Preparation and Characterization of PLGA-based Magnetic Polymer Nanoparticles for Targeting Pancreatic Adenocarcinoma.

AIMS: This study aims to develop a novel tumor-targeted molecular probe for pancreatic cancer imaging. The objective of this is to prepare a CKAAKN peptide-conjugated poly (lactic-co-glycolic acid)-poly (ethylene glycol) amphiphilic polymer (CKAAKN-PEG-PLGA) for the tumor-targeted delivery of magnetic resonance imaging (MRI) contrast agent ultrasmall superparamagnetic iron oxide (USPIO). BACKGROUND: The early diagnosis of pancreatic cancer is crucial for improving its prognosis, but the clinical application of many diagnostic methods is limited owing to a lack of specificity and sensitivity. METHODS: CKAAKN-PEG-PLGA was synthesized by the amidation reaction. USPIO-loaded polymeric magnetic nanoparticles (USPIO@CKAAKN-PEG-PLGA) were prepared by the emulsion solvent evaporation method. The in vitro tumor targeting and bio-safety of nanoparticles were evaluated by targeted cellular uptake, MR imaging and MTT assay. RESULTS: USPIO@CKAAKN-PEG-PLGA nanoparticles showed excellent biosafety with an average diameter of 104.5 ± 4.1 nm. Modification of CKAAKN peptide could improve USPIO binding ability to internalize into CKAAKN-positive BxPC-3 cells compared with non-targeting nanoparticles and the control group. The relative fluorescence intensity in BxPC-3 and HPDE6-C7 cells was 23.77 ± 4.18 and 6.44 ± 2.10 (p < 0.01), and respectively became 16.13 ± 0.83 and 11.74 ± 1.74 after the addition of free CKAAKN peptide. In vitro MR imaging studies showed that an obvious decrease in the signal intensity was observed in the targeted nanoparticles group incubated with BxPC-3 and HPDE6-C7 cells (p < 0.05). CONCLUSION: USPIO@CKAAKN-PEG-PLGA nanoparticles could significantly enhance the tumor specificity of USPIO in CKAAKN-positive pancreatic cancer cell BxPC-3, which is expected as a promising candidate of MRI contrast enhancement for the early diagnosis of pancreatic cancer.

Celastrol protects against early brain injury after subarachnoid hemorrhage in rats through alleviating blood-brain barrier disruption and blocking necroptosis.

BACKGROUND: Subarachnoid hemorrhage (SAH) is a life-threatening disease worldwide, and effective pharmaceutical treatment is still lacking. Celastrol is a plant-derived triterpene which showed neuroprotective potential in several types of brain insults. This study aimed to investigate the effects of celastrol on early brain injury (EBI) after SAH. METHODS: A total of sixty-one male Sprague-Dawley rats were used in this study. Rat SAH endovascular perforation model was established to mimic the pathological changes of EBI after SAH. Multiple methods such as 3.0T MRI scanning, immunohistochemistry, western blotting and propidium iodide (PI) labeling were used to explore the therapeutic effects of celastrol on SAH. RESULTS: Celastrol treatment attenuated SAH-caused brain swelling, reduced T2 lesion volume and ventricular volume in MRI scanning, and improved overall neurological score. Albumin leakage and the degradation of tight junction proteins were also ameliorated after celastrol administration. Celastrol protected blood-brain bairrer integrity through inhibiting MMP-9 expression and anti-neuroinflammatory effects. Additionally, necroptosis-related proteins RIP3 and MLKL were down-regulated and PI-positive cells in the basal cortex were less in the celastrol-treated SAH group than that in untreated SAH group. CONCLUSIONS: Celastrol exhibits neuroprotective effects on EBI after SAH and deserves to be further investigated as an add-on pharmaceutical therapy.

The Neuroprotective Effects of Necrostatin-1 on Subarachnoid Hemorrhage in Rats Are Possibly Mediated by Preventing Blood-Brain Barrier Disruption and RIP3-Mediated Necroptosis.

Despite the substantial efforts to elucidate the role of early brain injury in subarachnoid hemorrhage (SAH), an effective pharmaceutical therapy for patients with SAH continues to be unavailable. This study aims to reveal the role of necroptosis after SAH, and explore whether the disruption of the blood-brain barrier (BBB) and RIP3-mediated necroptosis following SAH in a rat SAH model are altered by necrostatin-1 via its selective inhibition of receptor-interacting protein kinase 1 (RIP1). Sixty-five rats were used in the experiments. The SAH model was established using endovascular perforation. Necrostatin-1 was intracerebroventricularly injected 1 h before SAH induction. The neuroprotective effects of necrostatin-1 were evaluated with multiple methods such as magnetic resonance imaging (MRI) scanning, immunohistochemistry, propidium iodide (PI) labeling, and western blotting. Pretreatment with necrostatin-1 attenuated brain swelling and reduced the lesion volume on T2 sequence and ventricular volume on MRI 72 h after SAH induction. Albumin leakage and the degradation of tight junction proteins were also ameliorated by necrostatin-1 administration. In addition, necrostatin-1 decreased the number of PI-positive cells in the basal cortex, reduced the levels of the RIP3 and MLKL proteins, and inhibited the production of the pro-inflammatory cytokines IL-1ß, IL-6, and TNF-α. Based on the findings from the present study, the selective RIP1 inhibitor necrostatin-1 functioned as a neuroprotective agent after SAH by attenuating brain swelling and BBB disruption. Moreover, the necrostatin-1 pretreatment prevented SAH-induced necroptosis by suppressing the activity of the RIP3/MLKL signaling pathway. These results will provide insights into new drugs and pharmacological targets to manage SAH, which are worth further study.

Superparamagnetic Iron Oxide Nanoparticles/Doxorubicin-Loaded Starch-Octanoic Micelles for Targeted Tumor Therapy.

The magnetic resonance imaging diagnosis and high-efficiency tumor targeting treatment are of notable importance for cancer therapy. In this study, starch-octanoic acid (ST-OA) micelles were successfully prepared to co-encapsulate the anti-tumor drug doxorubicin (DOX) and superparamagnetic iron oxide nanoparticles (SPIONs), taking advantage of the hydrophobic core of the core-shell micellar structure. Size distribution, morphology and in vitro release behaviors of micelles were investigated. In addition, magnetic properties and the anti-tumor theranostic performance were confirmed by conducting the cellular uptake, in vivo imaging and anti-tumor activity experiments. Therefore, co-encapsulation and specific delivery of the chemotherapeutic drug and contrast agent into tumor cells can realize the diagnosis and treatment of malignant tumor at the same time.

SPIO-loaded nanostructured lipid carriers as liver-targeted molecular T2-weighted MRI contrast agent.

BACKGROUND: Superparamagnetic iron oxide (SPIO) acts as a negative contrast agent in magnetic resonance imaging (MRI), and is widely used in clinical applications, including the diagnosis of hepatic diseases. Hepatocyte-targeted magnetic resonance contrast agents (MRCAs) can provide useful information for evaluating hepatic diseases. We prepared targeted magnetic nanostructured lipid carriers (MNLCs) to enhance the hepatocytes targeting efficiency. METHODS: In vitro characterizations of MNLCs were determined by transmission electron microscopy (TEM). The cytotoxicity assay of the MNLCs was measured by methyl tetrazolium (MTT) method. The uptaken study was measured by confocal microscopy, flow cytometry and MRI in vitro. The enhanced liver-targeting efficiency of MNLCs was measured by fluorescence imaging and MRI in vivo. RESULTS: Gal-NLC-SPIO was prepared successfully. The cytotoxicity assay of the MNLCs demonstrated that the MNLC had relatively low cytotoxicity and high biocompatibility for LO2 cells. More importantly, we confirmed that Gal-NLC-SPIO had greater uptake by LO2 cells than Gal-NLC-SPIO/PEG and free Gal in vitro. A liver distribution study of MNLCs in normal mice demonstrated that the fluorescent signal values to livers of the Gal-NLC-SPIO were significantly stronger than those of NLC-SPIO and Gal-NLC-SPIO/PEG. The liver targeting efficiency of Gal-NLC-SPIO was confirmed both in vitro and in vivo. CONCLUSIONS: We successfully developed liver-targeting MNLCs, which showed accurate hepatocytes targeting, and thus have the potential to be a new MRI contrast agent to help the diagnosis of liver diseases.

Magnesium lithospermate B loaded PEGylated solid lipid nanoparticles for improved oral bioavailability.

Magnesium lithospermate B (MLB) is an active polyphenol acid with multiple pharmacological activities and poor oral bioavailability. The present research aimed to construct MLB loaded solid lipid nanoparticles (MLB-SLNs) for oral delivery to enhance its bioavailability. MLB-SLNs were prepared by solvent diffusion method and subsequently modified with polyethylene glycol monostearate (PEG-SA) superficially. The particle sizes of MLB-SLNs varied from 82.57 to 53.50nm with an improved drug loading capacity (up to 16.18%) after PEG-SA modification. Pharmacokinetic study indicated that Cmax (peak plasma MLB concentration) and AUC (area under curve) of MLB-SLNs increased significantly compared to that of MLB solution in male SD rats. The relative bioavailability of MLB-SLNs with PEG-SA modification was 753.98% compared to MLB solution administered by tail intravenous injection. The enhanced transport mechanism could be further illustrated by the results that MLB-SLNs showed higher permeability across Madin-Daby canine kidney (MDCK) epithelial cell monolayer and MLB-SLNs with smaller particle size distribution and PEG-SA modification manifested stronger cellular internalization ability on MDCK cells. Thus, PEG-SA modified solid lipid nanoparticles confirmed with enhanced cellular transport and improved oral bioavailability can be a promising oral MLB delivery system.

Histidine provides long-term neuroprotection after cerebral ischemia through promoting astrocyte migration.

The formation of glial scar impedes the neurogenesis and neural functional recovery following cerebral ischemia. Histamine showed neuroprotection at early stage after cerebral ischemia, however, its long-term effect, especially on glial scar formation, hasn't been characterized. With various administration regimens constructed for histidine, a precursor of histamine, we found that histidine treatment at a high dose at early stage and a low dose at late stage demonstrated the most remarkable long-term neuroprotection with decreased infarct volume and improved neurological function. Notably, this treatment regimen also robustly reduced the glial scar area and facilitated the astrocyte migration towards the infarct core. In wound-healing assay and transwell test, histamine significantly promoted astrocyte migration. H2 receptor antagonists reversed the promotion of astrocyte migration and the neuroprotection provided by histidine. Moreover, histamine upregulated the GTP-bound small GTPase Rac1, while a Rac1 inhibitor, NSC23766, abrogated the neuroprotection of histidine and its promotion of astrocyte migration. Our data indicated that a dose/stage-dependent histidine treatment, mediated by H2 receptor, promoted astrocyte migration towards the infarct core, which benefited long-term post-cerebral ischemia neurological recovery. Therefore, targeting histaminergic system may be an effective therapeutic strategy for long-term cerebral ischemia injury through its actions on astrocytes.

Biological activity and magnetic resonance imaging of superparamagnetic iron oxide nanoparticles-labeled adipose-derived stem cells.

INTRODUCTION: No comparative study of adipose-derived stem cells (ADSCs) and bone marrow mesenchymal stem cells (BMSCs) by using superparamagnetic iron oxide nanoparticles (SPIOs)-labeling and magnetic resonance imaging (MRI) has been performed. METHODS: We studied the biological activity and MRI of ADSCs by labeling them with SPIOs and comparing them with BMSCs. After incubating the cells in culture medium with different levels of SPIOs (control group: 0 µg/ml; Groups 1 to 3: 25, 50, and 100 µg/ml) for 24 hours, we compared ADSCs with BMSCs in terms of intracellular iron content, labeling efficiency, and cell viability. Stem cells in the culture medium containing 50 µg/ml SPIOs were induced into osteoblasts and fat cells. Adipogenic and osteogenic differentiation potentials were compared. R2* values of MRI in vitro were compared. RESULTS: The results showed that labeling efficiency was highest in Group 2. Intracellular iron content and R2* values increased with increasing concentrations of SPIOs, whereas cell viability decreased with increasing concentrations of SPIOs, and adipogenic and osteogenic differentiation potentials decreased. However, we found no significant difference between the two kinds of cells for any of these indexes. CONCLUSIONS: ADSCs can be labeled and traced as easily as BMSCs in vitro. Given their abundance and higher proliferative capacity, as was previously shown, ADSCs may be better suited to stem cell therapy than are BMSCs.

Actively-targeted LTVSPWY peptide-modified magnetic nanoparticles for tumor imaging.

BACKGROUND: Magnetic resonance imaging (MRI) is widely used in modern clinical medicine as a diagnostic tool, and provides noninvasive and three-dimensional visualization of biological phenomena in living organisms with high spatial and temporal resolution. Therefore, considerable attention has been paid to magnetic nanoparticles as MRI contrast agents with efficient targeting ability and cellular internalization ability, which make it possible to offer higher contrast and information-rich images for detection of disease. METHODS: LTVSPWY peptide-modified PEGylated chitosan (LTVSPWY-PEG-CS) was synthesized by chemical reaction, and the chemical structure was confirmed by (1)H-NMR. LTVSPWY-PEG-CS-modified magnetic nanoparticles were prepared successfully using the solvent diffusion method. Their particle size, size distribution, and zeta potential were measured by dynamic light scattering and electrophoretic mobility, and their surface morphology was investigated by transmission electron microscopy. To investigate their selective targeting ability, the cellular uptake of the LTVSPWY-PEG-CS-modified magnetic nanoparticles was observed in a cocultured system of SKOV-3 cells which overexpress HER2 and A549 cells which are HER2-negative. The in vitro cytotoxicity of these nanoparticles in SKOV-3 and A549 cells was measured using the MTT method. The SKOV-3-bearing nude mouse model was used to investigate the tumor targeting ability of the magnetic nanoparticles in vivo. RESULTS: The average diameter and zeta potential of the LTVSPWY-PEG-CS-modified magnetic nanoparticles was 267.3 ± 23.4 nm and 30.5 ± 7.0 mV, respectively, with a narrow size distribution and spherical morphology. In vitro cytotoxicity tests demonstrated that these magnetic nanoparticles were carriers suitable for use in cancer diagnostics with low toxicity. With modification of the LTVSPWY homing peptide, magnetic nanoparticles could be selectively taken up by SKOV-3 cells overexpressing HER2 when cocultured with HER2-negative A549 cells. In vivo biodistribution results suggest that treatment with LTVSPWY-PEG-CS-modified magnetic nanoparticles/DiR enabled tumors to be identified and diagnosed more rapidly and efficiently in vivo. CONCLUSION: LTVSPWY-PEG-CS-modified magnetic nanoparticles are a promising contrast agent for early detection of tumors overexpressing HER2 and further diagnostic application.