Application of near-infrared fluorescence imaging in theranostics of gastrointestinal tumors

Gastrointestinal cancers have become an important cause of cancer-related death in humans. Improving the early diagnosis rate of gastrointestinal tumors and improving the effect of surgical treatment can significantly improve the survival rate of patients. The conventional diagnostic method is high-definition white-light endoscopy, which often leads to missed diagnosis. For surgical treatment, intraoperative tumor localization and post-operative anastomotic state evaluation play important roles in the effect of surgical treatment. As a new imaging method, near-infrared fluorescence imaging (NIRFI) has its unique advantages in the diagnosis and auxiliary surgical treatment of gastrointestinal tumors due to its high sensitivity and the ability to image deep tissues. In this review, we focus on the latest advances of NIRFI technology applied in early diagnosis of gastrointestinal tumors, identification of tumor margins, identification of lymph nodes, and assessment of anastomotic leakage. In addition, we summarize the advances of NIRFI systems such as macro imaging and micro imaging systems, and also clearly describe the application process of NIRFI from system to clinical application, and look into the prospect of NIRFI applied in the theranostics of gastrointestinal tumors.

Ready vascular permeability of a near-infrared fluorescent agent ASP5354 for intraoperative ureteral identification enables imaging of carcinoma tissues

This study investigates the ability of a near-infrared fluorescence (NIRF) imaging agent, ASP5354, for in vivo fluorescence imaging of esophageal squamous cell carcinoma (ESCC) tissues. The ability of ASP5354 was evaluated using a single dose of ASP5354 or indocyanine green (ICG), which was intravenously administered to a KYSE850 human ESCC xenograft mouse model. Subsequently, in vivo NIRF images of the mouse were obtained using a clinically available camera system. ASP5354-specific NIRF signals were strongly detectable in KYSE850 carcinoma tissues immediately (30 s) following ASP5354 administration compared with normal tissues. Meanwhile, ICG could not distinguish between normal and carcinomatous tissues. To elucidate the associated imaging mechanisms, the vascular permeability of ASP5354 and ICG was investigated in rat back dermis treated with saline or histamine, which enhances vascular permeability, using in vivo NIRF imaging. ASP5354 exhibited higher vascular permeability in histamine-treated skin than in normal skin. KYSE850 carcinoma tissues can be distinguished from normal tissues based on the measurement of ASP5354-specific NIRF signals, and the mechanism that enables imaging relies on the specific and rapid leakage of ASP5354 from the capillaries into the stroma of carcinoma tissues.

Targeted Photodynamic Diagnosis and Therapy for Esophageal Cancer: Potential Role of Functionalized Nanomedicine

Esophageal cancer is often diagnosed at the late stage when cancer has already spread and is characterized by a poor prognosis. Therefore, early diagnosis is vital for a better and efficient treatment outcome. Upper endoscopy with biopsy is the standard diagnostic tool for esophageal cancer but is challenging to diagnose at its premalignant stage, while conventional treatments such as surgery, chemotherapy, and irradiation therapy, are challenging to eliminate the tumor. Photodynamic diagnosis (PDD) and therapy (PDT) modalities that employ photosensitizers (PSs) are emerging diagnostic and therapeutic strategies for esophageal cancer. However, some flaws associated with the classic PSs have limited their clinical applications. Functionalized nanomedicine has emerged as a potential drug delivery system to enhance PS drug biodistribution and cellular internalization. The conjugation of PSs with functionalized nanomedicine enables increased localization within esophageal cancer cells due to improved solubility and stability in blood circulation. This review highlights PS drugs used for PDD and PDT for esophageal cancer. In addition, it focuses on the various functionalized nanomedicine explored for esophageal cancer and their role in targeted PDD and PDT for diagnosis and treatment.

Nanoparticles modified with vasculature-homing peptides for targeted cancer therapy and angiogenesis imaging

The two major challenges in cancer treatment include lack of early detection and ineffective therapies with various side effects. Angiogenesis is the key process in the growth, survival, invasiveness, and metastasis of many of cancerous tumors. Imaging of the angiogenesis could lead to diagnosis of tumors in the early stage and evaluation of the therapeutic responses. Angiogenic blood vessels express specific molecular markers different from normal blood vessels (in level or kind). This fact would make the tumor vasculature a suitable site to target therapeutics and imaging agents within the tumor. Surface modified nanoparticles using peptide ligands with high binding affinity to the vasculature markers, provide efficient delivery of therapeutic and imaging agents, while avoiding undesirable side effects. In this review, we discuss discoveries of various tumor targeting peptides useful for tumor angiogenesis imaging and targeted therapy with emphasis on surface modified nanomedicines using vasculature targeting peptides.

Emerging trends of receptor-mediated tumor targeting peptides: A review with perspective from molecular imaging modalities

Natural peptides extracted from natural components such are known to have a relatively short in-vivo half-life and can readily metabolize by endo- and exo-peptidases. Fortunately, synthetic peptides can be easily manipulated to increase in-vivo stability, membrane permeability and target specificity with some well-known natural families. Many natural as well as synthetic peptides target to their endogenous receptors for diagnosis and therapeutic applications. In order to detect these peptides externally, they must be modified with radionuclides compatible with single photon emission computed tomography (SPECT) or positron emission tomography (PET). Although, these techniques mainly rely on physiological changes and have profound diagnostic strength over anatomical modalities such as MRI and CT. However, both SPECT and PET observed to possess lack of anatomical reference frame which is a key weakness of these techniques, and unfortunately, cannot be available freely in most clinical centres especially in under-developing countries. Hence, it is need of the time to design and develop economic, patient friendly and versatile strategies to grapple with existing problems without any hazardous side effects. Optical molecular imaging (OMI) has emerged as a novel technique in field of medical science using fluorescent probes as imaging modality and has ability to couple with organic drugs, small molecules, chemotherapeutics, DNA, RNA, anticancer peptide and protein without adding chelators as necessary for radionuclides. Furthermore, this review focuses on difference in imaging modalities and provides ample knowledge about reliable, economic and patient friendly optical imaging technique rather radionuclide-based imaging techniques.

Dendrimer-based nanohybrids in cancer photomedicine

Cancer phototherapy with non-invasiveness and high therapeutical efficiency has emerged as a hot spot research in cancer management. Various nanomaterials have been involved in the development of novel photoactive agents to overcome the current limitations in cancer phototherapy. Dendrimers, as an excellent nanocarrier with unique physicochemical properties, have received extensive attention and much effort has been made in the development of dendrimer-based hybrid platforms for photomedicine applications. Dendrimers can be entrapped with photosensitive agents within their internal cavities and be surface modified with reactive molecules, constructing multifunctional nanoplatforms for cancer treatment. In this review, we concisely survey the design of several different kinds of dendrimer-based nanohybrids for cancer photomedicine applications, and provide an overview of their recent applications in molecular imaging, single-modality photothermal therapy or photodynamic therapy, combination therapy, and theranostics of cancer. In addition, we also briefly discuss the future perspectives in the area of dendrimer-based nanohybrids for cancer photomedicine.

Peptides for optical medical imaging and steps towards therapy

Optical medical imaging is a rapidly growing area of research and development that offers a multitude of healthcare solutions both diagnostically and therapeutically. In this review, some of the most recently described peptide-based optical probes are reviewed with a special emphasis on their in vivo use and potential application in a clinical setting.

Modulating angiogenesis with integrin-targeted nanomedicines

Targeting angiogenesis-related pathologies, which include tumorigenesis and metastatic processes, has become an attractive strategy for the development of efficient guided nanomedicines. In this respect, integrins are cell-adhesion molecules involved in angiogenesis signaling pathways and are overexpressed in many angiogenic processes. Therefore, they represent specific biomarkers not only to monitor disease progression but also to rationally design targeted nanomedicines. Arginine-glycine-aspartic (RGD) containing peptides that bind to specific integrins have been widely utilized to provide ligand-mediated targeting capabilities to small molecules, peptides, proteins, and antibodies, as well as to drug/imaging agent-containing nanomedicines, with the final aim of maximizing their therapeutic index. Within this review, we aim to cover recent and relevant examples of different integrin-assisted nanosystems including polymeric nanoconstructs, liposomes, and inorganic nanoparticles applied in drug/gene therapy as well as imaging and theranostics. We will also critically address the overall benefits of integrin-targeting.