Research Insight - Leveraging Microenvironment for Combined Cancer Therapy: The Role of NIR-II In Vivo Fluorescence Imaging

Professor Qinglai Yang from Hengyang Hospital of Nanhua University has made significant progress in cancer treatment research, focusing on NIR-II fluorescence imaging guided by molecular engineering nanoplatforms. Their findings were recently published in Analytical Chemistry (IF=7.4, Q1).

The study utilized the AniView 30F NIR In Vivo Animal Imaging System from Biolight Biotechnology, capturing NIR-II fluorescence images of mice with 4T1 tumors after injecting FTEP TBFc NPs. It also included images of the primary organs of these mice.

Malignant tumors significantly impact life quality, but traditional treatments like surgery, chemotherapy, and radiation often have limited efficacy and severe side effects. NIR light therapy, particularly NIR-II fluorescence imaging (1000-1700nm), has emerged as a promising alternative, offering better depth and resolution with minimal invasiveness.

However, traditional cancer therapies (surgery, chemotherapy, and radiation) exhibit low efficacy, high costs, and severe side effects, limiting their applicability. Among alternative therapies, near-infrared (NIR) light therapy has gained attention as an emerging cancer treatment strategy due to its minimal invasiveness, good specificity, and high controllability. NIR-induced generation of reactive oxygen species (ROS) and heat can disrupt intracellular biomolecules (lipids, proteins, and DNA), leading to cell apoptosis.

Advanced NIR-II fluorescence imaging technology (1000-1700nm) improves detection depth, resolution, and sensitivity.

Additionally, it induces less photodamage to tissues compared to NIR-I fluorescence imaging. However, the photophysical energy dissipation processes of NIR-based agents often compete with each other, making it challenging to balance fluorescence, heat, and ROS production. Therefore, the development of innovative platforms and methods that integrate precise real-time cancer diagnosis and monitoring with efficient multimodal therapy will help address practical challenges in clinical settings

Activatable Photothermal Theranostic Nanoplatforms (NPs), owing to their excellent responsiveness to substances in the tumor microenvironment and minimal cytotoxicity, represent a promising approach for cancer treatment. Glutathione (GSH) has long been recognized as essential in regulating tumor initiation. The elevated concentration of GSH (up to 10 mM) in the tumor microenvironment is much higher than that in normal blood and cellular GSH concentrations. The 'gold standard' strategy for the reaction of GSH in organic phototherapeutic nanoparticles (NPs) involves introducing disulfide bonds. However, due to its higher redox potential and more reaction sites, trisulfide bonds exhibit higher sensitivity to GSH. Consequently, they serve as a reduction-ultrasensitive functional trigger for tumor-specific treatment.

Chemodynamic Therapy (CDT) is an efficient tumor treatment method that generates highly toxic hydroxyl radicals (·OH) through the Fenton or Fenton-like reaction by dismutating endogenous H2O2. However, the efficacy of CDT is limited, restricting its clinical application. Enhancing the generation and potency of ·OH would be an effective approach to boost the CDT effect. Compared to traditional photothermal therapy (PTT), combining CDT with low-temperature photothermal therapy (HPTT) can induce localized tumor heating, accelerating the production of ·OH to enhance the treatment effect. Simultaneously, this approach minimizes damage to normal tissues.

Gas therapy is an emerging treatment strategy that leverages the biological effects of gases such as carbon monoxide (CO), hydrogen (H2), and hydrogen sulfide (H2S) to reverse the Warburg effect, leading to the death of tumor cells without harming normal cells. Ultra-small gas molecules can freely infiltrate the tumor stroma and penetrate biological membranes, inducing acute toxicity through miRNA regulation, mitochondrial damage, or uncontrolled intracellular acidification. The combination of Chemodynamic Therapy (CDT) with H2S gas therapy can enhance the CDT effect by first promoting the conversion of Fe3+ to Fe2+, thereby improving the efficiency of the Fenton reaction. On one hand, H2S can inhibit the activity of catalase, thereby reducing the consumption of hydrogen peroxide (H2O2) within the tumor. On the other hand, H2S can also inhibit mitochondrial cytochrome c oxidase (COX IV), leading to mitochondrial dysfunction and adenosine triphosphate (ATP) deficiency, thereby blocking heat shock protein (HSP) expression and enhancing the efficiency of low-temperature photothermal therapy (HPTT).

This research describes the rational design of near-infrared second window (NIR-II) fluorescence imaging-guided organic phototherapeutic nanoparticles (FTEP-TBFc NPs). The molecularly engineered phototherapeutic NPs exhibit sensitive responsiveness to glutathione (GSH), generating hydrogen sulfide (H2S) gas and delivering ferrocene molecules in the tumor microenvironment. Under 808 nm irradiation, FTEP-TBFc not only simultaneously produces fluorescence, heat, and singlet oxygen but also significantly enhances reactive oxygen species generation at a biologically safe laser power of 0.33 W/cm², improving both chemodynamic therapy (CDT) and photodynamic therapy (PDT). H2S inhibits the activities of catalase and cytochrome c oxidase IV (COX IV), leading to enhanced CDT and low-temperature photothermal therapy (HPTT). Furthermore, the reduced intracellular GSH concentration further enhances CDT efficacy and downregulates lipid hydroperoxide accumulation by inhibiting glutathione peroxidase 4 (GPX4), triggering ferroptosis. Overall, FTEP-TBFc NPs, as a multifunctional and efficient nanoparticle, demonstrate great potential in specific tumor imaging-guided multimodal cancer therapy. This unique strategy provides new perspectives and approaches for the design and application of activatable biomedical phototherapy.

In vivo imaging and pharmacokinetics

(a) NIR-II fluorescence images (prone+lateral) of 4T1 tumor bearing mice injected with FTEP TBFc NPs at different times. (b) Fluorescence images of mouse tumors and major organs (collected 24 hours)（ λ Ex: 808nm laser, filter: 900Lp, exposure time: 120ms). The fluorescence intensity of tumor (c) and major organ (d). (e) After 24 hours of injection of FTEP and FTEP TBFc NPs into 4T1 tumor bearing mice, use λ Ex: 808nm laser (0.33W/cm2, 10min) for photothermal imaging. (f) Time varying curves of blood concentration and corresponding blood sample fluorescence images in mice treated with FTEP TBFc NP within 48 hours. (g) Cumulative fecal excretion and corresponding fluorescence imaging of FTEP-TBFc NP treated mice 2-48 hours after intravenous injection. The dose of each group of samples in the figure is 100 μ L (100 μ M) . Three Balb/c mice per group were used for the experiment. Error: mean ± SD (n=3).

Reference:

Wu, G., Liu, F., Li, N., Wang, F., Yang, S., Wu, F., Xiao, H., Wang, M., Deng, S., Kuang, X., Fu, Q., Wu, P., Kang, Q., Sun, L., Li, Z., Lin, N., Wu, Y., Tan, S., Chen, G., Tan, X. and Yang, Q., 2023. Tumor Microenvironment-Responsive One-for-All Molecular-Engineered Nanoplatform Enables NIR-II Fluorescence Imaging-Guided Combinational Cancer Therapy. Analytical Chemistry, 95(47), pp.17372-17383. Available at: https://doi.org/10.1021/acs.analchem.3c03827 [Accessed 29 January 2024].