Rational Design of a Small Molecular Near-Infrared Fluorophore for Improved In Vivo Fluorescence Imaging

The near-infrared (NIR) fluorescence imaging modality has great potential for application in biomedical imaging research owing to its unique characteristics, such as low tissue autofluorescence and noninvasive visualization with high spatial resolution. Although a variety of NIR fluorophores are continuously reported, the commercially available NIR fluorophores are still limited, owing to complex synthetic processes and poor physicochemical properties. To address this issue, a small molecular NIR fluorophore (SMF800) was designed and developed in the present work to improve in vivo target-specific fluorescence imaging. After conjugation with pamidronate (PAM) and bovine serum albumin (BSA), the SMF800 conjugates exhibited successful in vivo targeting in bone and tumor tissues with low background uptake, respectively. The improved in vivo performance of the SMF800 conjugate demonstrated that the small molecular NIR fluorophore SMF800 can be widely used in a much broader range of imaging applications. The structure of SMF800, which was developed by considering two important physicochemical properties, water solubility and conjugatability, is first introduced. Therefore, this work suggests a simple and rational approach to design small, hydrophilic, and conjugatable NIR fluorophores for targeted bioimaging.

Near-Infrared Fluorescent Hydroxyapatite Nanoparticles for Targeted Photothermal Cancer Therapy

Near-infrared (NIR) fluorophores have attracted great attention due to their excellent optical and photothermal properties. Among them, a bone-targeted NIR fluorophore (named P800SO3) contains two phosphonate groups, which play important roles in binding with hydroxyapatite (HAP) as the main mineral component of bones. In this study, biocompatible and NIR fluorescent HAP nanoparticles functionalized with P800SO3 and polyethylene glycol (PEG) were readily prepared for tumor-targeted imaging and photothermal therapy (PTT). The PEGylated HAP nanoparticle (HAP800-PEG) demonstrated improved tumor targetability with high tumor-to-background ratios (TBR). Moreover, the HAP800-PEG also showed excellent photothermal properties, and the temperature of tumor tissue reached 52.3 °C under NIR laser irradiation, which could completely ablate the tumor tissue without recurrence. Therefore, this new type of HAP nanoparticle has great potential as a biocompatible and effective phototheranostic material, which enables the use of P800SO3 for targeted photothermal cancer treatment.

Enhanced Tumor Uptake and Retention of Cyanine Dye-Albumin Complex for Tumor-Targeted Imaging and Phototherapy

Heptamethine cyanine dyes are widely used for in vivo near-infrared (NIR) fluorescence imaging and NIR laser-induced cancer phototherapy due to their good optical properties. Since most of heptamethine cyanine dyes available commercially are highly hydrophobic, they can usually be used for in vivo applications after formation of complexes with blood plasma proteins, especially serum albumin, to increase aqueous solubility. The complex formation between cyanine dyes and albumin improves the chemical stability and optical property of the hydrophobic cyanine dyes, which is the bottom of their practical use. In this study, the complexes between three different heptamethine cyanine dyes, namely clinically available indocyanine green (ICG), commercially available IR-786 and zwitterionic ZW800-Cl, and bovine serum albumin (BSA), were prepared to explore the effect of cyanine dyes on their tumor uptake and retention. Among the three complexes, IR-786©BSA exhibited increased tumor accumulation with prolonged tumor retention, compared to other complexes. Moreover, IR-786 bound to BSA played an important role in tumor growth suppression due to its cytotoxicity. To achieve complete tumor ablation, the tumor targeted by IR-786©BSA was further exposed to 808 nm laser irradiation for effective photothermal cancer treatment.

Visible light-curable methacrylated glycol chitosan hydrogel patches for prenatal closure of fetal myelomeningocele

In this study, we prepared visible light-curable methacrylated glycol chitosan (MGC) hydrogel patches for the prenatal treatment of fetal myelomeningocele (MMC) and investigated their feasibility using a retinoic acid-induced fetal MMC rat model. 4, 5, and 6 w/v% of MGC were selected as candidate precursor solutions, and photo-cured for 20 s, because the resulting hydrogels were found to possess concentration dependent tunable mechanical properties and structural morphologies. Moreover, these materials exhibited no foreign body reactions with good adhesive properties in animal studies. The inflammation scoring assessment in vivo exhibited the absence of foreign body reactions in MGC hydrogel treated lesion. The complete epithelial coverage of MMC was made with using 6 w/v% MGC hydrogel followed by well-organized granulation along with noticeable decrease of abortion rate and wound size that highlight the therapeutic potential for the prenatal treatment of fetal MMC.

Tumor Targeting by Conjugation of Chlorambucil with Zwitterionic Near-Infrared Fluorophore for Cancer Phototherapy

Improving the tumor targeting of anticancer drugs to minimize systemic exposure remains challenging. The chemical conjugation of anticancer drugs with various near-infrared (NIR) fluorophores may provide an effective approach to improve NIR laser-induced cancer phototherapy. Towards this end, the selection of NIR fluorophores conjugated with hydrophobic anticancer drugs is an important consideration for targeted cancer photothermal therapy (PTT). In this study, a highly water-soluble zwitterionic NIR fluorophore (ZW800) was prepared to conjugate with a water-insoluble anticancer drug, chlorambucil (CLB), to improve tumor targeting, in vivo biodistribution, and PTT performance. The in vivo results using an HT-29 xenograft mouse model demonstrated that the CLB-ZW800 conjugate not only exhibited high tumor accumulation within 4 h after injection, but also showed rapid body clearance behavior for less systemic toxicity. Furthermore, the tumor tissue targeted by the CLB-ZW800 conjugate was exposed to 808 nm NIR laser irradiation to generate photothermal energy and promote apoptotic cell death for the effective PTT of cancer. Therefore, this study provides a feasible strategy for developing bifunctional PTT agents capable of tumor-targeted imaging and phototherapy by the conjugation of small molecule drugs with the versatile zwitterionic NIR fluorophore.

Molecular Tuning of IR-786 for Improved Brown Adipose Tissue Imaging

To overcome the limitations of brown adipose tissue (BAT) imaging with MRI and PET/CT, near-infrared (NIR) fluorescence imaging has been utilized in living animals because it is highly sensitive, noninvasive, nonradioactive, and cost-effective. To date, only a few NIR fluorescent dyes for detecting BAT have been reported based on the structure-inherent targeting strategy. Among them, IR-786, a commercial cyanine dye, was used firstly for quantitative NIR imaging of BAT perfusion in 2003. Owing to the high cytotoxicity, poor water solubility, and strong nonspecific background uptake of IR-786, the chemical structure of IR-786 should be redesigned to be more hydrophilic and less toxic so that it can show more BAT-specific accumulation. Here, we developed a BAT-specific NIR dye, BF800-AM, by incorporating the tyramine linker in the original structure of IR-786. After modifying the physicochemical properties of IR-786, in vivo results showed significant uptake of the newly designed BF800-AM in the BAT with improved signal-to-background ratio. Additional in vivo studies using mouse tumor models revealed that BF800-AM targeting to BAT is independent of tumor tissues, as distinct from IR-786 showing uptake in both tissues. Therefore, BF800-AM can be used for improved noninvasive visualization of BAT mass and activity in living animals.

Rapid Tumor Targeting of Renal-Clearable ZW800-1 Conjugate for Efficient Photothermal Cancer Therapy

The combination of near-infrared (NIR) fluorophores and photothermal therapy (PTT) provides a new opportunity for safe and effective cancer treatment. However, the precise molecular design of functional NIR fluorophores with desired properties, such as high tumor targetability and low nonspecific uptake, remains challenging. In this study, a renal-clearable NIR fluorophore conjugate with high tumor targetability was developed for efficient photothermal cancer therapy. The isoniazid (INH)–ZW800-1 conjugate (INH–ZW) was synthesized by conjugating an antibiotic drug, INH, with a well-known zwitterionic NIR fluorophore, ZW800-1, to improve in vivo performance and fluorescence-guided cancer phototherapy. INH–ZW not only showed rapid tumor accumulation without nonspecific tissue/organ uptake within 1 h after the injection but also generated thermal energy to induce cancer cell death under NIR laser irradiation. Compared with previously reported ZW800-1 conjugates, INH–ZW preserved the ideal biodistribution of ZW800-1 and facilitated improved tumor targeting and PTT. Together, these results demonstrate that the INH–ZW conjugate has great potential to serve as an effective PTT agent capable of rapid tumor targeting and high renal clearance, with excellent photothermal efficacy.

Bioinspired Camellia japonica carbon dots with high near-infrared absorbance for efficient photothermal cancer therapy

Since carbon dots (CDs) exhibit excellent biocompatibility, low cytotoxicity, near-infrared (NIR) absorbance, and superior photostability, many types of CDs are considered as powerful candidates for photothermal therapy (PTT) applications. However, the development of a desirable CD is still difficult due to insufficient photothermal conversion, thus resulting in the use of high laser power densities at a high dose of CDs for the PTT effect. Herein, bioinspired sulfur-doped CDs (S-CDs) with strong NIR absorbance were prepared from Camellia japonica flowers via a facile hydrothermal method for enhancing the photothermal conversion efficiency. The as-prepared S-CDs exhibited various advantages including cost-effective preparation, good water-solubility, high biocompatibility, intense NIR absorption, and excellent photothermal effect with robust photostability. Most importantly, the optimal low dose of S-CDs (45 μg mL^-1) successfully led to efficient PTT performance with a high photothermal conversion efficiency (55.4%) under moderate laser power (808 nm, 1.1 W cm^-2) for safe and effective cancer therapy.

Effect of HDAC9 inhibition on epithelial-mesenchymal transition in CD133+ prostate cancer cell lines

A small fraction of cancer cells known as cancer stem cells (CSCs) are considered to give rise to differentiated cancer cells and have been proposed to predict cancer recurrence and metastasis. There is further evidence that CSCs may act as metastatic precursors of epithelial-mesenchymal transition (EMT). In the present study, we investigated the key molecules involved in maintaining the stability of CSCs by inducing ectopic overexpression of CD133 to characterize EMT in human prostate cancer cell lines, including PC-3, DU145, and LnCaP cells. Additionally, we investigated whether a specific inhibitor of concomitantly expressed metastasis-related genes could alleviate EMT properties in CD133-overexpressing prostate cancer cells. Ectopic overexpression of CD133 in PC-3, DU145, and LnCaP cells led to an increase in the expression of HDAC9. Moreover, HDAC9 inhibition led to a decrease in EMT properties along with increased E-cadherin expression, a narrower wound gap distance, and enhanced cell invasiveness through the suppression of β-catenin activation and its translocation to the nucleus. Overall, these results suggest that HDAC9 inhibition plays a functional role in the modulation of EMT properties in CSC-like prostate cancer cells. Therefore, these findings could facilitate the development of therapeutic strategies for controlling prostate cancer metastasis.

Live cell imaging of highly activated natural killer cells against human hepatocellular carcinoma in vivo

BACKGROUND AIMS

Tracking administered natural killer (NK) cells in vivo is critical for developing an effective NK cell-based immunotherapy against human hepatocellular carcinoma (HCC). Here the authors established a new molecular imaging using ex vivo-activated NK cells and investigated real-time biodistribution of administered NK cells during HCC progression.

METHODS

Ex vivo-expanded NK cells from healthy donors were labeled with a near-infrared lipophilic cytoplasmic dye, and their proliferation, surface receptor expression and cytotoxicity activity were evaluated. Human HCC HepG2 cells were implanted into the livers of NOD.Cg-Prkdc^scid IL2rg^tm1Wjl/SzJ (NSG) mice. The authors administered 1,1'-dioctadecyltetramethyl indotricarbocyanine iodide (DiR)-labeled NK cells intravenously to non-tumor-bearing and intrahepatic HCC tumor-bearing NSG mice. Fluorescent imaging was performed using a fluorescence-labeled organism bioimaging instrument. Single cell suspensions from the resected organs were analyzed using flow cytometry.

RESULTS

The fluorescent DiR dye was nontoxic and did not affect the proliferation or surface receptor expression levels of the NK cells, even at high doses. The administered DiR-labeled NK cells immediately migrated to the lungs of the non-tumor-bearing NSG mice, with increased NK cell signals evident in the liver and spleen after 4 h. NK cells migrated to the intrahepatic tumor-bearing livers of both early- and late-stage HCC mice within 1 h of injection. In early-stage intrahepatic tumor-bearing mice, the fluorescence signal increased in the liver until 48 h post-injection and decreased 7 days after NK injection. In late-stage HCC, the NK cell fluorescence signal was the highest in the liver for 7 days after NK injection and persisted for 14 days. The purity of long-term persistent CD45⁺CD56⁺CD3^- NK cells was highest in early- and late-stage HepG2-bearing liver compared with normal liver 2 weeks after NK injection, whereas highest purity was still observed in the lungs of non-tumor-bearing mice. In addition, Ki-67 expression was detected in migrated human NK cells in the liver and lung up to 72 h after administration. With HepG2 tumor progression, NK cells reduced the expression of NKp30 and NKG2D.

CONCLUSIONS

Administered NK cells were successfully tracked in vivo by labeling the NK cells with near-infrared DiR dye. Highly expanded, activated NK cells migrated rapidly to the tumor-bearing liver, where they persisted for 14 days after administration, with high purity of CD45⁺CD56⁺CD3^- NK cells. Liver biodistribution and persistence of administered NK cells showed significantly different accumulation patterns during HCC progression.

A novel modified RANKL variant can prevent osteoporosis by acting as a vaccine and an inhibitor

BACKGROUND

The discovery of receptor activator of nuclear factor-ĸB ligand (RANKL) as the final effector in the pathogenesis of osteoporosis has led to a better understanding of bone remodeling. When RANKL binds to its receptor (RANK), osteoclastic differentiation and activation are initiated. Herein, we propose a strategy using a novel RANKL variant as a competitive inhibitor for RANKL. The RANKL variant activates LGR4 signaling, which competitively regulates RANK and acts as an immunogen that induces anti-RANKL antibody production.

METHODS

We modified the RANK-binding site on RANKL using minimal amino acid changes in the RANKL complex and its counterpart receptor RANK and tried to evaluate the inhibitory effects on osteoclastogenesis.

RESULTS

The novel RANKL variant did not bind RANK in osteoclast progenitor cells, but activated LGR4 through the GSK3-β signaling pathway, thereby suppressing activated T cell cytoplasmic nuclear factor calcineurin-dependent 1 (NFATc1) expression and activity during osteoclastogenesis. Our RANKL variant generated high levels of RANKL-specific antibodies, blocked osteoclastogenesis, and inhibited osteoporosis in ovariectomized mouse models. Generated anti-RANKL antibodies showed a high inhibitory effect on osteoclastogenesis in vivo and in vitro.

CONCLUSIONS

We observed that the novel RANKL indeed blocks RANKL via LGR4 signaling and generates anti-RANKL antibodies, demonstrating an innovative strategy in the development of general immunotherapy.

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

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

Small Molecules for Multi-Wavelength Near-Infrared Fluorescent Mapping of Regional and Sentinel Lymph Nodes in Colorectal Cancer Staging

Assessing lymph node (LN) status during tumor resection is fundamental for the staging of colorectal cancer. Current guidelines require a minimum of 12 LNs to be harvested during resection and ultra-staging regional lymph nodes by sentinel lymph node (SLN) assessment is being extensively investigated. The current study presents novel near-infrared (NIR) fluorescent dyes for simultaneous pan lymph node (PanLN; regional) and SLN mapping. PanLN-Forte was intravenously injected in mice and assessed for accumulation in regional LNs. SLN800 was injected intradermally in mice, after which the collection and retention of fluorescence in SLNs were measured using indocyanine green (ICG) and its precursor, SLN700, as references. LNs in the cervical, inguinal, jejunal, iliac, and thoracic basins could clearly be distinguished after a low dose intravenous injection of PanLN-Forte. Background fluorescence was significantly lower compared to the parent compound ZW800-3A (p < 0.001). SLN700 and SLN800 specifically targeted SLNs with fluorescence being retained over 40-fold longer than the current clinically used agent ICG. Using SLN700 and SLN800, absolute fluorescence in SLN was at least 10 times higher than ICG in second-tier nodes, even at 1 hour post-injection. Histologically, the fluorescent signal localized in the LN medulla (PanLN-Forte) or sinus entry (SLN700/SLN800). PanLN-Forte and SLN800 appear to be optimal for real-time NIR fluorescence imaging of regional and SLNs, respectively.

Indocyanine Green and Methyl-β-Cyclodextrin Complex for Enhanced Photothermal Cancer Therapy

A feasible and biocompatible supramolecular complex self-assembled from indocyanine green (ICG) and methyl-β-cyclodextrin (Mβ-CD) was developed for targeted cancer imaging, which enhanced fluorescence-guided photothermal cancer therapy. This study confirmed that the formation of an inclusion complex of the heterocyclic ICG moiety and Mβ-CD inner cavity could result in improved tumor targetability compared with free ICG. The ICG-CD complex could be used as a bifunctional phototherapeutic agent for targeted cancer phototherapy due to the high tumor targetability of the Mβ-CD moiety and effective photothermal performance of the near-infrared (NIR) ICG moiety. Upon NIR laser irradiation, the photothermal effect exerted by the ICG-CD complex significantly enhanced the temperature at the tumor site by 56.2 °C within 5 min. Targeting HT-29 tumors using the ICG-CD complex resulted in an apparent reduction in tumor volumes over the 9 days after photothermal treatment. Moreover, no tumor recurrence or body weight loss were observed after administering a single dose of ICG-CD complex with NIR laser irradiation. Therefore, the administration of the biocompatible ICG-CD complex in combination with NIR laser treatment can be safely explored as a potential strategy for future clinical applications.

Near-infra-red fluorescent chitosan oligosaccharide lactate for targeted cancer imaging and photothermal therapy

Photothermal therapy (PTT) is a promising approach for effective cancer treatment because of its non-invasive procedure, low toxicity to normal tissues, and high tumour ablation efficiency. Developing a PTT agent with precise tumour imaging capabilities is an essential prerequisite for effective PTT. In this study, we developed a bifunctional near-infra-red (NIR) fluorescent conjugate consisting of chitosan oligosaccharide lactate (COL) and the ZW800-1 NIR fluorophore (COL-ZW). We demonstrate that this conjugate is easy to use and that it is an effective theranostic agent for fluorescence-guided photothermal treatment. The temperature of COL-ZW increased by 62.3 °C after NIR laser irradiation (1.1 W/cm²) for 5 min in HT-29 tumour-bearing mice. The HT-29 tumours targeted by COL-ZW showed a remarkable decrease in tumour volume until a week after photothermal treatment. These in vivo results demonstrate that the bifunctional COL-ZW generates strong fluorescence and light-triggered PTT in tumour sites, indicating successful fluorescence-guided PTT. Importantly, no tumour recurrence or treatment-induced toxicity was observed after a single dose of COL-ZW with laser irradiation. Therefore, a combinatorial treatment with COL-ZW and NIR laser irradiation could serve as a promising strategy for photothermal cancer therapy.

Subnanosecond phase transition dynamics in laser-shocked iron

Iron is one of the most studied chemical elements due to its sociotechnological and planetary importance; hence, understanding its structural transition dynamics is of vital interest. By combining a short pulse optical laser and an ultrashort free electron laser pulse, we have observed the subnanosecond structural dynamics of iron from high-quality x-ray diffraction data measured at 50-ps intervals up to 2500 ps. We unequivocally identify a three-wave structure during the initial compression and a two-wave structure during the decaying shock, involving all of the known structural types of iron (α-, γ-, and ε-phase). In the final stage, negative lattice pressures are generated by the propagation of rarefaction waves, leading to the formation of expanded phases and the recovery of γ-phase. Our observations demonstrate the unique capability of measuring the atomistic evolution during the entire lattice compression and release processes at unprecedented time and strain rate.

Del-1, an Endogenous Inhibitor of TGF-β Activation, Attenuates Fibrosis

Uncontrolled activation of transforming growth factor (TGF)-β results in a wide range of pathologic conditions. Therapeutic interventions to regulate TGF-β signaling during fibrosis have been developed but the effectiveness is still limited. Here, we show that developmental endothelial locus-1 (Del-1) ameliorates fibrosis in mice by inhibiting α_v integrin-mediated activation of TGF-β. Del-1 bound to α_vβ₆ integrin, an important activator of TGF-β, and inhibited the binding of α_vβ₆ integrin to the latency-associated peptide (LAP), thereby suppressing α_v integrin-mediated activation of TGF-β. Lack of Del-1 increased colocalization of α_v integrin and LAP in the lungs, which was reversed by Del-1 supplementation. The crucial role of Del-1 in regulating TGF-β activity was recapitulated in a mouse model of fibrosis using an adenovirus expressing inactive TGF-β1. Del-1 supplementation improved the pathological characteristics of the mice and reduced mortality. Thus, we propose that Del-1 is a negative regulator of TGF-β activation and a potential anti-fibrotic factor.

Fluorometric Imaging for Early Diagnosis and Prognosis of Rheumatoid Arthritis

Early diagnosis and monitoring of disease progress are of significant importance in the effective treatment of rheumatoid arthritis (RA), because the continuing inflammation can lead to irreversible joint damage and systemic complications. However, applying imaging modalities for the prognosis of RA remains challenging, because no tissue-specific guidelines are available to monitor the progressive course of RA. In this study, fluorometric imaging of RA is reported using bioengineered targeted agents of the blood vessel, bone, and cartilage in combination with the customized optical fluorescence imaging system. Separate but simultaneous tissue-specific images of synovitis, cartilage destruction, and bone resorption are obtained from a mouse model of RA, which allows quantification of the prognosis of diseases at each stage. Thus, the fluorometric imaging of RA by using tissue-specific contrast agents plays a key role in the systemic treatment of RA by monitoring structural damage and disease progression.

Zwitterionic near-infrared fluorophore for targeted photothermal cancer therapy

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

Hydrogel Nanospike Patch as a Flexible Anti-Pathogenic Scaffold for Regulating Stem Cell Behavior

Vertically aligned nanomaterials, such as nanowires and nanoneedles, hold strong potential as efficient platforms onto which living cells or tissues can be interfaced for use in advanced biomedical applications. However, their rigid mechanical properties and complex fabrication processes hinder their integration onto flexible, tissue-adaptable, and large-area patch-type scaffolds, limiting their practical applications. In this study, we present a highly flexible patch that possesses a spiky hydrogel nanostructure array as a transplantable platform for enhancing the growth and differentiation of stem cells and efficiently suppressing biofilm formation. In vitro studies show that the hydrogel nanospike patch imposes a strong physical stimulus to the membranes of stem cells and enhances their osteogenic, chondrogenic, and adipogenic differentiation and the secretion of crucial soluble factors without altering cell viability. At the same time, the array exhibits effective bactericidal properties against Gram-positive and Gram-negative bacteria. In vivo studies further demonstrate that the flexible hydrogel patch with its spiky vertical nanostructures significantly promotes the regeneration of damaged cranial bone tissues while suppressing pathogenic bacterial infections in mouse models.

Near-Infrared Fluorescent Sorbitol Probe for Targeted Photothermal Cancer Therapy

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

Near-Infrared Contrast Agents for Bone-Targeted Imaging

Background

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

Methods

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

Results

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

Conclusion

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

A local drug delivery system based on visible light-cured glycol chitosan and doxorubicin⋅hydrochloride for thyroid cancer treatment in vitro and in vivo

Systemic drug delivery systems (SDDSs) for thyroid cancer treatment are associated with serious side effects including nausea, anorexia, and hair loss as a result of damage to normal tissues. In this study, we investigated the feasibility of a local DDS (LDDS) based on visible light-cured glycol chitosan (GC) hydrogel and doxorubicin⋅hydrochloride (DOX⋅HCl), called GC10/DOX, on thyroid cancer treatment in vivo. Visible light irradiation increased the storage modulus and swelling ratio of the GC10/DOX hydrogel precursor. The release of DOX⋅HCl from GC10/DOX exhibited two unique patterns comprising an initial burst within 18 hours, followed by a controlled and sustained release thereafter. In vitro cell viability testing showed that GC10/DOX had a greater antitumor effect than free DOX⋅HCl and GC10 hydrogel controls. In vivo, local injection of GC10/DOX near tumor tissue led to a superior antitumor effect compared with controls consisting of free DOX⋅HCl intravenously injected to the tail vein of thyroid cancer-bearing mouse and GC10 hydrogel subcutaneously injected near the tumor. Altogether, our results suggest that GC10/DOX may have clinical potential for thyroid cancer treatment.

The Cocktail Effect of BMP-2 and TGF-β1 Loaded in Visible Light-Cured Glycol Chitosan Hydrogels for the Enhancement of Bone Formation in a Rat Tibial Defect Model

Bone tissue engineering scaffolds offer the merits of minimal invasion as well as localized and controlled biomolecule release to targeted sites. In this study, we prepared injectable hydrogel systems based on visible light-cured glycol chitosan (GC) hydrogels containing bone morphogenetic protein-2 (BMP-2) and/or transforming growth factor-beta1 (TGF-β1) as scaffolds for bone formation in vitro and in vivo. The hydrogels were characterized by storage modulus, scanning electron microscopy (SEM) and swelling ratio analyses. The developed hydrogel systems showed controlled releases of growth factors in a sustained manner for 30 days. In vitro and in vivo studies revealed that growth factor-loaded GC hydrogels have no cytotoxicity against MC3T3-E1 osteoblast cell line, improved mRNA expressions of alkaline phosphatase (ALP), type I collagen (COL 1) and osteocalcin (OCN), and increased bone volume (BV) and bone mineral density (BMD) in tibia defect sites. Moreover, GC hydrogel containing BMP-2 (10 ng) and TGF-β1 (10 ng) (GC/BMP-2/TGF-β1-10 ng) showed greater bone formation abilities than that containing BMP-2 (5 ng) and TGF-β1 (5 ng) (GC/BMP-2/TGF-β1-5 ng) in vitro and in vivo. Consequently, the injectable GC/BMP-2/TGF-β1-10 ng hydrogel may have clinical potential for dental or orthopedic applications.

Multivalent Mannose-Decorated NIR Nanoprobes for Targeting Pan Lymph Nodes

Lymphadenectomy is a prerequisite for most malignancies to define the precise staging of cancer, as well as resect the possible metastases completely. While it improves prognosis, lymphadenectomy often causes postoperative edema or bleeding because of unclear surgical margins. In this study, we synthesized near-infrared (NIR) fluorescent nanoprobes with conjugating various mannose moieties on the surface to target macrophages in the lymph node. Armed with these NIR nanoprobes, we demonstrated the feasibility of intraoperative pan lymph nodes (PLN) mapping and real-time optical imaging under the NIR fluorescence imaging system. We found that even single mannose-conjugated ZW800-1 showed specific uptake in lymph nodes within 4 h, and multiple mannose-employed polyrotaxanes highlighted PLN efficiently with low background signals in major organs. This technology can help surgeons perform lymphadenectomy with ease and safety by identifying all regional lymph nodes proficiently after a single intravenous injection of NIR nanoprobes.

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

Introduction

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

Methods

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

Results

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

Conclusion

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

Developmental endothelial locus-1 prevents development of peritoneal adhesions in mice

Postoperative peritoneal adhesions, fibrous bands formed in the peritoneal cavity following surgery, represent a common, challenging and costly problem faced by surgeons and patients, for which effective therapeutic options are lacking. Since aberrant inflammation is one of the key mechanisms underlying peritoneal adhesion formation, here we set out to study the role of developmental endothelial locus-1 (Del-1), which has been recently identified as an endogenous inhibitor of inflammation, in the formation of postoperative peritoneal adhesions using a mouse model of peritoneal adhesions induced by ischemic buttons. Del-1-deficient mice had a higher incidence of adhesions, and their adhesions had higher quality and tenacity scores. Del-1 deficiency also led to enhanced inflammation mediators and collagen production. Finally, Del-1 supplementation decreased the incidence and severity of postoperative peritoneal adhesions. Taken together, these results indicate a protective role for Del-1 in postoperative peritoneal adhesion formation.

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

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

Enhanced Photodynamic Cancer Treatment by Mitochondria-Targeting and Brominated Near-Infrared Fluorophores

A noninvasive and selective therapy, photodynamic therapy (PDT) is widely researched in clinical fields; however, the lower efficiency of PDT can induce unexpected side effects. Mitochondria are extensively researched as target sites to maximize PDT effects because they play crucial roles in metabolism and can be used as cancer markers due to their high transmembrane potential. Here, a mitochondria targeting photodynamic therapeutic agent (MitDt) is developed. This photosensitizer is synthesized from heptamethine cyanine dyes, which are conjugated or modified as follows. The heptamethine meso-position is conjugated with a triphenylphosphonium derivative for mitochondrial targeting, the N-alkyl side chain is modified for regulation of charge balance and solubility, and the indolenine groups are brominated to enhance reactive oxygen species generation (ROS) after laser irradiation. The synthesized MitDt increases the cancer uptake efficiency due to the lipo-cationic properties of the triphenylphosphonium, and the PDT effects of MitDt are amplified after laser irradiation because mitochondria are susceptible to ROS, the response to which triggers an apoptotic anticancer effect. Consequently, these hypotheses are demonstrated by in vitro and in vivo studies, and the results indicate strong potential for use of MitDts as efficient single-molecule-based PDT agents for cancer treatment.

Endocrine-specific NIR fluorophores for adrenal gland targeting

The adrenal glands (AGs) are relatively small yet require definitive identification during their resection, or more commonly their avoidance. To enable image-guided surgery involving the AGs, we have developed novel near-infrared (NIR) fluorophores that target the AGs after a single intravenous injection, which provided dual-NIR image-guided resection or avoidance of the AGs during both open and minimally-invasive surgery.

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

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

Effects of ADAM10 and ADAM17 Inhibitors on Natural Killer Cell Expansion and Antibody-dependent Cellular Cytotoxicity Against Breast Cancer Cells In Vitro

BACKGROUND/AIM

The inhibition of a disintegrin and metalloproteinase (ADAM) has the potential to become a novel approach for natural killer (NK) cell-based cancer immunotherapy. Thus, the aim of this study was to investigate the influence of ADAM10 and ADAM17 inhibitors on expanded NK cell to enhance antibody-dependent cellular cytotoxicity (ADCC) in breast cancer cell lines.

MATERIALS AND METHODS

NK cells were expanded in medium supplemented with an ADAM10 or ADAM17 inhibitor to prevent the shedding of soluble CD16/FcγRIII. The expression level of CD16 and production of interferon-gamma (IFN-γ) was detected by flow cytometry using specific antibodies. ADCC activity of expanded NK cells was estimated in trastuzumab treated breast cancer cell lines such as MCF-7, MDA-MB-231, SKBR3, and BT-474 cells.

RESULTS

The ADAM17 inhibitor increased the purity of expanded NK cells to 90% after 14 days at 5 and 10 μM in vitro (p=0.043). However, the expansion rate of NK cells was decreased at 10 μM of the ADAM 17 inhibitor (p=0.043). Inhibition of ADAM10 suppressed the expansion of NK cells, although the NK purity was increased at 1 μM of the inhibitor. The expression of CD16 was significantly increased at 1 and 5 μM of the ADAM17 inhibitor (p=0.046, 0.028, respectively) during the culturing period. Inhibition of ADAM10 reduced the expression of CD16 on NK cells. The cytotoxic activity of the ADAM17 inhibitor treated NK cells against MCF-7 (p=0.039) and BT-474 (p=0.027) cells was significantly elevated. The ADCC activity of NK cells treated with 5 μM of ADAM17 inhibitor was significantly increased against SKBR-3 and BT-474 (p=0.027). Inhibition of ADAM17 increased the production of IFN-γ in expanded NK cells.

CONCLUSION

The inhibition of ADAM17 enhanced the purity of expanded NK cells and the ADCC activity of these cells against trastuzumab treated breast cancer cell lines.

Real-time in vivo imaging of metastatic bone tumors with a targeted near-infrared fluorophore

Tumors of the prostate or breast are particularly likely to metastasize to the bone, and early diagnosis of metastatic bone tumors is important for designing an effective treatment strategy. Imaging modalities for the detection of bone metastasis are limited, and radiation-based techniques are commonly used. Here, we investigated the efficacy of selective near-infrared (NIR) fluorescence detection of metastatic bone tumors and its role in the detection of bone metastasis in prostate and breast cancer cell lines and in a xenograft mouse model. A targeted NIR fluorophore was used to monitor metastatic bone tumors using a NIR fluorescence imaging system in real time, enabling the diagnosis of bone metastasis in vivo by providing the location of the metastatic bone tumor. The NIR fluorescence imaging technique using targeted NIR contrast agents is a potential tool for the early diagnosis of bone tumors.

A High-Affinity Repebody for Molecular Imaging of EGFR-Expressing Malignant Tumors

The accurate detection of disease-related biomarkers is crucial for the early diagnosis and management of disease in personalized medicine. Here, we present a molecular imaging of human epidermal growth factor receptor (EGFR)-expressing malignant tumors using an EGFR-specific repebody composed of leucine-rich repeat (LRR) modules. The repebody was labeled with either a fluorescent dye or radioisotope, and used for imaging of EGFR-expressing malignant tumors using an optical method and positron emission tomography. Our approach enabled visualization of the status of EGFR expression, allowing quantitative evaluation in whole tumors, which correlated well with the EGFR expression levels in mouse or patients-derived colon cancers. The present approach can be effectively used for the accurate detection of EGFR-expressing cancers, assisting in the development of a tool for detecting other disease biomarkers.

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

Although various clinical imaging modalities have been developed to visualize internal body structures and detect abnormal tissues prior to surgical procedures, most medical imaging modalities do not provide disease-specific images in real-time. Optical imaging can provide the surgeon with real-time visualization of the surgical field for intraoperative image-guided surgery. Imaging in the near-infrared (NIR) window (650-900 nm), also known as the "therapeutic window" has high potential by offering low absorbance and scattering in tissues resulting in minimized background autofluorescence. Clinically, optical fluorescence imaging with the targeted contrast agents provides opportunities for significant advances in intraoperative image-guided surgery. There are only two clinically available NIR fluorophores, indocyanine green (ICG) and methylene blue (MB), that support the image-guided surgery. However, neither of them perform in vivo by providing optimum specificity and stability for targeted image guidance. Therefore, it is of paramount importance to develop targeted NIR fluorophores for unmet clinical needs. Using the right combination of an NIR fluorescence imaging system and a targeted fluorophore, the desired target tissues can be imaged to provide real-time fluorescence guidance without changing the field-of-view during surgery. Thus, in a clinical discipline, the development of NIR fluorophores for 'structure-inherent targeting' is an unmet need for early phase diagnostics with accurate targeting.

Ectopic overexpression of CD133 in HNSCC makes it resistant to commonly used chemotherapeutics

Head and neck squamous cell carcinoma (HNSCC) is one of the most common cancers in the world. Resistance to cytotoxic chemotherapy is a major cause of mortality in patients with HNSCC. A small subset of cancer cells called cancer stem cells (CSCs) may be key contributors to drug resistance and tumor recurrence in HNSCC. The aim of this study was to determine whether CD133, which maintains properties of CSCs, promotes chemoresistance by arresting cell cycle transition and reducing apoptosis in HNSCC cells. CD133 overexpression was examined in KB cells, and colony forming and aldehyde dehydrogenase activity assays were performed. To investigate the role of CD133 in chemoresistance, cell death was analyzed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), Diff-Quick, flow cytometry, and western blot of apoptosis-related protein expression in fluorouracil (5-FU)- or cisplatin-treated cells. In addition, microarray and related protein expression assessments were performed to investigate the mechanism of chemoresistance against 5-FU and cisplatin in KB cells. Moreover, chemoresistance against 5-FU or cisplatin in a KB-inoculated mouse model was analyzed by hematoxylin and eosin staining, immunohistochemical study of CD133, and immunofluorescence of tumor tissue. In this study, we demonstrate that ectopic overexpression of CD133 significantly promotes properties of stemness in KB cell lines. Furthermore, CD133 promotes chemoresistance by arresting transition of the cell cycle and reducing apoptosis, which results in inhibition of tumor growth in 5-FU- or cisplatin-injected mouse tumor model. Taken together, our findings show that elevated levels of CD133 lead to HNSCC chemoresistance through increased stemness and cell cycle arrest.

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

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

Intraoperative Near-Infrared Fluorescence Imaging of Thymus in Preclinical Models

BACKGROUND

There are currently no thymus-specific contrast agents for biomedical imaging. Thus, finding ectopic thymic tissue during certain operations is extremely difficult. The purpose of the present study was to determine if near-infrared (NIR) fluorescence imaging could provide high sensitivity, real-time identification of thymic tissue during the operation.

METHODS

After initial in vivo screening of a 315-compound NIR fluorophore library for thymic uptake, methylene blue and five different 700-nm emitting candidate molecules were injected into CD-1 mice for quantitation of the signal-to-background ratio as a function of kinetics and dosing. Results were confirmed in 35-kg Yorkshire pigs. Dual-channel NIR imaging was also performed using a variety of 800-nm emitting NIR fluorophores targeted to various tissues in the mediastinum and neck.

RESULTS

The compound Oxazine 170 demonstrated the highest signal-to-background ratio (≥3) for thymic tissue relative to mediastinal fat, heart, lung, muscle, thyroid gland, and parathyroid gland, with peak signal-to-background ratio occurring 4 h after 1 intravenous injection of a human equivalent dose of approximately 7 mg. Simultaneous dual-channel NIR imaging permitted unambiguous identification of the thymus from surrounding tissues, such as endocrine glands and lymph nodes.

CONCLUSIONS

In mouse and pig, NIR fluorescence imaging using Oxazine 170 permits high sensitivity, real-time identification of thymic tissue for surgical procedures requiring its resection or avoidance. The performance of Oxazine 170 for imaging human thymic tissue is currently not known.

Near-Infrared Illumination of Native Tissues for Image-Guided Surgery

Our initial efforts to prepare tissue-specific near-infrared (NIR) fluorescent compounds generated successful correlation between physicochemical properties and global uptake in major organs after systemic circulation and biodistribution. Herein, we focus on the effects on biodistribution based on modulating electronic influencing moieties from donating to withdrawing moieties at both the heterocyclic site and through meso-substitution of pentamethine cyanine fluorophores. These selected modifications harnessed innate biodistribution pathways through the structure-inherent targeting, resulting in effective imaging of the adrenal glands, pituitary gland, lymph nodes, pancreas, and thyroid and salivary glands. These native-tissue contrast agents will arm surgeons with a powerful and versatile arsenal for intraoperative NIR imaging in real time.

Synergistic effects of hyperosmotic polymannitol based non-viral vectors and nanotopographical cues for enhanced gene delivery

Here, we report the synergistic effects of hyperosmotic and nanotopographical cues designed using non-viral vectors and nanopatterned matrices for gene delivery.