Biomechanical Response of Cancer Stem Cells to Low-Intensity Ultrasound.

The presence of stem cells in cancer may increase the chances of drug resistance and invasiveness. Low-intensity ultrasound (LIUS) can regulate the biological and mechanical properties of cells and participate in cellular migration and differentiation. Although LIUS has shown significant potential in cancer treatment, the effects of LIUS on migration and drug resistance of cancer stem cells (CSCs) are unclear from a biomechanical perspective. Hence, the objective of this work is to analyze the biomechanical response of LIUS to CSCs. In this study, we selected human ovarian cancer cell line A2780 and ovarian cancer stem cells (OCSCs) were enriched from A2780 cells and observed that OCSCs had higher drug sensitivity and lower invasiveness than A2780 cells after LIUS exposure. Furthermore, we further analyzed the changes in cell morphology, cytoskeleton, and membrane stiffness of A2780 cells and OCSCs at various intensities of LIUS, these results showed that LIUS could induce morphological changes, F-actin formation and increase membrane stiffness, which could help to suppress migration and reduce the drug resistance of OCSCs. Our findings will help establish a better understanding of the biomechanical response to LIUS in CSCs, and future studies on cancer will benefit from the careful consideration of the cellular response of CSCs to LIUS stimulation, ultimately allowing for the development of more effective therapies.

Ultrasound-visible engineered bacteria for tumor chemo-immunotherapy.

Our previous work developed acoustic response bacteria, which enable the precise tuning of transgene expression through ultrasound. However, it is still difficult to visualize these bacteria in order to guide the sound wave to precisely irradiate them. Here, we develop ultrasound-visible engineered bacteria and chemically modify them with doxorubicin (DOX) on their surfaces. These engineered bacteria (Ec@DIG-GVs) can produce gas vesicles (GVs), providing a real-time imaging guide for remote hyperthermia high-intensity focused ultrasound (hHIFU) to induce the expression of the interferon (IFN)-γ gene. The production of IFN-γ can kill tumor cells, induce macrophage polarization from the M2 to the M1 phenotype, and promote the maturation of dendritic cells. DOX can be released in the acidic tumor microenvironment, resulting in immunogenic cell death of tumor cells. The concurrent effects of IFN-γ and DOX activate a tumor-specific T cell response, producing the synergistic anti-tumor efficacy. Our study provides a promising strategy for bacteria-mediated tumor chemo-immunotherapy.

Modification of PEG reduces the immunogenicity of biosynthetic gas vesicles.

Nanobubbles have received great attention in ultrasound molecular imaging due to their capability to pass through the vasculature and reach extravascular tissues. Recently, gas vesicles (GVs) from archaea have been reported as acoustic contrast agents, showing great potential for ultrasound molecular imaging. However, the immunogenicity and biosafety of GVs has not yet been investigated. In this study, we examined the immune responses and biosafety of biosynthetic GVs and polyethylene glycol (PEG)-modified GVs (PEG-GVs) in vivo and in vitro. Our findings suggest that the plain GVs showed significantly stronger immunogenic response than PEG-GVs. Less macrophage clearance rate of the RES and longer circulation time were also found for PEG-GVs, thereby producing the better contrast imaging effect in vivo. Thus, our study demonstrated the PEG modification of biosynthetic GVs from Halobacterium NRC-1 is helpful for the future application of GVs in molecular imaging and treatment.

In-vivo programmable acoustic manipulation of genetically engineered bacteria.

Acoustic tweezers can control target movement through the momentum interaction between an acoustic wave and an object. This technology has advantages over optical tweezers for in-vivo cell manipulation due to its high tissue penetrability and strong acoustic radiation force. However, normal cells are difficult to acoustically manipulate because of their small size and the similarity between their acoustic impedance and that of the medium. In this study, we use the heterologous expression of gene clusters to generate genetically engineered bacteria that can produce numerous sub-micron gas vesicles in the bacterial cytoplasm. We show that the presence of the gas vesicles significantly enhances the acoustic sensitivity of the engineering bacteria, which can be manipulated by ultrasound. We find that by employing phased-array-based acoustic tweezers, the engineering bacteria can be trapped into clusters and manipulated in vitro and in vivo via electronically steered acoustic beams, enabling the counter flow or on-demand flow of these bacteria in the vasculature of live mice. Furthermore, we demonstrate that the aggregation efficiency of engineering bacteria in a tumour is improved by utilizing this technology. This study provides a platform for the in-vivo manipulation of live cells, which will promote the progress of cell-based biomedical applications.

Application of Genetically Encoded Molecular Imaging Probes in Tumor Imaging.

In recent years, imaging technology has made rapid progress to improve the sensitivity of tumor diagnostic. With the development of genetic engineering and synthetic biology, various genetically encoded molecular imaging probes have also been extensively developed. As a biomedical imaging method with excellent detectable sensitivity and spatial resolution, genetically encoded molecular imaging has great application potential in the visualization of cellular and molecular functions during tumor development. Compared to chemosynthetic dyes and nanoparticles with an imaging function, genetically encoded molecular imaging probes can more easily label specific cells or proteins of interest in tumor tissues and have higher stability and tissue contrast in vivo. Therefore, genetically encoded molecular imaging probes have attracted increasing attention from researchers in engineering and biomedicine. In this review, we aimed to introduce the genetically encoded molecular imaging probes and further explained their applications in tumor imaging.

Overview of Strategies to Improve Therapy against Tumors Using Natural Killer Cell.

NK cells are lymphocytes with antitumor properties and can directly lyse tumor cells in a non-MHC-restricted manner. However, the tumor microenvironment affects the immune function of NK cells, which leads to immune evasion. This may be related to the pathogenesis of some diseases. Therefore, great efforts have been made to improve the immunotherapy effect of natural killer cells. NK cells from different sources can meet different clinical needs, in order to minimize the inhibition of NK cells and maximize the response potential of NK cells, for example, modification of NK cells can increase the number of NK cells in tumor target area, change the direction of NK cells, and improve their targeting ability to malignant cells. Checkpoint blocking is also a promising strategy for NK cells to kill tumor cells. Combination therapy is another strategy for improving antitumor ability, especially in combination with oncolytic viruses and nanomaterials. In this paper, the mechanisms affecting the activity of NK cells were reviewed, and the therapeutic potential of different basic NK cell strategies in tumor therapy was focused on. The main strategies for improving the immune function of NK cells were described, and some new strategies were proposed.

Early ultrasound diagnosis of conjoined twins at eight weeks of pregnancy: A case report.

BACKGROUND: Conjoined twins are a rare occurrence, and the majority of these malformations are detected during second trimester screening. CASE SUMMARY: Herein we report a case of conjoined twins, which was diagnosed by ultrasound at 8 wk gestation and was normal at 7 wk gestation. The two fetuses shared one heart and were diagnosed as thoracopagus twins. This is the first report of conjoined twins diagnosed at 8 wk gestation. The pregnancy was terminated electively at 9 wk gestation. Because some congenital malformations can be diagnosed earlier, a prenatal ultrasound examination at an early gestational stage cannot be dismissed. CONCLUSION: This case demonstrates that a 7-8 wk gestation might be the earliest period when conjoined twins can be diagnosed by ultrasound.

Synergistic ultrasonic biophysical effect-responsive nanoparticles for enhanced gene delivery to ovarian cancer stem cells.

Ovarian cancer stem cells (OCSCs) that are a subpopulation within bulk tumor survive chemotherapy and conduce to chemo-resistance and tumor relapse. However, conventional gene delivery is unsuitable for the on-demand content release, which limits OCSCs therapeutic utility. Here, we reported ultrasound-targeted microbubble destruction (UTMD)-triggerable poly(ethylene glycol)-disulfide bond-polyethylenimine loaded microbubble (PSP@MB). Taking advantage of glutathione (GSH) responsiveness, ultrasound triggering and spatiotemporally controlled release manner, PSP@MB is expected to realize local gene delivery for OCSCs treatment. But the biophysical mechanisms of gene delivery via PSP@MB and ultrasound remain unknown. The aim of this study is to determine the potential of gene delivery to OCSCs via ultrasonic synergistic biophysical effects and GSH-sensitive PSP@MB. The GSH-sensitive disulfide bond cleavable properties of PSP@MB were confirmed by 1H NMR spectra and infrared spectroscopy. The biophysical mechanisms between PSP@MB and cells were confirmed by scanning electron microscopy (SEM) and confocal laser scanning microscope (CLSM) to optimize the ultrasonic gene delivery system. The gene transfection via ultrasound and PSP@MB was closely related to the biophysical mechanisms (sonoporation, enhanced-endocytosis, sonoprinting, and endosomal escape). Ultrasound combined with PSP@MB successfully delivered aldehyde dehydrogenase 1 (ALDH1) short hairpin RNA (shRNA) plasmid to OCSCs and promoted apoptosis of OCSCs. The gene transfection rate and apoptosis rate were (18.41 ± 2.41)% and (32.62 ± 2.36)% analyzed by flow cytometry separately. This study showed that ultrasound triggering and GSH responsive PSP@MB might provide a novel strategy for OCSCs treatment via sonoporation and enhanced-endocytosis.