In vivo quantification of SPIO nanoparticles for cell labeling based on MR phase gradient images

Homogenous multifunctional microspheres induce ferroptosis to promote the anti-hepatocarcinoma effect of chemoembolization

Transcatheter arterial chemoembolization (TACE) is one of the main palliative therapies for advanced hepatocellular carcinoma (HCC), which is also regarded as a promising therapeutic strategy for cancer treatment. However, drug-loaded microspheres (DLMs), as commonly used clinical chemoembolization drugs, still have the problems of uneven particle size and unstable therapeutic efficacy. Herein, gelatin was used as the wall material of the microspheres, and homogenous gelatin microspheres co-loaded with adriamycin and Fe₃O₄ nanoparticles (ADM/Fe₃O₄-MS) were further prepared by a high-voltage electrospray technology. The introduction of Fe₃O₄ nanoparticles into DLMs not only provided excellent T2-weighted magnetic resonance imaging (MRI) properties, but also improved the anti-tumor effectiveness under microwave-induced hyperthermia. The results showed that ADM/Fe₃O₄-MS plus microwave irradiation had significantly better antitumor efficacy than the other types of microspheres at both cell and animal levels. Our study further confirmed that ferroptosis was involved in the anti-tumor process of ADM/Fe₃O₄-MS plus microwave irradiation, and ferroptosis marker GPX4 was significantly decreased and ACSL4 was significantly increased, and ferroptosis inhibitors could reverse the tumor cell killing effect caused by ADM/Fe₃O₄-MS to a certain extent. Our results confirmed that microwave mediated hyperthermia could amplify the antitumor efficacy of ADM/Fe₃O₄-MS by activating ferroptosis and the introduction of Fe₃O₄ nanoparticles can significantly improve TACE for HCC. This study confirmed that it was feasible to use uniform-sized gelatin microspheres co-loaded with Fe₃O₄ nanoparticles and adriamycin to enhance the efficacy of TACE for HCC.

Engineered glycomaterial implants orchestrate large-scale functional repair of brain tissue chronically after severe traumatic brain injury

Severe traumatic brain injury (sTBI) survivors experience permanent functional disabilities due to significant volume loss and the brain's poor capacity to regenerate. Chondroitin sulfate glycosaminoglycans (CS-GAGs) are key regulators of growth factor signaling and neural stem cell homeostasis in the brain. However, the efficacy of engineered CS (eCS) matrices in mediating structural and functional recovery chronically after sTBI has not been investigated. We report that neurotrophic factor functionalized acellular eCS matrices implanted into the rat M1 region acutely after sTBI significantly enhanced cellular repair and gross motor function recovery when compared to controls 20 weeks after sTBI. Animals subjected to M2 region injuries followed by eCS matrix implantations demonstrated the significant recovery of "reach-to-grasp" function. This was attributed to enhanced volumetric vascularization, activity-regulated cytoskeleton (Arc) protein expression, and perilesional sensorimotor connectivity. These findings indicate that eCS matrices implanted acutely after sTBI can support complex cellular, vascular, and neuronal circuit repair chronically after sTBI.

Optimal scanning concentration of MR imaging for tumor-bearing nude mice with SPIO-shRNA molecular probe

The objective of this study is to investigate the signal changes and optimal scanning concentration of MRI in tumor tissues of tumor-bearing nude mice by SPIO-shRNA molecular probes. 30 BALB/c tumor-bearing nude mice were randomly divided into 5 groups with 6 mice in each group. At the given scanning time (before and 27 h after injection), the caudal vein was respectively injected with iron content of 6 mg·kg-1, 12 mg·kg-1, 18 mg·kg-1, 24 mg·kg-1, and 30 mg·kg-1, and MR examination was simultaneously performed to measure signal intensity changes of tumor tissue and contralateral muscle tissue in each concentration group. After each examination above, the nude mice were sacrificed immediately, and the tumor and muscle tissues were removed for HE and Prussian blue staining,and observed under light microscope. Nude mice in 6 mg, 12 mg and 18 mg groups all survived after probe injection, but some nude mice died in 24 mg and 30 mg groups after probe injection or during scanning. The signal changes of T2WI and T2*WI sequences were the most obvious in MR scanning sequences. Compared with other groups, the signal intensity of the tumor tissue in 18 mg, 24 mg and 30 mg groups were most obvious (P < 0.05), while the 18 mg, 24 mg and 30 mg groups reached no statistical difference (P > 0.05 ); HE staining indicated that structural disorder of tumor tissue as well as increase of nuclear atypia. Prussian Blue staining showed that blue-stained iron particles were present in each experimental group,and the most densely distributed were in 18 mg,24 mg and 30 mg groups. Tumor tissue could be well labeled with SPIO-shRNA molecular probes, and the optimal MR scanning concentration (iron content) is 18 mg·kg-1.

A new molecular probe: An NRP-1 targeting probe for the grading diagnosis of glioma in nude mice

Magnetic resonance molecular imaging, as a safe imaging technology, provides a new idea for the early qualitative and hierarchical diagnosis of gliomas. The purpose of this study was to design and evaluate the value of neuropilin-1 (NRP-1) targeting molecular probes in the hierarchical diagnosis of gliomas. First, we created an NRP-1 targeted magnetic resonance molecular probe (USPIO-PEG-tLyP-1) by combining the polypeptide tLyP-1 with ultra-small superparamagnetic iron oxide nanoparticles (USPIONs), detecting the physical properties by transmission electron microscopy (TEM) and dynamic light scattering (DLS). Second, in vivo experiments, we established two different degrees of malignant gliomas in-situ in nude mice by injecting U87 and CHG-5 cells. Then, to detect the binding ability of the probe with different grades of tumour tissues, we injected the probe into the tumour-bearing mice through the tail vein. Next, MRI was performed before injection, and 6 h, 12 h, 24 h after injection, and we found significantly more iron particles in the tumour tissues of U87 tumour-bearing mice than in tumour tissues of CHG-5 tumour-bearing mice. The signal intensities of the T2-weighted images of the tumour tissues of each group as well as microscopic observations by Prussian blue staining indicated that the binding ability of this molecular probe to U87 glioma (HGG) with high NRP-1 expression was significantly greater than that of CHG-5 glioma (LGG) with low NRP-1 expression (P < 0.01). Therefore, this study confirms that the novel molecular probe USPIO-PEG-tLyP-1 can be used for the grading diagnosis by MRI for gliomas of high and low grade with different NRP-1 expression levels.

Efficacy Evaluation and Tracking of Bone Marrow Stromal Stem Cells in a Rat Model of Renal Ischemia-Reperfusion Injury

Objectives

The aim of this study was to evaluate the effects of bone marrow stromal stem cells (BMSCs) on renal ischemia-reperfusion injury (RIRI) and dynamically monitor engrafted BMSCs in vivo for the early prediction of their therapeutic effects in a rat model.

Methods

A rat model of RIRI was prepared by clamping the left renal artery for 45 min. One week after renal artery clamping, 2 × 10⁶ superparamagnetic iron oxide- (SPIO-) labeled BMSCs were injected into the renal artery. Next, MR imaging of the kidneys was performed on days 1, 7, 14, and 21 after cell transplantation. On day 21, after transplantation, serum creatinine (Scr) and urea nitrogen (BUN) levels were assessed, and HE staining and TUNEL assay were also performed.

Results

The body weight growth rates in the SPIO-BMSC group were significantly higher than those in the PBS group (P < 0.05), and the Scr and BUN levels were also significantly lower than those in the PBS group (P < 0.05). HE staining showed that the degree of degeneration and vacuole-like changes in the renal tubular epithelial cells in the SPIO-BMSC group was significantly better than that observed in the PBS group. The TUNEL assay showed that the number of apoptotic renal tubular epithelial cells in the SPIO-BMSC group was significantly lower than that in the PBS group. The T2 value of the renal lesion was the highest on day 1 after cell transplantation, and it gradually decreased with time in both the PBS and SPIO-BMSC groups but was always the lowest in the SPIO-BMSC group.

Conclusion

SPIO-labeled BMSC transplantation can significantly promote the recovery of RIRI and noninvasive dynamic monitoring of engrafted cells and can also be performed simultaneously with MRI in vivo for the early prediction of therapeutic effects.

The application value of ultra-short echo time MRI in the quantification of liver iron overload in a rat model

Background

The quantitative evaluation of liver iron concentration (LIC) is important in guiding the treatment of blood transfusion-dependent patients. Conventionally, LIC is assessed through R2*or R2 values using magnetic resonance imaging (MRI). However, most of the studies using MRI to determine iron overload were restricted by the minimum echo time, so that severe iron overload could hardly be quantified. In our study, we demonstrate a new approach to overcome the limitation of the shortest echo time using ultra-short echo time (UTE) MRI to quantify liver iron overload of varying degrees in a rat model.

Methods

Sixty female Sprague-Dawley rats were included and randomly assigned into 10 equal groups. Group 1 was not injected with iron dextran. Groups 2 to 10 were intraperitoneally injected with iron dextran at a dose of 15 mg/kg every 3 days. On every 6th day, one group was randomly selected from groups 2 to 10 for MRI scanning and liver iron concentration (LIC) detection. For groups 1 to 10, images were acquired by UTE sequence using a 3.0T MR scanner, and the T2* value and R2* value were obtained (R2* =1/T2*). In addition, LIC was measured using an atomic absorption photometer. The correlation analysis between R2* value and LIC was performed and the regression equation of R2* and LIC was established and its reliability verified.

Results

For groups 1 to 10, R2* values and LIC ranged from 60.16±4.76 to 1,306.90±42.26 Hz and from 0.84±0.11 to 5.89±2.64 mg/g dry, respectively. The R2* value was linearly correlated to the LIC (r=0.897, P<0.001), and the linear regression equation was LIC = 0.005 × R2* + 1.783. The validation analysis results showed that the intragroup correlation coefficient (ICC) between the predicted and measured LIC was 89.5%.

Conclusions

The UTE sequence could be used for quantification of varying degrees of hepatic iron overload in the rat model, and the LIC could be predicted by using the R2* value on an MR 3.0T scanner.

USPIO enhanced lymph node MRI using 3D multi-echo GRE in a rabbit model

Ultrasmallsuperparamagnetic iron oxide (USPIO) has been suggested to be a negative MR contrast agent to detect metastatic lymph nodes. Previously reported studies have evaluated the diagnostic performance of USPIO-enhanced MR lymph node imaging based on signal intensity. In this study, we investigate the specific performance of three different parametric approaches (normalized signal intensity, R₂ * and susceptibility) using 3D multi-echo gradient echo to quantify the USPIO particles in lymph nodes. Nine rabbits with VX2 tumor implants were scanned before and after USPIO injection. From 3D multi-echo GRE magnitude and phase data, we generated multi-echo combined T₂ *-weighted images, an R₂ * map, and a quantitative susceptibility map. Eighteen lymph nodes (nine reactive and nine metastatic) were evaluated and showed remarkable signal drops in the area of USPIO accumulation. On parametric analysis, the R₂ * difference before and after USPIO injection was significantly different (p < 0.05) between reactive and metastatic lymph nodes; in contrast, the normalized signal intensity and susceptibility were not significantly different between the nodes. Our study showed the potential utility of USPIO-enhanced MRI using R2* mapping from 3D multi-echo GRE for the detection of lymph node metastasis and parametric analysis of lymph node status in a rabbit model. Copyright © 2016 John Wiley & Sons, Ltd.

Tracking and Quantification of Magnetically Labeled Stem Cells using Magnetic Resonance Imaging

Stem cell based therapies have critical impacts on treatments and cures of diseases such as neurodegenerative or cardiovascular disease. In vivo tracking of stem cells labeled with magnetic contrast agents is of particular interest and importance as it allows for monitoring of the cells' bio-distribution, viability, and physiological responses. Herein, recent advances are introduced in tracking and quantification of super-paramagnetic iron oxide (SPIO) nanoparticles-labeled cells with magnetic resonance imaging, a noninvasive approach that can longitudinally monitor transplanted cells. This is followed by recent translational research on human stem cells that are dual-labeled with green fluorescence protein (GFP) and SPIO nanoparticles, then transplanted and tracked in a chicken embryo model. Cell labeling efficiency, viability, and cell differentiation are also presented.

Cell-Based Therapy in TBI: Magnetic Retention of Neural Stem Cells In Vivo

Stem cell therapy is under active investigation for traumatic brain injury (TBI). Noninvasive stem cell delivery is the preferred method, but retention of stem cells at the site of injury in TBI has proven challenging and impacts effectiveness. To investigate the effects of applying a magnetic field on cell homing and retention, we delivered human neuroprogenitor cells (hNPCs) labeled with a superparamagnetic nanoparticle into post-TBI animals in the presence of a static magnetic field. We have previously devised a method of loading hNPCs with ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles Molday ION Rhodamine B (MIRB™). Labeling of hNPCs (MIRB-hNPCs) does not affect hNPC viability, proliferation, or differentiation. The 0.6 tesla (T) permanent magnet was placed ∼4 mm above the injured parietal cortex prior to intracarotid injection of 4 × 10(4) MIRB-hNPCs. Fluorescence imaging, Perls' Prussian blue histochemistry, immunocytochemistry with SC121, a human-specific antibody, and T2-weighted magnetic resonance imaging ex vivo revealed there was increased homing and retention of MIRB-hNPCs in the injured cortex as compared to the control group in which MIRB-hNPCs were injected in the absence of a static magnetic field. Fluoro-Jade C staining and immunolabeling with specific markers confirmed the viability status of MIRB-hNPCs posttransplantation. These results show that increased homing and retention of MIRB-hNPCs post-TBI by applying a static magnetic field is a promising technique to deliver cells into the CNS for treatment of neurological injuries and neurodegenerative diseases.