A new form of axonal pathology in a spinal model of neuromyelitis optica.

Neuromyelitis optica is a chronic neuroinflammatory disease, which primarily targets astrocytes and often results in severe axon injury of unknown mechanism. Neuromyelitis optica patients harbour autoantibodies against the astrocytic water channel protein, aquaporin-4 (AQP4-IgG), which induce complement-mediated astrocyte lysis and subsequent axon damage. Using spinal in vivo imaging in a mouse model of such astrocytopathic lesions, we explored the mechanism underlying neuromyelitis optica-related axon injury. Many axons showed a swift and morphologically distinct 'pearls-on-string' transformation also readily detectable in human neuromyelitis optica lesions, which especially affected small calibre axons independently of myelination. Functional imaging revealed that calcium homeostasis was initially preserved in this 'acute axonal beading' state, ruling out disruption of the axonal membrane, which sets this form of axon injury apart from previously described forms of traumatic and inflammatory axon damage. Morphological, pharmacological and genetic analyses showed that AQP4-IgG-induced axon injury involved osmotic stress and ionic overload, but does not appear to use canonical pathways of Wallerian-like degeneration. Subcellular analysis demonstrated remodelling of the axonal cytoskeleton in beaded axons, especially local loss of microtubules. Treatment with the microtubule stabilizer epothilone, a putative therapy approach for traumatic and degenerative axonopathies, prevented axonal beading, while destabilizing microtubules sensitized axons for beading. Our results reveal a distinct form of immune-mediated axon pathology in neuromyelitis optica that mechanistically differs from known cascades of post-traumatic and inflammatory axon loss, and suggest a new strategy for neuroprotection in neuromyelitis optica and related diseases.

Associations between Differential Aging and Lifestyle, Environment, Current, and Future Health Conditions: Findings from Canadian Longitudinal Study on Aging.

INTRODUCTION: An aging population will bring a pressing challenge for the healthcare system. Insights into promoting healthy longevity can be gained by quantifying the biological aging process and understanding the roles of modifiable lifestyle and environmental factors, and chronic disease conditions. METHODS: We developed a biological age (BioAge) index by applying multiple state-of-art machine learning models based on easily accessible blood test data from the Canadian Longitudinal Study of Aging (CLSA). The BioAge gap, which is the difference between BioAge index and chronological age, was used to quantify the differential aging, i.e., the difference between biological and chronological age, of the CLSA participants. We further investigated the associations between the BioAge gap and lifestyle, environmental factors, and current and future health conditions. RESULTS: BioAge gap had strong associations with existing adverse health conditions (e.g., cancers, cardiovascular diseases, diabetes, and kidney diseases) and future disease onset (e.g., Parkinson's disease, diabetes, and kidney diseases). We identified that frequent consumption of processed meat, pork, beef, and chicken, poor outcomes in nutritional risk screening, cigarette smoking, exposure to passive smoking are associated with positive BioAge gap ("older" BioAge than expected). We also identified several modifiable factors, including eating fruits, legumes, vegetables, related to negative BioAge gap ("younger" BioAge than expected). CONCLUSIONS: Our study shows that a BioAge index based on easily accessible blood tests has the potential to quantify the differential biological aging process that can be associated with current and future adverse health events. The identified risk and protective factors for differential aging indicated by BioAge gap are informative for future research and guidelines to promote healthy longevity.

Individualized Prospective Prediction of Opioid Use Disorder.

OBJECTIVE: Opioid use disorder (OUD) is a chronic relapsing disorder with a problematic pattern of opioid use, affecting nearly 27 million people worldwide. Machine learning (ML)-based prediction of OUD may lead to early detection and intervention. However, most ML prediction studies were not based on representative data sources and prospective validations, limiting their potential to predict future new cases. In the current study, we aimed to develop and prospectively validate an ML model that could predict individual OUD cases based on representative large-scale health data. METHOD: We present an ensemble machine-learning model trained on a cross-linked Canadian administrative health data set from 2014 to 2018 (n = 699,164), with validation of model-predicted OUD cases on a hold-out sample from 2014 to 2018 (n = 174,791) and prospective prediction of OUD cases on a non-overlapping sample from 2019 (n = 316,039). We used administrative records of OUD diagnosis for each subject based on International Classification of Diseases (ICD) codes. RESULTS: With 6409 OUD cases in 2019 (mean [SD], 45.34 [14.28], 3400 males), our model prospectively predicted OUD cases at a high accuracy (balanced accuracy, 86%, sensitivity, 93%; specificity 79%). In accord with prior findings, the top risk factors for OUD in this model were opioid use indicators and a history of other substance use disorders. CONCLUSION: Our study presents an individualized prospective prediction of OUD cases by applying ML to large administrative health datasets. Such prospective predictions based on ML would be essential for potential future clinical applications in the early detection of OUD.

Non-cell-autonomous function of DR6 in Schwann cell proliferation.

Death receptor 6 (DR6) is an orphan member of the TNF receptor superfamily and controls cell death and differentiation in a cell-autonomous manner in different cell types. Here, we report an additional non-cell-autonomous function for DR6 in the peripheral nervous system (PNS). DR6-knockout (DR6 KO) mice showed precocious myelination in the PNS Using an in vitro myelination assay, we demonstrate that neuronal DR6 acts in trans on Schwann cells (SCs) and reduces SC proliferation and myelination independently of its cytoplasmic death domain. Mechanistically, DR6 was found to be cleaved in neurons by "a disintegrin and metalloprotease 10" (ADAM10), releasing the soluble DR6 ectodomain (sDR6). Notably, in the in vitro myelination assay, sDR6 was sufficient to rescue the DR6 KO phenotype. Thus, in addition to the cell-autonomous receptor function of full-length DR6, the proteolytically released sDR6 can unexpectedly also act as a paracrine signaling factor in the PNS in a non-cell-autonomous manner during SC proliferation and myelination. This new mode of DR6 signaling will be relevant in future attempts to target DR6 in disease settings.

Development of 18F-Labeled Vinyl Sulfone-PSMAi Conjugates as New PET Agents for Prostate Cancer Imaging.

Radiolabeled prostate-specific membrane antigen (PSMA) ligands have been rapidly adopted as part of patient care for prostate cancer. In this study, a new series of 18F-labeled PSMA-targeting agents was developed based on the high-affinity Glu-ureido-Lys scaffold and 18F-vinyl sulfones (VSs), the tumor uptake and tumor/major organ contrast of which could be tuned by pharmacokinetic linkers within the molecules. In particular, 18F-PEG3-VS-PSMAi showed the highest tumor uptake (12.1 ± 2.2%ID/g at 0.5 h p.i.) and 18F-PEG2-VS-PSMAi showed the highest tumor-to-liver ratio (T/L = 3.7 ± 1.0, 4.8 ± 1.2, and 6.3 ± 1.1 at 0.5, 1.5, and 3 h p.i. respectively). Significantly, compared with the FDA-approved 68Ga-PSMA-11, the newly developed 18F-PEG3-VS-PSMAi has an almost double tumor uptake (P < 0.0001) when tested in the same animal model. In conclusion, 18F-VS-labeled PSMA ligands are promising PET agents with prominent tumor uptake and high contrast. The lead agents 18F-PEG2-VS-PSMAi and 18F-PEG3-VS-PSMAi warrant further evaluation in prostate cancer patients.

CRMP2 mediates Sema3F-dependent axon pruning and dendritic spine remodeling.

Regulation of axon guidance and pruning of inappropriate synapses by class 3 semaphorins are key to the development of neural circuits. Collapsin response mediator protein 2 (CRMP2) has been shown to regulate axon guidance by mediating semaphorin 3A (Sema3A) signaling; however, nothing is known about its role in synapse pruning. Here, using newly generated crmp2-/- mice we demonstrate that CRMP2 has a moderate effect on Sema3A-dependent axon guidance in vivo, and its deficiency leads to a mild defect in axon guidance in peripheral nerves and the corpus callosum. Surprisingly, crmp2-/- mice display prominent defects in stereotyped axon pruning in hippocampus and visual cortex and altered dendritic spine remodeling, which is consistent with impaired Sema3F signaling and with models of autism spectrum disorder (ASD). We demonstrate that CRMP2 mediates Sema3F signaling in primary neurons and that crmp2-/- mice display ASD-related social behavior changes in the early postnatal period as well as in adults. Together, we demonstrate that CRMP2 mediates Sema3F-dependent synapse pruning and its dysfunction shares histological and behavioral features of ASD.

Feasibility of resource utilization of the refractory evaporation concentrate of gas field wastewater exhibiting high salinity: Application of UV/Fenton, desulfurization, distillation and crystallization process after pre-treatment.

The evaporation concentrate of gas field wastewater (EC-GFW) is a new type of refractory actual wastewater produced by the three-effect evaporation of gas field wastewater, exhibiting extremely high salinity and complex organic components. This study proposed a set of processes consisting of AOPs, precipitation, distillation, and crystallization for the systematic treatment of EC-GFW. In this paper, the optimal conditions for the processes after pre-treatment were investigated. The optimal operating parameters of UV/Fenton process were determined to be 180 min of reaction time, 4 of initial pH, 0.6 mol/L of H2O2 dosage, 10:1 of n(H2O2): n(Fe2+) value, and 30 W of UV power. Fenton's reagent was added in two steps (0 min and 90 min) for effective utilization. The results showed that the TOC (Total organic carbon) removal efficiency during the two-stage oxidation reached 93% with TOC in the effluent of 132 mg/L. Then, 82.3% of sulfate ions were removed by the desulfurization process using 50 g/L of CaCl2 within 10 min at a pH of 5 before distillation. It was found that the TOC in the influent of distillation played a decisive role in the quality of the effluent and purity of the crystalline salt, which was expected to be controlled lower than 132 mg/L. The final condensate could utilize to reuse, 99% of main pollutants of which have been removed, reducing the pressure of water supply on site. Simultaneously, the industrial-grade NaCl with extensive application prospect can be recovered. The harmless disposal and resource utilization of EC-GFW was achieved on a laboratory scale, providing the data support and theoretical guidance for treating EC-GFW at gas field project site.

FAP-Targeted Photodynamic Therapy Mediated by Ferritin Nanoparticles Elicits an Immune Response against Cancer Cells and Cancer Associated Fibroblasts.

Cancer-associated fibroblasts (CAFs) are present in many types of tumors and play a pivotal role in tumor progression and immunosuppression. Fibroblast-activation protein (FAP), which is overexpressed on CAFs, has been indicated as a universal tumor target. However, FAP expression is not restricted to tumors, and systemic treatment against FAP often causes severe side effects. To solve this problem, a photodynamic therapy (PDT) approach was developed based on ZnF16Pc (a photosensitizer)-loaded and FAP-specific single chain variable fragment (scFv)-conjugated apoferritin nanoparticles, or αFAP-Z@FRT. αFAP-Z@FRT PDT efficiently eradicates CAFs in tumors without inducing systemic toxicity. When tested in murine 4T1 models, the PDT treatment elicits anti-cancer immunity, causing suppression of both primary and distant tumors, i.e. abscopal effect. Treatment efficacy is enhanced when αFAP-Z@FRT PDT is used in combination with anti-PD1 antibodies. Interestingly, it is found that the PDT treatment not only elicits a cellular immunity against cancer cells, but also stimulates an anti-CAFs immunity. This is supported by an adoptive cell transfer study, where T cells taken from 4T1-tumor-bearing animals treated with αFAP PDT retard the growth of A549 tumors established on nude mice. Overall, our approach is unique for permitting site-specific eradication of CAFs and inducing a broad spectrum anti-cancer immunity.

RXH-Reactive 18F-Vinyl Sulfones as Versatile Agents for PET Probe Construction.

Efficient radiolabeling reactions are important chemical tools in biomedical research especially in probe construction. Herein, three 18F-labeled vinyl sulfones were prepared. In particular, 18F-PEG1-VS (((2-(2-(fluoro-18F)ethoxy)ethyl)sulfonyl)ethane) could not only allow chemoselective labeling of bioactive molecules containing -XH (X = S, NH) groups, but also react with red blood cells both in vitro and in living mice for potential cell tracking applications. In addition, these hydrophilic agents were found to cross the blood brain barrier (BBB) efficiently and localize at the cerebellum region. In summary, 18F-labeled vinyl sulfones provide a versatile platform for PET probe construction.

Tetrazine-TCO Ligation: A Potential Simple Approach to Improve Tumor Uptake through Enhanced Blood Circulation.

Targeted imaging via peptides has been extensively investigated for both diagnostic and therapeutic applications. However, peptides can be cleared out from the blood circulation quickly, leading to only moderate to low accumulation in regions of interest. Previously, 18F-sTCO-DiPhTz-RGDyK demonstrated relatively high blood retention with increased tumor uptake at the late time point (5.3 ± 0.4 and 8.9 ± 0.5%ID/g tumor uptake at 1 h p.i. and 4 h p.i., respectively). In this study, we aim to develop a novel platform based on TCO/tetrazine ligation that could be used not only to label the peptides with F-18 for PET but also to lead to increased or persistent tumor uptake potentially due to enhanced blood circulation of the labeled peptides. We first constructed systems containing different combinations of TCOs/tetrazines and found that the tetrazine moiety played a more important role to facilitate the enhanced blood circulation compared with TCO moiety. Four clinically relevant peptides including NT20.3, RGD, BBN, and exendin-4 were then evaluated, and the increased tumor uptake at a late time point was demonstrated by the combination of 18F-sTCO-DiPhTz system to NT20.3, RGD, and exendin-4. The plasma binding components of the PET agents were investigated by electrophoresis and autoradiography and indicated that transferrin and hemopexin could be the major proteins in blood plasma for binding with 18F-sTCO-DiPhTz conjugates. In summary, we have discovered a TCO/tetrazine system that could not only be used for PET probe construction but also potentially improve the tumor uptake and retention of fast-clearing peptides. Although additional binding experiments are still needed for some of the constructs, the promising preliminary result suggested that this strategy may be used to convert fast-clearing bioligands into relatively long circulating agents with enhanced tumor uptake/retention for either imaging or therapy applications.

Improving Tumor-to-Background Contrast through Hydrophilic Tetrazines: The Construction of 18 F-Labeled PET Agents Targeting Nonsmall Cell Lung Carcinoma.

Bioorthogonal reactions have been widely used in the biomedical field. 18 F-TCO/Tetrazine ligation is the most reactive radiolabelled inverse electron demand Diels-Alder reaction, but its application had been limited due to modest contrast ratios of the resulting conjugates. Herein, we describe the use of hydrophilic tetrazines to improve tumor-to-background contrast of neurotensin receptor targeted PET agents. PET agents were constructed using a rapid Diels-Alder reaction of the radiolabeled trans-cyclooctene (18 F-sTCO) with neurotensin (NT) conjugates of a 3,6-diaryltetrazine, 3-methyl-6-aryltetrazine, and a derivative of 3,6-di(2-hydroxyethyl)tetrazine. Although cell binding assays demonstrated all agents have comparable binding affinity, the conjugate derived from 3,6-di(2-hydroxyethyl)tetrazine demonstrated the highest tumor to muscle contrast, followed by conjugates of the 3-methyl-6-aryltetrazine and 3,6-diaryltetrazine.

Development of Bispecific NT-PSMA Heterodimer for Prostate Cancer Imaging: A Potential Approach to Address Tumor Heterogeneity.

Prostate cancer is a heterogeneous disease with a poor survival rate at late stage. In this report, a dual targeting PET agent was developed to partially address the tumor heterogeneity issue. The heterodimer F-BCN-PSMA-NT was designed to target PSMA and neurotensin receptor1 (NTR1), both of which have demonstrated great potential in prostate cancer management. The heterodimer was synthesized through the conjugation of Glu-urea-lys(Ahx) (PSMA targeting motif) and NT20.3 (NTR1 targeting motif) to a symmetric trifunctional linker, bearing an azide group for further modification. Radio-labeling was performed using strain promoted azide-alkyne click reaction with high yield. Cell based assays suggested that F-BCN-PSMA-NT has comparable or only slightly reduced binding affinity with the corresponding monomers. Small animal PET clearly demonstrated that the heterodimer probe has prominent uptake not only in NTR1 positive/PSMA negative PC-3 tumors (1.4 ± 0.3%ID/g), but also in the PSMA positive/NTR1 negative LnCap tumors (1.3 ± 0.2%ID/g). The tracer showed comparable tumor to background ratio with each monomer. In summary, prostate cancer is a heterogeneous disease in need of improved diagnostics and treatments. The PSMA-NT heterodimer represents a new class of molecules that can be used to target two distinct antigens related to prostate cancer. In addition to the imaging applications demonstrated in this study, the agent also holds great potential on the treatment of heterogeneous prostate cancer.

Evaluation of neurotensin receptor 1 as potential biomarker for prostate cancer theranostic use.

INTRODUCTION: Despite recent developments in the diagnosis and treatment of prostate cancer, the advanced stages still have poor survival rates. This warrants further exploration of related molecular targets for patient screening, detection of metastatic disease, and treatment/treatment monitoring. Recent studies have indicated that neurotensin receptors (NTSRs) and their ligand neurotensin (NTS) critically affect the progression of prostate cancers. In this study, we evaluated the expression of neurotensin receptor1 (NTSR1) in patient tissues and performed NTSR1 PET imaging in a prostate cancer animal model. METHODS: The NTSR1 expression was evaluated in 97 cases of prostate cancer and 100 cases of benign prostatic hyperplasia (BPH) of clinical patients by immunohistochemistry staining. The expression profile of PSMA and GRPR was also performed for comparison. The mRNA expression of NTSR1 in LnCap and PC-3 cells was measured by PCR. NTSR1 PET, and biodistribution studies were performed in PC-3 xenografts using 18F-DEG-VS-NT. RESULTS: NTSR1 showed high or moderate expression in 91.8% of prostate cancer tissue, compared with PSMA (86.7%) and GRPR (65.3%). All examined PSMA-negative tissues showed positive NTSR1 expression, suggesting the potential complementary role of NTSR1 targeted imaging or therapy. Only 8% of BPH shows strong or moderate expression of NTSR1, which is significantly lower than that in prostate cancer (91.8%). PCR results indicated LNCap (an androgen-dependent prostate cancer cell) showed negative NTSR1 expression while PC-3 demonstrated positive expression (an androgen-independent prostate cancer cell), which correlated well with previously reported western blot results. In a preclinical animal model, NTSR1 targeted PET probe 18F-DEG-VS-NT demonstrated prominent tumor accumulation and low background. CONCLUSION: We have demonstrated that NTSR1 is a promising molecular marker for prostate cancer based on patient tissue staining. The NTSR targeted probe 18F-DEG-VS-NT demonstrated high tumor to background contrast in animal models, which could be valuable in selecting patients for therapies targeting NTSR1 as well as monitoring therapeutic efficacy during treatment accordingly.

Development of [18F]AlF-NOTA-NT as PET Agents of Neurotensin Receptor-1 Positive Pancreatic Cancer.

Several studies have suggested that neurotensin receptors (NTRs) and neurotensin (NT) greatly affect the growth and survival of pancreatic ductal adenocarcinoma (PDAC). Developing NTR-targeted PET probes could therefore be important for the management of a pancreatic cancer patient by providing key information on the NTR expression profile noninvasively. Despite the initial success on the synthesis of 18F-labeled NT PET probes, the labeling procedure generally requires lengthy steps including azeotropic drying of 18F. Using a straightforward chelation method, here we report the simple preparation of aluminum-18F-NOTA-NT starting from aqueous 18F. The cell binding test demonstrated that [19F]AlF-NOTA-NT maintained high receptor-binding affinity to NTR1. This probe was then further evaluated in NTR1 positive pancreatic tumor models (AsPC-1 and PANC-1). After the administration of [18F]AlF-NOTA-NT, small animal PET studies showed a high contrast between tumor and background in both models at 1 and 4 h time points. A blocking experiment was performed to demonstrate the receptor specificity: the tumor uptake in AsPC1 without and with blocking agent was 1.0 ± 0.2 and 0.1 ± 0.0%ID/g, respectively, at 4 h post injection. In summary, a NTR specific PET agent, [18F]AlF-NOTA-NT, was prepared through the simple chelation method. This NTR-targeted PET probe may not only be used to detect NTR1 positive pancreatic tumors (diagnosis), but also it may be fully integrated to NTR target therapy leading to personalized medicine (theranostic).

Protein Nanocage Mediated Fibroblast-Activation Protein Targeted Photoimmunotherapy To Enhance Cytotoxic T Cell Infiltration and Tumor Control.

Carcinoma-associated fibroblasts (CAFs) are found in many types of cancer and play an important role in tumor growth and metastasis. Fibroblast-activation protein (FAP), which is overexpressed on the surface of CAFs, has been proposed as a universal tumor targeting antigen. However, recent studies show that FAP is also expressed on multipotent bone marrow stem cells. A systematic anti-FAP therapy may lead to severe side effects and even death. Hence, there is an urgent need of a therapy that can selectively kill CAFs without causing systemic toxicity. Herein we report a nanoparticle-based photoimmunotherapy (nano-PIT) approach that addresses the need. Specifically, we exploit ferritin, a compact nanoparticle protein cage, as a photosensitizer carrier, and we conjugate to the surface of ferritin a FAP-specific single chain variable fragment (scFv). With photoirradiation, the enabled nano-PIT efficiently eliminates CAFs in tumors but causes little damage to healthy tissues due to the localized nature of the treatment. Interestingly, while not directly killing cancer cells, the nano-PIT caused efficient tumor suppression in tumor-bearing immunocompetent mice. Further investigations found that the nano-PIT led to suppressed C-X-C motif chemokine ligand 12 (CXCL12) secretion and extracellular matrix (ECM) deposition, both of which are regulated by CAFs in untreated tumors and mediate T cell exclusion that prevents physical contact between T cells and cancer cells. By selective killing of CAFs, the nano-PIT reversed the effect, leading to significantly enhanced T cell infiltration, followed by efficient tumor suppression. Our study suggests a new and safe CAF-targeted therapy and a novel strategy to modulate tumor microenvironment (TME) for enhanced immunity against cancer.

Impact of Managers' Coaching Conversations on Staff Knowledge Use and Performance in Long-Term Care Settings.

BACKGROUND: Extended lifespans and complex resident care needs have amplified resource demands on nursing homes. Nurse managers play an important role in staff job satisfaction, research use, and resident outcomes. Coaching skills, developed through leadership skill-building, have been shown to be of value in nursing. AIMS: To test a theoretical model of nursing home staff perceptions of their work context, their managers' use of coaching conversations, and their use of instrumental, conceptual and persuasive research. METHODS: Using a two-group crossover design, 33 managers employed in seven Canadian nursing homes were invited to attend a 2-day coaching development workshop. Survey data were collected from managers and staff at three time points; we analyzed staff data (n = 333), collected after managers had completed the workshop. We used structural equation modeling to test our theoretical model of contextual characteristics as causal variables, managers' characteristics, and coaching behaviors as mediating variables and staff use of research, job satisfaction, and burnout as outcome variables. RESULTS: The theoretical model fit the data well (χ2 = 58, df = 43, p = .06) indicating no significant differences between data and model-implied matrices. Resonant leadership (a relational approach to influencing change) had the strongest significant relationship with manager support, which in turn influenced frequency of coaching conversations. Coaching conversations had a positive, non-significant relationship with staff persuasive use of research, which in turn significantly increased instrumental research use. Importantly, coaching conversations were significantly, negatively related to job satisfaction. LINKING EVIDENCE TO ACTION: Our findings add to growing research exploring the role of context and leadership in influencing job satisfaction and use of research by healthcare practitioners. One-on-one coaching conversations may be difficult for staff not used to participating in such conversations. Resonant leadership, as expected, has a significant impact on manager support and job satisfaction among nursing home staff.

Imaging Neurotensin Receptor in Prostate Cancer With 64Cu-Labeled Neurotensin Analogs.

INTRODUCTION: Neurotensin receptor 1 (NTR-1) is expressed and activated in prostate cancer cells. In this study, we explore the NTR expression in normal mouse tissues and study the positron emission tomography (PET) imaging of NTR in prostate cancer models. MATERIALS AND METHODS: Three 64Cu chelators (1, 4, 7, 10-tetraazacyclododecane-1, 4, 7, 10-tetraacetic acid [DOTA], 1,4,7-triazacyclononane-N,N',N″-triacetic acid [NOTA], or AmBaSar) were conjugated to an NT analog. Neurotensin receptor binding affinity was evaluated using cell binding assay. The imaging profile of radiolabeled probes was compared in well-established NTR+ HT-29 tumor model. Stability of the probes was tested. The selected agents were further evaluated in human prostate cancer PC3 xenografts. RESULTS: All 3 NT conjugates retained the majority of NTR binding affinity. In HT-29 tumor, all agents demonstrated prominent tumor uptake. Although comparable stability was observed, 64Cu-NOTA-NT and 64Cu-AmBaSar-NT demonstrated improved tumor to background contrast compared with 64Cu-DOTA-NT. Positron emission tomography/computed tomography imaging of the NTR expression in PC-3 xenografts showed high tumor uptake of the probes, correlating with the in vitro Western blot results. Blocking experiments further confirmed receptor specificity. CONCLUSIONS: Our results demonstrated that 64Cu-labeled neurotensin analogs are promising imaging agents for NTR-positive tumors. These agents may help us identify NTR-positive lesions and predict which patients and individual tumors are likely to respond to novel interventions targeting NTR-1.

Evaluation of neurotensin receptor 1 as a potential imaging target in pancreatic ductal adenocarcinoma.

Pancreatic cancer is one of the deadliest human malignancies and lack of effective diagnostic and therapeutic methods. Accumulating evidence suggests that the neurotensin (NT) and neurotensin receptors (NTRs) play key roles in pancreatic adenocarcinoma growth and survival. In this study, we not only evaluate the NTR1 expression in pancreatic cancer patient samples, but also explore the PET and fluorescence imaging of NTR1 expression in pancreatic cancer animal models. The NTR1 expression was evaluated by immunohistochemistry staining in clinical patient tissue samples with pancreatic ductal adenocarcinoma, insulinoma, and pancreatitis. The results showed 79.4% positive rate of NRT1 expression in pancreatic ductal adenocarcinoma, compared with 33.3 and 22.7% in insulinoma and pancreatitis samples, respectively. High NTR1 gene expression was also found in Panc-1 cells and confirmed by cell immunofluorescence. 64Cu-AmBaSar-NT and IRDye800-NT were synthesized as imaging probes and maintained the majority of NTR1-binding affinity. In vivo imaging demonstrated that 64Cu-AmBaSar-NT has prominent tumor uptake (3.76 ± 1.45 and 2.29 ± 0.10%ID/g at 1 and 4 h post-injection). NIR fluorescent imaging with IRDye800-NT demonstrated good tumor-to-background contrast (8.09 ± 0.38 × 108 and 6.67 ± 0.43 × 108 (p/s/cm2/sr)/(µW/cm2) at 30 and 60 min post-injection). Fluorescence guided surgery was also performed as a proof of principle experiment. In summary, our results indicated that NTR1 is a promising target for pancreatic ductal adenocarcinoma imaging and therapy. The imaging probes reported here may not only be considered for improved diagnosis of pancreatic ductal adenocarcinoma, but also has the potential to be fully integrated into patient screening and treatment monitoring of future NTR1 targeted therapies.

Molecular Imaging of P-glycoprotein in Chemoresistant Tumors Using a Dual-Modality PET/Fluorescence Probe.

Overexpression of P-glycoprotein (Pgp) has been considered a primary cause for multidrug resistance in a variety of cancers for three decades. However, clinical translation of Pgp targeted therapeutics has been hindered by lack of patient preselection based on the Pgp presence in tumors. We aim to develop a molecularly targeted probe for imaging tumoral Pgp in vivo with positron emission tomography (PET) and fluorescence, and to provide a tool for preselecting the patients with tumoral Pgp expression. Thus, a Pgp monoclonal antibody 15D3 was chemically modified with IRDye800 (IR800) and DOTA chelator. The specificity of the antibody conjugates DOTA-Pab-IR800 was verified in Pgp-expressing 3T3-MDR1 and control 3T3 cells. After radiolabeling with 64Cu, the probe was applied in small animal PET imaging of Pgp in a mouse xenograft model of NCI/ADR-Res cells, which are chemoresistant through overexpression of Pgp. Quantification analysis of the PET images demonstrated that the tumor uptake of the radioactive probe was 9.9 ± 1.4, 12.1 ± 1.2, and 10.5 ± 1.0%ID/g at 4, 24, and 48 h post injection. The tumor-to-muscle ratio was 20.9 at 48 h post injection based on biodistribution studies. Fluorescence imaging was performed following PET experiments, and it demonstrated excellent tumor accumulation of this dual-modality probe in the NCI/ADR-Res tumors. Further, an image-guided surgery was successfully performed using the fluorescence modality of the probe, demonstrating potential utility of this probe in image-guided surgical removal of Pgp-positive drug resistant tumors in the patients. In conclusion, this study clearly demonstrated that the Pgp-targeted antibody probe, 64Cu-DOTA-Pab-IR800, could provide a promising diagnosis tool for detection of Pgp-expressing tumors in vivo.

Red Blood Cell-Facilitated Photodynamic Therapy for Cancer Treatment.

Photodynamic therapy (PDT) is a promising treatment modality for cancer management. So far, most PDT studies have focused on delivery of photosensitizers to tumors. O2, another essential component of PDT, is not artificially delivered but taken from the biological milieu. However, cancer cells demand a large amount of O2 to sustain their growth and that often leads to low O2 levels in tumors. The PDT process may further potentiate the oxygen deficiency, and in turn, adversely affect the PDT efficiency. In the present study, a new technology called red blood cell (RBC)-facilitated PDT, or RBC-PDT, is introduced that can potentially solve the issue. As the name tells, RBC-PDT harnesses erythrocytes, an O2 transporter, as a carrier for photosensitizers. Because photosensitizers are adjacent to a carry-on O2 source, RBC-PDT can efficiently produce 1O2 even under low oxygen conditions. The treatment also benefits from the long circulation of RBCs, which ensures a high intraluminal concentration of photosensitizers during PDT and hence maximizes damage to tumor blood vessels. When tested in U87MG subcutaneous tumor models, RBC-PDT shows impressive tumor suppression (76.7%) that is attributable to the codelivery of O2 and photosensitizers. Overall, RBC-PDT is expected to find wide applications in modern oncology.