A small-molecule TrkB ligand improves dendritic spine phenotypes and atypical behaviors in female Rett syndrome mice.

Rett syndrome (RTT) is a neurodevelopmental disorder caused by mutations in MECP2, which encodes methyl-CpG-binding protein 2, a transcriptional regulator of many genes, including brain-derived neurotrophic factor (BDNF). BDNF levels are lower in multiple brain regions of Mecp2-deficient mice, and experimentally increasing BDNF levels improve atypical phenotypes in Mecp2 mutant mice. Due to the low blood-brain barrier permeability of BDNF itself, we tested the effects of LM22A-4, a brain-penetrant, small-molecule ligand of the BDNF receptor TrkB (encoded by Ntrk2), on dendritic spine density and form in hippocampal pyramidal neurons and on behavioral phenotypes in female Mecp2 heterozygous (HET) mice. A 4-week systemic treatment of Mecp2 HET mice with LM22A-4 restored spine volume in MeCP2-expressing neurons to wild-type (WT) levels, whereas spine volume in MeCP2-lacking neurons remained comparable to that in neurons from female WT mice. Female Mecp2 HET mice engaged in aggressive behaviors more than WT mice, the levels of which were reduced to WT levels by the 4-week LM22A-4 treatment. These data provide additional support to the potential usefulness of novel therapies not only for RTT but also to other BDNF-related disorders.

A small-molecule TrkB ligand improves dendritic spine phenotypes and atypical behaviors in female Rett syndrome mice.

Rett syndrome (RTT) is a neurodevelopmental disorder caused by mutations in methyl-CpG-binding protein-2 (MECP2), encoding a transcriptional regulator of many genes, including brain-derived neurotrophic factor (Bdnf). BDNF mRNA and protein levels are lower in RTT autopsy brains and in multiple brain regions of Mecp2-deficient mice, and experimentally increasing BDNF levels improve atypical phenotypes in Mecp2 mutant mice. Due to the low blood-brain barrier permeability of BDNF itself, we tested the effects of a brain penetrant, small molecule ligand of its TrkB receptors. Applied in vitro, LM22A-4 increased dendritic spine density in pyramidal neurons in cultured hippocampal slices from postnatal day (P) 7 male Mecp2 knockout (KO) mice as much as recombinant BDNF, and both effects were prevented by the TrkB receptor inhibitors K-252a and ANA-12. Consistent with its partial agonist activity, LM22A-4 did not affect spine density in CA1 pyramidal neurons in slice cultures from male wildtype (WT) mice, where typical BDNF levels outcompete its binding to TrkB. To identify neurons of known genotypes in the "mosaic" brain of female Mecp2 heterozygous (HET) mice, we treated 4-6-month-old female MeCP2-GFP WT and HET mice with peripheral injections of LM22A-4 for 4 weeks. Surprisingly, mutant neurons lacking MeCP2-GFP showed dendritic spine volumes comparable to that in WT controls, while MeCP2-GFP-expressing neurons showed larger spines, similar to the phenotype we described in symptomatic male Mecp2 KO mice where all neurons lack MeCP2. Consistent with this non-cell-autonomous mechanism, a 4-week systemic treatment with LM22A-4 had an effect only in MeCP2-GFP-expressing neurons in female Mecp2 HET mice, bringing dendritic spine volumes down to WT control levels, and without affecting spines of MeCP2-GFP-lacking neurons. At the behavioral level, we found that female Mecp2 HET mice engaged in aggressive behaviors significantly more than WT controls, which were reduced to WT levels by a 4-week systemic treatment with LM22A-4. Altogether, these data revealed differences in dendritic spine size and altered behaviors in Mecp2 HET mice, while providing support to the potential usefulness of BDNF-related therapeutic approaches such as the partial TrkB agonist LM22A-4.

National Trends in Hyperglycemia and Diabetic Ketoacidosis in Children, Adolescents, and Young Adults With Type 1 Diabetes: A Challenge Due to Age or Stage of Development, or Is New Thinking About Service Provision Needed?

OBJECTIVE: Adolescence is associated with high-risk hyperglycemia. This study examines the phenomenon in a life course context. RESEARCH DESIGN AND METHODS: A total of 93,125 people with type 1 diabetes aged 5 to 30 years were identified from the National Diabetes Audit and/or the National Paediatric Diabetes Audit for England and Wales for 2017/2018-2019/2020. For each audit year, the latest HbA1c and hospital admissions for diabetic ketoacidosis (DKA) were identified. Data were analyzed in sequential cohorts by year of age. RESULTS: In childhood, unreported HbA1c measurement is uncommon; however, for 19-year-olds, it increases to 22.3% for men and 17.3% for women, and then reduces to 17.9% and 13.1%, respectively, for 30-year-olds. Median HbA1c for 9-year-olds is 7.6% (60 mmol/mol) (interquartile range 7.1-8.4%, 54-68 mmol/mol) in boys and 7.7% (61 mmol/mol) (8.0-8.4%, 64-68 mmol/mol) in girls, increasing to 8.7% (72 mmol/mol) (7.5-10.3%, 59-89 mmol/mol) and 8.9% (74 mmol/mol) (7.7-10.6%, 61-92 mmol/mol), respectively, for 19-year-olds before falling to 8.4% (68 mmol/mol) (7.4-9.7%, 57-83 mmol/mol) and 8.2% (66 mmol/mol) (7.3-9.7%, 56-82 mmol/mol), respectively, for 30-year-olds. Annual hospitalization for DKA rose steadily in age from 6 years (2.0% for boys, 1.4% for girls) and peaked at 19 years for men (7.9%) and 18 years for women (12.7%), reducing to 4.3% for men and 5.4% for women at age 30 years. For all ages over 9 years, the prevalence of DKA was higher in female individuals. CONCLUSIONS: HbA1c and the prevalence of DKA increase through adolescence and then decline. Measurement of HbA1c, a marker of clinical review, falls abruptly in the late teenage years. Age-appropriate services are needed to overcome these issues.

Educational Attainment and Childhood-Onset Type 1 Diabetes.

OBJECTIVE: To quantify associations of educational outcomes with type 1 diabetes status and glycemic management (HbA1c). RESEARCH DESIGN AND METHODS: This was a record linkage study of schools and higher (college) education data sets linked to national diabetes audits. The population includes all Welsh children attending school between 2009 and 2016, yielding eight academic cohorts with attainment data, including 263,426 children without diabetes and 1,212 children diagnosed with type 1 diabetes. Outcomes include standardized educational attainment for those aged 16 years, higher education participation for those aged ≥18 years, and school absences among those aged 6-16 years. RESULTS: Comparison between children with type 1 diabetes and children without diabetes showed no strong evidence of associations for student attainment (0.001 SD, 95% CI -0.047 to 0.049, P < 0.96, n = 1,212 vs. 263,426) or higher education entry rates (odds ratio 1.067, 95% CI 0.919-1.239, P < 0.39, n = 965 vs. 217,191), despite nine more sessions of absence from school annually (P < 0.0001). However, attainment in children in the most optimal HbA1c quintile was substantially better than for children without diabetes (0.267 SD, 95% CI 0.160-0.374, P < 0.001) while being worse than for children without diabetes in the least optimal quintile (-0.395 SD, 95% CI -0.504 to -0.287, P < 0.001). Attainment did not differ by duration of "exposure" to diabetes based on age at diagnosis. CONCLUSIONS: Despite more school absences, diabetes diagnosis is not associated with educational attainment or entry into higher education, although attainment does vary by HbA1c level, which may be explained in part (or wholly) by unobserved shared personal, family, or socioeconomic characteristics associated with both success in education and effective glycemic self-management.

Differences in retinopathy prevalence and associated risk factors across 11 countries in three continents: A cross-sectional study of 156,090 children and adolescents with type 1 diabetes.

OBJECTIVE: To examine the prevalence, time trends, and risk factors of diabetic retinopathy (DR) among youth with type 1 diabetes (T1D) from 11 countries (Australia, Austria, Denmark, England, Germany, Italy, Luxemburg, Netherlands, Slovenia, United States, and Wales). SUBJECTS AND METHODS: Data on individuals aged 10-21 years with T1D for >1 year during the period 2000-2020 were analyzed. We used a cross-sectional design using the most recent year of visit to investigate the time trend. For datasets with longitudinal data, we aggregated the variables per participant and observational year, using data of the most recent year to take the longest observation period into account. DR screening was performed through quality assured national screening programs. Multiple logistic regression models adjusted for the year of the eye examination, age, gender, minority status, and duration of T1D were used to evaluate clinical characteristics and the risk of DR. RESULTS: Data from 156,090 individuals (47.1% female, median age 15.7 years, median duration of diabetes 5.2 years) were included. Overall, the unadjusted prevalence of any DR was 5.8%, varying from 0.0% (0/276) to 16.2% between countries. The probability of DR increased with longer disease duration (aORper-1-year-increase  = 1.04, 95% CI: 1.03-1.04, p < 0.0001), and decreased over time (aORper-1-year-increase  = 0.99, 95% CI: 0.98-1.00, p = 0.0093). Evaluating possible modifiable risk factors in the exploratory analysis, the probability of DR increased with higher HbA1c (aORper-1-mmol/mol-increase-in-HbA1c  = 1.03, 95% CI: 1.03-1.03, p < 0.0001) and was higher among individuals with hypertension (aOR = 1.24, 95% CI: 1.11-1.38, p < 0.0001) and smokers (aOR = 1.30, 95% CI: 1.17-1.44, p < 0.0001). CONCLUSIONS: The prevalence of DR in this large cohort of youth with T1D varied among countries, increased with diabetes duration, decreased over time, and was associated with higher HbA1c, hypertension, and smoking.

Temporal Changes in Hemoglobin A1c and Diabetes Technology Use in DPV, NPDA, and T1DX Pediatric Cohorts from 2010 to 2018.

Objective: The German/Austrian Diabetes Patient Follow-up Registry (Diabetes-Patienten-Verlaufsdokumentation or DPV), England/Wales National Pediatric Diabetes Audit (NPDA), and Type 1 Diabetes Exchange (T1DX) in the United States investigated changes in hemoglobin A1c (HbA1c) and diabetes technology use from 2010 to 2018. Methods: Registry/audit data from 2010 to 2018 were analyzed in annual cohorts using linear regression for those <18 years of age with type 1 diabetes diagnosed at age >6 months. Time trends in HbA1c, pump, and continuous glucose monitoring (CGM) use were studied using repeated measurements linear and logistic regression models with an autoregressive covariance structure and with year and data source as independent variables. Results: A total of 1,172,980 visits among 114,264 (54,119 DPV, 43,550 NPDA, 16,595 T1DX) patients were identified. HbA1c remained clinically stable in DPV (7.7% [61 mmol/mol] to 7.6% [60 mmol/mol]), decreased in the NPDA (8.7% [72 mmol/mol] to 7.9% [63 mmol/mol]), and increased in T1DX (8.0% [64 mmol/mol] to 8.5% [69 mmol/mol] from 2010 to 2018). In all registries/audits, insulin pump and CGM use increased over time with greatest pump use in T1DX and lowest uptake reported in NPDA. Conclusions: These data reveal three different longitudinal patterns of change in registry/audit HbA1c from 2010 to 2018. Diabetes technology use increased throughout, at different rates. Quality improvement (QI) programs in DPV have been ongoing for 25 years, began in NPDA in 2009 and T1DX in 2016. We speculate that in England/Wales, development of networks, peer review, and implementation of QI measures contributed to reductions in population HbA1c. Many of these interventions had been implemented in DPV before 2010. Further efforts to understand this improvement, including the role of QI, and continued success within standardized documentation and benchmarking could inform T1DX programs to reduce HbA1c.

A collaborative comparison of international pediatric diabetes registries.

BACKGROUND: An estimated 1.1 million children and adolescents aged under 20 years have type 1 diabetes worldwide. Principal investigators from seven well-established longitudinal pediatric diabetes registries and the SWEET initiative have come together to provide an international collaborative perspective and comparison of the registries. WORK FLOW: Information and data including registry characteristics, pediatric participant clinical characteristics, data availability and data completeness from the Australasian Diabetes Data Network (ADDN), Danish Registry of Childhood and Adolescent Diabetes (DanDiabKids), Diabetes prospective follow-up registry (DPV), Norwegian Childhood Diabetes Registry (NCDR), National Paediatric Diabetes Audit (NPDA), Swedish Childhood Diabetes Registry (Swediabkids), T1D Exchange Quality Improvement Collaborative (T1DX-QI), and the SWEET initiative was extracted up until 31 December 2020. REGISTRY OBJECTIVES AND OUTCOMES: The seven diabetes registries and the SWEET initiative collectively show data of more than 900 centers and around 100,000 pediatric patients, the majority with type 1 diabetes. All share the common objectives of monitoring treatment and longitudinal outcomes, promoting quality improvement and equality in diabetes care and enabling clinical research. All generate regular benchmark reports. Main differences were observed in the definition of the pediatric population, the inclusion of adults, documentation of CGM metrics and collection of raw data files as well as linkage to other data sources. The open benchmarking and access to regularly updated data may prove to be the most important contribution from registries. This study describes aspects of the registries to enable future collaborations and to encourage the development of new registries where they do not exist.

The role of MeCP2 in learning and memory.

Gene transcription is a crucial step in the sequence of molecular, synaptic, cellular, and systems mechanisms underlying learning and memory. Here, we review the experimental evidence demonstrating that alterations in the levels and functionality of the methylated DNA-binding transcriptional regulator MeCP2 are implicated in the learning and memory deficits present in mouse models of Rett syndrome and MECP2 duplication syndrome. The significant impact that MeCP2 has on gene transcription through a variety of mechanisms, combined with well-defined models of learning and memory, make MeCP2 an excellent candidate to exemplify the role of gene transcription in learning and memory. Together, these studies have strengthened the concept that precise control of activity-dependent gene transcription is a fundamental mechanism that ensures long-term adaptive behaviors necessary for the survival of individuals interacting with their congeners in an ever-changing environment.

Ventral hippocampal projections to the medial prefrontal cortex regulate social memory.

Inputs from the ventral hippocampus (vHIP) to the medial prefrontal cortex (mPFC) are implicated in several neuropsychiatric disorders. Here, we show that the vHIP-mPFC projection is hyperactive in the Mecp2 knockout mouse model of the autism spectrum disorder Rett syndrome, which has deficits in social memory. Long-term excitation of mPFC-projecting vHIP neurons in wild-type mice impaired social memory, whereas their long-term inhibition in Rett mice rescued social memory deficits. The extent of social memory improvement was negatively correlated with vHIP-evoked responses in mPFC slices, on a mouse-per-mouse basis. Acute manipulations of the vHIP-mPFC projection affected social memory in a region and behavior selective manner, suggesting that proper vHIP-mPFC signaling is necessary to recall social memories. In addition, we identified an altered pattern of vHIP innervation of mPFC neurons, and increased synaptic strength of vHIP inputs onto layer five pyramidal neurons as contributing factors of aberrant vHIP-mPFC signaling in Rett mice.

The World Health Organization Code and exclusive breastfeeding in China, India, and Vietnam.

Promoting exclusive breastfeeding (EBF) is a highly feasible and cost-effective means of improving child health. Regulating the marketing of breastmilk substitutes is critical to protecting EBF. In 1981, the World Health Assembly adopted the World Health Organization International Code of Marketing of Breastmilk Substitutes (the Code), prohibiting the unethical advertising and promotion of breastmilk substitutes. This comparative study aimed to (a) explore the relationships among Code enforcement and legislation, infant formula sales, and EBF in India, Vietnam, and China; (b) identify best practices for Code operationalization; and (c) identify pathways by which Code implementation may influence EBF. We conducted secondary descriptive analysis of available national-level data and seven high level key informant interviews. Findings indicate that the implementation of the Code is a necessary but insufficient step alone to improve breastfeeding outcomes. Other enabling factors, such as adequate maternity leave, training on breastfeeding for health professionals, health systems strengthening through the Baby Friendly Hospital Initiative, and breastfeeding counselling for mothers, are needed. Several infant formula industry strategies with strong conflict of interest were identified as harmful to EBF. Transitioning breastfeeding programmes from donor-led to government-owned is essential for long-term sustainability of Code implementation and enforcement. We conclude that the relationships among the Code, infant formula sales, and EBF in India, Vietnam, and China are dependent on countries' engagement with implementation strategies and the presence of other enabling factors.

Longitudinal far red gene-reporter imaging of cancer metastasis in preclinical models: a tool for accelerating drug discovery.

In this short communication, we demonstrate for the first time, the use of far red fluorescent gene reporter, iRFP to longitudinally and non-invasively track the in vivo process of lymphatic metastases from an orthotopic site of mammary implantation through lymphatic vessels and to draining lymph nodes. Potentially useful to accelerate cancer drug discovery as an in vivo screening tool to monitor the pharmacological arrest of metastasis, we show that the custom as well as commercial small animal imaging devices have adequate performance to detect the gene reporter in stably expressing metastatic cancer cells.

The camKK2/camKIV relay is an essential regulator of hepatic cancer.

UNLABELLED: Hepatic cancer is one of the most lethal cancers worldwide. Here, we report that the expression of Ca(2+) /calmodulin-dependent protein kinase kinase 2 (CaMKK2) is significantly up-regulated in hepatocellular carcinoma (HCC) and negatively correlated with HCC patient survival. The CaMKK2 protein is highly expressed in all eight hepatic cancer cell lines evaluated and is markedly up-regulated relative to normal primary hepatocytes. Loss of CaMKK2 function is sufficient to inhibit liver cancer cell growth, and the growth defect resulting from loss of CaMKK2 can be rescued by ectopic expression of wild-type CaMKK2 but not by kinase-inactive mutants. Cellular ablation of CaMKK2 using RNA interference yields a gene signature that correlates with improvement in HCC patient survival, and ablation or pharmacological inhibition of CaMKK2 with STO-609 impairs tumorigenicity of liver cancer cells in vivo. Moreover, CaMKK2 expression is up-regulated in a time-dependent manner in a carcinogen-induced HCC mouse model, and STO-609 treatment regresses hepatic tumor burden in this model. Mechanistically, CaMKK2 signals through Ca(2+) /calmodulin-dependent protein kinase 4 (CaMKIV) to control liver cancer cell growth. Further analysis revealed that CaMKK2 serves as a scaffold to assemble CaMKIV with key components of the mammalian target of rapamycin/ribosomal protein S6 kinase, 70 kDa, pathway and thereby stimulate protein synthesis through protein phosphorylation. CONCLUSION: The CaMKK2/CaMKIV relay is an upstream regulator of the oncogenic mammalian target of rapamycin/ribosomal protein S6 kinase, 70 kDa, pathway, and the importance of this CaMKK2/CaMKIV axis in HCC growth is confirmed by the potent growth inhibitory effects of genetically or pharmacologically decreasing CaMKK2 activity; collectively, these findings suggest that CaMKK2 and CaMKIV may represent potential targets for hepatic cancer.

Comparison of DOTA and NODAGA as chelators for (64)Cu-labeled immunoconjugates.

INTRODUCTION: Bifunctional chelators have been shown to impact the biodistribution of monoclonal antibody (mAb)-based imaging agents. Recently, radiolabeled 1,4,7-triazacyclononane,1-glutaric acid-4,7-acetic acid (NODAGA)-peptide complexes have demonstrated improved in vivo stability and performance compared to their 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) counterparts. Here, we investigated if similar utility could be achieved with mAbs and compared (64)Cu-labeled DOTA and NODAGA-immunoconjugates for the detection of epithelial cell adhesion molecule (EpCAM) in a prostate cancer model. METHODS: DOTA and NODAGA-immunoconjugates of an EpCAM targeting mAb (mAb7) were synthesized and radiolabeled with (64)Cu (DOTA: 40°C for 1hr; NODAGA: 25°C for 1hr). The average number of chelators per mAb was quantified by isotopic dilution, and the biological activity of the immunoconjugates was evaluated by flow cytometry and ELISA. Radioligand assays were performed to compare cellular uptake and determine the dissociation constant (Kd) and maximum number of binding sites (Bmax) for the immunoconjugates using DsRed-transfected PC3-cells. A PC3-DsRed xenograft tumor model was established in nude mice and used to perform biodistribution studies to compare organ uptake and pharmacokinetics. RESULTS: (64)Cu-DOTA-mAb7 and (64)Cu-NODAGA-mAb7 were prepared with chelator/protein ratios of 2-3 and obtained in comparable radiochemical yields ranging from 59 to 71%. Similar immunoreactivity was observed with both agents, and mock labeling studies indicated that incubation at room temperature or 40°C did not affect potency. (64)Cu-NODAGA-mAb7 demonstrated higher in vitro cellular uptake while (64)Cu-DOTA-mAb7 had higher Kd and Bmax values. From the biodistribution data, we found similar tumor uptake (13.44±1.21%ID/g and 13.24±4.86%ID/g for (64)Cu-DOTA-mAb7 and (64)Cu-NODAGA-mAb7, respectively) for both agents at 24hr, although normal prostate tissue was significantly lower for (64)Cu-NODAGA-mAb7. (64)Cu-NODAGA-mAb7 also had less accumulation in the liver, suggesting excellent retention of the chelation complex in vivo. This was further confirmed by the higher blood activity of (64)Cu-NODAGA-mAb7, which corresponds to increased bioavailability afforded by the enhanced in vivo stability of the agent. Although tumor/muscle ratios were comparable, tumor/prostate ratios were >2-fold and 1.5-fold higher for (64)Cu-NODAGA-mAb7 at 24 and 48hr, respectively, and suggest better ability to discriminate tumor tissue with (64)Cu-NODAGA-mAb7 in our prostate cancer model. CONCLUSIONS: To the best of our knowledge, this study represents the first comparison of (64)Cu-labeled DOTA and NODAGA immunoconjugates in vivo. Our results show favorable in vivo performance for (64)Cu-NODAGA-mAb7 which builds upon previous data on our hybrid mAb7 imaging agent by increasing the detection sensitivity for metastatic prostate tumors, as well as for other types of cancer that express EpCAM.

Deglycosylation of mAb by EndoS for improved molecular imaging.

PURPOSE: Monoclonal antibodies (mAbs) have been shown preclinically as reliable targeting moieties for antigen imaging using near-infrared fluorescence (NIRF) molecular imaging. However, crystallizable fragment-gamma receptor (FcγRs) expressed on immune cells also bind mAbs through defined epitopes on the constant fragment (Fc) of IgG. Herein, we evaluate the potential impact Fc interactions have on mAb agent imaging specificity. PROCEDURE: Through the removal of conserved glycans within the Fc domain, shown to have Fc/FcγR interactions, we evaluate their impact on non-specific binding/accumulation of a NIRF-labeled mAb-based imaging agent in lymph nodes (LNs) in inflamed animals and in an orthotopic prostate cancer animal model of LN metastasis. RESULTS: Deglycosylation of a murine mAb against the human epithelial cell adhesion marker using endoglycosidase EndoS significantly reduced non-specific binding in the LNs of inflamed animals and in cancer-negative LNs of tumor-bearing animals. Sensitivity remained unchanged while improvement in imaging specificity increased imaging accuracy. CONCLUSION: The reduction of non-specific binding through deglycosylation of a mAb-based imaging agent shows that reducing Fc/FcγR interactions can improve imaging accuracy.

Targeting pili in enterococcal pathogenesis.

Passive protection, the administration of antibodies to prevent infection, has garnered significant interest in recent years as a potential prophylactic countermeasure to decrease the prevalence of hospital-acquired infections. Pili, polymerized protein structures covalently anchored to the peptidoglycan wall of many Gram-positive pathogens, are ideal targets for antibody intervention, given their importance in establishing infection and their accessibility to antibody interactions. In this work, we demonstrated that a monoclonal antibody to the major component of Enterococcus faecalis pili, EbpC, labels polymerized pilus structures, diminishes biofilm formation, and significantly prevents the establishment of a rat endocarditis infection. The effectiveness of this anti-EbpC monoclonal provides strong evidence in support of its potential as a preventative. In addition, after radiolabeling, this monoclonal identified the site of enterococcal infection, providing a rare example of molecularly specific imaging of an established bacterial infection and demonstrating the versatility of this agent for use in future diagnostic and therapeutic applications.

In vivo imaging of orthotopic prostate cancer with far-red gene reporter fluorescence tomography and in vivo and ex vivo validation.

Fluorescence gene reporters have recently become available for excitation at far-red wavelengths, enabling opportunities for small animal in vivo gene reporter fluorescence tomography (GRFT). We employed multiple projections of the far-red fluorescence gene reporters IFP1.4 and iRFP, excited by a point source in transillumination geometry in order to reconstruct the location of orthotopically implanted human prostate cancer (PC3), which stably expresses the reporter. Reconstruction was performed using a linear radiative-transfer-based regularization-free tomographic method. Positron emission tomography (PET) imaging of a radiolabeled antibody-based agent that targeted epithelial cell adhesion molecule overexpressed on PC3 cells was used to confirm in vivo GRFT results. Validation of GRFT results was also conducted from ex vivo fluorescence imaging of resected prostate tumor. In addition, in mice with large primary prostate tumors, a combination of GRFT and PET showed that the radiolabeled antibody did not penetrate the tumor, consistent with known tumor transport limitations of large (∼150 kDa) molecules. These results represent the first tomography of a living animal using far-red gene reporters.

Detection of lymphangiogenesis by near-infrared fluorescence imaging and responses to VEGF-C during healing in a mouse full-dermis thickness wound model.

Noninvasive, longitudinal near-infrared fluorescence (NIRF) imaging was used to detect and quantify lymphangiogenesis following a full-dermis thickness incision in the presence and absence of locally administered vascular endothelial growth factor-C (VEGF-C), a well-known regulator of lymphangiogenesis. Peripheral cytokines/chemokines were also measured in treated and sham-injected animals. Lymphangiogenesis was detected via NIRF imaging by day 7-8 and confirmed by intravital microscopy, while angiogenesis was observed by day 2-3 postincision (PI). All lymph vessel parameters quantified were significantly greater on wounded vs. nonwounded sides of mice. Lymph vessel parameters appeared larger on wounded sides of VEGF-C- relative to NaCl-treated mice, although differences were not significant. Interleukin-1α and interleukin-22 were significantly elevated at day 7 PI relative to respective preincision levels in VEGF-C-treated mice, and decreased by day 21 PI to levels nearing those measured preincision. For the majority of cytokines/chemokines measured, mean responses were significantly greater in VEGF-C- vs. NaCl-treated animals. Local VEGF-C administration may stimulate lymphangiogenesis during tissue repair and regeneration via mediating systemic cytokine/chemokine levels. NIRF imaging can be utilized to detect lymphangiogenesis during wound healing, and offers a promising platform to complement current methods for monitoring wound status and studying the effects of growth factors on healing.

Tumor margin detection using quantitative NIRF molecular imaging targeting EpCAM validated by far red gene reporter iRFP.

PURPOSE: Wide-field surgical excision reduces the chance of residual disease, but can also lead to disfigurement and devastating morbidities when resection is close to critical structures. We hypothesize that near-infrared fluorescence (NIRF) imaging can enable accurate detection of tumor margins for image-guided resection. EXPERIMENTAL DESIGN: An orthotopic model of human prostate cancer (PCa) was used to assess primary tumor margins using a NIRF-labeled antibody against epithelial cell adhesion molecule (EpCAM). PCa cells stably expressing far red fluorescent gene reporter, iRFP, enabled colocalization with NIRF signals for direct assessment of tumor margins. RESULTS: Using receiver operating characteristic analysis, far red fluorescence was validated against standard pathology of primary and metastatic lesions with >96 % accuracy. Primary tumor margins were more accurately detected by quantitative NIRF imaging using the EpCAM-targeting antibody as compared to a NIRF-labeled isotype control antibody. CONCLUSIONS: NIRF molecular imaging may enable real-time and accurate assessment of tumor margins.

Non-invasive optical imaging of the lymphatic vasculature of a mouse.

The lymphatic vascular system is an important component of the circulatory system that maintains fluid homeostasis, provides immune surveillance, and mediates fat absorption in the gut. Yet despite its critical function, there is comparatively little understanding of how the lymphatic system adapts to serve these functions in health and disease. Recently, we have demonstrated the ability to dynamically image lymphatic architecture and lymph "pumping" action in normal human subjects as well as in persons suffering lymphatic dysfunction using trace administration of a near-infrared fluorescent (NIRF) dye and a custom, Gen III-intensified imaging system. NIRF imaging showed dramatic changes in lymphatic architecture and function with human disease. It remains unclear how these changes occur and new animal models are being developed to elucidate their genetic and molecular basis. In this protocol, we present NIRF lymphatic, small animal imaging using indocyanine green (ICG), a dye that has been used for 50 years in humans, and a NIRF dye-labeled cyclic albumin binding domain (cABD-IRDye800) peptide that preferentially binds mouse and human albumin. Approximately 5.5 times brighter than ICG, cABD-IRDye800 has a similar lymphatic clearance profile and can be injected in smaller doses than ICG to achieve sufficient NIRF signals for imaging. Because both cABD-IRDye800 and ICG bind to albumin in the interstitial space, they both may depict active protein transport into and within the lymphatics. Intradermal (ID) injections (5-50 µl) of ICG (645 µM) or cABD-IRDye800 (200 µM) in saline are administered to the dorsal aspect of each hind paw and/or the left and right side of the base of the tail of an isoflurane-anesthetized mouse. The resulting dye concentration in the animal is 83-1,250 µg/kg for ICG or 113-1,700 µg/kg for cABD-IRDye800. Immediately following injections, functional lymphatic imaging is conducted for up to 1 hr using a customized, small animal NIRF imaging system. Whole animal spatial resolution can depict fluorescent lymphatic vessels of 100 microns or less, and images of structures up to 3 cm in depth can be acquired. Images are acquired using V++ software and analyzed using ImageJ or MATLAB software. During analysis, consecutive regions of interest (ROIs) encompassing the entire vessel diameter are drawn along a given lymph vessel. The dimensions for each ROI are kept constant for a given vessel and NIRF intensity is measured for each ROI to quantitatively assess "packets" of lymph moving through vessels.

Multimodal chelation platform for near-infrared fluorescence/nuclear imaging.

Dual-labeled compounds containing nuclear and near-infrared fluorescence contrast have the potential to molecularly guide surgical resection of cancer by extending whole-body diagnostic imaging findings into the surgical suite. To simplify the dual labeling process for antibody-based agents, we designed a multimodality chelation (MMC) scaffold which combined a radiometal chelating agent and fluorescent dye into a single moiety. Three dye-derivatized MMC compounds were synthesized and radiolabeled. The IRDye 800CW conjugate, 4, had favorable optical properties and showed rapid clearance in vivo. Using 4, an epithelial cell adhesion molecule (EpCAM) targeting MMC-immunoconjugate was prepared and dual-labeled with (64)Cu. In vitro binding activity was confirmed after MMC conjugation. Multimodal imaging studies showed higher tumor accumulation of (64)Cu-7 compared to nontargeted (64)Cu-4 in a prostate cancer model. Further evaluation in different EpCAM-expressing cell lines is warranted as well as application of the MMC dual labeling approach with other monoclonal antibodies.