Radiolabelling of lipid-based nanocarriers with fluorine-18 for in vivo tracking by PET

Multicellular tumor spheroid model to study the multifaceted role of tumor-associated macrophages in PDAC

While considerable efforts have been made to develop new therapies, progress in the treatment of pancreatic cancer has so far fallen short of patients' expectations. This is due in part to the lack of predictive in vitro models capable of accounting for the heterogeneity of this tumor and its low immunogenicity. To address this point, we have established and characterized a 3D spheroid model of pancreatic cancer composed of tumor cells, cancer-associated fibroblasts, and blood-derived monocytes. The fate of the latter has been followed from their recruitment into the tumor spheroid to their polarization into a tumor-associated macrophage (TAM)-like population, providing evidence for the formation of an immunosuppressive microenvironment.This 3D model well reproduced the multiple roles of TAMs and their influence on drug sensitivity and cell migration. Furthermore, we observed that lipid-based nanosystems consisting of sphingomyelin and vitamin E could affect the phenotype of macrophages, causing a reduction of characteristic markers of TAMs. Overall, this optimized triple coculture model gives a valuable tool that could find useful application for a more comprehensive understanding of TAM plasticity as well as for more predictive drug screening. This could increase the relevance of preclinical studies and help identify effective treatments.

Synthetic 18F labeled biomolecules that are selective and promising for PET imaging: major advances and applications

The concept of positron emission tomography (PET) based imaging was developed more than 40 years ago. It has been a widely adopted technique for detecting and staging numerous diseases in clinical settings, particularly cancer, neuro- and cardio-diseases. Here, we reviewed the evolution of PET and its advantages over other imaging modalities in clinical settings. Primarily, this review discusses recent advances in the synthesis of 18F radiolabeled biomolecules in light of the widely accepted performance for effective PET. The discussion particularly emphasizes the 18F-labeling chemistry of carbohydrates, lipids, amino acids, oligonucleotides, peptides, and protein molecules, which have shown promise for PET imaging in recent decades. In addition, we have deliberated on how 18F-labeled biomolecules enable the detection of metabolic changes at the cellular level and the selective imaging of gross anatomical localization via PET imaging. In the end, the review discusses the future perspective of PET imaging to control disease in clinical settings. We firmly believe that collaborative multidisciplinary research will further widen the comprehensive applications of PET approaches in the clinical management of cancer and other pathological outcomes.

[18F]-Radiolabelled Nanoplatforms: A Critical Review of Their Intrinsic Characteristics, Radiolabelling Methods, and Purification Techniques

A wide range of nano-objects is found in many applications of our everyday life. Recognition of their peculiar properties and ease of functionalization has prompted their engineering into multifunctional platforms that are supposed to afford efficient tools for the development of biomedical applications. However, bridging the gap between bench to bedside cannot be expected without a good knowledge of their behaviour in vivo, which can be obtained through non-invasive imaging techniques, such as positron emission tomography (PET). Their radiolabelling with [18F]-fluorine, a technique already well established and widely used routinely for PET imaging, with [18F]-FDG for example, and in preclinical investigation using [18F]-radiolabelled biological macromolecules, has, therefore, been developed. In this context, this review highlights the various nano-objects studied so far, the reasons behind their radiolabelling, and main in vitro and/or in vivo results obtained thereof. Then, the methods developed to introduce the radioelement are presented. Detailed indications on the chemical steps involved are provided, and the stability of the radiolabelling is discussed. Emphasis is then made on the techniques used to purify and analyse the radiolabelled nano-objects, a point that is rarely discussed despite its technical relevance and importance for accurate imaging. The pros and cons of the different methods developed are finally discussed from which future work can develop.

Effectiveness of a novel gene nanotherapy based on putrescine for cancer treatment

Gene therapy has long been proposed for cancer treatment. However, the use of therapeutic nucleic acids presents several limitations such as enzymatic degradation, rapid clearance, and poor cellular uptake and efficiency. In this work we propose the use of putrescine, a precursor for higher polyamine biosynthesis for the preparation of cationic nanosystems for cancer gene therapy. We have formulated and characterized putrescine-sphingomyelin nanosystems (PSN) and studied their endocytic pathway and intracellular trafficking in cancer cells. After loading a plasmid DNA (pDNA) encoding the apoptotic Fas Ligand (FasL), we proved their therapeutic activity by measuring the cell death rate after treatment of MDA-MB-231 cells. We have also used xenografted zebrafish embryos as a first in vivo approach to demonstrate the efficacy of the proposed PSN-pDNA formulation in a more complex model. Finally, intratumoral and intraperitoneal administration to mice-bearing MDA-MB-231 xenografts resulted in a significant decrease in tumour cell growth, highlighting the potential of the developed gene therapy nanoformulation for the treatment of triple negative breast cancer.

Fully automated 18F-fluorination of N-succinimidyl-4-[18F]fluorobenzoate ([18F]SFB) for indirect labelling of nanobodies

N-succinimidyl-4-[¹⁸F]fluorobenzoate ([¹⁸F]SFB), a widely used labeling agent to introduce the 4-[¹⁸F]fluorobenzoyl-prosthetic group, is normally obtained in three consecutive steps from [¹⁸F]fluoride ion. Here, we describe an efficient one-step labeling procedure of [¹⁸F]SFB starting from a tin precursor. This method circumvents volatile radioactive side-products and simplifies automatization. [¹⁸F]SFB was obtained after HPLC purification in a yield of 42 + 4% and a radiochemical purity (RCP) > 99% (n = 6). In addition, we investigate the automation of the coupling of [¹⁸F]SFB to a nanobody (cAbBcII10, targeting β-lactamase enzyme) and purification by size exclusion chromatography (PD-10 desalting column) to remove unconjugated reagent. Production and use of [¹⁸F]SFB were implemented on a radiosynthesis unit (Neptis^®). The fully automated radiosynthesis process including purification and formulation required 160 min of synthesis time. [¹⁸F]SFB-labeled nanobody was obtained in a yield of 21 + 2% (activity yield 12 + 1% non-decay corrected) and a radiochemical purity (RCP) of > 95% (n = 3). This approach simplifies [¹⁸F]SFB synthesis to one-step, enhances the yield in comparison to the previous report and enables the production of radiolabeled nanobody on the same synthesis module.

The future of early cancer detection

A proactive approach to detecting cancer at an early stage can make treatments more effective, with fewer side effects and improved long-term survival. However, as detection methods become increasingly sensitive, it can be difficult to distinguish inconsequential changes from lesions that will lead to life-threatening cancer. Progress relies on a detailed understanding of individualized risk, clear delineation of cancer development stages, a range of testing methods with optimal performance characteristics, and robust evaluation of the implications for individuals and society. In the future, advances in sensors, contrast agents, molecular methods, and artificial intelligence will help detect cancer-specific signals in real time. To reduce the burden of cancer on society, risk-based detection and prevention needs to be cost effective and widely accessible.

Before in vivo studies: In vitro screening of sphingomyelin nanosystems using a relevant 3D multicellular pancreatic tumor spheroid model

Sphingomyelin nanosystems have already shown to be promising carriers for efficient delivery of anticancer drugs. For further application in the treatment of pancreatic tumor, the investigation on relevant in vitro models able to reproduce its physio-pathological complexity, is mandatory. Accordingly, a 3D heterotype spheroid model of pancreatic tumor has been herein constructed to investigate the potential of bare and polyethylene glycol-modified lipids nanosystems in terms of their ability to penetrate the tumor mass and deliver drugs. Regardless of their surface properties, the lipid nanosystems successfully diffused through the spheroid without inducing toxicity, showing a clear safety profile. Loading of the bare nanosystems with a lipid prodrug of gemcitabine was used to evaluate their therapeutic potential. While the nanosystems were more effective than the free drug on 2D cell monocultures, this advantage, despite their efficient penetration capacity, was lost in the 3D tumor model. The latter, being able to mimic the tumor and its microenvironment, was capable to provide a more realistic information on the cell sensitivity to treatments. These results highlight the importance of using appropriate 3D tumour models as tools for proper in vitro evaluation of nanomedicine efficacy and their timely optimisation, so as to identify the best candidates for later in vivo evaluation.

Nanomaterial Probes for Nuclear Imaging

Nuclear imaging is a powerful non-invasive imaging technique that is rapidly developing in medical theranostics. Nuclear imaging requires radiolabeling isotopes for non-invasive imaging through the radioactive decay emission of the radionuclide. Nuclear imaging probes, commonly known as radiotracers, are radioisotope-labeled small molecules. Nanomaterials have shown potential as nuclear imaging probes for theranostic applications. By modifying the surface of nanomaterials, multifunctional radio-labeled nanomaterials can be obtained for in vivo biodistribution and targeting in initial animal imaging studies. Various surface modification strategies have been developed, and targeting moieties have been attached to the nanomaterials to render biocompatibility and enable specific targeting. Through integration of complementary imaging probes to a single nanoparticulate, multimodal molecular imaging can be performed as images with high sensitivity, resolution, and specificity. In this review, nanomaterial nuclear imaging probes including inorganic nanomaterials such as quantum dots (QDs), organic nanomaterials such as liposomes, and exosomes are summarized. These new developments in nanomaterials are expected to introduce a paradigm shift in nuclear imaging, thereby creating new opportunities for theranostic medical imaging tools.

Manganese Ferrite Nanoparticles Encapsulated into Vitamin E/Sphingomyelin Nanoemulsions as Contrast Agents for High-Sensitive Magnetic Resonance Imaging

Magnetic resonance imaging (MRI) is one of the most powerful non-invasive imaging modalities used in clinics due to its great spatial resolution and excellent soft-tissue contrast, though still less sensitive than other techniques such as the nuclear imaging modalities. This lack of sensitivity can be improved with the use of contrast agents based on nanomaterials. In recent years, researchers have focused on the development of magnetic nanoparticles, given their role as enhancers of the contrast signal based on the magnetic resonance. Manganese ferrite nanoparticles stand out, given their high magnetic susceptibility and magnetic soft nature. Herein, 10 nm MnFe₂ O₄ nanoparticles, functionalized with the natural antioxidant vitamin E (VitE-MFO) are encapsulated into simple, biodegradable and non-toxic nanoemulsions (NEs), by a reproducible one-step method obtaining stable 150 nm-sized magnetic nanoemulsions (VitE-MFO-NEs). After encapsulation, the superparamagnetic properties of VitE-MFO are maintained and MR imaging studies reveal an extremely high transverse relaxivity for VitE-MFO-NEs (652.9 × 10^-3  m^-1  s^-1 ), twofold higher than VitE-MFO value. Moreover, VitE-MFO-NEs show great in vivo biocompatibility and good signal in in vivo and ex vivo MRI, which indicates their great potential for biomedical imaging enhancing the negative MR contrast and significantly improving the sensitivity of MRI.

Modulation of Colorectal Tumor Behavior via lncRNA TP53TG1-Lipidic Nanosystem

Long non-coding RNAs (lncRNAs) are an emerging group of RNAs with a crucial role in cancer pathogenesis. In gastrointestinal cancers, TP53 target 1 (TP53TG1) is an epigenetically regulated lncRNA that represents a promising therapeutic target due to its tumor suppressor properties regulating the p53-mediated DNA damage and the intracellular localization of the oncogenic YBX1 protein. However, to translate this finding into the clinic as a gene therapy, it is important to develop effective carriers able to deliver exogenous lncRNAs to the targeted cancer cells. Here, we propose the use of biocompatible sphingomyelin nanosystems comprising DOTAP (DSNs) to carry and deliver a plasmid vector encoding for TP53TG1 (pc(TP53TG1)-DSNs) to a colorectal cancer cell line (HCT-116). DSNs presented a high association capacity and convenient physicochemical properties. In addition, pc(TP53TG1)-DSNs showed anti-tumor activities in vitro, specifically a decrease in the proliferation rate, a diminished colony-forming capacity, and hampered migration and invasiveness of the treated cancer cells. Consequently, the proposed strategy displays a high potential as a therapeutic approach for colorectal cancer.

Biodistribution of 68/67Ga-Radiolabeled Sphingolipid Nanoemulsions by PET and SPECT Imaging

Background and Purpose

Non-invasive imaging methodologies, especially nuclear imaging techniques, have undergone an extraordinary development over the last years. Interest in the development of innovative tracers has prompted the emergence of new nanomaterials with a focus on nuclear imaging and therapeutical applications. Among others, organic nanoparticles are of the highest interest due to their translational potential related to their biocompatibility and biodegradability. Our group has developed a promising new type of biocompatible nanomaterials, sphingomyelin nanoemulsions (SNs). The aim of this study is to explore the potential of SNs for nuclear imaging applications.

Methods

Ready-to-label SNs were prepared by a one-step method using lipid derivative chelators and characterized in terms of their physicochemical properties. Stability was assessed under storage and after incubation with human serum. Chelator-functionalized SNs were radiolabeled with ⁶⁷Ga and ⁶⁸Ga, and the radiochemical yield (RCY), radiochemical purity (RCP) and radiochemical stability (RCS) were determined. Finally, the biodistribution of ^67/68Ga-SNs was evaluated in vivo and ex vivo.

Results

Here, we describe a simple and mild one-step method for fast and efficient radiolabeling of SNs with ⁶⁸Ga and ⁶⁷Ga radioisotopes. In vivo experiments showed that ^67/68Ga-SNs can efficiently and indistinctly be followed up by PET and SPECT. Additionally, we proved that the biodistribution of the ^67/68Ga-SNs can be conveniently modulated by modifying the surface properties of different hydrophilic polymers, and therefore the formulation can be further adapted to the specific requirements of different biomedical applications.

Conclusion

This work supports ^67/68Ga-SNs as a novel probe for nuclear imaging with tunable biodistribution and with great potential for the future development of nanotheranostics.

Sphingomyelin nanosystems loaded with uroguanylin and etoposide for treating metastatic colorectal cancer

Colorectal cancer is the third most frequently diagnosed cancer malignancy and the second leading cause of cancer-related deaths worldwide. Therefore, it is of utmost importance to provide new therapeutic options that can improve survival. Sphingomyelin nanosystems (SNs) are a promising type of nanocarriers with potential for association of different types of drugs and, thus, for the development of combination treatments. In this work we propose the chemical modification of uroguanylin, a natural ligand for the Guanylyl Cyclase (GCC) receptor, expressed in metastatic colorectal cancer tumors, to favour its anchoring to SNs (UroGm-SNs). The anti-cancer drug etoposide (Etp) was additionally encapsulated for the development of a combination strategy (UroGm-Etp-SNs). Results from in vitro studies showed that UroGm-Etp-SNs can interact with colorectal cancer cells that express the GCC receptor and mediate an antiproliferative response, which is more remarkable for the drugs in combination. The potential of UroGm-Etp-SNs to treat metastatic colorectal cancer cells was complemented with an in vivo experiment in a xenograft mice model.

Imaging cancer cells with nanostructures: Prospects of nanotechnology driven non-invasive cancer diagnosis

The application of nanostructured materials in medicine is a rapidly evolving area of research that includes both the diagnosis and treatment of various diseases. Metals, metal oxides and carbon-based nanomaterials have shown much promise in medical technological advancements due to their tunable physical, chemical and biological properties. The nanoscale properties, especially the size, shape, surface chemistry and stability makes them highly desirable for diagnosing and treating various diseases, including cancers. Major applications of nanomaterials in cancer diagnosis include in vivo bioimaging and molecular marker detection, mainly as image contrast agents using modalities such as radio, magnetic resonance, and ultrasound imaging. When a suitable targeting ligand is attached on the nanomaterial surface, it can help pinpoint the disease site during imaging. The application of nanostructured materials in cancer diagnosis can help in the early detection, treatment and patient follow-up . This review aims to gather and present the information regarding the application of nanotechnology in cancer diagnosis. We also discuss the challenges and prospects regarding the application of nanomaterials as cancer diagnostic tools.