Smart Microbubble Eluting Theranostic Stent for Noninvasive Ultrasound Imaging and Prevention of Restenosis

Phase-transition nanodroplets with immunomodulatory capabilities for potentiating mild magnetic hyperthermia to inhibit tumour proliferation and metastasis

BACKGROUND

Magnetic hyperthermia (MHT)-mediated thermal ablation therapy has promising clinical applications in destroying primary tumours. However, traditional MHT still presents the challenges of damage to normal tissues adjacent to the treatment site and the destruction of tumour-associated antigens due to its high onset temperature (> 50 °C). In addition, local thermal ablation of tumours often exhibits limited therapeutic inhibition of tumour metastasis.

RESULTS

To address the above defects, a hybrid nanosystem (SPIOs + RPPs) was constructed in which phase transition nanodroplets with immunomodulatory capabilities were used to potentiate supermagnetic iron oxide nanoparticle (SPIO)-mediated mild MHT (< 44 °C) and further inhibit tumour proliferation and metastasis. Magnetic-thermal sensitive phase-transition nanodroplets (RPPs) were fabricated from the immune adjuvant resiquimod (R848) and the phase transition agent perfluoropentane (PFP) encapsulated in a PLGA shell. Because of the cavitation effect of microbubbles produced by RPPs, the temperature threshold of MHT could be lowered from 50℃ to approximately 44℃ with a comparable effect, enhancing the release and exposure of damage-associated molecular patterns (DAMPs). The exposure of calreticulin (CRT) on the cell membrane increased by 72.39%, and the released high-mobility group B1 (HMGB1) increased by 45.84% in vivo. Moreover, the maturation rate of dendritic cells (DCs) increased from 4.17 to 61.33%, and the infiltration of cytotoxic T lymphocytes (CTLs) increased from 10.44 to 35.68%. Under the dual action of mild MHT and immune stimulation, contralateral and lung metastasis could be significantly inhibited after treatment with the hybrid nanosystem.

CONCLUSION

Our work provides a novel strategy for enhanced mild magnetic hyperthermia immunotherapy and ultrasound imaging with great clinical translation potential.

Bioactive inorganic nanomaterials for cancer theranostics

Bioactive materials are a special class of biomaterials that can react in vivo to induce a biological response or regulate biological functions, thus achieving a better curative effect than traditional inert biomaterials. For cancer theranostics, compared with organic or polymer nanomaterials, inorganic nanomaterials possess unique physical and chemical properties, have stronger mechanical stability on the basis of maintaining certain bioactivity, and are easy to be compounded with various carriers (polymer carriers, biological carriers, etc.), so as to achieve specific antitumor efficacy. After entering the nanoscale, due to the nano-size effect, high specific surface area and special nanostructures, inorganic nanomaterials exhibit unique biological effects, which significantly influence the interaction with biological organisms. Therefore, the research and applications of bioactive inorganic nanomaterials in cancer theranostics have attracted wide attention. In this review, we mainly summarize the recent progress of bioactive inorganic nanomaterials in cancer theranostics, and also introduce the definition, synthesis and modification strategies of bioactive inorganic nanomaterials. Thereafter, the applications of bioactive inorganic nanomaterials in tumor imaging and antitumor therapy, including tumor microenvironment (TME) regulation, catalytic therapy, gas therapy, regulatory cell death and immunotherapy, are discussed. Finally, the biosafety and challenges of bioactive inorganic nanomaterials are also mentioned, and their future development opportunities are prospected. This review highlights the bioapplication of bioactive inorganic nanomaterials.

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.

Triggered and monitored drug release from bifunctional hybrid nanocomposites

Polymer-coated carbon dot-containing calcium carbonate nanoparticles are reported as unique nanocomposites capable of encapsulating a chemotherapeutic drug and displaying afterglow behaviour.

Smart magnetic resonance imaging-based theranostics for cancer

Smart theranostics are dynamic platforms that integrate multiple functions, including at least imaging, therapy, and responsiveness, in a single agent. This review showcases a variety of responsive theranostic agents developed specifically for magnetic resonance imaging (MRI), due to the privileged position this non-invasive, non-ionising imaging modality continues to hold within the clinical imaging field. Different MRI smart theranostic designs have been devised in the search for more efficient cancer therapy, and improved diagnostic efficiency, through the increase of the local concentration of therapeutic effectors and MRI signal intensity in pathological tissues. This review explores novel small-molecule and nanosized MRI theranostic agents for cancer that exhibit responsiveness to endogenous (change in pH, redox environment, or enzymes) or exogenous (temperature, ultrasound, or light) stimuli. The challenges and obstacles in the design and in vivo application of responsive theranostics are also discussed to guide future research in this interdisciplinary field towards more controllable, efficient, and diagnostically relevant smart theranostics agents.

A non-invasive nanoparticles for multimodal imaging of ischemic myocardium in rats

BACKGROUND

Ischemic heart disease (IHD) is the leading cause of morbidity and mortality worldwide, and imposes a serious economic load. Thus, it is crucial to perform a timely and accurate diagnosis and monitoring in the early stage of myocardial ischemia. Currently, nanoparticles (NPs) have emerged as promising tools for multimodal imaging, because of their advantages of non-invasion, high-safety, and real-time dynamic imaging, providing valuable information for the diagnosis of heart diseases.

RESULTS

In this study, we prepared a targeted nanoprobe (termed IMTP-Fe3O4-PFH NPs) with enhanced ultrasound (US), photoacoustic (PA), and magnetic resonance (MR) performance for direct and non-invasive visual imaging of ischemic myocardium in a rat model. This successfully designed nanoprobe had excellent properties such as nanoscale size, good stability, phase transformation by acoustic droplet vaporization (ADV), and favorable safety profile. Besides, it realized obvious targeting performance toward hypoxia-injured cells as well as model rat hearts. After injection of NPs through the tail vein of model rats, in vivo imaging results showed a significantly enhanced US/PA/MR signal, well indicating the remarkable feasibility of nanoprobe to distinguish the ischemic myocardium.

CONCLUSIONS

IMTP-Fe3O4-PFH NPs may be a promising nanoplatform for early detection of ischemic myocardium and targeted treatment under visualization for the future.

Synergistic agents for tumor-specific therapy mediated by focused ultrasound treatment

This minireview highlights the recent advances in the therapeutic agents that aim to provide synergistic enhancements of focused ultrasound treatment of tumors. Even though focused ultrasound therapy itself can bring therapeutic effects in cancers, many biochemical agents have been reported in the literature to enhance the treatment efficacy significantly. Until now, many mechanisms have been researched to advance the therapy, such as sonodynamic-plus-chemo-therapy, microbubble-aided therapy, localized release or delivery of nanomaterials, and multimodal image-guided therapy. Here, the novel materials adopted in each mechanism are briefly reviewed to provide a trend in the field and encourage future research towards the successful deployment of focused ultrasound therapy in real clinical environments.

Interface Engineering of Fully Metallic Stents Enabling Controllable H2O2 Generation for Antirestenosis

Despite significant advances in the design of metallic materials for bare metal stents (BMSs), restenosis induced by the accumulation of smooth muscle cells (SMCs) has been a major constraint on improving the clinical efficacy of stent implantation. Here, a new strategy for avoiding this issue by utilizing hydrogen peroxide (H₂O₂) generated by the galvanic coupling of nitinol (NiTi) stents and biodegradable magnesium-zinc (Mg-Zn) alloys is reported. The amount of H₂O₂ released is carefully optimized via the biodegradability engineering of the alloys and by controlling the immersion time to selectively inhibit the proliferation and function of SMCs without harming vascular endothelial cells. Based on demonstrations of its unique capabilities, a fully metallic stent with antirestenotic functionality was successfully fabricated by depositing Mg layers onto commercialized NiTi stents. The introduction of surface engineering to yield a patterned Mg coating ensured the maintenance of a stable interface between Mg and NiTi during the process of NiTi stent expansion, showing high feasibility for clinical application. This new concept of an inert metal/degradable metal hybrid system based on galvanic metal coupling, biodegradability engineering, and surface patterning can serve as a novel way to construct functional and stable BMSs for preventing restenosis.

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.

Calcium-based biomaterials for diagnosis, treatment, and theranostics

Calcium-based biomaterials with good biosafety and bio-absorbability are promising for biomedical applications such as diagnosis, treatment, and theranostics.

PEGylated stereocomplex polylactide coating of stent for upregulated biocompatibility and drug storage

Treatment of coronary heart disease by percutaneous coronary intervention (PCT) is usually limited to the high restenosis rate after implantation of bare-metal stent. To solve the problem, the coating of PEGylated stereocomplex poly(l-lactide) (PEG-cPLA) was utilized on the surface modification of stainless steel (SS) sheet. Specifically, the 3-aminopropyltriethoxysilane (APTES)-modified methoxy-poly(ethylene glycol)-poly(d-lactide) (mPEG-PDLA) was grafted onto the surface of hydroxylated SS sheet through coupling reaction, and poly(l-lactide)-poly(ethylene glycol)-poly(l-lactide) (PLLA-PEG-PLLA) was coated onto the surface through stereocomplex interaction between DLA and LLA units. The increase of contact angle firstly confirmed the changes of surface composition and hydrophilicity for the PEG-scPLA-modified SS sheet. The decreased fibrinogen adsorption, down-regulated platelet activation, and improved adhesion of human umbilical vein endothelial cells (HUVECs) indicated the excellent biocompatibility of PEG-scPLA-modified SS sheet. In addition, the drug loading capability of SS sheet was greatly upregulated through the formation of scPLA coating on the surface, where fluorescein (FLU) was chosen as a model molecule. Overall, the surface modification of SS sheet with PEG-scPLA could enhance the comprehensive performances, such as biocompatibility and drug loading capability, demonstrating that PEG-scPLA is a promising coating of coronary stent for PCT.