Population Pharmacokinetic Modeling and Simulation of Pudexacianinium (ASP5354) for Dose Setting of a Phase 2 First-in-Patient Study: A Novel Imaging Agent for Intraoperative Ureter Visualization during Abdominopelvic Surgery

Pudexacianinium (ASP5354) chloride is an indocyanine green derivative designed to enable enhanced ureter visualization during surgery. The objective of the present analysis was to determine appropriate doses of pudexacianinium for a phase 2, dose-ranging study (NCT04238481). Real-time urine pudexacianinium concentration is considered a good pharmacodynamic surrogate marker, since ureter visualization likely depends on its concentration in the ureter. Using plasma and urine concentrations of pudexacianinium from a phase 1 single-ascending-dose (0.1-24.0 mg) study in healthy participants, a 3-compartment population pharmacokinetic model with a urine output compartment was developed and effectively described the concentration-time profiles. The individual estimated glomerular filtration rates had a significant impact on drug clearance. Simulations suggested that a 1.0 mg intravenous injection would achieve target urine concentrations over 1 μg/mL (determined from previous nonclinical studies) for 3 hours postdose, assuming a urine production rate of 1.0 mL/min. Based on this simulation, doses of 0.3, 1.0, and 3.0 mg were proposed for the phase 2 study. The observed plasma concentrations were generally consistent with model predictions. For urine, although only limited data could be obtained due to the difficulties of spot urine collection from surgical patients, intraoperative ureter visualization was successful at 1.0 and 3.0 mg.

High-sensitivity dynamic diffuse fluorescence tomography system for fluorescence pharmacokinetics

SIGNIFICANCE

Dynamic diffuse fluorescence tomography (DFT) can recover the static distribution of fluorophores and track dynamic temporal events related to physiological and disease progression. Dynamic imaging indocyanine green (ICG) approved by the food and drug administration is still under-exploited because of its characteristics of low quantum yield and relatively rapid tissue metabolism.

AIM

In order to acquire the ICG tomographic image sequences for pharmacokinetic analysis, a dynamic DFT system was proposed.

APPROACH

A fiber-based dynamic DFT system adopts square-wave modulation lock-in photon-counting scheme and series-parallel measurement mode, which possesses high sensitivity, large dynamic range, high anti-ambient light ability in common knowledge, as well as good cost performance. In order to investigate the effectiveness of the proposed system, the measurement stability and the anti-crosstalk-a crucial factor affecting the system parallelization-were assessed firstly, then a series of static phantoms, dynamic phantoms and in vivo mice experiments were conducted to verify the imaging capability.

RESULTS

The system has the limited dynamic range of 100 dB, the fluctuation of photon counting within 3%, and channel-to-channel crosstalk ratio better than 1.35. Under the condition of a sufficient signal-to-noise ratio, a complete measurement time for one frame image was 10.08 s. The experimental results of static phantoms with a single target and three targets showed that this system can accurately obtain the positions, sizes, and shapes of the targets and the reconstructed images exhibited a high quantitativeness. Further, the self-designed dynamic phantom experiments demonstrated the capability of the system to capture fast changing fluorescence signals. Finally, the in vivo experiments validated the practical capability of the system to effectively track the ICG metabolism in living mice.

CONCLUSIONS

These results demonstrate that our proposed system can be utilized for assessing ICG pharmacokinetics, which may provide a valuable tool for tumor detection, drug assessment, and liver function evaluation.

A Smart Multifunctional Nanoparticle for Enhanced Near-Infrared Image-Guided Photothermal Therapy Against Gastric Cancer

BACKGROUND

Surgery is considered to be a potentially curative approach for gastric cancer. However, most cases are diagnosed at a very advanced stage for the lack of typical symptoms in the initial stage, which makes it difficult to completely surgical resect of tumors. Early diagnosis and precise personalized intervention are urgent issues to be solved for improving the prognosis of gastric cancer. Herein, we developed an RGD-modified ROS-responsive multifunctional nanosystem for near-infrared (NIR) imaging and photothermal therapy (PTT) against gastric cancer.

METHODS

Firstly, the amphiphilic polymer was synthesized by bromination reaction and nucleophilic substitution reaction of carboxymethyl chitosan (CMCh) and 4-hydroxymethyl-pinacol phenylborate (BAPE). Then, it was used to encapsulate indocyanine green (ICG) and modified with RGD to form a smart multifunctional nanoparticle targeted to gastric cancer (CMCh-BAPE-RGD@ICG). The characteristics were determined, and the targeting capacity and biosafety were evaluated both in vitro and in vivo. Furthermore, CMCh-BAPE-RGD@ICG mediated photothermal therapy (PTT) effect was studied using gastric cancer cells (SGC7901) and SGC7901 tumor model.

RESULTS

The nanoparticle exhibited suitable size (≈ 120 nm), improved aqueous stability, ROS-responsive drug release, excellent photothermal conversion efficiency, enhanced cellular uptake, and targeting capacity to tumors. Remarkably, in vivo studies suggested that CMCh-BAPE-RGD@ICG could accurately illustrate the location and margin of the SGC7901 tumor through NIR imaging in comparison with non-targeted nanoparticles. Moreover, the antitumor activity of CMCh-BAPE-RGD@ICG-mediated PTT could effectively suppress tumor growth by inducing necrosis and apoptosis in cancer cells. Additionally, CMCh-BAPE-RGD@ICG demonstrated excellent biosafety both in vitro and in vivo.

CONCLUSION

Overall, our study provides a biocompatible theranostic nanoparticle with enhanced tumor-targeting ability and accumulation to realize NIR image-guided PTT in gastric cancer.

Intraoperative laparoscopic detection of sentinel lymph nodes with indocyanine green and superparamagnetic iron oxide in a swine gallbladder cancer model

Mapping of sentinel lymph nodes (SLNs) can enable less invasive surgery. However, mapping is challenging for cancers of difficult-to-access visceral organs, such as the gallbladder, because the standard method using radioisotopes (RIs) requires preoperative tracer injection. Indocyanine green (ICG) and superparamagnetic iron oxide (SPIO) have also been used as alternative tracers. In this study, we modified a previously reported magnetic probe for laparoscopic use and evaluated the feasibility of detecting SLNs of the gallbladder using a laparoscopic dual tracer method by injecting ICG and SPIO into five swine and one cancer-bearing swine. The laparoscopic probe identified SPIO nanoparticles in the nodes of 4/5 swine in situ, the magnetic field counts were 2.5-15.9 μT, and fluorescence was detected in SLNs in all five swine. ICG showed a visual lymph flow map, and SPIO more accurately identified each SLN with a measurable magnetic field quite similar to the RI. We then developed an advanced gallbladder cancer model with lymph node metastasis using recombination activating gene 2-knockout swine. We identified an SLN in the laparoscopic investigation, and the magnetic field count was 3.5 μT. The SLN was histologically determined to be one of the two metastatic lymph nodes. In conclusion, detecting the SLNs of gallbladder cancer in situ using a dual tracer laparoscopic technique with ICG and SPIO was feasible in a swine model.

Camouflaged Gold Nanodendrites Enable Synergistic Photodynamic Therapy and NIR Biowindow II Photothermal Therapy and Multimodal Imaging

Gold nanodendrite (AuND)-based nanotheranostic agents with versatile capabilities were fabricated by optimizing the geometrical configurations (dendrite length and density) of AuND to achieve localized surface plasmon resonance (LSPR) in near-infrared biowindow II (NIR-II), and then subsequently functionalizing with a mitochondria-targeting compound (triphenylphosphonium, TPP), loading with an NIR-photosensitizer (indocyanine green, ICG) and coating with the macrophage cell membrane (MCM) to trap ICG within AuND and selectively interact with MDA-MB-231 cells. The novel AuND-TPP-ICG@MCM system enabled the integration of multimodal fluorescence/photoacoustic/surface-enhanced Raman imaging with synergistic therapies of NIR-II photothermal therapy and NIR-I photodynamic therapy for cancer treatment. Enhanced hyperthermia and elevated production of reactive oxygen species within the tumors via MCM coating and mitochondria targeting afforded a synergistic efficacy for tumor eradication with limited side effects. The demonstrated biocompatibility, multi-imaging capability, and high therapeutic efficiency under NIR laser irradiation indicate the potentials of this multifunctional nanotheranostic platform for clinical utility in cancer therapy.

Maltohexaose-indocyanine green (MH-ICG) for near infrared imaging of endocarditis

Infectious endocarditis is a life-threatening disease, and diagnostics are urgently needed to accurately diagnose this disease especially in the case of prosthetic valve endocarditis. We show here that maltohexaose conjugated to indocyanine green (MH-ICG) can detect Staphylococcus aureus (S. aureus) infection in a rat model of infective endocarditis. The affinity of MH-ICG to S. aureus was determined and had a Km and Vmax of 5.4 μM and 3.0 X 10⁻⁶ μmol/minutes/10⁸ CFU, respectively. MH-ICG had no detectable toxicity to mammalian cells at concentrations as high as 100 μM. The in vivo efficiency of MH-ICG in rats was evaluated using a right heart endocarditis model, and the accumulation of MH-ICG in the bacterial vegetations was 2.5 ± 0.2 times higher than that in the control left ventricular wall. The biological half-life of MH-ICG in healthy rats was 14.0 ± 1.3 minutes, and approximately 50% of injected MH-ICG was excreted into the feces after 24 hours. These data demonstrate that MH-ICG was internalized by bacteria with high specificity and that MH-ICG specifically accumulated in bacterial vegetations in a rat model of endocarditis. These results demonstrate the potential efficacy of this agent in the detection of infective endocarditis.

One-Pot Fabrication of Hollow Porphyrinic MOF Nanoparticles with Ultrahigh Drug Loading toward Controlled Delivery and Synergistic Cancer Therapy

Hollow nanostructures have attracted significant research interest in drug delivery systems due to their high capacities for drug loading and unique physicochemical properties, showing great potential in specific biomedical applications. Herein, hollow porphyrinic metal-organic framework (H-PMOF) nanoparticles with a mesoporous spherical shell have been fabricated via a facile self-sacrificial ZIF-8 nanoparticle template strategy. The H-PMOF nanoplatform not only demonstrates a greatly enhanced photodynamic therapy efficacy compared with nonhollow porphyrinic MOF nanoparticles but also can be used as a superior drug carrier to co-load doxorubicin (DOX) and indocyanine green (ICG) with an ultrahigh drug-loading capacity of 635%. Furthermore, cancer cell membrane camouflage of the (DOX and ICG)@H-PMOF composite nanoparticles affords a biomimetic nanoplatform, that is, (DOX and ICG)@H-PMOF@mem (DIHPm for short), with an outstanding homologous tumor-targeting and immune-escaping ability. Interestingly, DIHPm shows both pH-controlled and near-infrared laser-triggered DOX release. Both in vitro and in vivo studies of DIHPm demonstrate an excellent imaging-guided synergistic photodynamic/photothermal/chemotherapy anticancer activity with negligible systemic toxicity. The development of the high-performance H-PMOF nanoplatform provides new insights into the design of MOF-based multifunctional nanomedicines for combination cancer therapy and precise theranostics.

Inclusion of IR-820 into Soybean-Phosphatides-Based Nanoparticles for Near-Infrared-Triggered Release and Endolysosomal Escape in HaCaT Keratinocytes at Insignificant Cytotoxic Level

PURPOSE

The degradation of drugs within endolysosomes has been widely addressed as a cause of poor bioavailability. One of the strategies to allow molecules to escape from a destructive fate is to introduce a photosensitizing moiety into a drug carrier enabling the permeabilization of endosomes and endolysosomes upon irradiation. This paper presents an alternative delivery nanosystem composed of cost-effective soybean phosphatides mixed with IR-820, a near-infrared (NIR) sensitizer, to load various active compounds and trigger an endolysosomal escape with a low cytotoxic effect.

METHODS

IR-820-incorporated phosphatides-based nanoparticles were formulated using a thin-film hydration method to encapsulate different molecular probes and a drug model. The nanoparticles were characterized in vitro using dynamic light scattering, transmission electron microscopy, as well as ultraviolet-visible and fluorescence spectroscopy techniques. The NIR-corresponding generation of the photochemical products, the content release, and the cytotoxicity toward the HaCaT keratinocyte cell line were evaluated. The cellular internalization and endolysosomal escape were monitored using a cytochemical marker and fluorescent probes with a colocalization analysis.

RESULTS

The IR-820-combined nanoparticles revealed the NIR-triggered changes in the singlet oxygen presence, nanoparticle architecture, and release rate without being cytotoxic. Additionally, the nanoplatform appeared to enhance cellular uptake of the macromolecules. The localization of the cytochemical marker and the colocalization analysis on the fluorescence signals of the encapsulated fluorophore and the lysosome-labeling reporter implied the transient endolysosomal escape of the cargo within the HaCaT cells after NIR irradiation.

CONCLUSION

The inclusion of IR-820 into a soybean-phosphatides base ingredient provides NIR responsiveness, particularly the endolysosomal escape of the payload, to the formulated nanoparticles, while preserving the beneficial properties as a drug carrier. This alternative delivery nanomedicine system has future potential to provide high bioavailability of cytosolic drugs utilizing time- and spatial-controllable NIR triggerability as well as the synergistic therapeutic effects with NIR-biomodulation.

In situ tumor-triggered subcellular precise delivery of multi-drugs for enhanced chemo-photothermal-starvation combination antitumor therapy

Rationale: Drug combination therapy for cancer treatment exerts a more potent antitumor effect. The targeted delivery and release of multiple drugs in a patient's body thus presents a more effective treatment approach, warranting further research. Methods: Two antitumor drugs (ICG: indocyanine green and THP: pirarubicin) were successfully screened to sequentially trigger self-assembling peptides (P60) to produce bacteria-sized particles (500-1000 nm, P60-ICG-THP). First, after mixing equal amount of P60 and ICG, trace amount of water (the mass ratio between P60 and water: 100:1) was used to trigger their assembly into P60-ICG. Subsequently, the assembly of P60-ICG and THP was further triggered by ultrasound treatment to produce P60-ICG-THP. Results: P60-ICG-THP constituted a cluster of several nanoparticles (50-100 nm) and possessed a negative charge. Owing to its size and charge characteristics, P60-ICG-THP could remain outside the cell membrane, avoiding the phagocytic clearance of blood and normal tissue cells in vivo. However, after localizing in the tumor, the size and charge switches of P60-ICG-THP, rapidly triggered by the low pH of the tumor microenvironment, caused P60-ICG-THP to segregate into two parts: (i) positively charged nanoparticles with a size of approximately 50 nm, and (ii) negatively charged particles of an uneven size. The former, mainly carrying THP (chemotherapeutic agent), could immediately cross the cell membrane and deliver pirarubicin into the nucleus of tumor cells. The latter, carrying ICG (used for photothermal therapy), could also enter the cell via the endocytosis pathway or accumulate in tumor blood vessels to selectively block the supply of nutrients and oxygen (cancer starvation). Both these particles could avoid the rapid excretion of ICG in the liver and were conducive to accumulation in the tumor tissue for photothermal therapy. Conclusion: Our drug delivery system not only achieves the precise subcellular delivery of two anticancer drugs due to their size and charge switches in the tumor site, but also provides a new strategy to combine chemotherapy, photothermal therapy, and cancer starvation therapy for the development of a highly efficient antitumor therapeutic regimen.

Multifunctional nanobubbles carrying indocyanine green and paclitaxel for molecular imaging and the treatment of prostate cancer

BACKGROUND

Combining ultrasound imaging with photoacoustic imaging provides tissue imaging with high contrast and resolution, thereby enabling rapid, direct measurements and the tracking of tumour growth and metastasis. Moreover, ultrasound-targeted nanobubble destruction (UTND) provides an effective way to deliver drugs, effectively increasing the content of the drug in the tumour area and reducing potential side effects, thereby successfully contributing to the treatment of tumours.

RESULTS

In this study, we prepared multifunctional nanobubbles (NBs) carrying indocyanine green (ICG) and paclitaxel (PTX) (ICG-PTX NBs) and studied their applications in ultrasound imaging of prostate cancer as well as their therapeutic effects on prostate cancer when combined with UTND. ICG-PTX NBs were prepared by the mechanical oscillation method. The particle size and zeta potential of the ICG-PTX NBs were 469.5 ± 32.87 nm and - 21.70 ± 1.22 mV, respectively. The encapsulation efficiency and drug loading efficiency of ICG were 68% and 2.52%, respectively. In vitro imaging experiments showed that ICG-PTX NBs were highly amenable to multimodal imaging, including ultrasound, photoacoustic and fluorescence imaging, and the imaging effect was positively correlated with their concentration. The imaging effects of tumour xenografts also indicated that ICG-PTX NBs were of good use for multimodal imaging. In experiments testing the growth of PC-3 cells in vitro and tumour xenografts in vivo, the ICG-PTX NBs + US group showed more significant inhibition of cell proliferation and the promotion of cell apoptosis compared to the other groups (P < 0.05). Blood biochemical analysis of the six groups showed that the levels of aspartate aminotransferase (AST), phenylalanine aminotransferase (ALT), serum creatinine (CRE) and blood urea nitrogen (BUN) in the ICG-PTX NBs and the ICG-PTX NBs + US groups were significantly lower than those in the PTX group (P < 0.05). Moreover, H&E staining of tissue sections from vital organs showed no obvious abnormalities in the ICG-PTX NBs and the ICG-PTX NBs + US groups.

CONCLUSIONS

ICG-PTX NBs can be used as a non-invasive, pro-apoptotic contrast agent that can achieve multimodal imaging, including ultrasound, fluorescence and photoacoustic imaging, and can succeed in the local treatment of prostate cancer providing a potential novel method for integrated research on prostate cancer diagnosis and treatment.

The indocyanine green retention test as a noninvasive marker for esophageal varices in patients with hepatocellular carcinoma

BACKGROUND

The indocyanine green 15-minute retention (ICG-r15) test was considered as a noninvasive marker of esophageal varices (EV) in cirrhotic patients. However, the performance of ICG-r15 in patients with hepatocellular carcinoma (HCC) has rarely been assessed. The aim of this study is to evaluate the value of ICG-r15 as a noninvasive marker of EV in patients with HCC.

METHODS

From October 2007 to December 2018, the study retrospectively enrolled 137 HCC patients with compensated hepatic function who received ICG-r15 tests and endoscopy screening for EV. The predictive value of the ICG-r15 test and other noninvasive markers was also evaluated for the diagnosis of EV, including the aspartate aminotransferase (AST)/alanine aminotransferase ratio, platelet count/spleen diameter ratio, AST/platelet ratio index, Lok index, FIB-4, and Park index.

RESULTS

In the study cohort, 30 (21.9%) patients had EV. The area under the receiver operating characteristic curve for determining EV by ICG-r15 was 0.784 (95% CI: 0.686-0.881, -2 ln (L): 77.889, Akaike information criterion: 79.889), and it had the best predictive value compared with other noninvasive markers. The cutoff value of ICG-r15 to identify EV was 31.0%, and it had 40.0% sensitivity and 98.1% specificity. The cutoff value to exclude EV was 9.5% with 86.7% sensitivity and 50.5% specificity. In the multivariate analysis, ICG-r15 (odds ratio [OR]: 1.062, 1.014-1.114; p = 0.015) and the Park index (OR: 1.535, 1.091-2.159; p = 0.014) were independently related to the presence of EV.

CONCLUSION

ICG-r15 is a practical noninvasive marker with cutoff values of 9.5% for excluding EV and 31.0% for identifying EV in patients with HCC.

A nanoplatform with tumor-targeted aggregation and drug-specific release characteristics for photodynamic/photothermal combined antitumor therapy under near-infrared laser irradiation

Due to their high biocompatibility, high spatial resolution, chromatographic capability, and adjustable size and morphology, magnetic nanoparticles have become the most promising nanomaterials for clinical application in noninvasive imaging and drug delivery for the treatment of malignant tumors. Herein, a novel magnetic nanoparticle coated with calcium carbonate was prepared and loaded with near-infrared drugs to be used as a multifunctional theranostic nanoplatform for the diagnosis and treatment of malignant tumors. Then, these drug-loaded nanoparticles were used for combined photodynamic/photothermal therapy by intravenous administration that was simultaneously guided by fluorescence/MR imaging. Due to the targeted induction of the external magnetic field and tumor response degradation of the calcium carbonate layer, the nanoprobe demonstrated excellent tumor targeting and greatly improved drug aggregation at the tumor site. Finally, single wavelength-mediated photothermal/photodynamic therapy was applied to liver cancer model mice, ultimately achieving an exciting antitumor therapeutic effect. This study may promote further exploration of nanoplatforms based on magnetic nanoparticles for clinical application in the treatment of malignant tumors.

Transforming Complexity to Simplicity: Protein-Like Nanotransformer for Improving Tumor Drug Delivery Programmatically

It was difficult for nanodrugs to simultaneously meet the contradictory requirements of prolonged circulation time, augmented cellular uptake, rapid lysosome escape, precise drug release, and tumor penetration in tumor drug delivery. We prepared a nanotransformer (DTIG) through assembling doxorubicin, tannic acid, and indocyanine green to overcome this dilemma. Hydrophilic DTIG showed prolonged blood circulation time. Besides, DTIG could be efficiently internalized by tumor cells through transforming into hydrophobic particles in an acidic tumor microenvironment. Subsequently, oversized hydrophobic particles were further formed in acidic lysosomes to escape from it through rupturing the lysosome. These hydrophobic DTIGs could rapidly revert to a smaller hydrophilic nanoassembly and release the payloads in cytoplasm. Similar to denaturation and renaturation of protein, these high-efficiency instantaneous transformations were activated by proton. Besides, photothermal therapy of DTIG promoted drug penetration efficiency in tumor. This optimized drug delivery process of DTIG finally offered potent antitumor efficacy and an obvious advantage on prognosis.

Liposome-Templated Indocyanine Green J- Aggregates for In Vivo Near-Infrared Imaging and Stable Photothermal Heating

Indocyanine green (ICG) is an FDA-approved near-infrared fluorescent dye that has been used in optical imaging and photothermal therapy. Its rapid in vivo clearance and photo-degradation have limited its application. ICG pharmacokinetics and biodistribution have been improved via liposomal encapsulation, while its photothermal stability has been enhanced by ICG J-aggregate (IJA) formation. In the present work, we report a simple approach to engineer a nano-sized, highly stable IJA liposomal formulation. Our results showed that lipid film hydration and extrusion method led to efficient IJA formation in rigid DSPC liposomes, as supported by molecular dynamics modeling. The engineered DSPC-IJA formulation was nano-sized, and with spectroscopic and photothermal properties comparable to free IJA. Promisingly, DSPC-IJA exhibited high fluorescence, which enabled its in vivo tracking, showing prolonged blood circulation and significantly higher tumor fluorescence signals, compared to free ICG and IJA. Furthermore, DSPC-IJA demonstrated high photo-stability in vivo after multiple cycles of 808 nm laser irradiation. Finally, doxorubicin was loaded into liposomal IJA to utilize the co-delivery capabilities of liposomes. In conclusion, with both liposomes and ICG being clinically approved, our novel liposomal IJA could offer a clinically relevant theranostic platform enabling multimodal imaging and combinatory chemo- and photothermal cancer therapy.

A novel treatment strategy using indocyanine green for transarterial chemoembolization in BCLC stage C hepatocellular carcinoma

PURPOSE

The aim of our study was to propose a strategy based on indocyanine green (ICG) (SBI) to provide better clinical guidelines for transarterial chemoembolization (TACE) treatments for Barcelona clinic liver cancer (BCLC) stage C hepatocellular carcinoma (HCC) patients.

MATERIALS AND METHODS

From October 2005 to December 2012, 112 BCLC stage C HCC patients initially treated with TACE were investigated, randomly divided into a training cohort (n = 79) and validation cohort (n = 33). In training group, the patients were grouped based on their 15 minutes ICG retention rate (ICG R15), different chemo drugs and dose of lipidol in TACE. Overall survival (OS) and progression-free survival (PFS) were analyzed in subgroups. Strategy based on ICG was built and verified in validation group.

RESULTS

For those patients with ICG R15 values >10%, the lipiodol ≤10 mL group showed better survival than the lipiodol >10 mL group. For those patients with ICG R15 values ≤10%, the group that received triple-drug chemotherapy treatments with lipiodol diameter ratio values between 1 and 3 showed better survival than the other group. Patients who conformed with the SBI had better survival times than those who did not conform with the SBI, in both the training cohort (median OS 10.3 vs 5.1 months; P < .001; median PFS, 3.3 vs 2.1 months; P = .006) and the validation cohort (median OS 8.9 vs 7.1 months; P = .087; median PFS, 6.6 vs 2.3 months; P < .001).

CONCLUSIONS

The SBI is suitable and may provide survival benefits for TACE treatments in BCLC stage C HCC patients.

[Intraoperative fluorescence angiography and cholangiography with indocyanine green in hepatobiliary surgery]

Intraoperative fluorescence angiography and cholangiography with indocyanine green (ICG) are increasingly used in routine hepatobiliary surgery. Its usage is manifold. It improves and facilitates navigation especially in minimal invasive and robotic surgery and therefore increases the safety of the surgical intervention. In laparoscopic cholecystectomy for example, the bileduct anatomy can be easily visualized, even in complicated cholecystitis or anatomical variants without being too time consuming. ICG fluorescence also enables the visualization of vascular structures and perfusion. Anatomical liver resections, for example in hepatocellular carcinoma (HCC), can be performed easily as liver segments and territories can be identified. Anatomical resection is becoming more important, e.g. in the treatment of HCC. Another useful application is the intraoperative detection of bile leakages after liver resection. In particular, the intraoperative control of a biliodigestive anastomosis is possible with ICG fluorescence cholangiography and therefore reduces morbidity. Even primary and secondary liver tumors can be detected with ICG fluorescence. Whereas well-differentiated HCCs homogeneously take up ICG, poorly differentiated HCCs and metastases do not: however, in these cases the adjacent liver parenchyma stores ICG more intensively than healthy liver tissue, which creates a ring-like fluorescence pattern. To conclude, the use of ICG fluorescence in hepatobiliary surgery is diverse but in Germany it is still at the beginning compared to other countries.

Tumor-Microenvironment-Activatable Nanoreactor Based on a Polyprodrug for Multimodal-Imaging-Medicated Enhanced Cancer Chemo/Phototherapy

Anticancer nanomedicine-based multimodal imaging and synergistic therapy hold great promise in cancer diagnosis and therapy owing to their abilities to improve therapeutic efficiency and reduce unnecessary side effects, producing promising clinical prospects. Herein, we integrated chemotherapeutic drug camptothecin (CPT) and near-infrared-absorbing new indocyanine green (IR820) into a single system by charge interaction and obtained a tumor-microenvironment-activatable PCPT_SS/IR820 nanoreactor to perform thermal/fluorescence/photoacoustic-imaging-guided chemotherapy and photothermal therapy simultaneously. Specifically, the generated PCPT_SS/IR820 showed an excellent therapeutic agent loading content and size stability, and the trials in vitro and in vivo suggested that the smart PCPT_SS/IR820 could deeply permeate into tumor tissues due to its suitable micellar size. Upon near-infrared laser irradiation, the nanoreactor further produced a terrific synergism of chemo-photo treatment for cancer therapy. Therefore, the PCPT_SS/IR820 polyprodrug-based nanoreactor holds outstanding promise for multimodal imaging and combined dual therapy.

Multifunctional Theranostic Liposomes Loaded with a Hypoxia-Activated Prodrug for Cascade-Activated Tumor Selective Combination Therapy

Photodynamic therapy (PDT) is becoming a promising therapeutic regimen but is limited by the hypoxic microenvironment in solid tumors and the undesirable post-treatment phototoxicity side effects on normal tissues. To overcome these restrictions and enhance the antitumor therapeutic effect, near-infrared (NIR) light-activated, cancer cell-specific, hypoxia prodrug-loaded chlorin e6 liposomes were developed for tumor selective combination therapy guided by multimodal imaging. The photothermal agent indocyanine green (ICG) and hypoxia-activated prodrug tirapazamine (TPZ) were coencapsulated into the liposomes, followed by modification with cRGD and conjugation with Gd^III to form ICG/TPZ@Ce6-Gd^III theranostic liposomes (ITC-Gd^III TLs). In the ITC-Gd^III TLs, both the fluorescence and photodynamic effect of Ce6 were quenched by ICG via fluorescence resonance energy transfer. The ITC-Gd^III TLs can effectively reach the tumor site through the enhanced permeability and retention effect as well as the cRGD-mediated active targeting ability. The fluorescence and photodynamic effect of Ce6 can be activated by the photothermal effect of ICG under NIR light. Upon subsequent irradiation with a 660 nm laser, the released Ce6 could kill cancer cells by generating cytotoxic singlet oxygen. Furthermore, the PDT process would induce hypoxia, which in turn activated the antitumor activity of the codelivered hypoxia-activated prodrug TPZ for a combination antitumor effect. The TLs could be utilized for multimodal imaging (fluorescence/photoacoustic/magnetic resonance imaging)-guided cascade-activated tumor inhibition with optimized therapeutic efficiency and minimized side effects, holding great potential for constructing intelligent nanotheranostics.

Glutathione-Priming Nanoreactors Enable Fluorophore Core/Shell Transition for Precision Cancer Imaging

In an attempt to develop an imaging probe with ultra-high sensitivity for a broad range of tumors in vivo and inspired by the concept of chemical synthetic nanoreactors, we designed a type of glutathione-priming fluorescent nanoreactor (GPN) with an albumin-coating shell and hydrophobic polymer core containing disulfide bonds, protonatable blocks, and indocyanine green (ICG), a near-infrared fluorophore. The albumin played multiple roles including biocompatible carriers, hydrophilic stabilizer, "receptor" of the fluorophores, and even targeting molecules. The protonation of the hydrophobic core triggered the outside-to-core transport of acidic glutathione (GSH), as well as the core-to-shell transference of ICGs after the disulfide bond cleavage by GSH, which induced strong binding of fluorophores with albumins on the GPN shell, initiating intensive fluorescence signals. As a result, the GPNs demonstrated extremely high response sensitivity and imaging contrast, proper time window, and broad cancer specificity. In fact, an orthogonal activation pattern was found in vitro with an ON/OFF ratio up to 24.7-fold. Furthermore, the nanoprobes specifically amplified the tumor signals in five cancer-bearing mouse models and actualized tumor margin delineation with a contrast up to 20-fold, demonstrating much better imaging efficacy than the other four commercially available probes. Therefore, the GPNs provide a new paradigm in developing high-performance bioresponsive nanoprobes.

Photoacoustic diagnosis of pharmacokinetics and vascular shutdown effects in photodynamic treatment with indocyanine green-lactosome for a subcutaneous tumor in mice

Indocyanine green lactosome (ICG-lactosome) is an attractive new-generation agent for photodynamic therapy (PDT) that is characterized by a near-infrared excitation wavelength and high stability in the bloodstream. Fluorescence imaging has been used to examine its pharmacokinetics in vivo, but no depth-resolved information can be obtained with this method. In this study, we applied photoacoustic (PA) imaging to visualize the depth distribution of ICG-lactosome in a mouse subcutaneous tumor model. With this method, the depth distribution of blood vessels can also be visualized, enabling detection of vascular shutdown effects due to PDT. We performed PA imaging of both the distributions of ICG-lactosome and blood vessels in a tumor before and after PDT, and we found that PA signals originating from ICG-lactosome were greatly increased at 18 h after drug injection but rapidly decreased after PDT. These results indicate efficient accumulation of ICG-lactosome and rapid photobleaching due to the PDT reaction in the tumor, respectively. After PDT, PA amplitudes of hemoglobin were significantly decreased, being attributable to vascular shutdown effects. These results show the usefulness of PA imaging for monitoring not only photosensitizer accumulation and bleaching but also vascular responses in PDT with ICG-lactosome. This method can be applied to the diagnosis of many types of PDT processes.

A Novel Fluorescent Clinical Method to Rapidly Quantify Plasma Volume

OBJECTIVES

To determine the performance of a rapid fluorescent indicator technique for measuring plasma volume (PV).

METHODS

This was an open-label, observational evaluation of a two-component intravenous visible fluorescent dye technique to rapidly measure PV in 16 healthy subjects and 16 subjects with chronic kidney disease (8 stage 3 and 8 stage 4 CKD), at 2 clinical research sites. The method consisted of a single intravenous injection of 12 mg of a large 150-kDa carboxy-methyl dextran conjugated to a fluorescent rhodamine-derived dye as the PV marker (PVM), and 35 mg of a small 5-kDa carboxy-methyl dextran conjugated to fluorescein, the renal clearance marker. Dye concentrations were quantified 15 min after the injections for initial PV measurements using the indicator-dilution principle. Additional samples were taken over 8 h to evaluate the stability of the PVM as a determinant of PV. Blood volumes (BV) were calculated based on PV and the subject's hematocrit. Pharmacokinetic parameters were calculated from the plasma concentration data taken over several days using noncompartmental methods (Phoenix WinNonlin®). Linear correlation and Bland-Altman plots were used to compare visible fluorescent injectate-measured PV compared to Nadler's formula for estimating PV. Finally, 8 healthy subjects received 350 mL infusion of a 5% albumin solution in normal saline over 30 min and a repeat PV determination was then carried out.

RESULTS

PV and BV varied according to weight and body surface area, with PV ranging from 2,115 to 6,234 mL and 28.6 to 41.9 mL/kg when weight adjusted. Both parameters were stable for > 6 h with repeated plasma measurements of the PVM. There was no difference between healthy subjects and CKD subjects. Overall, there was general agreement with Nadler's estimation formula for the mean PV in subjects. A 24-h repeat dose measurement in 8 healthy subjects showed PV variability of 98 ± 121 mL (mean = 3.8%). Additionally, following an intravenous bolus of 350 mL of a 5% albumin solution in normal saline in 8 healthy subjects, the mean (SD) measured increase in PV was 356 (±50.0) mL post-infusion. There were no serious adverse events reported during the study.

CONCLUSIONS

This minimally invasive fluorescent dye approach safely allowed for rapid, accurate, and reproducible determination of PV, BV, and dynamic monitoring of changes following fluid administration.

Core-Satellite Nanomedicines for in Vivo Real-Time Monitoring of Enzyme-Activatable Drug Release by Fluorescence and Photoacoustic Dual-Modal Imaging

It remains an unresolved challenge to achieve spatial and temporal monitoring of drug release from nanomedicines (NMs) in vivo, which is of crucial importance in disease treatment. To tackle this issue, we constructed core-satellite ICG/DOX@Gel-CuS NMs, which consist of gelatin (Gel) nanoparticles (NPs) with payloads of near-infrared fluorochrome indocyanine green (ICG) and chemo-drug doxorubicin (DOX) and surrounding CuS NPs. The fluorescence of ICG was initially shielded by satellite CuS NPs within the intact ICG/DOX@Gel-CuS NMs and increased in proportion to the amount of DOX released from NMs in response to enzyme-activated NMs degradation. For more comprehensive understanding of the drug-release profile, a theoretical model derived from computer simulation was employed to reconstruct the enzyme-activatable drug release of the ICG/DOX@Gel-CuS NMs, which demonstrated the underlying kinetics functional relationship between the released DOX amount and recovered ICG fluorescence intensity. The kinetics of drug release in vivo was assessed by administrating ICG/DOX@Gel-CuS NMs both locally and systemically into MDA-MB-231 tumor-bearing mice. Upon accumulation of ICG/DOX@Gel-CuS NMs in the tumor, overexpressed enzymes triggered the degradation of the gelatin scaffold as well as the release of DOX and ICG, which can be visually depicted with the ICG fluorescence signal increasing only in the tumor area by fluorescence imaging. Additionally, the photoacoustic signal from CuS NPs was independent from the physical status of ICG/DOX@Gel-CuS NMs and hence was utilized for real-time NMs tracking. Thus, by taking advantage of the core-satellite architecture and NMs degradability in tumor site, the DOX release profile of ICG/DOX@Gel-CuS NMs was monitored by fluorescence and photoacoustic dual-modal imaging in a real-time noninvasive manner.

Phototheranostics: Active Targeting of Orthotopic Glioma Using Biomimetic Proteolipid Nanoparticles

Advances in phototheranostics revolutionized glioma intraoperative fluorescence imaging and phototherapy. However, the lack of desired active targeting agents for crossing the blood-brain barrier (BBB) significantly compromises the theranostic efficacy. In this study, biomimetic proteolipid nanoparticles (NPs) with U.S. Food and Drug Administration (FDA)-approved indocyanine green (ICG) were constructed to allow fluorescence imaging, tumor margin detection, and phototherapy of orthotopic glioma in mice. By embedding glioma cell membrane proteins into NPs, the obtained biomimetic ICG-loaded liposome (BLIPO-ICG) NPs could cross BBB and actively reach glioma at the early stage thanks to their specific binding to glioma cells due to their excellent homotypic targeting and immune escaping characteristics. High accumulation in the brain tumor with a signal to background ratio of 8.4 was obtained at 12 h post-injection. At this time point, the glioma and its margin were clearly visualized by near-infrared fluorescence imaging. Under the imaging guidance, the glioma tissue could be completely removed as a proof of concept. In addition, after NIR laser irradiation (1 W/cm², 5 min), the photothermal effect exerted by BLIPO-ICG NPs efficiently suppressed glioma cell proliferation with a 94.2% tumor growth inhibition. No photothermal damages of normal brain tissue and treatment-induced side effects were observed. These results suggest that the biomimetic proteolipid NP is a promising phototheranostic nanoplatform for brain-tumor-specific imaging and therapy.

Chemodrug-Gated Biodegradable Hollow Mesoporous Organosilica Nanotheranostics for Multimodal Imaging-Guided Low-Temperature Photothermal Therapy/Chemotherapy of Cancer

Noninvasive physical treatment with relatively low intensity stimulation and the development of highly efficient anticancer medical strategy are still desirable for cancer therapy. Herein a versatile, biodegradable, hollow mesoporous organosilica nanocapsule (HMONs) nanoplatform that is capped by the gemcitabine (Gem) molecule through a pH-sensitive acetal covalent bond is designed. The fabricated nanocapsule exhibits desirable small molecule release at the tumor tissues/cell sites and shows a reduced risk for drug accumulation. After loading indocyanine green (ICG), the heat-shock protein 90 (Hsp 90) inhibitor, and 17AAG and modification with polyethylene glycol (NH₂-PEG), the resulting ICG-17AAG@HMONs-Gem-PEG exhibited a precisely controlled release of ICG and 17AAG and low-temperature photothermal therapy (PTT) (∼41 °C) with excellent tumor destruction efficacy. In addition, ICG loading conferred the nanoplatform with near-infrared fluorescence imaging (FL) and photoaccoustic (PA) imaging capability. In short, this work not only presents a smart drug self-controlled nanoplatform with pH-responsive payload release and theranostic performance but also provides an outstanding low-temperature PTT strategy, which is highly valid in the inhibition of cancer cells with minimal damage to the organism. Therefore, this research provides a paradigm that has a chemodrug-gated HMONs-based theranostic nanoplatform with intrinsic biodegradability, multimodal imaging capacity, high low-temperature PTT/chemotherapy efficacy, and reduced systemic toxicity.

On-Demand Versatile Prodrug Nanomicelle for Tumor-Specific Bioimaging and Photothermal-Chemo Synergistic Cancer Therapy

Photothermal therapy is a promising approach for antitumor application although regrettably restricted by available photothermal agents. Physical entrapment of organic near-infrared dyes into nanosystems was extensively studied to reverse the dilemma. However, problems still remained, such as drug bursting and leakage. We developed here an amphiphilic prodrug conjugate by chemically modifying indocyanine green derivative (ICG-COOH) and paclitaxel (PTX) to hyaluronic acid (HA) backbone for integration of photothermal-chemotherapy and specific tumor imaging. The prepared ICG-HA-PTX conjugates could self-assemble into nanomicelles to improve the stability and reduce systemic toxicity of the therapeutic agents. The high local concentration of ICG-COOH in nanomicelles resulted in fluorescence self-quenching, leading to no fluorescence signal being detected in circulation. When the nanomicelles reached the tumor site via electron paramagnetic resonance effect and HA-mediated active targeting, the overexpressed esterase in tumor cells ruptured the ester linkage between drugs and HA, achieving tumor-targeted therapy and specific imaging. A series of in vitro and in vivo experiments demonstrated that the easily prepared ICG- HA-PTX nanomicelles with high stability, smart release behavio r, and excellent tumor targeting ability showed formidable synergy in tumor inhibition, which provided new thoughts in developing an organic near-infrared-dye-based multifunctional delivery system for tumor theranostics.

Assessing indocyanine green pharmacokinetics in mouse liver with a dynamic diffuse fluorescence tomography system

Fluorescence pharmacokinetic rates in tissues can provide additional specific and quantitative physiological and pathological information for evaluating organ function. This modality requires a highly sensitive diffuse fluorescence tomography (DFT) working in dynamic way to finally extract the pharmacokinetic rates from the measured pharmacokinetics-associated temporally varying boundary intensity, normally with the support of a priori anatomy. This paper is devoted to study pharmacokinetics of indocyanine green (ICG) in mouse liver based on synergistic dynamic-DFT and X-ray computer tomography (XCT): A highly sensitive dynamic DFT system of CT-scanning mode working with parallel 4 photomultiplier-tube photon-counting channels generates informative and instantaneous sampling datasets; An XCT system provides priori information of the target localization for improvement of the reconstruction quality; An analysis procedure extracts the pharmacokinetic rates from the reconstructed ICG concentration-time curves, using the Gauss-Newton scheme for fitting to a 2-compartment model. The uptake and excretion rates of ICG which were obtained in livers of 10 healthy mice in the in vivo experiments can be used to quantitatively evaluate liver function. The results can validate the effectiveness of both the imaging measurements system and pharmacokinetic analysis method.

Future Liver Remnant Indocyanine Green Plasma Clearance Rate as a Predictor of Post-hepatectomy Liver Failure After Portal Vein Embolization

PURPOSE

To evaluate the utility of future liver remnant plasma clearance rate of indocyanine green (ICGK-F) for predicting post-hepatectomy liver failure (PHLF) compared with percentage future liver remnant volume-to-total liver volume ratio (%FLR) after portal vein embolization (PVE).

MATERIALS AND METHODS

PVE procedures in 20 patients (15 patients underwent PVE with absolute ethanol; 5 patients with gelatin particles) from 2010 to 2017 were analyzed. %FLR = future liver remnant volume (ml)/[total liver volume (ml) - tumor volume (ml)] × 100; ICGK-F = plasma clearance rate of indocyanine green (ICGK) × %FLR/100 were calculated before and after PVE. PHLF was categorized according to the criteria of the International Study Group of Liver Surgery. For predicting PHLF, we compared the ICGK-F and %FLR after PVE between the grade A PHLF group and the non-grade A PHLF (grades B and C) group.

RESULTS

All PVE procedures were successful. While the ICGK-F of the grade A PHLF group (median 0.073, n = 16) was about twice that of the non-grade A PHLF group (median 0.043, n = 4), showing a significant difference (Mann-Whitney U test: P = 0.002), there was no significant difference in %FLR between the grade A PHLF group and the non-grade A PHLF group (Mann-Whitney U test: P = 0.335).

CONCLUSION

ICGK-F was significantly higher in the grade A PHLF group than in the non-grade A PHLF group (grades B and C), and ICGK-F was more useful for predicting PHLF than %FLR.

Folic acid modified cell membrane capsules encapsulating doxorubicin and indocyanine green for highly effective combinational therapy in vivo

A combination of chemotherapy and phototherapy has emerged as a promising strategy for cancer treatment. To achieve effective combinational therapy of cancer with reduced toxicity, it is highly desirable to improve the targeting of chemotherapeutic and near-infrared photosensitizers to enhance their accumulation in tumor. Here we report a novel tumor targeting cell membrane capsule (CMC), originate from living cells, to load doxorubicin hydrochloride (DOX) and indocyanine green (ICG), for combinational photo-chemotherapy against cancer. As a result, folic acid modified CMC (CMC-FA, with a diameter about 200 nm and a FA density of 0.4 molecule/nm²) showed 3-4 fold higher cell uptake by cancer cells in vitro and 2.3 times higher accumulation in mouse cancer xenografts in vivo than pristine CMC. DOX and ICG with therapeutically significant concentrations can be sequentially encapsulated into CMC-FA by temporary permeating the plasma membranes with high efficiency. The systematic administration of cancer targeting CMC-FA loaded with DOX and ICG could significantly inhibit tumor growth in mouse xenografts in the presence of a near-infrared light at 808 nm, without noticeable toxicity. These findings suggest that cancer targeting CMC may have considerable benefits in drug delivery and combinational cancer therapy.

STATEMENT OF SIGNIFICANCE

A combination of chemotherapy and photothermal/photodynamic therapy has emerged as a promising strategy for cancer therapy. In current study, a novel cancer targeting cell membrane capsule (CMC-FA), originate from living cells and surface modified with folic acid, was developed to load doxorubicin hydrochloride (DOX) and indocyanine green (ICG), for combinational photo-chemotherapy against cancer. The systematic administration of drug loaded CMC-FA can significantly inhibit tumor growth in mouse xenografts in the presence of a near-infrared light at 808 nm, without noticeable toxicity. This study provides a simple and robust strategy to develop biocompatible therapeutic cell membrane capsules, holds strong translational potential in precise cancer treatment.

Co-delivery of cisplatin and CJM-126 via photothermal conversion nanoparticles for enhanced synergistic antitumor efficacy

Polymeric biomaterials that can be smartly disassembled through the cleavage of the covalent bonds in a controllable way upon an environmental stimulus such as pH change, redox, special enzymes, temperature, or ultrasound, as well as light irradiation, but are otherwise stable under normal physiological conditions have attracted great attention in recent decades. The 2-(4-aminophenyl) benzothiazole molecule (CJM-126), as one of the benzothiazole derivatives, has exhibited a synergistic effect with cisplatin (CDDP) and restrains the bioactivities of a series of human breast cancer cell lines. In our study, novel NIR-responsive targeted binary-drug-loaded nanoparticles encapsulating indocyanine green (ICG) dye were prepared as a new co-delivery and combined therapeutic vehicle. The prepared drug-loaded polymeric nanoparticles (TNPs/CDDP-ICG) are stable under normal physiological conditions, while burst drugs release upon NIR laser irradiation in a mild acidic environment. The results further confirmed that the designed co-delivery platform showed higher cytotoxicity than the single free CDDP due to the synergistic treatment of CJM-126 and CDDP in vitro. Taken together, the work might provide a promising approach for effective site-specific antitumor therapy.

Design of liver functional reserve monitor based on three-wavelength from red light to IR

BACKGROUND

The preoperative evaluation of liver functional reserve is very important to determine the excision of liver lobe for the patients with liver cancer. There already exist many effective evaluation methods, but these ones have many disadvantages such as large trauma, complicated process and so on.

OBJECTIVE

Therefore, it is essential to develop a fast, accurate and simple detection method of liver functional reserve for the practical application in the clinical engineering field.

METHODS

According to the principle of spectrophotometry, this paper proposes a detection method of liver functional reserve based on three-wavelength from red light to infrared light (IR), in which the artery pulse, the vein pulse and the move of tissue are taken into account.

RESULTS

By using photoelectric sensor technology and excreting experiment of indocyanine green, a minimally invasive, fast and simple testing equipment is designed in this paper.

CONCLUSIONS

The testing result shows this equipment can greatly reduce the interference from human body and ambient, realize continuous and real-time detection of arterial degree of blood oxygen saturation and liver functional reserve.

Quantitative analysis of facial soft tissue perfusion during hypotensive anesthesia using laser-assisted indocyanine green fluorescence angiography

The aim of this study was to quantitatively evaluate the efficacy of induced hypotensive anesthesia in decreasing facial soft tissue perfusion during orthognathic surgery using laser-assisted indocyanine green fluorescence angiography. This retrospective study involved the evaluation of 16 patients who underwent orthognathic surgery. Data collection included facial tissue perfusion of the bilateral cheeks and chin at normotension and with pharmacologically induced hypotensive anesthesia. There were statistically significant differences in the facial tissue perfusion at normal and depressed levels of blood pressure (P<0.001). This study used an objective measure to demonstrate the long-standing belief that hypotensive anesthesia is efficacious in reducing tissue perfusion in the surgical field. The data suggest that pharmacologically depressing the level of mean arterial pressure by 18% may result in a 41-52% decrease in facial soft tissue perfusion. This study reports a novel method of quantitative analysis.

Nanoparticles target early-stage breast cancer metastasis in vivo

Despite advances in cancer therapy, treating cancer after it has metastasized remains an unmet clinical challenge. In this study we demonstrate that 100 nm liposomes target triple-negative murine breast-cancer metastases post intravenous administration. Metastatic breast cancer was induced in BALB/c mice either experimentally, by a tail vein injection of 4T1 cells, or spontaneously, after implanting a primary tumor xenograft. To track their biodistribution in vivo the liposomes were labeled with multi-modal diagnostic agents, including indocyanine green and rhodamine for whole-animal fluorescent imaging, gadolinium for magnetic resonance imaging (MRI), and europium for a quantitative biodistribution analysis. The accumulation of liposomes in the metastases peaked at 24 h post the intravenous administration, similar to the time they peaked in the primary tumor. The efficiency of liposomal targeting to the metastatic tissue exceeded that of a non-liposomal agent by 4.5-fold. Liposomes were detected at very early stages in the metastatic progression, including metastatic lesions smaller than 2 mm in diameter. Surprisingly, while nanoparticles target breast cancer metastasis, they may also be found in elevated levels in the pre-metastatic niche, several days before metastases are visualized by MRI or histologically in the tissue. This study highlights the promise of diagnostic and therapeutic nanoparticles for treating metastatic cancer, possibly even for preventing the onset of the metastatic dissemination by targeting the pre-metastatic niche.

Multiparametric evaluation of hindlimb ischemia using time-series indocyanine green fluorescence imaging

Peripheral arterial disease (PAD) can further cause lower limb ischemia. Quantitative evaluation of the vascular perfusion in the ischemic limb contributes to diagnosis of PAD and preclinical development of new drug. In vivo time-series indocyanine green (ICG) fluorescence imaging can noninvasively monitor blood flow and has a deep tissue penetration. The perfusion rate estimated from the time-series ICG images is not enough for the evaluation of hindlimb ischemia. The information relevant to the vascular density is also important, because angiogenesis is an essential mechanism for post-ischemic recovery. In this paper, a multiparametric evaluation method is proposed for simultaneous estimation of multiple vascular perfusion parameters, including not only the perfusion rate but also the vascular perfusion density and the time-varying ICG concentration in veins. The target method is based on a mathematical model of ICG pharmacokinetics in the mouse hindlimb. The regression analysis performed on the time-series ICG images obtained from a dynamic reflectance fluorescence imaging system. The results demonstrate that the estimated multiple parameters are effective to quantitatively evaluate the vascular perfusion and distinguish hypo-perfused tissues from well-perfused tissues in the mouse hindlimb. The proposed multiparametric evaluation method could be useful for PAD diagnosis. The estimated perfusion rate and vascular perfusion density maps (left) and the time-varying ICG concentration in veins of the ankle region (right) of the normal and ischemic hindlimbs.

Prefabricated Cervical Skin Flaps for Hemi-Facial Resurfacing: Elucidating the Natural History of Postoperative Edema Using Indocyanine Green

BACKGROUND

The increases in capillary wall permeability and capillary hydrostatic pressure are considered to be the causes for the acute swelling seen in flaps; however, disruption of the circulating flap lymphatics could be another contributory factor. In this study we monitor the development of flap edema in a series of 18 prefabricated flaps and aim to delineate the natural history of this phenomenon by use of lymphography.

METHODS

Postoperative swelling was monitored in a series of 18 pre-expanded prefabricated cervical skin flaps used for hemi-facial burns-scar resurfacing. Time to spontaneous resolution, presence or absence of venous congestion, and clinical outcome were recorded. In two cases, indocyanine-green (ICG) lymphography was used to monitor the dermal backflow pattern until swelling had completely resolved. Average moving velocity of ICG after injection as well as flap thickness was also recorded over the follow-up period.

RESULTS

The average moving velocity of ICG in the flap lymphatics improved from 0.48 cm/min to 1.5 cm/min in the first 12 days after flap transfer. The dermal backflow pattern was stardust in the first 12 days, indicating moderate lymphedema, transforming to splash from week three, and a robust collecting lymphatic vessel occurring from the fifth month, indicating mild lymphedema and lymphatic channel recovery, respectively.

CONCLUSION

Transient swelling was observed in all prefabricated flaps in our series. We postulate that this is mostly secondary to lymphatic disruption that subsides as lymphangiogenesis takes place. ICG lymphography is an inexpensive, safe, and easy-to-use imaging technology that could be used in the monitoring of postoperative lymphedema seen in prefabricated flaps.

Indocyanine green fluorescence imaging in hepatobiliary surgery

Indocyanine green (ICG) is a fluorescent dye that has been widely used for fluorescence imaging during hepatobiliary surgery. ICG is injected intravenously, selectively taken up by the liver, and then secreted into the bile. The catabolism and fluorescence properties of ICG permit a wide range of visualization methods in hepatobiliary surgery. We have characterized the applications of ICG during hepatobiliary surgery into: 1) liver mapping, 2) cholangiography, 3) tumor visualization, and 4) partial liver graft evaluation. In this literature review, we summarize the current understanding of ICG use during hepatobiliary surgery. Intra-operative ICG fluorescence imaging is a safe, simple, and feasible method that improves the visualization of hepatobiliary anatomy and liver tumors. Intravenous administration of ICG is not toxic and avoids the drawbacks of conventional imaging. In addition, it reduces post-operative complications without any known side effects. ICG fluorescence imaging provides a safe and reliable contrast for extra-hepatic cholangiography when detecting intra-hepatic bile leakage following liver resection. In addition, liver tumors can be visualized and well-differentiated hepatocellular carcinoma tumors can be accurately identified. Moreover, vascular reconstruction and outflow can be evaluated following partial liver transplantation. However, since tissue penetration is limited to 5-10mm, deeper tissue cannot be visualized using this method. Many instances of false positive or negative results have been reported, therefore further characterization is required.

Noninvasive in vivo multispectral optoacoustic imaging of apoptosis in triple negative breast cancer using indocyanine green conjugated phosphatidylserine monoclonal antibody

Noninvasive and nonradioactive imaging modality to track and image apoptosis during chemotherapy of triple negative breast cancer is much needed for an effective treatment plan. Phosphatidylserine (PS) is a biomarker transiently exposed on the outer surface of the cells during apoptosis. Its externalization occurs within a few hours of an apoptotic stimulus by a chemotherapy drug and leads to presentation of millions of phospholipid molecules per apoptotic cell on the cell surface. This makes PS an abundant and accessible target for apoptosis imaging. In the current work, we show that PS monoclonal antibody tagged with indocyanine green (ICG) can help to track and image apoptosis using multispectral optoacoustic tomography <italic<in vivo</italic<. When compared to saline control, the doxorubicin treated group showed a significant increase in uptake of ICG-PS monoclonal antibody in triple negative breast tumor xenografted in NCr nude female mice. Day 5 posttreatment had the highest optoacoustic signal in the tumor region, indicating maximum apoptosis and the tumor subsequently shrank. Since multispectral optoacoustic imaging does not involve the use of radioactivity, the longer the circulatory time of the PS antibody can be exploited to monitor apoptosis over a period of time without multiple injections of commonly used imaging probes such as Tc-99m Annexin V or F-18 ML10. The proposed apoptosis imaging technique involving multispectral optoacoustic tomography, monoclonal antibody, and near-infrared absorbing fluorescent marker can be an effective tool for imaging apoptosis and treatment planning.

Biomimetic HDL nanoparticle mediated tumor targeted delivery of indocyanine green for enhanced photodynamic therapy

Photodynamic therapy has emerged as a promising strategy for cancer treatment. To ensure the efficient delivery of a photosensitizer to tumor for anticancer effect, a safe and tumor-specific delivery system is highly desirable. Herein, we introduce a novel biomimetic nanoparticle named rHDL/ICG (rHDL/I), by loading amphiphilic near-infrared (NIR) fluorescent dye indocyanine green (ICG) into reconstituted high density lipoproteins (rHDL). In this system, rHDL can mediate photoprotection effect and receptor-guided tumor-targeting transportation of cargos into cells. Upon NIR irradiation, ICG can generate fluorescent imaging signals for diagnosis and monitoring therapeutic activity, and produce singlet oxygen to trigger photodynamic therapy (PDT). Our studies demonstrated that rHDL/I exhibited excellent size and fluorescence stability, light-triggered controlled release feature, and neglectable hemolytic activity. It also showed equivalent NIR response compared to free ICG under laser irradiation. Importantly, the fluorescent signal of ICG loaded in rHDL/I could be visualized subcellularly in vitro and exhibited metabolic distribution in vivo, presenting superior tumor targeting and internalization. This NIR-triggered image-guided nanoparticle produced outstanding therapeutic outcomes against cancer cells, demonstrating great potential of biomimetic delivery vehicles in future clinical practice.

Cerebral microvascular blood flow and CO2 reactivity in pulmonary arterial hypertension

Hypocapnia and endothelial dysfunction might impair microvascular cerebral blood flow (CBF_micr) and cerebrovascular reactivity to CO₂ (CVR_CO2). Pulmonary arterial hypertension (PAH) is characteristically associated with chronic alveolar hyperventilation and microvascular endothelial dysfunction. We therefore determined CBF_micr (pre-frontal blood flow index (BFI) by the indocyanine green-near infrared spectroscopy methodology) during hypocapnia and hypercapnia in 25 PAH patients and 10 gender- and age-matched controls. Cerebral BFI was lower in patients than controls at similar transcutaneous PCO₂ (PtcCO₂) levels in both testing conditions. In fact, while BFI increased from hypocapnia to hypercapnia in all controls, it failed to increase in 17/25 (68%) patients. Thus, BFI increased to a lesser extent from hypo to hypercapnia ("Δ") in patients, i.e., they showed lower Δ BFI/Δ PtcCO₂ ratios than controls. In conclusion, CBF_micr and CVR_CO2 are lessened in clinically stable, mildly-impaired patients with PAH. These abnormalities might be associated with relevant clinical outcomes (hyperventilation and dyspnea, cognition, cerebrovascular disease) being potentially amenable to pharmacological treatment.

An Activatable Theranostic Nanomedicine Platform Based on Self-Quenchable Indocyanine Green-Encapsulated Polymeric Micelles

Self-quenchable indocyanine green (ICG)-encapsulated micelles with folic acid (FA)-targeting specificity (FA-ICG-micelles) were developed for biologically activatable photodynamic theranostics. FA-ICG-micelles were successfully prepared using the thin-film hydration method, which allows ICG to be encapsulated with a high drug loading that induces an efficient ICG-based quenched state. FA-ICG-micelles are initially in the "OFF" state with no fluorescence signal or phototoxicity, but they become highly fluorescent and phototoxic in cellular degradative environments. Importantly, via folate receptor-mediated endocytosis, the FA targeting of FA-ICG-micelles enhanced intracellular uptake and photodynamic therapy (PDT) efficacy. Systematic administration of FA-ICG-micelles to folate receptor-positive tumor-bearing mice elicited prolonged blood circulation, enhanced tumor accumulation and improved therapeutic efficiency compared to free ICG. Therefore, based on the FA-targeted specificity and switchable photoactivity, FA-ICG-micelles have potential for photodynamic theranostics in cancer.

Principal component analysis of dynamic fluorescence images for diagnosis of diabetic vasculopathy

Indocyanine green (ICG) fluorescence imaging has been clinically used for noninvasive visualizations of vascular structures. We have previously developed a diagnostic system based on dynamic ICG fluorescence imaging for sensitive detection of vascular disorders. However, because high-dimensional raw data were used, the analysis of the ICG dynamics proved difficult. We used principal component analysis (PCA) in this study to extract important elements without significant loss of information. We examined ICG spatiotemporal profiles and identified critical features related to vascular disorders. PCA time courses of the first three components showed a distinct pattern in diabetic patients. Among the major components, the second principal component (PC2) represented arterial-like features. The explained variance of PC2 in diabetic patients was significantly lower than in normal controls. To visualize the spatial pattern of PCs, pixels were mapped with red, green, and blue channels. The PC2 score showed an inverse pattern between normal controls and diabetic patients. We propose that PC2 can be used as a representative bioimaging marker for the screening of vascular diseases. It may also be useful in simple extractions of arterial-like features.

Post-Prandial Protein Handling: You Are What You Just Ate

Background

Protein turnover in skeletal muscle tissue is highly responsive to nutrient intake in healthy adults.

Objective

To provide a comprehensive overview of post-prandial protein handling, ranging from dietary protein digestion and amino acid absorption, the uptake of dietary protein derived amino acids over the leg, the post-prandial stimulation of muscle protein synthesis rates, to the incorporation of dietary protein derived amino acids in de novo muscle protein.

Design

12 healthy young males ingested 20 g intrinsically [1-¹³C]-phenylalanine labeled protein. In addition, primed continuous L-[ring-²H₅]-phenylalanine, L-[ring-²H₂]-tyrosine, and L-[1-¹³C]-leucine infusions were applied, with frequent collection of arterial and venous blood samples, and muscle biopsies throughout a 5 h post-prandial period. Dietary protein digestion, amino acid absorption, splanchnic amino acid extraction, amino acid uptake over the leg, and subsequent muscle protein synthesis were measured within a single in vivo human experiment.

Results

55.3±2.7% of the protein-derived phenylalanine was released in the circulation during the 5 h post-prandial period. The post-prandial rise in plasma essential amino acid availability improved leg muscle protein balance (from -291±72 to 103±66 μM·min^-1·100 mL leg volume^-1; P<0.001). Muscle protein synthesis rates increased significantly following protein ingestion (0.029±0.002 vs 0.044±0.004%·h^-1 based upon the muscle protein bound L-[ring-²H₅]-phenylalanine enrichments (P<0.01)), with substantial incorporation of dietary protein derived L-[1-¹³C]-phenylalanine into de novo muscle protein (from 0 to 0.0201±0.0025 MPE).

Conclusion

Ingestion of a single meal-like amount of protein allows ~55% of the protein derived amino acids to become available in the circulation, thereby improving whole-body and leg protein balance. About 20% of the dietary protein derived amino acids released in the circulation are taken up in skeletal muscle tissue following protein ingestion, thereby stimulating muscle protein synthesis rates and providing precursors for de novo muscle protein synthesis.

Trial Registration

trialregister.nl 3638

Tumor-Specific Formation of Enzyme-Instructed Supramolecular Self-Assemblies as Cancer Theranostics

Despite the effort of developing various nanodelivery systems, most of them suffer from undesired high uptakes by the reticuloendothelial system, such as liver and spleen. Herein we develop an endogenous phosphatase-triggered coassembly strategy to form tumor-specific indocyanine green (ICG)-doped nanofibers (5) for cancer theranostics. Based on coordinated intermolecular interactions, 5 significantly altered near-infrared absorbance of ICG, which improves the critical photoacoustic and photothermal properties. The phosphatase-instructed coassembly process, as well as its theranostic capability, was successfully conducted at different levels ranging from in vitro, living cell, tissue mimic, to in vivo. Specifically, the tumor uptake of ICG was markedly increased to 15.05 ± 3.78%ID/g, which was 25-fold higher than that of free ICG (0.59 ± 0.24%ID/g) at 4 h after intravenous injection. The resulting ultrahigh T/N ratios (>15) clearly differentiated tumors from the surrounding normal tissue. Complete tumor elimination with high therapeutic accuracy has been successfully achieved upon laser irradiation (0.8 W/cm(2), 5 min) within 24-48 h postinjection. As the first example, in vivo formation of tumor-specific ICG-doped nanofiber for PTT theranostics owns the immense potential for clinical translation of personalized nanomedicine with targeted drug delivery as well as for cancer theranostics.

Current use and perspective of indocyanine green clearance in liver diseases

Indocyanine green (ICG) is a water-soluble anionic compound that binds to plasma proteins after intravenous administration. It is selectively taken up at the first pass by hepatocytes and excreted unchanged into the bile. With the development of ICG elimination measurement by spectrophotometry, the ICG retention test has become a safe, rapid, reproducible, inexpensive and noninvasive tool for the assessment of liver function. Clinical evidence suggests that the ICG retention test can enable the establishment of tailored management strategies by providing prognostic information. In particular, this method has been evaluated as a prognostic marker in patients with advanced cirrhosis or awaiting liver transplantation. In addition, it is used as a marker of portal hypertension in cirrhotic patients, as a prognostic factor in intensive care units and for the assessment of liver function in patients undergoing liver surgery. Since recent technology enables ICG-PDR to be measured noninvasively at the bedside, this parameter is an attractive addition to liver function and regional haemodynamic monitoring. However, the current state-of-the-art as concerns this technology remains at a low level of evidence and thorough assessment is required.

Comparative biodistribution in mice of cyanine dyes loaded in lipid nanoparticles

Two near infrared cyanine dyes, DiD (1,1'-dioctadecyl-3,3,3',3'-tetramethylindotricarbocyanine perchlorate) and ICG (Indocyanine Green) were loaded in lipid nanoparticles (LNP). DiD-LNP and ICG-LNP presented similar physicochemical characteristics (hydrodynamic diameter, polydispersity, zeta potential), encapsulation efficiency, and colloidal stability when stored in PBS buffer. However, whereas DiD had similar biodistribution than cholesteryl-1-(14)C-oleate ([(14)C]CHO, a constituent of the nanoparticle used as a reference radiotracer), ICG displayed a different biodistribution pattern, similar to that of the free dye, indicative of its immediate leakage from the nanovector after blood injection. NMR spectroscopy using Proton NOE (Nuclear Overhauser Effect) measurements showed that the localization of the dye in the lipid nanoparticles was slightly different: ICG, more amphiphilic than DiD, was found both inside the lipid core and at particle interface, whereas DiD, more hydrophobic, appeared exclusively located inside the particle core. The ICG release rate from the particles was 7% per 1 month under storage conditions (4 °C, dark, 10% of lipids), whereas no leakage could be detected for DiD. ICG leakage increased considerably in the presence of BSA 40 g/L (45% leakage in 24h at 100 mg/mL of lipids), because of the high affinity of the fluorophore for plasma proteins. On the contrary, no DiD leakage was observed, until high dilution of the nanoparticles which triggered their dissociation (45% leakage in 24h at 1 mg/mL of lipids). Altogether, the subtle difference in dye localization into the nanoparticles, the partial dissociation of the LNP in diluted media, and more importantly the high ICG affinity for plasma proteins, accounted for the differences observed in the fluorescence biodistribution after tail vein injection of the dye-loaded nanoparticles.

Evaluation of the novel near-infrared fluorescence tracers pullulan polymer nanogel and indocyanine green/γ-glutamic acid complex for sentinel lymph node navigation surgery in large animal models

BACKGROUND

This study aimed to examine tracers designed to overcome the disadvantages of indocyanine green (ICG), which disperses quickly to multiple lymph nodes, using a near-infrared (NIR) imaging system in animal models.

METHODS

Diluted ICG, ICG/poly-γ-glutamic acid (PGA) complex, and IRDye900-conjugated pullulan-cholesterol nanoprobe "near-infrared polynagogel" (NIR-PNG) were injected into the stomachs of dogs and pigs, and the patterns of dispersion were observed using an NIR imaging system. To compare retention times, fluorescence signals were evaluated in the stomach and small bowel of animals 1 week after injection.

RESULTS

A diluted concentration (~0.1 mg/ml) of ICG was optimal for NIR imaging compared with the conventional concentration (5 mg/ml) for visual inspection. When injected into the stomach, the signals of ICG and ICG/PGA complex were relatively large at the injection site, and signals were detected at multiple sentinel nodes and lymph nodes beyond them. The NIR-PNG signal intensity was relatively small at the injection site and limited to only one sentinel node with no additional node. When evaluated 1 week after injection, only the NIR-PNG signal was detected in the canine stomach, and the signal intensity at the lymph nodes of the porcine small bowel was the highest with NIR-PNG, followed by ICG/PGA complex and finally ICG.

CONCLUSION

NIR-PNG showed the best characteristics of less dispersion and longer retention in the sentinel nodes, and ICG/PGA complex remained longer than diluted ICG. These tracers could potentially be used as optimal tracers for sentinel node navigation surgery in gastric cancer.

In vitro and in vivo analysis of indocyanine green-labeled panitumumab for optical imaging-a cautionary tale

Indocyanine green (IC-Green), the only FDA approved near-infrared (NIR) fluorophore for clinical use, is attractive to researchers for the development of targeted optical imaging agents by modification of its structure and conjugation to monoclonal antibodies (mAbs) or their fragments. IC-Green derivative, ICG-sulfo-OSu (ICG-sOSu), is frequently used for antibody conjugation. However, ICG-sOSu is amphiphilic and readily facilitates aggregation of mAbs that is not easily separable from the desired immunoconjugates. Complications originating from this behavior are frequently overlooked by researchers. This study examined detailed chemical and biological characteristics of an ICG-sOSu-labeled mAb, panitumumab, and provided a clinically applicable strategy to deliver a pure conjugation product. Size-exclusion high-performance liquid chromatography (SE-HPLC) analysis of conjugation reactions, performed at molar reaction ratios of ICG-sOSu: mAb of 5, 10, or 20, resulted in isolable desired ICG-sOSu-panitumumab conjugation product in 72%, 53%, and 19% yields, respectively, with the remainder consisting of high molecular weight aggregates (>150 kDa) 14%, 30%, and 51%, respectively. The HPLC-purified ICG-sOSu-panitumumab products were analyzed by native and SDS polyacrylamide gel electrophoresis (PAGE) followed by optical imaging. Results indicated that the interaction between ICG-sOSu and panitumumab was due to both covalent and noncovalent binding of the ICG-sOSu to the protein. Noncovalently bound dye in the ICG-sOSu-panitumumab conjugate products was removed by extraction with ethyl acetate to further purify the HPLC-isolated conjugation products. With conserved immunoreactivity, excellent target-specific uptake of the doubly purified bioconjugates was observed with minimal liver retention in athymic nude mice bearing HER1-expressing tumor xenografts. In summary, the preparation of well-defined bioconjugate products labeled with commercial ICG-sOSu dye is not a simple process and control of the conjugation reaction ratio and conditions is crucial. Furthermore, absolute purification and characterization of the products is necessitated prior to in vivo optical imaging. Use of validated and characterized dye conjugate products should facilitate the development of clinically viable and reproducible IC-Green derivative and other NIR dye mAb conjugates for optical imaging applications.

Development of human serum albumin conjugated with near-infrared dye for photoacoustic tumor imaging

Photoacoustic (PA) imaging has emerged as a noninvasive diagnostic method which detects ultrasonic waves thermoelastically induced by optical absorbers irradiated with laser. For tumor diagnosis, PA contrast agent has been proposed to enhance the PA effect for detecting tumors sensitively. Here, we prepared a human serum albumin (HSA) conjugated with indocyanine green (ICG) as a PA contrast agent allowing enhanced permeability and retention effect for sensitive tumor imaging. The feasibility of PA imaging with HSA-ICG to detect allografted tumors was evaluated in tumor-bearing mice. In vivo fluorescence imaging and radiolabeled biodistribution study showed that the biodistribution dramatically changed as the number of ICG bound to HSA increased, and the maximum accumulation of ICG was achieved when around three ICG molecules were loaded on an HSA. In vivo PA imaging demonstrated a tumor-selective and dose-dependent increase of PA signal intensity in mice injected with HSA-ICG (R2 = 0.88, 387% increase for HSA-ICG, 104 nmol ICG). In conclusion, HSA-ICG clearly visualized the allografted tumors with high tumor-to-background ratios having high quantitative and spatial resolution for the sensitive PA imaging of tumors. HSA-ICG could be useful as a favorable contrast agent for PA tumor imaging for the management of cancer.

Dynamic contrast enhanced fluorescent molecular imaging of vascular disruption induced by combretastatin-A4P in tumor xenografts

Dynamic contrast enhanced (DyCE) fluorescence imaging was recently demonstrated for identifying the organs in mice based on principal component analysis (PCA) of contrast kinetics following infusion of indocyanine green (ICG). It occurred to us that this approach could be used to evaluate acute effects of vascular disrupting agents (VDAs), since these cause massive vascular shutdown. As proof of principle, we have examined the action of combretastatin-A4P (CA4P) on MCF7 human breast tumors growing in nude mice. Tumors were implanted in the thigh and allowed to grow to about 7 mm diameter. Indocyanine green (ICG; 50 microl 260 microM) was administered as a bolus by tail vein injection to anesthetized mice. The fluorescence time course was acquired over 200 s using a sensitive charge-coupled device (CCD) camera system. CA4P was then administered IP (120 mg/kg in 100 microl saline) and DyCE repeated following administration of fresh ICG two and 24 hours later. At 2 hours the developed fluorescence intensity was much reduced in the tumors indicating vascular impairment, which was confirmed histologically. After 24 hours there was considerable recovery. Good reproducibility was found for control mice and normal organs. We believe the method shows promise for developing VDAs by evaluating and optimizing therapeutic drug doses and combinations.

Modified forward model for eliminating the time-varying impact in fluorescence molecular tomography

In conventional fluorescence molecular tomography, the distribution of fluorescent contrast agents is reconstructed with the assumption of constant concentration during data acquisition for each image frame. However, the concentration of fluorescent contrast target is usually time-varying in experiments or in-vivo studies. In this case, the reconstruction methods cannot be directly applied to the fluorescence measurements without considering the time-varying effects of concentration. We propose a modified forward model by dividing the fluorescence yield distribution into two parts: one is a constant representing the spatial distribution of the fluorescent target and the other is an impact factor representing the effects of the concentration change and other possible factors. By extracting spatial distribution information from the reconstruction result, the location and volume of the fluorescent target can be obtained accurately. Both simulation and phantom experiments are carried out and the results indicate that, by using the modified forward model, the quality of reconstruction could be significantly improved in terms of accurate localization and strong anti-noise ability.