Indocyanine green: An old drug with novel applications

Oligo(styryl)benzenes liposomal AIE-dots for bioimaging and phototherapy in an in vitro model of prostate cancer

Whilst the development of advanced organic dots with aggregation-induced emission characteristics (AIE-dots) is being intensively studied, their clinical translation in efficient biotherapeutic devices has yet to be tackled. This study explores the synergistic interplay of oligo(styryl)benzenes (OSBs), potent fluorogens with an increased emission in the aggregate state, and Indocyanine green (ICG) as dual Near Infrared (NIR)-visible fluorescent nanovesicles with efficient reactive oxygen species (ROS) generation capacity for cancer treatment using photodynamic therapy (PDT). The co-loading of OSBs and ICG in different nanovesicles has been thoroughly investigated. The nanovesicles' physicochemical properties were manipulated via molecular engineering by modifying the structural properties of the lipid bilayer and the number of oligo(ethyleneoxide) chains in the OSB structure. Diffusion Ordered Spectroscopy (DOSY) NMR and spectrofluorometric studies revealed key differences in the structure of the vesicles and the arrangement of the OSB and ICG in the bilayer. The in vitro assessment of these OSB-ICG nanovesicles revealed that the formulations can increase the temperature and generate ROS after photoirradiation, showing for the first time their potential as dual photothermal/photodynamic (PTT/PDT) agents in the treatment of prostate cancer. Our study provides an exciting opportunity to extend the range of applications of OSB derivates to potentiate the toxicity of phototherapy in prostate and other types of cancer.

Indocyanine green uptake by human tumor and non‑tumor cell lines and tissue

Indocyanine green (ICG) is a potential promising dye for a better intraoperative tumor border definition and an improved patient outcome by potentially improving tumor border visualization compared with traditional white light guided surgery. Here, the cellular uptake of ICG in human squamous cell carcinoma (SCC026) and immortalized non-cancer skin (HaCaT) cell lines was evaluated to study the tumor-specific cellular uptake of ICG. The spatial distribution of ICG inside tumor tissue was investigated in tissue sections of head and neck squamous cell carcinoma at a microscopic level. ICG uptake and internalization was observed in living cells after 2.5 h and in the nucleus after 24 h. In dead cells, higher and faster uptake was observed. In the tissue sections, higher ICG signal intensity could be detected in connective tissue and surrounding clusters and blood vessels. In conclusion, no distinct ICG uptake by tumor cells was detected in cancer cell lines and tumor tissue. ICG localization in certain regions of tumor tissue appears to be a result of enhanced tissue permeability and retention, but not specific to tumor cells.

Tailoring Indocyanine Green J-Aggregates for Imaging, Cancer Phototherapy, and Drug Delivery: A Review

Indocyanine green J-aggregates (ICG-Jagg) have emerged as a significant subject of interest in biomedical applications due to their unique optical properties, tunable size, and excellent biocompatibility. This comprehensive review aims to provide an in-depth exploration of ICG-Jagg, with a focus on elucidating the diverse facets of their preparation and the factors that influence the preparation process. Additionally, the review discusses their applications in biomedical diagnostics, such as imaging and contrast agents, as well as their utilization in drug delivery and various phototherapeutic interventions.

Determining Accurate Dye Combinations for Sentinel Lymph Node Detection: A Systematic Review

Background

Lymphatic dyes are commonly used to map the drainage path from tumor to lymphatics, which are biopsied to determine if spread has occurred. A blue dye in combination with technetium-99 is considered the gold standard for mapping, although many other dyes and dye combinations are used. Not all of these substances have the same detection efficacy.

Methods

A systematic review of PubMed, SCOPUS, Web of Science, and Medline was performed. The predefined search terms were (indocyanine green OR isosulfan blue OR lymphazurin OR patent blue OR methylene blue OR fluorescein OR technetium-99) AND combination AND dye AND (sentinel lymph node biopsy OR lymphedema OR lymphatics OR lymph OR microsurgery OR cancer OR tumor OR melanoma OR carcinoma OR sarcoma).

Results

The initial search returned 4267 articles. From these studies, 37 were selected as candidates that met inclusion criteria. After a full-text review, 34 studies were selected for inclusion. Eighty-nine methods of sentinel lymph node (SLN) detection were trialed using 22 unique dyes, dye combinations, or other tracers. In total, 12,157 SLNs of 12,801 SLNs were identified. Dye accuracy ranged from 100% to 69.8% detection. Five dye combinations had 100% accuracy. Dye combinations were more accurate than single dyes.

Conclusions

Combining lymphatic dyes improves SLN detection results. Replacing technetium-99 with ICG may allow for increased access to SLN procedures with comparable results. The ideal SLN tracer is a low-cost molecule with a high affinity for lymphatic vessels due to size and chemical composition, visualization without specialized equipment, and no adverse effects.

Mn(iii), Fe(iii) and Zn(ii)-serum albumin as innovative multicolour contrast agents for photoacoustic imaging

Here we propose innovative photoacoustic imaging (PAI) contrast agents, based on the loading of Mn(iii)-, Fe(iii)- or Zn(ii)-protoporphyrin IX in serum albumin. These systems show different absorption wavelengths, opening the way to multicolor PA imaging. They were characterized in vitro for assessing stability, biocompatibility, and their optical and contrastographic properties. Finally, a proof of concept in vivo study was carried out in breast cancer bearing mice, to evaluate its effectiveness for cancer imaging.

Deciphering the Role of H-Ferritin Nanocages in Improving Tumor-Targeted Delivery of Indocyanine Green: Combined Analysis of Murine Tissue Homogenates with UHPLC-MS/MS and Fluorescence

We investigated the relevance of encapsulation in H-ferritin nanocages (HFn) in determining an improved tumor-targeted delivery of indocyanine green (ICG). Since from previous experiments, the administration of HFn loaded with ICG (HFn-ICG) resulted in an increased fluorescence signal of ICG, our aim was to uncover if the nanoformulation could have a major role in driving a specific targeting of the dye to the tumor or rather a protective action on ICG's fluorescence. Here, we took advantage of a combined analysis involving ultrahigh performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) on murine tissue homogenates matched with fluorescence intensities analysis detected by ex vivo optical imaging. The quantification of ICG content performed on different organs over time combined with the fluorescent signal detection confirmed the superior delivery of ICG thanks to the nanoformulation. Our results showed that HFn-ICG drives a real accumulation at the tumor instead of only having a role in the preservation of ICG's fluorescence, further supporting its use as a delivery system of ICG for fluorescence-guided surgery applications in oncology.

Mastectomy Skin Flap Stability Prediction Using Indocyanine Green Angiography: A Randomized Prospective Trial

BACKGROUND

The first step in successful breast reconstruction is obtaining a stable skin flap. Indocyanine green (ICG) angiography has recently been studied for its value and usefulness in predicting the stability of skin flaps; however, relevant prospective studies of its clinical efficacy are limited.

OBJECTIVES

The aim of this study was to prospectively investigate the clinical impact on breast reconstruction outcomes of the intraoperative use of ICG angiography.

METHODS

Between March and December 2021, 64 patients who underwent immediate breast reconstruction at the authors' institution were prospectively enrolled. They were classified into an experimental group (n = 39; undergoing ICG angiography) and a control group (n = 25; undergoing gross inspection alone). In the absence of viable skin, debridement was performed at the surgeon's discretion. Skin complications were categorized as skin necrosis (the transition of the skin flap to full-thickness necrosis) or skin erosion (a skin flap that did not deteriorate or become necrotic but lacked intactness).

RESULTS

The 2 groups were matched in terms of basic demographic characteristics and incision line necrosis ratio (P = .354). However, intraoperative debridement was significantly more frequent in the experimental group (51.3% vs 48.0%, P = .006). The authors additionally classified skin flap necrosis into partial- and full-thickness necrosis, with a higher predominance of partial-thickness necrosis in the experimental vs control group (82.8% vs 55.6%; P = .043).

CONCLUSIONS

Intraoperative ICG angiography does not directly minimize skin erosion or necrosis. However, compared to gross examination alone, it enables surgeons to perform a more active debridement during surgery, thereby contributing to a lower incidence of advanced skin necrosis. In breast reconstruction, ICG angiography may be useful for assessing the viability of the postmastectomy skin flap and could contribute to successful reconstruction.

LEVEL OF EVIDENCE

4.

Glycolysis inhibition for synergistic phototherapy of triple-negative breast cancer

Phototherapy is a local and precise therapeutic technique for tumor treatment. However, the therapeutic effects of photothermal and photodynamic therapies are inevitably encountered by hypoxia of the tumor microenvironment and heat shock protein induced by hyperthermia, respectively. Herein, we found that mannose, a glucose analog, could reverse tumor hypoxia by inhibiting glycolysis of cancer cells and suppressing the expression of heat shock protein through inhibiting cellular adenosine triphosphate (ATP) generation. Next, we used lipid nanoparticles simultaneously loaded with indocyanine green (ICG) and mannose molecules, named imLipo, for tumor therapy. Both in vitro and in vivo experiments evidenced that the imLipo nanoplatform has significant therapeutic efficacy through synergistic phototherapy under single near-infrared laser irradiation. This work shows that glycolysis inhibition can overcome the challenges of phototherapy. In addition, all three parts (mannose, ICG, and lipid) of imLipo are clinically approved and our designed nanoplatforms have great potential for future tumor treatment.

The Wonder Dye: Uses and Implications of Indigocyanine Green in Various Surgeries

Indigocyanine green (ICG) is a fluorophore dye that has been extensively used in recent modern times for bioimaging in numerous surgeries to aid in easier identification of occult and often tricky-to-find anatomical structures. Surgery becomes complex and challenging due to multiple anatomical anomalies, pathological fibrosis, obesity, or previous surgeries. To overcome these obstacles in surgery, the surgeon yearns to know the structures present beyond their white light vision so that while dissecting the organ, they can avoid injuring the critical systems in the vicinity of dissection. Near-infrared (NIR) imaging aids in visualising the tissues at depth/in the area of dissection, thereby preventing any possible surgical catastrophes due to them inadvertently damaging surrounding vital structures. Various advantages in surgeries like gastric sleeve surgery, lymph node and tumour detection, localisation of ureters and biliary tracts, and intraoperative tissue perfusion of flaps have been described in this study. This review article aims to compile a short list of utilities of ICG with NIR imaging in various surgical interventions. The merits and demerits of this imaging technique have been noted. The study points out the uses of ICG fluorescence imaging under different surgical fronts. This review article concludes by comparing the results of studies performed by various authors. Results have been compared to conventional surgical modalities.

Indocyanine green dye and its application in gastrointestinal surgery: The future is bright green

Indocyanine green (ICG) is a water-soluble fluorescent dye that is minimally toxic and widely used in gastrointestinal surgery. ICG facilitates anatomical identification of structures (e.g., ureters), assessment of lymph nodes, biliary mapping, organ perfusion and anastomosis assessment, and aids in determining the adequacy of oncological margins. In addition, ICG can be conjugated to artificially created antibodies for tumour markers, such as carcinoembryonic antigen for colorectal, breast, lung, and gastric cancer, prostate-specific antigen for prostate cancer, and cancer antigen 125 for ovarian cancer. Although ICG has shown promising results, the optimization of patient factors, dye factors, equipment, and the method of assessing fluorescence intensity could further enhance its utility. This review summarizes the clinical application of ICG in gastrointestinal surgery and discusses the emergence of novel dyes such as ZW-800 and VM678 that have demonstrated appropriate pharmacokinetic properties and improved target-to-background ratios in animal studies. With the emergence of robotic technology and the increasing reporting of ICG utility, a comprehensive review of clinical application of ICG in gastrointestinal surgery is timely and this review serves that aim.

Application of a Self-developed, Low-budget Indocyanine Green Camera in Surgical Imaging - a Single Institution's Experiences

INTRODUCTION

Indocyanine green is a fluorescent dye, the use of which is becoming more and more widespread in different areas of surgery. Several international studies deal with the dye's usefulness in intraoperative angiography, the localization of tumors, the more precise identification of anatomical structures, the detection of lymph nodes and lymph ducts, etc. The application of the dye is safe, but a suitable equipment park is required for its use, which entails relatively high costs.

OBJECTIVES

The aim of our research is to create a detector system on a low budget, to be used safely in everyday practice and to illustrate its operation with practical examples at our own institute.

METHODS

By modifying a web camera, using filter lenses and special LEDs, we created a device suitable for exciting and detecting indocyanine green fluorescence. We prove its excellent versatility during the following procedures at our institute: breast tumor surgery, kidney transplantation, bowel resection, parathyroid surgery and liver tumor resection.

RESULTS

The finished camera has an LED light source with a peak wavelength of 780 nm, and the incoming light is filtered by a bandpass filter with a center wavelength of 832 nm. A low budget ($112), easy-to-use tool was created, which is suitable for taking advantage of the opportunities provided by indocyanine green.

The magic mirror: a novel intraoperative monitoring method for parathyroid glands

The accurate detection of parathyroid glands (PGs) during surgery is of great significance in thyroidectomy and parathyroidectomy, which protects the function of normal PGs to prevent postoperative hypoparathyroidism and the thorough removal of parathyroid lesions. Existing conventional imaging techniques have certain limitations in the real-time exploration of PGs. In recent years, a new, real-time, and non-invasive imaging system known as the near-infrared autofluorescence (NIRAF) imaging system has been developed to detect PGs. Several studies have confirmed that this system has a high parathyroid recognition rate and can reduce the occurrence of transient hypoparathyroidism after surgery. The NIRAF imaging system, like a magic mirror, can monitor the PGs during surgery in real time, thus providing great support for surgeries. In addition, the NIRAF imaging system can evaluate the blood supply of PGs by utilizing indocyanine green (ICG) to guide surgical strategies. The NIRAF imaging system and ICG complement each other to protect normal parathyroid function and reduce postoperative complications. This article reviews the effectiveness of the NIRAF imaging system in thyroidectomies and parathyroidectomies and briefly discusses some existing problems and prospects for the future.

Activatable fluorescent probes for real-time imaging-guided tumor therapy

Surgery and drug therapy are the two principal options for cancer treatment. However, their clinical benefits are hindered by the difficulty of accurate location of the tumors and timely monitoring of the treatment efficacy of drugs, respectively. Rapid development of imaging techniques provides promising tools to address these challenges. Compared with conventional imaging techniques such as magnetic resonance imaging and computed tomography etc., fluorescence imaging exhibits high spatial resolution, real-time imaging capability, and relatively low costs devices. The advancements in fluorescent probes further accelerate the implementation of fluorescence imaging in tumor diagnosis and treatment monitoring. In particular, the emergence of site-specifically activatable fluorescent probes fits the demands of tumor delineation and real-time feedback of the treatment efficacy. A variety of small molecule probes or nanoparticle-based probes have been developed and explored for the above-mentioned applications. This review will discuss recent advances in fluorescent probes with a special focus on activatable nanoprobes and highlight the potential implementation of activatable nanoprobes in fluorescence imaging-guided surgery as well as imaging-guided drug therapy.

Indocyanine green as a near-infrared theranostic agent for ferroptosis and apoptosis-based, photothermal, and photodynamic cancer therapy

Ferroptosis is a recently discovered programmed cell death pathway initiated by reactive oxygen species (ROS). Cancer cells can escape ferroptosis, and strategies to promote cancer treatment are crucial. Indocyanine green (ICG) is a near-infrared (NIR) fluorescent molecule used in the imaging of residual tumor removal during surgery. Growing attention has been paid to the anticancer potential of ICG-NIR irradiation by inducing ROS production and theranostic effects. Organic anion transmembrane polypeptide (OATP) 1B3 is responsible for ICG metabolism. Additionally, the overexpression of OATP1B3 has been reported in several cancers. However, whether ICG combined with NIR exposure can cause ferroptosis remains unknown and the concept of treating OATP1B3-expressing cells with ICG-NIR irradiation has not been validated. We then used ICG as a theranostic molecule and an OATP1B3-transfected fibrosarcoma cell line, HT-1080 (HT-1080-OATP1B3), as a cell model. The HT-1080-OATP1B3 cell could promote the uptake of ICG into the cytoplasm. We observed that the HT-1080-OATP1B3 cells treated with ICG and exposed to 808-nm laser irradiation underwent apoptosis, as indicated by a reduction in mitochondrial membrane potential, and upregulation of cleaved Caspase-3 and Bax but downregulation of Bcl-2 expression. Moreover, lipid ROS production and consequent ferroptosis and hyperthermic effect were noted after ICG and laser administration. Finally, in vivo study findings also revealed that ICG with 808-nm laser irradiation has a significant effect on cancer suppression. ICG is a theranostic molecule that exerts synchronous apoptosis, ferroptosis, and hyperthermia effects and thus can be used in cancer treatment. Our findings may facilitate the development of treatment modalities for chemo-resistant cancers.

Indocyanine green for targeted imaging of the gall bladder and fluorescence navigation

Researchers nowadays have devoted extra attention to the different biomedical applications of indocyanine green (ICG), a US Food and Drug Administration-approved fluorescent compound in the fields such as drug delivery, medical imaging and disease diagnosis. In addition, hepatic function evaluation could be conducted by using ICG before surgical procedures and angiographic assessment of blood. Therefore, ICG will be expected to be excellent imaging and targeting agent in various preclinical and clinical model systems. However, whether ICG possesses the potential for the gall bladder's intraoperative imaging guidance needs to be further explored in vivo animal experiments. Herein, near-infrared fluorophores ICG can display the specific uptake by the gall bladder cells and tissues. The dynamic process of biodistribution and the clearance of ICG in vivo in mice are clearly shown in real-time live-body imaging. Furthermore, ICG was rapidly excreted into the bile and lately biodistributed to the stomach after treatment in mice. Meanwhile, the signal-to-background ratio of the gall bladder demonstrated a tremendously higher level compared to other organs (stomach, heart, liver, lung, pancreas, spleen, intestine and duodenum). In conclusion, fluorescence navigation using ICG fluorescence imaging will provide good visualization and detection of the target lesions (gall bladder) in clinics such as diagnostic medical imaging and intraoperative navigation.