Nanobubbles for enhanced ultrasound imaging of tumors

The fabrication and initial applications of nanobubbles (NBs) have shown promising results in recent years. A small particle size is a basic requirement for ultrasound contrast-enhanced agents that penetrate tumor blood vessel pores to allow for targeted imaging and therapy. However, the nanoscale size of the particles used has the disadvantage of weakening the imaging ability of clinical diagnostic ultrasound. In this work, we fabricated a lipid NBs contrast-enhanced ultrasound agent and evaluated its passive targeting ability in vivo. The results showed that the NBs were small (436.8 ± 5.7 nm), and in vitro ultrasound imaging suggested that the ultrasonic imaging ability is comparable to that of microbubbles (MBs). In vivo experiments confirmed the ability of NBs to passively target tumor tissues. The NBs remained in the tumor area for a longer period because they exhibited enhanced permeability and retention. Direct evidence was obtained by direct observation of red fluorescence-dyed NBs in tumor tissue using confocal laser scanning microscopy. We have demonstrated the ability to fabricate NBs that can be used for the in vivo contrast-enhanced imaging of tumor tissue and that have potential for drug/gene delivery

Noninvasive and quantitative measurement of C4d deposition for the diagnosis of antibody-mediated cardiac allograft rejectionResearch in context

Background: C4d is a specific biomarker for the diagnosis of antibody-mediated rejection (AMR) after cardiac transplantation. Although strongly recommended, routine C4d surveillance is hindered by the invasive nature of endomyocardial biopsy. Targeted ultrasound (US) has high sensitivity, and C4d is abundantly expressed within the graft of patients experiencing AMR, which makes it possible to visualize C4d deposition in vivo using targeted US. Methods: We designed a serial dilution of C4d-targeted microbubbles (MBC4d) using a streptavidin-biotin conjugation system. A rat model of AMR with C4d deposition was established by pre-sensitization with skin transplantation before cardiac transplantation. MBC4d were injected into recipients and then qualitatively and quantitatively analyzed using the destruction-replenishment method with a clinical US imaging system and analyzed by software. Findings: We successfully obtained qualitative images of C4d deposition in a wide cardiac allograft section, which, for the first time, reflected real-time C4d distribution. Moreover, normal intensity difference was used for quantitative analysis and exhibited an almost nearly linear correlation with the grade of C4d deposition according to the pathologic evidence. In addition, MBC4d injection did not affect the survival and aggravate injury, which demonstrates its safety. Interpretation: This study demonstrates a noninvasive, quantitative and safe evaluation method for C4d. As contrast-enhanced US has been widely used in clinical settings, this technology is expected to be applied quickly to clinical practice. Fund: National Natural Science Foundation of China and Guangdong Province, Leading Scientific Talents of Guangdong special support program, the Science and Technology Project of Guangdong Province and Guangzhou City. Keywords: Noninvasive, Antibody-mediated rejection, C4d, Cardiac transplantation, Targeted microbubble

MicroRNA-340 Inhibits Esophageal Cancer Cell Growth and Invasion by Targeting Phosphoserine Aminotransferase 1

Background/Aims: Emerging evidence indicates that microRNA (miR)-340 is downregulated in various human cancers, suggesting that it acts as a tumor suppressor. The aim of the present study was to evaluate the expression and role of miR-340 in human esophageal squamous cell carcinoma (ESCC). Methods: The expression of miR-340 was examined in 64 paired ESCC and adjacent non-tumor tissues by quantitative real time PCR. The effects of miR-340 on ESCC cell proliferation and metastasis were examined by MTT and Matrigel invasion assays. Tumor growth was assessed by subcutaneous inoculation of cells into BALB/c nude mice. Targets of miR-340 were identified by bioinformatics and verified by luciferase reporter assays, quantitative real-time PCR, and western blotting. Results: MiR-340 was significantly downregulated in ESCC tumor tissues compared to adjacent non-tumor tissues and in ESCC cell lines compared to esophageal endothelial cells. Overexpression of miR-340 inhibited ESCC cell growth, colony formation, and invasion, and tumor growth in a xenograft mouse model. PSAT1 was identified as a direct target of miR-340 and its ectopic expression partially reversed the miR-340 mediated inhibition of viability, invasion and EMT in ESCC cells. The expression of miR-340 was negatively correlated with that of PSAT1 in human ESCC samples. Conclusion: MiR-340 functions as a tumor suppressor by modulating the expression of PSAT1 and may contribute to the progression and invasiveness of ESCC

pH-sensitive nanomicelles for controlled and efficient drug delivery to human colorectal carcinoma LoVo cells.

BackgroundThe triblock copolymers PEG-P(Asp-DIP)-P(Lys-Ca) (PEALCa) of polyethylene glycol (PEG), poly(N-(N',N'-diisopropylaminoethyl) aspartamide) (P(Asp-DIP)), and poly (lysine-cholic acid) (P(Lys-Ca)) were synthesized as a pH-sensitive drug delivery system. In neutral aqueous environment such as physiological environment, PEALCa can self-assemble into stable vesicles with a size around 50-60 nm, avoid uptake by the reticuloendothelial system (RES), and encase the drug in the core. However, the PEALCa micelles disassemble and release drug rapidly in acidic environment that resembles lysosomal compartments.Methodology/principal findingsThe anticancer drug Paclitaxel (PTX) and hydrophilic superparamagnetic iron oxide (SPIO) were encapsulated inside the core of the PEALCa micelles and used for potential cancer therapy. Drug release study revealed that PTX in the micelles was released faster at pH 5.0 than at pH 7.4. Cell culture studies showed that the PTX-SPIO-PEALCa micelle was effectively internalized by human colon carcinoma cell line (LoVo cells), and PTX could be embedded inside lysosomal compartments. Moreover, the human colorectal carcinoma (CRC) LoVo cells delivery effect was verified in vivo by magnetic resonance imaging (MRI) and histology analysis. Consequently effective suppression of CRC LoVo cell growth was evaluated.Conclusions/significanceThese results indicated that the PTX-SPION-loaded pH-sensitive micelles were a promising MRI-visible drug release system for colorectal cancer therapy

Sequential ultrasound molecular imaging for noninvasive identification and assessment of non-alcoholic steatohepatitis in mouse models

Background and objective: Noninvasive non-alcoholic steatohepatitis (NASH) assessment is a clinical challenge to the management of non-alcoholic fatty liver disease. We aim to develop diagnostic models based on sequential ultrasound molecular imaging (USMI) for the noninvasive identification of NASH in mouse models. Methods: Animal experiments were approved by the Animal Ethics Committee of South China Agricultural University. Forty-nine C57BL/6 mice were divided into normal control, non-alcoholic fatty liver, NASH, and hepatitis groups. Sequential USMI was implemented using CD36-targeted microbubbles (MBs-CD36) and intercellular adhesion molecule-1 (ICAM-1)-targeted microbubbles (MBs-ICAM-1) to visualize hepatic steatosis and inflammation. The targeting signal of USMI was quantified as the normalized intensity difference (NID) with the destruction-replenishment method. Correlation analysis was conducted between the NID-MBs-CD36 and pathological steatosis score and between the NID-MBs-ICAM-1 and pathological inflammation score. Finally, diagnostic models combining NID-MBs-CD36 with NID-MBs-ICAM-1 were established for NASH diagnosis. Results: MBs-CD36 and MBs-ICAM-1 were successfully prepared and used for sequential USMI in all mice. NID-MBs-CD36 values increased with the progression of steatosis, while NID-MBs-ICAM-1 values increased in parallel with the progression of inflammation. A strong positive correlation was identified between NID-MBs-CD36 and pathological steatosis grade (rs = 0.9078, P < 0.0001) and between NID-MBs-ICAM-1 and pathological inflammation grade (rs = 0.9071, P < 0.0001). Among various sequential USMI-based diagnostic models, the serial testing model showed high diagnostic performance in detecting NASH, with 95% sensitivity, 97% specificity, 95% positive predictive values, 97% negative predictive values, and 96% accuracy. Conclusions: Sequential USMI using MBs-CD36 and MBs-ICAM-1 allows noninvasive grading of hepatic steatosis and inflammation. Sequential USMI-based diagnostic models hold great potential in the noninvasive identification of NASH