents mediated anti-proliferation and apoptosis

This study evaluated pembrolizumab-conjugated, doxorubicin (DOX)-loaded microbubbles (PDMs) in combination with ultrasound (US) as molecular imaging agents for early diagnosis of B cell lymphomas, and as a targeted drug delivery system. Pembrolizumab, a monoclonal CD20 antibody, was attached to the surfaces of DOX-loaded microbubbles. PDM binding to B cell lymphoma cells was assessed using immunofluorescence. The cytotoxic effects of PDMs in combination with ultrasound (PDMs + US) were evaluated in vitro in CD20+ and CD20- cell lines, and its antitumor activities were assessed in Raji (CD20+) and Jurkat (CD20-) lymphoma cell-grafted mice. PDMs specifically bound to CD20+ cells in vitro and in vivo. Contrast enhancement was monitored in vivo via US. PDM peak intensities and contrast enhancement durations were higher in Raji than in Jurkat cell-grafted mice (p < 0.05). PDMs + US treatment resulted in improved antitumor effects and reduced systemic toxicity in Raji cell-grafted mice compared with other treatments (p < .05). Our results showed that PDMs + US enhanced tumor targeting, reduced systemic toxicity, and inhibited CD20+ B cell lymphoma growth in vivo. Targeted PDMs could be employed as US molecular imaging agents for early diagnosis, and are an effective targeted drug delivery system in combination with US for CD20+ B cell malignancy treatment.

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.

Tumor-self-targeted "thermoferroptosis-sensitization" magnetic nanodroplets for multimodal imaging-guided tumor-specific therapy

Ferroptosis-based nanomedicine has drawn increasing attention in antitumor therapy because of the advantages of this unconventional mode of apoptosis, but the difficulties of delivery to the tumor site and surface-to-core penetration after arrival seriously hinder further clinical transformation and application. Herein, we propose an unprecedented strategy of injecting magnetic nanodroplets (MNDs) to solve these two longstanding problems. MNDs are nanocarriers that can carry multifunctional drugs and imaging materials. MNDs can effectively accumulate in the tumor site by active tumor targeting (multifunctional drugs) and passive tumor targeting (enhanced permeability and retention effect), allowing diffusion of the MNDs from the surface to the core through mild-temperature magnetic fluid hyperthermia (MHT) under multimodal imaging guidance. Finally, the ferroptosis pathway is activated deep within the tumor site through the drug release. This approach was inspired by the ability of mild-temperature MHT to allow MNDs to quickly pass through the blood vessel-tumor barrier and deeply penetrate the tumor tissue from the surface to the core to amplify the antitumor efficacy of ferroptosis. This strategy is termed as "thermoferroptosis sensitization". Importantly, this behavior can be performed under the guidance of multimodal imaging, making the design of MNDs for cancer therapy safer and more reasonable.

Dual-sonosensitizer loaded phase-transition nanoparticles with tumor-targeting for synergistically enhanced sonodynamic therapy

Sonodynamic therapy (SDT) is a fast-growing therapy activated by using ultrasound to initiate a catalytic reaction of sensitizing agents and kill tumor cells through producing reactive oxygen species (ROS). Both sinoporphyrin sodium (DVDMS) and IR780 are preeminent sonosensitizers and have been used in SDT alone. In this study, tumor targeting multifunctional composite nanoparticles (DVDMS@IR780@PFP@PLGA, DIPP-NPs) were synthesized by encapsulating DVDMS, IR780 and perfluoropentane (PFP) to synergistically enhance SDT and achieve imaging of tumors. The loaded IR780 is regarded as a "navigator" to accurately identify and target tumor cells/tissues. DVDMS and IR780 not only can realize the directed SDT, but also can perform photoacoustic (PA) imaging. PFP plays its role in enhancing the ultrasound (US) imaging. Generally, DIPP-NPs not only have an obvious synergistic anti-tumor effect, but also are able to carry out dual-mode imaging, which paves a promising way for tumor therapy.

Nanoparticles based on polymers modified with pH-sensitive molecular switch and low molecular weight heparin carrying Celastrol and ferrocene for breast cancer treatment

Triple negative breast cancer (TNBC) metastasis is still one of the obstacles in clinical treatment, while highly-effective cancer drugs usually cannot be used for their hydrophobicity and comprehensive system toxicity. This study built a kind of pH-sensitive nanoparticles (PP/H NPs) constructed by poly (lactic-co-glycolic acid) modified with β-cyclodextrin (PLGA-β-CD), polyethyleneimine grafted with benzimidazole (PEI-BM) and low molecular weight heparin (LMWH) to delivery Celastrol (Cela) and ferrocene (Fc) for breast cancer therapy. PLGA-β-CD and PEI-BM were synthesized by amidation reaction, the amphipathic polymer nanoparticles with 108.37 ± 1.02 nm were self-assembled in water. After PP/H NPs treatment, the half maximal inhibitory concentration (IC50) decreased by 91% compared with Cela, and ROS level was also elevated. PP/H NPs led to substantial tumor inhibiting rate (TIR, 65.86%), utilized LMWH to strengthen the anti-metastasis effect of PP/H NPs. PP/H NPs took advantage of exogenous chemotherapeutics and endogenous ROS to inhibit tumor growth, and combined with LMWH to hinder breast cancer metastasis.

An acoustic field-based conformal transfection system for improving the gene delivery efficiency

Ultrasound-activated microbubble destruction is a promising platform for gene delivery due to the low toxicity, non-invasiveness, and high specificity. However, the gene transfection efficiency is still low, especially for suspension cells. It is desirable to develop a universal gene delivery tool that overcomes the drawbacks existing in ultrasound-mediated methods. Here, we present a three-dimensional acoustic field-based conformal transfection (AFCT) system by designing a Sono-hole that can fit the three-dimensional acoustic field to maximally utilize the acoustic energy from bubble cavitation, thus greatly promoting the gene delivery efficiency. Surprisingly, compared with the traditional two-dimensional transfection system, the gene transfection efficiency of the AFCT system increased by more than 3 times, achieving nearly 30%. The parameters including acoustic pressure, duration, duty cycle, DNA concentrations, and bubble kinds were optimized to obtain higher gene transfection. In conclusion, our study provides an effective ultrasound-based gene delivery approach for gene transfection, especially for suspension-cultured cells.

Hierarchically Releasing Bio-Responsive Nanoparticles for Complete Tumor Microenvironment Modulation via TGF-β Pathway Inhibition and TAF Reduction

The aggressive progression of breast cancer is impacted significantly by the tumor microenvironment (TME). The current chemotherapy normally causes cytotoxicity to tumor cells, while does not effectively modulate the TME. Thus, the chemotherapy effect of breast cancer is usually dissatisfactory. In this study, a kind of hierarchically releasing bio-responsive nanoparticles (R(D)/H(S) NPs), constructed by β-cyclodextrin-grafted heparin and pH-sensitive pseudorotaxane, were investigated to enhance the breast cancer chemotherapeutic efficacy through TME modulation. Doxorubicin (DOX) and transforming growth factor-β (TGF-β) receptor inhibitor (SB431542) loaded onto R(D)/H(S) NPs were released rapidly for the respective response to low pH in endosomes/lysosomes and heparanase (HPSE) in TME. Our results showed that R(D)/H(S) NPs effectively inhibited the formation of tumor-associated fibroblasts (TAFs) and reduced TGF-β and collagen I secretion. Besides, the immunosuppressive microenvironment was effectively reversed into immunogenic, characterized by increased CD8⁺ and CD4⁺ T cell infiltration, which distinctly inhibited breast cancer metastasis. Therefore, R(D)/H(S) NPs remodeled the TME by downregulating TAFs, TGF-β, and collagen I; activating the immune microenvironment; and then amplifying the chemotherapeutic efficacy of DOX.

Visualized podocyte-targeting and focused ultrasound responsive glucocorticoid nano-delivery system against immune-associated nephropathy without glucocorticoid side effect

Glucocorticoids are widely used in the treatment of nephritis, however, its dose-dependent side effects, such as the increased risk of infection and metabolic disturbances, hamper its clinical use. This study reports a visualized podocyte-targeting and focused ultrasound responsive glucocorticoid nano-delivery system (named as Dex/PFP@LIPs-BMS-α), which specific delivers dexamethasone (Dex) to podocyte targets and reduces systemic side effects.

Methods: The glucocorticoid nano-delivery system was synthesized by a lipid thin film and a simple facile acoustic-emulsification method. This glucocorticoid nano-delivery system used BMS-470539 (BMS-α), a synthetic compound, as a “navigator” to specifically identify and target the melanocortin-1 receptor (MC-1R) on podocytes. The loaded perfluoropentane (PFP) realizes the directed "explosion effect" through ultrasound-targeted microbubble destruction (UTMD) technology under the coordination of low intensity focused ultrasound (LIFU) to completely release Dex.

Results: Both in vitro and in vivo experiments have demonstrated that Dex/PFP@LIPs-BMs-α accurately gathered to podocyte targets and improved podocyte morphology. Moreover, in vivo, proteinuria and serum creatinine levels were significantly reduced in the group treated with Dex/PFP@LIPs-BMS-α, and no severe side effects were detected. Furthermore, Dex/PFP@LIPs-BMS-α, with capabilities of ultrasound, photoacoustic and fluorescence imaging, provided individualized visual guidance and the monitoring of treatment.

Conclusion: This study provides a promising strategy of Dex/PFP@LIPs-BMS-α as effective and safe against immune-associated nephropathy.

Preventive Effect of Albumin Nano TPA Gene Plasmid Ultrasound Microbubble Carrier System on Thrombosis after Cardiac Valve Replacement

After cardiac valve replacement, most patients will have different degrees of thrombosis, different parts of the thrombus, and even more frequent occurrence of postoperative thrombosis; therefore, the prevention of postoperative thrombosis is particularly important. The purpose of this study was to investigate the preventive effect of albumin nano tPA gene plasmid ultrasound microbubble carrier system on thrombosis, especially in cardiac valve. The experimental control method was used. Firstly, 11 dogs meeting the experimental requirements were selected. Secondly, the data of albumin nanoparticles and microbubbles were analyzed. The average size of albumin particles was 132.0 nm, the average size of microbubbles was 3.1 ± 1.6 μm, and the zeta potential was 13.70 ± 1.95 MV. The concentration of microbubbles was 4.2 ± 1.3 × 10/ml. Finally, 11 dogs were divided into two groups. The experimental group was treated with albumin nanoparticles ultrasound microbubble, and the others were the control group. It was found that the levels of tPA and D-dimer in the experimental group were significantly increased and maintained at a high level at 1 week after operation, and the prothrombin time was detected and the international normalized ratio was calculated at the same time. No significant changes were found in the experimental group.

Heparanase-driven sequential released nanoparticles for ferroptosis and tumor microenvironment modulations synergism in breast cancer therapy

The normal chemotherapy only induces the intracellular apoptosis pathway to promote primary tumor cells death, while not inhibit tumor metastasis. Herein, we proposed a kind of heparanase (HPSE)-driven sequential released nanoparticles, which modified with β-cyclodextrin (β-CD) grafted heparin (NLC/H(D + F + S) NPs) co-loading with doxorubicin (DOX), ferrocene (Fc), and TGF-β receptor inhibitor (SB431542). NLC/H(D + F + S) NPs successfully inhibited breast cancer metastasis by intracellular and extracellular hybrid mechanism. DOX and Fc loaded in NLC/H(D + F + S) NPs effectively enhanced intracellular ROS level to activate ferroptosis pathway, the enhanced ROS also induced the apoptosis pathway and decreased MMP-9 expression to synergize with ferroptosis for tumor therapy. In extracellular site, SB431542 was sequentially released by HPSE-driven, which blocked tumor metastasis by modulating tumor microenvironment, decreasing TAFs activation, and reducing the secretion of TGF-β. In addition, anti-tumor immune response induced by ferroptosis further strengthened the effect of tumor therapy. Finally, under the help of intracellular and extracellular mechanisms launched by NLC/H(D + F + S) NPs, the satisfactory anti-tumor metastasis effect was obtained in the in vivo anti-tumor assays. Therefore, NLC/H(D + F + S) NPs was a novel dosage regimen for breast cancer therapy through intracellular and extracellular mechanisms, in which ferroptosis induced by ROS played an important role.

Engineering patient-specific cancer immunotherapies

Research into the immunological processes implicated in cancer has yielded a basis for the range of immunotherapies that are now considered the fourth pillar of cancer treatment (alongside surgery, radiotherapy and chemotherapy). For some aggressive cancers, such as advanced non-small-cell lung carcinoma, combination immunotherapies have resulted in unprecedented treatment efficacy for responding patients, and have become frontline therapies. Individualized immunotherapy, enabled by the identification of patient-specific mutations, neoantigens and biomarkers, and facilitated by advances in genomics and proteomics, promises to broaden the responder patient population. In this Perspective, we give an overview of immunotherapies leveraging engineering approaches, including the design of biomaterials, delivery strategies and nanotechnology solutions, for the realization of individualized cancer treatments such as nanoparticle vaccines customized with neoantigens, cell therapies based on patient-derived dendritic cells and T cells, and combinations of theranostic strategies. Developments in precision cancer immunotherapy will increasingly rely on the adoption of engineering principles.

Tissue Targeting and Ultrasound-Targeted Microbubble Destruction Delivery of Plasmid DNA and Transfection In Vitro

Introduction

Ultrasound-targeted microbubble destruction (UTMD) has been shown a promising approach for target-specific gene delivery and treatment of many diseases in the past decade. To improve the therapeutic potential of UTMD, the gene carrier of microbubbles should possess adequate DNA condensation capability and (or) specific cell or tissue selectivity. The tissue-targeted and ultrasound-targeted cationic microbubbles were developed to meet gene therapy.

Methods

A tissue-targeted stearic acid-inserted cationic microbubbles (SCMBs) were prepared for ultrasound-targeted gene delivery. Branched PEI was modified with stearic acid and further mixed with 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) and biot-1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy (polyethylene glycol)-2000] (ammonium salt) (Biot-DSPE-PEG2000), intercellular adhesion molecule-1 (ICAM-1) antibody and plasmid DNA to prepare cationic microbubbles through ultrasonic hydration. The ICAM-1 antibody and plasmid DNA were expected to assemble to the surface of SCMBs via biotin-avidin interaction and electrostatic interaction, respectively.

Results

It was found that the SCMBs had higher zeta potential compared with neutral microbubbles (NMBs) and cationic microbubbles (CMBs). In contrast, DNA incorporated SCMBs4 showed negative potential, exhibiting good DNA-binding capacity. Confocal images showed that the HeLa cells were attached around by the SCMBs4 from the view of green fluorescence of fluorescein isothiocyanate-loaded IgG which conjugated to ICAM-1 antibody on their surface. After ultrasound treatment, HeLa cells treated with SCMBs exhibited slightly stronger red fluorescence under confocal laser scanning microscope, indicating a synergistic promotion for transfection efficiency.

Conclusions

This tissue- and ultrasound-targeted cationic microbubble demonstrated here showed a promising strategy for improving gene therapy in the future.

Mitochondria-Targeted and Ultrasound-Activated Nanodroplets for Enhanced Deep-Penetration Sonodynamic Cancer Therapy

Sonodynamic therapy (SDT), a promising alternative for cancer therapy, utilizes a sonosensitizer combined with ultrasound (US) irradiation to damage tumor cells/tissues for therapeutic purposes. The ability of sonosensitizers to specifically accumulate in tumor cells/tissues could greatly influence their therapeutic efficiency. In this work, we report the use of US-activated sonosensitizer (IR780)-based nanodroplets (IR780-NDs) for SDT, which provide numerous benefits for killing cancer cells compared with traditional methods. For instance, IR780-NDs showed effective surface-to-core diffusion both in vitro and in vivo. In the presence of US, the acoustic droplet vaporization (ADV) effect significantly assisted the conveyance of IR780-NDs from the circulatory system to tumor regions, and the acoustic wave force also increased the penetration depth within tumor tissues. Furthermore, IR780-NDs possesses mitochondrial targeting capabilities, which improves the precision and accuracy of SDT delivery. During the in vitro assessment, the overproduction of reactive oxygen species (ROS) was observed following mitochondrial targeting, which rendered cancer cells more susceptible to ROS-induced apoptosis. Additionally, IR780-ND is a suitable candidate for photoacoustic and fluorescence imaging and can also enhance US imaging because of the ADV-generated bubbles, which provides the potential for SDT guidance and monitoring. Therefore, with combined modalities, IR780-NDs can be a promising theranostics nanoplatform for cancer therapy.

Highly efficient gene release in spatiotemporal precision approached by light and pH dual responsive copolymers

Triblock copolymer of poly(ethylene glycol)-b-poly(2-dimethylaminoethyl methacrylate)-b-poly(pyrenylmethyl methacrylate) (PEG-b-PDMAEMA-b-PPy) has been developed for use as an ideal gene delivery system, which showed both high stability under physiological conditions and efficient gene release in a mimetic cancer environment. The siRNA release from this system without external stimulation was 16% in 1 h and then remained steady. However, the photo-triggered siRNA release was 78% within 1 h and was higher than 91% after 24 h. The remarkable contrast between the stability and release efficiency of these siRNA-condensed micelleplexes before and after photo-irradiation has been rationalized by the light- and pH-induced structural transitions of the triblock copolymer micelles. The negligible cytotoxicity, high cellular uptake efficiency, and remarkable knockdown efficiency shown in in vitro tests further revealed the promising potential of these triblock copolymer micelleplexes for use in stimuli-responsive gene therapy.

HAase-sensitive dual-targeting irinotecan liposomes enhance the therapeutic efficacy of lung cancer in animals

Among all cancers, lung cancer is one of the most common and serious types of cancer. It is challenging for site-specific delivery of anticancer therapeutics to tumor cells. Herein, we developed a novel“smart” dual-targeting liposomal platform to respond to the highly expressed hyaluronidase (HAase) in the tumor microenvironment and improve tumor targeting and antitumor efficacy.

Methods: In our design, the HA was used as a sensitive linker between a liposomal lipid and long chain PEG block to synthesize three functional conjugates in order to prepare“smart” liposomal platform modified with epidermal growth factor receptor (EGFR) antibody (GE11) and cell-penetrating peptide (TATp). Using irinotecan as a model therapeutic, evaluations were performed on the human lung adenocarcinoma A549 cells as well as the xenografted A549 cancer cells in nude mice.

Results: The GE11/HA/TATp-irinotecan liposomes evidently increased the uptake of irinotecan and showed significant antitumor efficacy in the xenografted A549 cancer cells in nude mice by intravenous administration. The mechanisms were defined to be two aspects: GE11 exhibits high affinity for EGFR binding and the degradation of the HA by HAase results in the long-chain PEG removal and exposure of the previously hidden surface-attached TATp to enhance the target cell internalization.

Conclusion: Our findings suggest that this functional liposomal platform may provide a novel strategy for treating lung cancers because of effective intracellular delivery.

A dual-targeting strategy for enhanced drug delivery and synergistic therapy based on thermosensitive nanoparticles

The functionalized nanoparticles have been widely studied and reported as carriers of drug transport recently. Furthermore, many groups have focused more on developing novel and efficient treatment methods, such as photodynamic therapy and photothermal therapy, since both therapies have shown inspiring potential in the application of antitumor. The mentioned treatments exhibited the superiority of cooperative manner and showed the ability to compensate for the adverse effects caused by conventional monotherapy in proposed strategies. In view of the above descriptions, we formulated a thermosensitive drug delivery system, which achieved the enhanced delivery of cisplatin and two photosensitizers (ICG and Ce6) by dual-targeting traction. Drawing on the thin film hydration method, cisplatin and photosensitizers were encapsulated inside nanoparticles. Meanwhile, the targeting peptide cRGD and targeting molecule folate can be modified on the surface of nanoparticles to realize the active identification of tumor cells. The measurements of dynamic light scattering showed that the prepared nanoparticles had an ideal dispersibility and uniform particle size of 102.6 nm. On the basis of the results observed from confocal laser scanning microscope, the modified nanoparticles were more efficient endocytosed by MCF-7 cells as a contrast to SGC-7901 cells. Photothermal conversion-triggered drug release and photo-therapies produced a significant apoptosis rate of 85.9% on MCF-7 cells. The distinguished results made it believed that the formulated delivery system had conducted great efforts and innovations for the realization of concise collaboration and provided a promising strategy for the treatment of breast cancer.

Porphyrin-grafted Lipid Microbubbles for the Enhanced Efficacy of Photodynamic Therapy in Prostate Cancer through Ultrasound-controlled In Situ Accumulation

Photodynamic therapy (PDT) holds promise for focal therapy of prostate cancer (PCa). However, the therapeutic efficacy needs improvement, and further development of PDT for PCa has challenges, including uncertainty of photosensitizers (PSs) accumulation at the tumor site and difficulty in visualizing lesions using conventional ultrasound (US) imaging. We have developed novel porphyrin-grafted lipid (PGL) microbubbles (MBs; PGL-MBs) and propose a strategy to integrate PGL-MBs with US imaging to address these limitations and enhance PDT efficacy.

METHODS

PGL-MBs have two functions: imaging guidance by contrast-enhanced ultrasound (CEUS) and targeted delivery of PSs by ultrasound targeted microbubble destruction (UTMD). PGL-MBs were prepared and characterized before and after low-frequency US (LFUS) exposure. Then, in vitro studies validated the efficacy of PDT with PGL-MBs in human prostate cancer PC3 cells. PC3-xenografted nude mice were used to validate CEUS imaging, accumulation at the tumor site, and in vivo PDT efficacy.

RESULTS

PGL-MBs showed good contrast enhancement for US imaging and were converted into nanoparticles upon LFUS exposure. The resulting uniquely structured nanoparticles avoided porphyrin fluorescence quenching and efficiently accumulated at the tumor site through the sonoporation effect created with the assistance of US to achieve excellent PDT efficacy.

CONCLUSIONS

This is the first preclinical investigation of MBs applied in PDT for PCa. PGL-MBs possess favorable CEUS imaging effects to enhance the localization of tumors. PGL-MBs with LFUS control PS accumulation at the tumor site to achieve highly effective PDT of PCa. This strategy carries enormous clinical potential for PCa management.

Drug Release from Phase-Changeable Nanodroplets Triggered by Low-Intensity Focused Ultrasound

Background: As one of the most effective triggers with high tissue-penetrating capability and non-invasive feature, ultrasound shows great potential for controlling the drug release and enhancing the chemotherapeutic efficacy. In this study, we report, for the first time, construction of a phase-changeable drug-delivery nanosystem with programmable low-intensity focused ultrasound (LIFU) that could trigger drug-release and significantly enhance anticancer drug delivery. Methods: Liquid-gas phase-changeable perfluorocarbon (perfluoropentane) and an anticancer drug (doxorubicin) were simultaneously encapsulated in two kinds of nanodroplets. By triggering LIFU, the nanodroplets could be converted into microbubbles locally in tumor tissues for acoustic imaging and the loaded anticancer drug (doxorubicin) was released after the microbubble collapse. Based on the acoustic property of shell materials, such as shell stiffness, two types of nanodroplets (lipid-based nanodroplets and PLGA-based nanodroplets) were activated by different acoustic pressure levels. Ultrasound irradiation duration and power of LIFU were tested and selected to monitor and control the drug release from nanodroplets. Various ultrasound energies were introduced to induce the phase transition and microbubble collapse of nanodroplets in vitro (3 W/3 min for lipid nanodroplets; 8 W/3 min for PLGA nanodroplets). Results: We detected three steps in the drug-releasing profiles exhibiting the programmable patterns. Importantly, the intratumoral accumulation and distribution of the drug with LIFU exposure were significantly enhanced, and tumor proliferation was substantially inhibited. Co-delivery of two drug-loaded nanodroplets could overcome the physical barriers of tumor tissues during chemotherapy. Conclusion: Our study provides a new strategy for the efficient ultrasound-triggered chemotherapy by nanocarriers with programmable LIFU capable of achieving the on-demand drug release.

Circulating Magnetic Microbubbles for Localized Real-Time Control of Drug Delivery by Ultrasonography-Guided Magnetic Targeting and Ultrasound

Image-guided and target-selective modulation of drug delivery by external physical triggers at the site of pathology has the potential to enable tailored control of drug targeting. Magnetic microbubbles that are responsive to magnetic and acoustic modulation and visible to ultrasonography have been proposed as a means to realize this drug targeting strategy. To comply with this strategy in vivo, magnetic microbubbles must circulate systemically and evade deposition in pulmonary capillaries, while also preserving magnetic and acoustic activities in circulation over time. Unfortunately, challenges in fabricating magnetic microbubbles with such characteristics have limited progress in this field. In this report, we develop magnetic microbubbles (MagMB) that display strong magnetic and acoustic activities, while also preserving the ability to circulate systemically and evade pulmonary entrapment.

Methods: We systematically evaluated the characteristics of MagMB including their pharmacokinetics, biodistribution, visibility to ultrasonography and amenability to magneto-acoustic modulation in tumor-bearing mice. We further assessed the applicability of MagMB for ultrasonography-guided control of drug targeting.

Results: Following intravenous injection, MagMB exhibited a 17- to 90-fold lower pulmonary entrapment compared to previously reported magnetic microbubbles and mimicked circulation persistence of the clinically utilized Definity microbubbles (>10 min). In addition, MagMB could be accumulated in tumor vasculature by magnetic targeting, monitored by ultrasonography and collapsed by focused ultrasound on demand to activate drug deposition at the target. Furthermore, drug delivery to target tumors could be enhanced by adjusting the magneto-acoustic modulation based on ultrasonographic monitoring of MagMB in real-time.

Conclusions: Circulating MagMB in conjunction with ultrasonography-guided magneto-acoustic modulation may provide a strategy for tailored minimally-invasive control over drug delivery to target tissues.

Anionic Polymer and Quantum Dot Excipients to Facilitate siRNA Release and Self-Reporting of Disassembly in Stimuli-Responsive Nanocarrier Formulations

The incorporation of anionic excipients into polyplexes is a promising strategy for modulating siRNA binding versus release and integrating diagnostic capabilities; however, specific design criteria and structure-function relationships are needed to facilitate the development of nanocarrier-based theranostics. Herein, we incorporated poly(acrylic acid) (PAA) and quantum dot (QD) excipients into photolabile siRNA polyplexes to increase gene silencing efficiencies by up to 100% and enable self-reporting of nanocarrier disassembly. Our systematic approach identified the functional relationships between gene silencing and key parameters such as excipient loading fractions and molecular weights that facilitated the establishment of design rules for optimization of nanocarrier efficacy. For example, we found that PAA molecular weights ∼10-20× greater than that of the coencapsulated siRNA exhibited the most efficient release and silencing. Furthermore, siRNA release assays and RNAi modeling allowed us to generate a PAA "heat map" that predicted gene silencing a priori as a function of PAA molecular weight and loading fraction. QDs further promoted selective siRNA release and provided visual as well as Förster resonance energy transfer (FRET)-based monitoring of the dynamic changes in nanostructure in situ. Moreover, even with the addition of anionic components, our formulations exhibited substantially improved stability and shelf life relative to typical formulations, with complete stability after a week of storage and full activity in the presence of serum. Taken together, this study enabled synergistic improvements in siRNA release and diagnostic capabilities, along with the development of mechanistic insights that are critical for advancing the translation of nucleic acid theranostics into the clinic.

Magnetic Nanoliposomes as in Situ Microbubble Bombers for Multimodality Image-Guided Cancer Theranostics

Nanosized drug delivery systems have offered promising approaches for cancer theranostics. However, few are effective to simultaneously maximize tumor-specific uptake, imaging, and therapy in a single nanoplatform. Here, we report a simple yet stimuli-responsive anethole dithiolethione (ADT)-loaded magnetic nanoliposome (AML) delivery system, which consists of ADT, hydrogen sulfide (H₂S) pro-drug, doped in the lipid bilayer, and superparamagnetic nanoparticles encapsulated inside. HepG2 cells could be effectively bombed after 6 h co-incubation with AMLs. For in vivo applications, after preferentially targeting the tumor tissue when spatiotemporally navigated by an external magnetic field, the nanoscaled AMLs can intratumorally convert to microsized H₂S bubbles. This dynamic process can be monitored by magnetic resonance and ultrasound dual modal imaging. Importantly, the intratumoral generated H₂S bubbles imaged by real-time ultrasound imaging first can bomb to ablate the tumor tissue when exposed to higher acoustic intensity; then as gasotransmitters, intratumoral generated high-concentration H₂S molecules can diffuse into the inner tumor regions to further have a synergetic antitumor effect. After 7-day follow-up observation, AMLs with magnetic field treatments have indicated extremely significantly higher inhibitions of tumor growth. Therefore, such elaborately designed intratumoral conversion of nanostructures to microstructures has exhibited an improved anticancer efficacy, which may be promising for multimodal image-guided accurate cancer therapy.

Multifunctional hard-shelled microbubbles for differentiating imaging, cavitation and drug release by ultrasound

Polymeric microbubbles bearing a hard shell exhibit prominent stability and tunable acoustical properties that serve the purposes of biomedical imaging and ultrasound (US)-triggered cavitations.

Diamonds, Digital Health, and Drug Development: Optimizing Combinatorial Nanomedicine

The field of nanomedicine has already seen substantial progress in the clinic, with multiple formulations being evaluated through clinical studies. From poly(lactic-co-glycolic acid) and cyclodextrin-based drug-delivery platforms to metallic nanoparticles for photothermal treatment and imaging, nanotechnology has enabled versatile strategies to treat and to diagnose a wide range of disorders. However, as the field as a whole pushes forward, barriers that have always challenged conventional drug development have already started to impact nanomedicine translation. These include exorbitant costs, substantial time to development, and the uncertainty of achieving major improvements in efficacy or safety. Of note, there has been, until recent advances, a virtual inability to identify optimal drug doses either as monotherapies or components of combination therapy. In this Nano Focus, we assess how the impact of nanotechnology in the clinic can be optimized through systematically designed combinatorial nanotherapy. In addition, we provide a clinical perspective on how a recently unveiled technology platform can substantially alter the landscape of combinatorial nanomedicine, drug development, as well as conventional drug development.