Quantitative, real-time in vivo tracking of magnetic nanoparticles using multispectral optoacoustic tomography (MSOT) imaging

Recurrent and convolutional neural networks for sequential multispectral optoacoustic tomography (MSOT) imaging

Multispectral optoacoustic tomography (MSOT) is a beneficial technique for diagnosing and analyzing biological samples since it provides meticulous details in anatomy and physiology. However, acquiring high through-plane resolution volumetric MSOT is time-consuming. Here, we propose a deep learning model based on hybrid recurrent and convolutional neural networks to generate sequential cross-sectional images for an MSOT system. This system provides three modalities (MSOT, ultrasound, and optoacoustic imaging of a specific exogenous contrast agent) in a single scan. This study used ICG-conjugated nanoworms particles (NWs-ICG) as the contrast agent. Instead of acquiring seven images with a step size of 0.1 mm, we can receive two images with a step size of 0.6 mm as input for the proposed deep learning model. The deep learning model can generate five other images with a step size of 0.1 mm between these two input images meaning we can reduce acquisition time by approximately 71%.

Evaluation of transfection efficacy, biodistribution, and toxicity of branched amphiphilic peptide capsules (BAPCs) associated with mRNA

Nanoparticles (NPs) have been shown to be a suitable mRNA delivery platform by conferring protection against ribonucleases and facilitating cellular uptake. Several NPs have succeeded in delivering mRNA intranasally, intratracheally, and intramuscularly in preclinical settings. However, intravenous mRNA delivery has been less explored. Only a few NPs have been tested for systemic delivery of mRNA, many of which are formulated with polyethylene glycol (PEG). The incorporation of PEG presents some tradeoffs that must be carefully considered when designing a systemic delivery model. For example, while the addition of PEG may prolong circulation time by preventing early clearance by the mononuclear phagocytic system (MPS), it has also been reported that treating patients with PEGylated drugs can result in hypersensitivity reactions due to anti-PEG antibodies. Thus, it is desirable to have alternative PEG-free delivery methods for mRNA to avoid these adverse effects while preserving the beneficial effects. Our research group developed BAPCs (branched amphiphilic peptide capsules), a peptide-based nanoparticle that resists disruption by chaotropes, proteases, and elevated temperature, thus displaying significant stability and shelf-life. In this study, we demonstrated that similarly to PEG, mRNA shields the BAPC cationic surface to avoid early clearance by the MPS. Multispectral optoacoustic tomography (MSOT) and fluorescence reflectance imaging were imaging techniques used to analyze biodistribution within major MPS organs. Analysis of pro-inflammatory cytokine expression showed that BAPC-mRNA complexes do not cause chronic inflammation. Additionally, BAPCs enhance intracellular delivery of mRNA with negligible cytotoxicity or oxidative stress. These results might pave the way for future therapeutic applications of BAPCs as a delivery platform for systemic mRNA delivery.

Multispectral optoacoustic tomography for the non-invasive identification of patients with severe anemia in vivo

The immediate diagnosis of severe anemia is crucial for patient outcome. However, reliable non-invasive point-of-care diagnostic tools for e.g., ICU monitoring are currently lacking. Using an advanced Multispectral Optoacoustic Tomography (MSOT) research device, we first substantiated a strong positive correlation of MSOT-signal and absolute hemoglobin concentration ex vivo in blood samples. In a clinical exploratory proof-of-concept study, we then evaluated 19 patients with different severities of anemia and controls by non-invasive in vivo measurement of hemoglobin in the radial artery. Our approach proved excellent in identifying patients with severe anemia triggering RBC transfusion based on a strong positive correlation of MSOT-signal intensity and hemoglobin concentration for 700 nm single wavelength and HbR unmixed MSOT-parameter analysis. In conclusion, our study lays the foundation to further develop MSOT-based real-time quantitative perfusion analyses in follow-up preclinical and clinical imaging studies and as a promising diagnostic tool to improve patient care in the future. DRKS00021442.

Photonic and magnetic materials for on-demand local drug delivery

Nanomedicine has been considered a promising tool for biomedical research and clinical practice in the 21st century because of the great impact nanomaterials could have on human health. The generation of new smart nanomaterials, which enable time- and space-controlled drug delivery, improve the limitations of conventional treatments, such as non-specific targeting, poor biodistribution and permeability. These smart nanomaterials can respond to internal biological stimuli (pH, enzyme expression and redox potential) and/or external stimuli (such as temperature, ultrasound, magnetic field and light) to further the precision of therapies. To this end, photonic and magnetic nanoparticles, such as gold, silver and iron oxide, have been used to increase sensitivity and responsiveness to external stimuli. In this review, we aim to report the main and most recent systems that involve photonic or magnetic nanomaterials for external stimulus-responsive drug release. The uniqueness of this review lies in highlighting the versatility of integrating these materials within different carriers. This leads to enhanced performance in terms of in vitro and in vivo efficacy, stability and toxicity. We also point out the current regulatory challenges for the translation of these systems from the bench to the bedside, as well as the yet unresolved matter regarding the standardization of these materials.

Tumor cell membrane-based peptide delivery system targeting the tumor microenvironment for cancer immunotherapy and diagnosis

The development of an effective delivery system for peptides targeting the tumor microenvironment has always been a hot topic of research in the field of cancer diagnosis and therapy. In this study, superparamagnetic iron oxide nanoparticles (SPIO NPs) were encapsulated with H460 lung cancer cell membranes (SPIO NP@M), and two peptides, namely PD-L1 inhibitory peptide (TPP1) and MMP2 substrate peptide (PLGLLG), were conjugated to the H460 membrane (SPIO NP@M-P). Homologous targeting, cytotoxicity, and pharmacokinetics of SPIO NP@M-P were evaluated. The TPP1 peptide was delivered and released to the tumor microenvironment through the homotypic effect of tumor cell membrane and specific digestion by the tumor-specific enzyme MMP2. The newly developed delivery system (SPIO NP@M-P) for the PD-L1 inhibitory peptide could effectively extend the half-life of the peptides (60 times longer than that for peptides alone) and could maintain the ability to reactivate T cells and inhibit the tumor growth both in vitro and in vivo. Furthermore, SPIO NPs in the system could be used as a tumor imaging agent and thus show the effect of peptide treatment. The SPIO NP@M might serve as a promising theranostic platform for therapeutic application of peptides in cancer therapy. STATEMENT OF SIGNIFICANCE: A multifunctional delivery system (SPIO NP@M) was constructed for effectively delivering therapeutic peptides into the tumor microenvironment for cancer diagnosis and therapy. In this paper, the TPP-1 peptide inhibiting the binding of PD-L1 and PD-1 was delivered and released into the tumor microenvironment by the homotypic targeting of H460 cell membrane and specific digestion by the MMP2 enzyme. SPIO NPs in this system were aggregated effectively at the tumor sites and were used for magnetic resonance imaging of tumors. The SPIO NP@M-P delivery system could effectively extend the half-life of the TPP-1 peptide (60 times longer than that of the free peptide) and could maintain the ability to re-activate T cells and inhibit tumor growth in vitro and in vivo. In conclusion, the SPIO NP@M system coated with lung cancer cell membrane and loaded with the PD-L1-blocking TPP-1 peptide could be a promising integrated platform for tumor diagnosis and treatment.

Development of Multispectral Optoacoustic Tomography as a Clinically Translatable Modality for Cancer Imaging

The use of optoacoustic imaging takes advantage of the photoacoustic effect to generate high-contrast, high-resolution medical images at penetration depths of up to 5 cm. Multispectral optoacoustic tomography (MSOT) is a type of optoacoustic imaging system that has seen promising preclinical success with a recent emergence into the clinic. Multiwavelength illumination of tissue allows for the mapping of multiple chromophores, which are generated endogenously or exogenously. However, translation of MSOT to the clinic is still in its preliminary stages. For successful translation, MSOT requires refinement of probes and data-acquisition systems to tailor to the human body, along with more intuitive, real-time visualization settings. The possibilities of optoacoustic imaging, namely MSOT, in the clinic are reviewed here. ©RSNA, 2020.

Implant-based direction of magnetic nanoporous silica nanoparticles - influence of macrophage depletion and infection

Implant associated infections are still key problem in surgery. In the present study, the combination of a magnetic implant with administered magnetic nanoporous silica nanoparticles as potential drug carriers was examined in mice in dependence of local infection and macrophages as influencing factors. Four groups of mice (with and without implant infection and with and without macrophage depletion) received a magnet on the left and a titanium control on the right hind leg. Then, fluorescent nanoparticles were administered and particle accumulations at implant surfaces and in inner organs as well as local tissue reactions were analyzed. Magnetic nanoparticles could be found at the surfaces of magnetic implants in different amounts depending on the treatment groups and only rarely at titanium surfaces. Different interactions of magnetic implants, particles, infection and surrounding tissues occurred. The general principle of targeted accumulation of magnetic nanoparticles could be proven.

Skin Barriers in Dermal Drug Delivery: Which Barriers Have to Be Overcome and How Can We Measure Them?

Although, drugs are required in the various skin compartments such as viable epidermis, dermis, or hair follicles, to efficiently treat skin diseases, drug delivery into and across the skin is still challenging. An improved understanding of skin barrier physiology is mandatory to optimize drug penetration and permeation. The various barriers of the skin have to be known in detail, which means methods are needed to measure their functionality and outside-in or inside-out passage of molecules through the various barriers. In this review, we summarize our current knowledge about mechanical barriers, i.e., stratum corneum and tight junctions, in interfollicular epidermis, hair follicles and glands. Furthermore, we discuss the barrier properties of the basement membrane and dermal blood vessels. Barrier alterations found in skin of patients with atopic dermatitis are described. Finally, we critically compare the up-to-date applicability of several physical, biochemical and microscopic methods such as transepidermal water loss, impedance spectroscopy, Raman spectroscopy, immunohistochemical stainings, optical coherence microscopy and multiphoton microscopy to distinctly address the different barriers and to measure permeation through these barriers in vitro and in vivo.