Structure-Inherent Targeting of Near-Infrared Fluorophores for Image-Guided Surgery

Small Mitochondria-Targeting Fluorophore with Multifunctional Therapeutic Activities against Prostate Cancer via the HIF1α/OATPs Pathway

Prostate cancer (PCa) is considered to be the most prevalent malignancy in males worldwide. Abiraterone is a 17α-hydroxylase/C17, 20-lyase (CYP17) inhibitor that has been approved for use in patients with prostate cancer. However, several negative aspects, such as drug resistance, toxicity, and lack of real-time monitoring of treatment responses, could appear with long-term use. Therefore, the development of anticancer agents with specific targeting to avoid side effects is imperative. Here, we used MHI-148, a type of heptamethine cyanine (HC) near-infrared fluorescence dye (NIRF), as a prototype structure to synthesize two theranostic agents, Abi-DZ-1 and Abi-783. The new compound Abi-DZ-1 retained the excellent photophysical characteristics and NIRF imaging property of MHI-148, and it could preferentially accumulate in prostate cancer cells but not in normal prostate epithelial cells via the HIF1α/organic anion-transporting polypeptides axis. NIRF imaging using Abi-DZ-1 selectively identified tumors in mice bearing PCa xenografts. Moreover, Abi-DZ-1 treatment significantly retarded the tumor growth in both a cell-derived xenograft model and a patient-derived tumor xenograft model. This finding demonstrated that Abi-DZ-1 may hold promise as a potential multifunctional theranostic agent for future tumor-targeted imaging and precision therapy. Constructing theranostic agents using the NIRF dye platform holds great promise in accurate therapy and intraoperative navigation.

Near-infrared fluorophores methylene blue for targeted imaging of the stomach in intraoperative navigation

Near-infrared (NIR) fluorescence imaging-guided surgery is increasingly concerned in gastrointestinal surgery because it can potentially improve clinical outcomes. This new technique can provide intraoperative image guidance for surgical margin evaluation and help surgeons examine residual lesions and small tumors during surgery. NIR fluorophores methylene blue (MB) is a promising fluorescent probe because of its safety and intraoperative imaging in the clinic. However, whether MB possesses the potential to perform intraoperative navigation of the stomach and gastric tumors needs to be further explored. Therefore, the current study mainly validated MB's usefulness in animal models' intraoperative imaging of stomach and gastric tumors. NIR fluorophores MB can exhibit specific uptake by the gastric epithelial cells and cancer cells. It is primarily found that MB can directly target the stomach in mice. Interestingly, MB was applied for the NIR imaging of gastric cancer cell xenografts, suggesting that MB cannot specifically target subcutaneous and orthotopic gastric tumors in xenograft models. Thus, it can be concluded that MB has no inherent specificity for gastric tumors but specificity for gastric tissues. Apparently, MB-positive and negative NIR imaging are meaningful in targeting gastric tissues and tumors. MB is expected to represent a helpful NIR agent to secure precise resection margins during the gastrectomy and resection of gastric tumors.

Near-infrared-dye labeled tumor vascular-targeted dimer GEBP11 peptide for image-guided surgery in gastric cancer

Introduction

Positive resection margins occur in about 2.8%-8.2% gastric cancer surgeries and is associated with poor prognosis. Intraoperative guidance using Nearinfrared (NIR) fluorescence imaging is a promising technique for tumor detection and margin assessment. The goal of this study was to develop a tumor-specific probe for real-time intraoperative NIR fluorescence imaging guidance.

Methods

The tumor vascular homing peptide specific for gastric cancer, GEBP11, was conjugated with a near-infrared fluorophore, Cy5.5. The binding specificity of the GEBP11 probes to tumor vascular endothelial cells were confirmed by immunofluorescent staining. The ability of the probe to detect tumor lesions was evaluated in two xenograft models. An orthotopic gastric cancer xenograft model was used to evaluate the efficacy of the GEBP11 NIR probes in real-time surgical guidance.

Results

In vitro assay suggested that both mono and dimeric GEBP11 NIR probes could bind specifically to tumor vascular epithelial cells, with dimeric peptides showed better affinity. In tumor xenograft mice, live imaging suggested that comparing with free Cy5.5 probe, significantly stronger NIR signals could be detected at the tumor site at 24-48h after injection of mono or dimeric GEBP11 probes. Dimeric GEBP11 probe showed prolonged and stronger NIR signals than mono GEBP11 probe. Biodistribution assay suggested that GEBP11 NIR probes were enriched in gastric cancer xenografts. Using dimeric GEBP11 NIR probes in real-time surgery, the tumor margins and peritoneal metastases could be clearly visualized. Histological examination confirmed the complete resection of the tumor.

Conclusion

(GEBP11)2-ACP-Cy5.5 could be a potential useful probe for intraoperative florescence guidance in gastric cancer surgery.

In vivo fluorescence imaging: success in preclinical imaging paves the way for clinical applications

Advances in diagnostic imaging have provided unprecedented opportunities to detect diseases at early stages and with high reliability. Diagnostic imaging is also crucial to monitoring the progress or remission of disease and thus is often the central basis of therapeutic decision-making. Currently, several diagnostic imaging modalities (computed tomography, magnetic resonance imaging, and positron emission tomography, among others) are routinely used in clinics and present their own advantages and limitations. In vivo near-infrared (NIR) fluorescence imaging has recently emerged as an attractive imaging modality combining low cost, high sensitivity, and relative safety. As a preclinical tool, it can be used to investigate disease mechanisms and for testing novel diagnostics and therapeutics prior to their clinical use. However, the limited depth of tissue penetration is a major challenge to efficient clinical use. Therefore, the current clinical use of fluorescence imaging is limited to a few applications such as image-guided surgery on tumors and retinal angiography, using FDA-approved dyes. Progress in fluorophore development and NIR imaging technologies holds promise to extend their clinical application to oncology, cardiovascular diseases, plastic surgery, and brain imaging, among others. Nanotechnology is expected to revolutionize diagnostic in vivo fluorescence imaging through targeted delivery of NIR fluorescent probes using antibody conjugation. In this review, we discuss the latest advances in in vivo fluorescence imaging technologies, NIR fluorescent probes, and current and future clinical applications.

How to dissect the pelvic nerves: from microanatomy to surgical rules. An evidence-based clinical review

Background: Advanced gynaecological procedures often include extensive pelvic dissections, with the nervous structures involved in the disease. Nerve-sparing and preservation is a key factor in reducing postoperative morbidity. Objectives: The goal of this review is to describe in detail the structure of the pelvic nerves and to gather information from other surgical specialties to give recommendations for safe nerve dissection applied in different gynaecological subspecialties. Materials and methods: An extensive literature review was carried out in PubMed and Google Scholar. The search included articles concerning peripheral nerve anatomy, mechanisms of injury and different dissection techniques, with the most exhaustive being analysed for the review. Articles from different fields of medicine like orthopaedics, plastic surgery, maxillofacial surgery dealing with peripheral nerve injuries and repair have been reviewed. Results: The following review demonstrates the in-depth anatomy and mechanism of injury of the peripheral nerves, describes the different techniques for neurolysis and proposes some directions for safe nerve dissection. Conclusion: When performing complex gynaecological surgeries, the surgeon should avoid unnecessary nerve handling, apply nerve-sparing techniques whenever possible and use the new devices to preserve the nervous structures. Advanced gynaecological surgeries should be performed in specialised centres by expert surgeons with comprehensive knowledge in neuropelveology. What is new? To our knowledge, this is the first article focused on peripheral nerves that collects data from such a wide range of specialties in order to propose the most comprehensive recommendations that could be applied in pelvic surgery.

Tumor-Associated Immune-Cell-Mediated Tumor-Targeting Mechanism with NIR-II Fluorescence Imaging

The strategy of structure-inherent tumor targeting (SITT) with cyanine-based fluorophores is receiving more attention because no chemical conjugation of targeting moieties is required. However, the targeting mechanism behind SITT has not yet been well explained. Here, it is demonstrated that heptamethine-cyanine-based fluorophores possess not only targetability of tumor microenvironments without the need for additional targeting ligands but also second near-infrared spectral window (NIR-II) imaging capabilities, i.e., minimum scattering and ultralow autofluorescence. The new SITT mechanism suggests that bone-marrow-derived and/or tissue-resident/tumor-associated immune cells can be a principal target for cancer detection due to their abundance in tumoral tissues. Among the tested, SH1 provides ubiquitous tumor targetability and a high tumor-to-background ratio (TBR) ranging from 9.5 to 47 in pancreatic, breast, and lung cancer mouse models upon a single bolus intravenous injection. Furthermore, SH1 can be used to detect small cancerous tissues smaller than 2 mm in diameter in orthotopic lung cancer models. Thus, SH1 could be a promising cancer-targeting agent and have a bright future for intraoperative optical imaging and image-guided cancer surgery.

Label-Free Iron Oxide Nanoparticles as Multimodal Contrast Agents in Cells Using Multi-Photon and Magnetic Resonance Imaging

INTRODUCTION

The inherent fluorescence properties of iron oxide nanoparticles (IONPs) were characterized, and their applicability for multiphoton imaging in cells was tested in combination with their magnetic resonance imaging (MRI) capabilities.

METHODS

Superparamagnetic iron oxide nanoparticles were synthesized and subsequently coated with polyethylene glycol to make them water-dispersible. Further characterization of the particles was performed using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), dynamic light scattering (DLS), superconducting quantum interference device (SQUID) and magnetic resonance relaxivity measurements. MRI and fluorescence properties of bare IONPs were first studied in solution and subsequently in A549-labeled cells.

RESULTS

The particles, with a core size of 11.3 ± 4.5 nm, showed a good negative MRI contrast in tissue-mimicking phantoms. In vitro studies in mammalian A549 cells demonstrate that these IONPs are biocompatible and can also produce significant T2/T2* contrast enhancement in IONPs-labeled cells. Furthermore, excitation-wavelength dependent photoluminescence was observed under one- and two-photon excitation.

DISCUSSION

The obtained results indicated that IONPs could be used for fluorescence label-free bioimaging at multiple wavelengths, which was proven by multiphoton imaging of IONPs internalization in A549 cancer cells.

Tumor-targeted near-infrared fluorophore for fluorescence-guided phototherapy

A tumor-targeted near-infrared (NIR) fluorophore CA800SO3 was developed for fluorescence-guided phototherapy. This new type of NIR fluorophore showed high tumor targetability based on the structure-inherent targeting approach. This fluorophore generated sufficient hyperthermia and reactive oxygen species (ROS) simultaneously for synergistic cancer phototherapy, induced by an 808 nm laser irradiation.

Stimulus-Responsive Sequential Release Systems for Drug and Gene Delivery

In recent years, a range of studies have been conducted with the aim to design and characterize delivery systems that are able to release multiple therapeutic agents in controlled and programmed temporal sequences, or with spatial resolution inside the body. This sequential release occurs in response to different stimuli, including changes in pH, redox potential, enzyme activity, temperature gradients, light irradiation, and by applying external magnetic and electrical fields. Sequential release (SR)-based delivery systems, are often based on a range of different micro- or nanocarriers and may offer a silver bullet in the battle against various diseases, such as cancer. Their distinctive characteristic is the ability to release one or more drugs (or release drugs along with genes) in a controlled sequence at different times or at different sites. This approach can lengthen gene expression periods, reduce the side effects of drugs, enhance the efficacy of drugs, and induce an anti-proliferative effect on cancer cells due to the synergistic effects of genes and drugs. The key objective of this review is to summarize recent progress in SR-based drug/gene delivery systems for cancer and other diseases.

Zwitterionic near-infrared fluorophore for targeted photothermal cancer therapy

A zwitterionic NIR fluorophore ZW800-Cl showed intrinsic preferential tumor accumulation and an excellent photothermal capability without the need for chemical modifications with tumor-specific ligands and photosensitizers.

NIR fluorescence-guided tumor surgery: new strategies for the use of indocyanine green

Surgery is the frontline treatment for a large number of cancers. The objective of these excisional surgeries is the complete removal of the primary tumor with sufficient safety margins. Removal of the entire tumor is essential to improve the chances of a full recovery. To help surgeons achieve this objective, near-infrared fluorescence-guided surgical techniques are of great interest. The concomitant use of fluorescence and indocyanine green (ICG) has proved effective in the identification and characterization of tumors. Moreover, ICG is authorized by the Food and Drug Administration and the European Medicines Agency and is therefore the subject of a large number of studies. ICG is one of the most commonly used fluorophores in near-infrared fluorescence-guided techniques. However, it also has some disadvantages, such as limited photostability, a moderate fluorescence quantum yield, a high plasma protein binding rate, and undesired aggregation in aqueous solution. In addition, ICG does not specifically target tumor cells. One way to exploit the capabilities of ICG while offsetting these drawbacks is to develop high-performance near-infrared nanocomplexes formulated with ICG (with high selectivity for tumors, high tumor-to-background ratios, and minimal toxicity). In this review article, we focus on recent developments in ICG complexation strategies to improve near-infrared fluorescence-guided tumor surgery. We describe targeted and nontargeted ICG nanoparticle models and ICG complexation with targeting agents.

Near-Infrared Fluorescent Sorbitol Probe for Targeted Photothermal Cancer Therapy

Abstract: Photothermal therapy (PTT) using a near-infrared (NIR) heptamethine cyanine fluorophore has emerged as an alternative strategy for targeted cancer therapy. NIR fluorophores showing a high molar extinction coefficient and low fluorescence quantum yield have considerable potential applications in photothermal cancer therapy. In this study, a bifunctional sorbitol-ZW800 conjugate was used as an advanced concept of photothermal therapeutic agents for in vivo cancer imaging and therapy owing to the high tumor targetability of the sorbitol moiety and excellent photothermal property of NIR heptamethine cyanine fluorophore. The sorbitol-ZW800 showed an excellent photothermal effect increased by 58.7 °C after NIR laser irradiation (1.1 W/cm2) for 5 min. The HT-29 tumors targeted by sorbitol-ZW800 showed a significant decrease in tumor volumes for 7 days after photothermal treatment. Therefore, combining the bifunctional sorbitol-ZW800 conjugate and NIR laser irradiation is an alternative way for targeted cancer therapy, and this approach holds great promise as a safe and highly efficient NIR photothermal agent for future clinical applications.

Near-Infrared Contrast Agents for Bone-Targeted Imaging

Background

For the bone-specific imaging, a structure-inherent targeting of bone tissue recently has been reported a new strategy based on incorporation of targeting moieties into the chemical structure of near-infrared (NIR) contrast agents, while conventional methods require covalent conjugation of bone-targeting ligands to NIR contrast agents. This will be a new approach for bone-targeted imaging by using the bifunctional NIR contrast agents.

Methods

The goal of this review is to provide an overview of the recent advances in optical imaging of bone tissue, highlighting the structure-inherent targeting by developing NIR contrast agents without the need for a bone-targeting ligand such as bisphosphonates.

Results

A series of iminodiacetated and phosphonated NIR contrast agents for the structure-inherent targeting of bone tissue showed excellent bone-targeting ability in vivo without non-specific binding. Additionally, the phosphonated NIR contrast agents could be useful in the diagnosis of bone metastasis.

Conclusion

By developing bone-targeted NIR contrast agents, optical imaging of bone tissue makes it very attractive for preclinical studies of bone growth or real-time fluorescence guided surgery resulting in high potential to shift the clinical paradigms.

Real-Time Fluorescence Imaging in Thoracic Surgery

Near-infrared (NIR) fluorescence imaging provides a safe and cost-efficient method for immediate data acquisition and visualization of tissues, with technical advantages including minimal autofluorescence, reduced photon absorption, and low scattering in tissue. In this review, we introduce recent advances in NIR fluorescence imaging systems for thoracic surgery that improve the identification of vital tissues and facilitate the resection of tumorous tissues. When coupled with appropriate NIR fluorophores, NIR fluorescence imaging may transform current intraoperative thoracic surgery methods by enhancing the precision of surgical procedures and augmenting postoperative outcomes through improvements in diagnostic accuracy and reductions in the remission rate.

pH-dependent and cathepsin B activable CaCO3 nanoprobe for targeted in vivo tumor imaging

Background: The intraoperative visualization of tumor cells is a powerful modality for surgical treatment of solid tumors. Since the completeness of tumor excision is closely correlated with the survival of patients, probes that can assist in distinguishing tumor cells are highly demanded.

Purpose: In the present study, a fluorescent probe JF1 was synthesized for imaging of tumor cells by conjugating a substrate of cathepsin B (quenching moiety) to Oregon Green derivative JF2 using a self-immolative linker.

Methods: JF1 was then loaded into the folate-PEG modified CaCO₃ nanoparticles. The folate receptor-targeted, pH-dependent, and cathepsin B activable CaCO₃ nanoprobe was test in vitro and in vivo for tumor imaging.

Results: CaCO₃ nanoprobe demonstrated good stability and fast lighting ability in tumors under low pH conditions. It also showed lower fluorescence background than the single cathepsin B dependent fluorescent probe. The pH-dependent and cathepsin B controlled “turn-on” property enables precise and fast indication of tumor in vitro and in vivo.

Conclusion: This strategy of controlled drug delivery enables in vivo imaging of tumor nodules with a high signal-to-noise ratio, which has great potential in surgical tumor treatment.

Polymalic acid chlorotoxin nanoconjugate for near-infrared fluorescence guided resection of glioblastoma multiforme

Maximal surgical resection of glioma remains the single most effective treatment. Tools to guide the resection while avoiding removal of normal brain tissues can aid surgeons in achieving optimal results. One strategy to achieve this goal is to rely upon interoperative fluorescence staining of tumor cells in vivo, that can be visualized by the surgeon during resection. Towards this goal we have designed a biodegradable fluorescent mini nano imaging agent (NIA) with high specificity for U87MG glioma cells and previously unmet high light emission. The NIA is the conjugate of polymalic acid (PMLA) with chlorotoxin for tumor targeting, indocyanine green (ICG) for NIR fluorescence and the tri-leucin peptide as fluorescence enhancer. PMLA as a multivalent platform carries several molecules of ICG and the other ligands. The NIA recognizes multiple sites on glioma cell surface, demonstrated by the effects of single and combined competitors. Systemic IV injection into xenogeneic mouse model carrying human U87MG glioblastoma indicated vivid tumor cell binding and internalization of NIA resulting in intensive and long-lasting tumor fluorescence. The NIA is shown to greatly improve tumor removal supporting its utility in clinical applications.

An NIR-Fluorophore-Based Therapeutic Endoplasmic Reticulum Stress Inducer

The endoplasmic reticulum (ER) stress signaling or unfolded protein response (UPR) is a common feature of many human diseases, including cancer. Excessive activation of ER stress directly induces cell death, holding a new promising strategy for the therapeutic intervention of cancer. Current ER-stress-inducing agents mainly target UPR components or proteasomes, which exert limited treatment efficacy and undesired side effects due to unselective ER stress and poor tumor-specific distribution. In this study, a unique near-infrared (NIR) fluorophore, IR-34, is synthesized and identified to selectively and efficiently trigger tumoricidal ER stress by targeting the mitochondrial protein NDUFS1. IR-34 is demonstrated to specifically accumulate in living cancer cells for tumor NIR imaging and drastically inhibit tumor growth and recurrence without causing apparent toxicity. Thus, this multifunctional NIR fluorophore may represent a novel theranostic agent for tumor imaging-guided treatment and also strengthens the idea that mitochondria could be a useful target for therapeutic ER stress in cancer cells.

Real-Time Tracking of Ex Vivo-Expanded Natural Killer Cells Toward Human Triple-Negative Breast Cancers

Introduction

Ex vivo-expanded natural killer (NK) cells are a potential candidate for cancer immunotherapy based on high cytotoxicity against malignant tumor cells. However, a limited understanding of the migration of activated NK cells toward solid tumors is a critical dilemma in the development of effective and adoptive NK cell-based immunotherapy.

Methods

Ex vivo-expanded NK cells from healthy donors were stained with near-infrared fluorophores at different concentrations. NK cell proliferation and cytotoxicity were assessed using a WST-8 assay, while the expression levels of surface molecules were analyzed by flow cytometry. To investigate the biodistribution of NK cells in both normal and tumor-bearing NSG mice, NK cells labeled with ESNF13 were subjected to NIR fluorescence imaging using the Mini-FLARE imaging system. Finally, mice were sacrificed and histopathological tests were performed in resected organs.

Results

The signal intensity of ESNF-stained NK cells was long-lasting at 72 h using concentrations as low as 0.04 µM. At a low dose range, ESNF13 did not affect NK cell purity, expression levels of surface receptors, or cytotoxic functions against MDA-MB-231 cancer cells. Ex vivo-expanded NK cells labeled with ESNF13 had a 4-h biodistribution in non-tumor-bearing NSG mice that mainly localized to the lungs immediately after injection and then fully migrated to the kidney after 4 h. In an MDA-MB-231 tumor-bearing NSG mice with extensive metastasis in both lungs, the fluorescence signal was dominant in both lungs and steady at 1, 2, and 4 h post-injection. In a early phase of tumor progression, administered NK cell migrated to the lungs and tumor sites within 30 min post-injection, the signal dominated the tumor site after 1 h, and remained steady at 4 h.

Conclusion

Optical imaging with NIR fluorophore ESNF13 is a highly sensitive, applicable, and inexpensive method for the real-time tracking of ex vivo-expanded NK cells both in vitro and in vivo. Administered NK cells had different patterns of NK cell distribution and accumulation to the tumor site according to tumor progression in triple-negative breast cancer xenograft models.

Rapid Differential Diagnosis of Breast Microcalcification Using Targeted Near-Infrared Fluorophores

Early detection and differential diagnosis of breast microcalcifications are of significant importance in effective treatment of early breast cancer, because mineral composition of breast calcification is directly associated with different pathological states. However, applying image-based modalities for component identification in breast calcification remains challenging, because no calcification-specific contrast agent is available to distinguish between benign and malignant (type I and type II, respectively) calcifications of breast lesions. In this study, real-time near-infrared (NIR) fluorescence imaging of breast microcalcifications using targeted NIR fluorophores in combination with dual-channel NIR fluorescence imaging system is reported. This strategy can be used to solve major problem in mammography and ultrasonography methods for the differentiation of benign and malignant microcalcifications. Thus, this novel technology shows significant potential for breast cancer diagnosis and image-guided surgery performed with increased precision and efficiency by providing differential diagnosis of breast microcalcifications.

Low-Dose Evans Blue Dye for Near-Infrared Fluorescence Imaging in Photothrombotic Stroke Model

Background: Evans blue dye (EBD) is the most common indicator to analyze the extent of blood-brain barrier (BBB) breakdown in several neurological disease models. However, the high-dose of EBD (51.9 mg/kg) is usually required for visualization of blue color by the human eye that brings potential safety issues. Methods: To solve this problem, low-dose of EBD was applied for the near-infrared (NIR) fluorescence-assisted quantitation of BBB breakdown in photothrombotic stoke model. Animals were allocated to seven dose groups ranging from 1.35 nmol (5.19 μg/kg) to 13.5 μmol (51.9 mg/kg) EBD. Results: EBD was undetectable in the non-ischemic brain tissue, and the fluorescence signals in the infarcted hemisphere seemed proportional to the injected dose in the dose range. Although the maximum fluorescence signals in brain tissue were obtained with the injections of 1.35 nmol ~ 13.5 μmol EBD, the background signals in the neighboring brain tissues were significantly increased as well. Since the high concentration of EBD is necessary for color-based identification of the infarcted lesion in brain tissues, even 10-fold diluted could not be distinguished visually by naked eye. Conclusions: NIR fluorescence-assisted method could potentially provide new opportunities to study BBB leakage just using small amount of EBD in different pathological conditions and to test the efficacy of various therapeutic strategies to protect the BBB.

Evaluation of a Centyrin-Based Near-Infrared Probe for Fluorescence-Guided Surgery of Epidermal Growth Factor Receptor Positive Tumors

Tumor-targeted near-infrared fluorescent dyes have the potential to improve cancer surgery by enabling surgeons to locate and resect more malignant lesions where good visualization tools are required to ensure complete removal of malignant tissue. Although the tumor-targeted fluorescent dyes used in humans to date have been either small organic molecules or high molecular weight antibodies, low molecular weight protein scaffolds have attracted significant attention because they penetrate solid tumors almost as efficiently as small molecules, but can be infinitely mutated to bind almost any antigen. Here we describe the use of a 10 kDa protein scaffold, a Centyrin, to target a near-infrared fluorescent dye to tumors that overexpress the epidermal growth factor receptor (EGFR) for fluorescence-guided surgery (FGS). We have developed and optimized the dose and time required for imaging small tumor burdens with minimal background fluorescence in real-time fluorescence-guided surgery of EGFR-expressing tumor xenografts in murine models. We demonstrate that the Centyrin-near-infrared dye conjugate (CNDC) binds selectively to human EGFR+ cancer cells with an EC50 of 2 nM, localizes to EGFR+ tumor xenografts in athymic nude mice and that uptake of the dye in xenografts is significantly reduced when EGFR are blocked by preinjection of excess unlabeled Centyrin. Taken together, these data suggest that CNDCs can be used for intraoperative identification and surgical removal of EGFR-expressing lesions and that Centyrins targeted to other tumor-specific antigens should prove similarly useful in fluorescence guided surgery of cancer. In addition, we demonstrate that the CNDC is detected in the NIR region of the spectrum and can be utilized for fluorescence-guided surgery (FGS). In addition, we propose that with its eventual complete clearance from EGFR-negative tissues and its quantitative retention in the tumor mass for >24 h, a Centyrin-targeted NIR dye should provide excellent tumor contrast when injected at least 6-8 h before initiation of cancer surgery in human patients.

ZW800-1 for Assessment of Blood-Brain Barrier Disruption in a Photothrombotic Stroke Model

Background: Since it is known that serum albumin-bound dyes can cross the blood-brain barrier (BBB) after ischemia, Evans Blue dye is commonly used to assess BBB disruption because of its rapid binding to serum albumin. In addition, indocyanine green (ICG), a clinically available dye, binds to serum proteins that could also be used for assessment of BBB impairment. Unlike these near-infrared (NIR) dyes, zwitterionic NIR fluorophore (ZW800-1) shows no serum binding, ultralow non-specific tissue uptake, and rapid elimination from the body via renal filtration. In this study, we report the use of ZW800-1 as a NIR fluorescence imaging agent for detecting BBB disruption in rat stroke models. Methods: Three types of NIR fluorophores, Evans Blue, ICG, and ZW800-1, were administered intraperitoneally into rat photothrombotic stroke models by using 4% concentration of each NIR dye. The NIR fluorescence signals in the infarcted brain tissue and biodistribution were observed in real-time using the Mini-FLARE^® imaging system up to 24 h post-injection. Results: ZW800-1 provided successful visualization of the ischemic injury site in the brain tissue, while the remaining injected dye was clearly excreted from the body within a certain period of time. Although Evans Blue and ICG provided mapping of the infarcted brain lesions, they exhibited high non-specific uptake in most of the tissues and organs and persisted in the body over 24 h post-injection. Conclusion: Our results suggest the promising application of ZW800-1 as a new strategy in BBB experiments and future therapeutic development.