Nanomaterials provide large surface areas, relative to their volumes, on which to load functions. One challenge, however, has been to achieve precise control in loading multiple functionalities. Traditional bioconjugation techniques, which randomly target the surface functional groups of nanomaterials, have been found increasingly inadequate for such control--a drawback which may substantially slow down or prohibit the translational efforts. In the current study, we evaluated ferritin nanocages as candidate nanoplatforms for multifunctional loading. Ferritin nanocages can be either genetically or chemically modified to impart functionalities to their surfaces, and metal cations can be encapsulated in their interiors by association with metal binding sites. Moreover, different types of ferritin nanocages can be disassembled under acidic condition and reassembled at pH of 7.4, providing a facile way to achieve function hybridization. We were able to use combinations of these unique properties to produce a number of multifunctional ferritin nanostructures with precise control of their composition. We then studied these nanoparticles, both in vitro and in vivo, to evaluate their potential suitability as multimodality imaging probes. A good tumor targeting profile was observed, which was attributable to both the enhanced permeability and retention (EPR) effect and biovector mediated targeting. This, in combination with the generalizability of the function loading techniques, promises ferritin particles as a powerful nanoplatfom in the era of nanomedicine.Keywords ferritin nanocage; multimodality molecular imaging; positron emission tomography; near-infrared fluorescence imaging; integrin; RGD peptideThe idea of multimodality imaging has recently gained popularity 1, 2 . The rationale arises from the notion of improving the quality and accuracy of disease management by combining * To whom correspondence should be addressed, Shawn.Chen@nih.gov. ⊥ Both authors contributed equally to this work. Supporting InformationAdditional information regarding the expression and purification of Fn and R-Fn, preparation of C-Fn, synthesis of chimeric ferritin nanocages, cell binding assay, small animal PET and NIRF optical imaging studies, immunofluorescence staining, results of DLS analysis of R-Fn, and results of ex vivo imaging of excised tumors. This material is available free of charge via the Internet at http://pubs.acs.org. 6,7 . Such a transition to multimodal imaging poses a challenge to the design and synthesis of new generations of imaging probes. It requires that a targeting motif be integrated in a compact and controllable way with multiple imaging tags--something that is difficult to achieve with traditional biomaterials such as peptides and proteins. The emergence of nanotechnology, however, is expected to provide solutions to such challenges. With large ratios of surface-area-to-volume and multiple binding sites, nanomaterials can be loaded with a number of motifs [8][9][10] . However, the monotonicity of the...

The imaging of sentinel lymph nodes (SLNs), the first defense against primary tumor metastasis, has been considered as an important strategy for noninvasive tracking tumor metastasis in clinics. In this study, we report the development and application of mesoporous silica-based triple-modal nanoprobes that integrate multiple functional moieties to facilitate near-infrared optical, magnetic resonance (MR) and positron emission tomography (PET) imaging. After embedding near-infrared dye ZW800, the nanoprobe was labeled with T1 contrast agent Gd3+ and radionuclide 64Cu through chelating reactions. High stability and long intracellular retention time of the nanoprobes was confirmed by in vitro characterization, which facilitate long-term in vivo imaging. Longitudinal multimodal imaging was subsequently achieved to visualize tumor draining SLNs up to 3 weeks in a 4T1 tumor metastatic model. Obvious differences in uptake rate, amount of particles, and contrast between metastatic and contralateral sentinel lymph nodes were observed. These findings provide very helpful guidance for the design of robust multifunctional nanomaterials in SLNs’ mapping and tumor metastasis diagnosis.

An ongoing effort in the field of nanomedicine is to develop nanoplatforms with both imaging and therapeutic functions, the “nano-theranostics”. We have previously developed a human serum albumin (HSA) coated iron oxide nanoparticle (HINP) formula and used multiple imaging modalities to validate its tumor targeting attributes. In the current study, we sought to impart doxorubicin (Dox) onto the HINPs and to assess the potential of the conjugates as theranostic agents. In a typical preparation, we found that about 0.5 mg of Dox and 1 mg of iron oxide nanoparticles (IONPs, Fe content) could be loaded into 10 mg of HSA matrices. The resulting D-HINPs (Dox loaded HINPs) have a hydrodynamic size of 50 nm and are able to release Dox in a sustained fashion. More impressively, the HINPs can assist the translocation of Dox across cell membrane and even its accumulation in the nucleus. In vivo, D-HINPs retained a tumor targeting capability of HINPs, as manifested by both in vivo MRI and ex vivo immunostaining results. In a follow-up therapeutic study on a 4T1 murine breast cancer xenograft model, D-HINPs showed a striking tumor suppression effect that was comparable to Doxil and greatly outperformed free Dox. Such a strategy can be readily extended to load other types of small molecules, making HINP a promising theranostic nanoplatform.

Purpose Glucagon-like peptide type 1 (GLP-1) is an incretin peptide that augments glucose-stimulated insulin release following oral consumption of nutrients. Its message is transmitted via a G protein-coupled receptor called GLP-1R, which is colocalized with pancreatic β-cells. The GLP-1 system is responsible for enhancing insulin release, inhibiting glucagon production, inhibiting hepatic gluconeogenesis, inhibiting gastric mobility, and suppression of appetite. The abundance of GLP-1R in pancreatic β-cells in insulinoma, a cancer of the pancreas, and the activity of GLP-1 in the cardiovascular system have made GLP-1R a target for molecular imaging. Methods We prepared 18F radioligands for GLP-1R by the reaction of [18F]FBEM, a maleimide prosthetic group, with [Cys0] and [Cys40] analogs of exendin-4. The binding affinity, cellular uptake and internalization, in vitro stability, and uptake and specificity of uptake of the resulting compounds were determined in an INS-1 xenograft model in nude mice. Results The [18F]FBEM-[Cysx]-exendin-4 analogs were obtained in good yield (34.3±3.4%, n=11), based on the starting compound [18F]FBEM), and had a specific activity of 45.51±16.28 GBq/μmol (1.23±0.44 Ci/μmol, n=7) at the end of synthesis. The C-terminal isomer, [18F]FBEM-[Cys40]-exendin-4, had higher affinity for INS-1 tumor cells (IC50 1.11±0.057 nM) and higher tumor uptake (25.25±3.39 %ID/g at 1 h) than the N-terminal isomer, [18F]FBEM-[Cys0]-exendin-4 (IC50 2.99±0.06 nM, uptake 7.20±1.26 %ID/g at 1 h). Uptake of both isomers into INS-1 tumor, pancreas, stomach, and lung could be blocked by preinjection of nonradiolabeled [Cysx]-exendin-4 (p<0.05). Conclusion [18F]FBEM-[Cys40]-exendin-4 and [18F]FBEM-[Cys0]-exendin-4 have high affinity for GLP-1R and display similar in vitro cell internalization. The higher uptake into INS-1 xenograft tumors exhibited by [18F]FBEM-[Cys40]-exendin-4 suggests that this compound would be the better tracer for imaging GLP-1R.

Stem cell engineering, the manipulation and control of cells, harnesses tremendous potential for diagnosis and therapy of disease; however, it is still challenging to impart multifunctionalization onto stem cells to achieve both. Here we describe a mesenchymal stem cell (MSC)-based multifunctional platform to target orthotopic glioblastoma by integrating the tumor targeted delivery of mesenchymal stem cells and the multimodal imaging advantage of mesoporous silica nanoparticles (MSNs). Rapid cellular uptake, long retention time and stability of particles exemplify the potential that the combination of MSNs and MSCs has as a stem cell-based multifunctional platform. Using such a platform, we verified tumor-targeted delivery of MSCs by in vivo multimodal imaging in an orthotopic U87MG glioblastoma model, displaying higher tumor uptake than particles without MSCs. As a proof-of-concept, this MSC platform opens a new vision for multifunctional applications of cell products by combining the superiority of stem cells and nanoparticles for actively targeted delivery.

Background The present study was to investigate the effects and mechanism of Luteolin on myocardial infarct size, cardiac function and cardiomyocyte apoptosis in diabetic rats with myocardial ischemia/reperfusion (I/R) injury.Methodology/Principal FindingsDiabetic rats underwent 30 minutes of ischemia followed by 3 h of reperfusion. Animals were pretreated with or without Luteolin before coronary artery ligation. The severity of myocardial I/R induced LDH release, arrhythmia, infarct size, cardiac function impairment, cardiomyocyte apoptosis were compared. Western blot analysis was performed to elucidate the target proteins of Luteolin. The inflammatory cytokine production were also examined in ischemic myocardium underwent I/R injury. Our results revealed that Luteolin administration significantly reduced LDH release, decreased the incidence of arrhythmia, attenuated myocardial infarct size, enhanced left ventricular ejection fraction and decreased myocardial apoptotic death compared with I/R group. Western blot analysis showed that Luteolin treatment up-regulated anti-apoptotic proteins FGFR2 and LIF expression, increased BAD phosphorylation while decreased the ratio of Bax to Bcl-2. Luteolin treatment also inhibited MPO expression and inflammatory cytokine production including IL-6, IL-1a and TNF-a. Moreover, co-administration of wortmannin and Luteolin abolished the beneficial effects of Luteolin.Conclusions/SignificanceThis study indicates that Luteolin preserves cardiac function, reduces infarct size and cardiomyocyte apoptotic rate after I/R injury in diabetic rats. Luteolin exerts its action by up-regulating of anti-apoptotic proteins FGFR2 and LIF expression, activating PI3K/Akt pathway while increasing BAD phosphorylation and decreasing ratio of Bax to Bcl-2.

Objective The αvβ3 integrin represents a potential target for noninvasive imaging of angiogenesis. The purpose of this study was to evaluate a novel one-step labeled integrin αvβ3 targeting PET probe, 18F-AlF-NOTA-PRGD2, for angiogenesis imaging in a myocardial infract/reperfusion (MI/R) animal model. Methods Male SD rats underwent 45 min transient left coronary artery occlusion followed by reperfusion. The myocardial infarction was confirmed by ECG, 18F-FDG imaging and cardiac ultrasound. In vivo PET imaging were used to determine myocardial uptake of 18F-AlF-NOTA-PRGD2 at different time points following reperfusion. The control peptide RAD was labeled with a similar procedure and used to confirm the specificity. Ex vivo autoradiographic analysis and CD31/CD61 double immunofluoresence staining were performed to validate the PET results. Results Myocardial origin of the 18F-AlF-NOTA-PRGD2 accumulation was confirmed by 18F-FDG and autoradiography. PET imaging demonstrated increased focal accumulation of 18F-AlF-NOTA-PRGD2 in the infarcted area started at day 3 (0.28 ± 0.03 %ID/g, p < 0.05), peaked between 1 and 3 weeks (0.59 ± 0.16 and 0.55 ± 0.13 %ID/g, respectively). The focal accumulation decreased but still kept at a higher level than the sham group after 4 months of reperfusion (0.31 ± 0.01 %ID/g, p < 0.05). Pretreatment with unlabeled RGD peptide significantly decreased tracer uptake, indicating integrin specificity of this tracer. At 1 week after MI/R, uptake of the control tracer 18F-AlF-NOTA-RAD that does not bind to integrin, in the infarcted area, was only 0.21 ± 0.01 %ID/g. Autoradiographic imaging showed the same trend of uptake in myocardial infarction area. The time course of focal tracer uptake was consistent with the pattern of vascular density and integrin β3 expression as measured by CD31 and CD61 immunostaining analysis. Conclusion PET imaging using one-step labeled 18F-AlF-NOTA-PRGD2 allows noninvasive visualization of ischemia-reperfusion induced myocardial angiogenesis longitudinally. The favorable in vivo kinetics and easy production method of this integrin targeted PET tracer facilitates its future clinical translation for lesion evaluation and therapy response monitoring in patients with occlusive cardiovascular diseases.

This study indicates that TSN pretreatment reduces infarct size and improves cardiac dysfunction after I/R injury in diabetic rats. This was accompanied with decreased cardiac apoptosis and inflammation. The possible mechanism responsible for the effects of TSN is associated with the PI3K/Akt-dependent pathway.