CT/NIRF dual-modal imaging tracking and therapeutic efficacy of transplanted mesenchymal stem cells labeled with Au nanoparticles in silica-induced pulmonary fibrosis

A multi-modality imaging strategy to determine the multiple in vivo fates of human umbilical cord mesenchymal stem cells at different periods of acute liver injury treatment

Human umbilical cord mesenchymal stem cells (HUCMSCs) are applied for disease therapy as a new type of drug in many countries. Their effects are not only presented by live cells, but also apoptotic bodies or cell fragments of dead cells. Therefore, it is meaningful to determine the multiple fates of HUCMSCs in vivo. Although various probes combining different imaging modalities have been developed to label and trace transplanted HUCMSCs in vivo, the status of the cells (live, dead, or apoptotic) was not distinguished, and a thorough understanding of the multiple fates of HUCMSCs after transplantation in vivo is lacking. Therefore, a magnetic resonance (MR)/near infrared fluorescent (NIRF)/bioluminescence (BI) multi-modality imaging strategy was developed. Iron oxide nanoparticles (IONPs) were assembled into 100 nm nanoparticles using epigallocatechin gallate as a chemical linker to increase the MR signal and reduce the exocytosis of IONPs for direct cell labeling and longitudinal MR imaging tracking. Fluorescent probes for apoptosis (DEVD-Cy-OH) were also loaded in the above assemblies to monitor the cell status. Meanwhile, the cell surface was labeled with the fluorescent dye Cy7 via bioorthogonal reactions to visualize the NIRF signal. Luciferase was lentivirally transfected into live cells to generate bioluminescence. Such labeling did not affect either the viability, proliferation, migration, differentiation characteristics of HUCMSCs or their therapeutic effects on acute liver injury mice in vivo. The in vivo fates of HUCMSCs were monitored via MR/NIRF/BI multi-modality imaging in acute liver injury mice. Although MR and Cy7 signals aggregated in injured liver for 7 days, the BI signals persisted for less than 24 hours. There was an increase in DEVD-Cy-OH signals in the injured liver, but they were almost at the basal level. That means that HUCMSCs survive in mice for a short time, and the dead form of HUCMSCs accumulated in a large quantity and sustained for a long time, which might contribute to their therapeutic effect.

Magnetic Particle Imaging: From Tracer Design to Biomedical Applications in Vasculature Abnormality

Magnetic particle imaging (MPI) is an emerging non-invasive tomographic technique based on the response of magnetic nanoparticles (MNPs) to oscillating drive fields at the center of a static magnetic gradient. In contrast to magnetic resonance imaging (MRI), which is driven by uniform magnetic fields and projects the anatomic information of the subjects, MPI directly tracks and quantifies MNPs in vivo without background signals. Moreover, it does not require radioactive tracers and has no limitations on imaging depth. This article first introduces the basic principles of MPI and important features of MNPs for imaging sensitivity, spatial resolution, and targeted biodistribution. The latest research aiming to optimize the performance of MPI tracers is reviewed based on their material composition, physical properties, and surface modifications. While the unique advantages of MPI have led to a series of promising biomedical applications, recent development of MPI in investigating vascular abnormalities in cardiovascular and cerebrovascular systems, and cancer are also discussed. Finally, recent progress and challenges in the clinical translation of MPI are discussed to provide possible directions for future research and development.

Fluorescence-Based Mono- and Multimodal Imaging for In Vivo Tracking of Mesenchymal Stem Cells

The advancement of stem cell therapy has offered transformative therapeutic outcomes for a wide array of diseases over the past decades. Consequently, stem cell tracking has become significant in revealing the mechanisms of action and ensuring safe and effective treatments. Fluorescence stands out as a promising choice for stem cell tracking due to its myriad advantages, including high resolution, real-time monitoring, and multi-fluorescence detection. Furthermore, combining fluorescence with other tracking modalities-such as bioluminescence imaging (BLI), positron emission tomography (PET), photoacoustic (PA), computed tomography (CT), and magnetic resonance (MR)-can address the limitations of single fluorescence detection. This review initially introduces stem cell tracking using fluorescence imaging, detailing various labeling strategies such as green fluorescence protein (GFP) tagging, fluorescence dye labeling, and nanoparticle uptake. Subsequently, we present several combinations of strategies for efficient and precise detection.

Multispectral optoacoustic tomography is more sensitive than micro-computed tomography for tracking gold nanorod labelled mesenchymal stromal cells

Tracking the fate of therapeutic cell types is important for assessing their safety and efficacy. Bioluminescence imaging (BLI) is an effective cell tracking technique, but poor spatial resolution means it has limited ability to precisely map cells in vivo in 3D. This can be overcome by using a bimodal imaging approach that combines BLI with a technique capable of generating high-resolution images. Here we compared the effectiveness of combining either multispectral optoacoustic tomography (MSOT) or micro-computed tomography (micro-CT) with BLI for tracking the fate of luciferase+ human mesenchymal stromal cells (MSCs) labelled with gold nanorods. Following subcutaneous administration in mice, the MSCs could be readily detected with MSOT but not with micro-CT. We conclude that MSOT is more sensitive than micro-CT for tracking gold nanorod-labelled cells in vivo and depending on the route of administration, can be used effectively with BLI to track MSC fate in mice.

Inorganic nanoparticle-integrated mesenchymal stem cells: A potential biological agent for multifaceted applications

Mesenchymal stem cell (MSC)-based therapies are flourishing. MSCs could be used as potential therapeutic agents for regenerative medicine due to their own repair function. Meanwhile, the natural predisposition toward inflammation or injury sites makes them promising carriers for targeted drug delivery. Inorganic nanoparticles (INPs) are greatly favored for their unique properties and potential applications in biomedical fields. Current research has integrated INPs with MSCs to enhance their regenerative or antitumor functions. This model also allows the in vivo fate tracking of MSCs in multiple imaging modalities, as many INPs are also excellent contrast agents. Thus, INP-integrated MSCs would be a multifunctional biologic agent with great potential. In this review, the current roles performed by the integration of INPs with MSCs, including (i) enhancing their repair and regeneration capacity via the improvement of migration, survival, paracrine, or differentiation properties, (ii) empowering tumor-killing ability through agent loaded or hyperthermia, and (iii) conferring traceability are summarized. An introduction of INP-integrated MSCs for simultaneous treatment and tracking is also included. The promising applications of INP-integrated MSCs in future treatments are emphasized and the challenges to their clinical translation are discussed.

Lessons from the history of inorganic nanoparticles for inhalable diagnostics and therapeutics

The respiratory tract is one of the most accessible ones to exogenous nanoparticles, yet drug delivery by their means to it is made extraordinarily challenging because of the plexus of aerodynamic, hemodynamic and biomolecular factors at cellular and extracellular levels that synergistically define the safety and efficacy of this process. Here, the use of inorganic nanoparticles (INPs) for inhalable diagnostics and therapies of the lung is viewed through the prism of the history of studies on the interaction of INPs with the lower respiratory tract. The most conceptually and methodologically innovative and illuminative studies are referred to in the chronological order, as they were reported in the literature, and the trends in the progress of understanding this interaction of immense therapeutic and toxicological significance are being deduced from it. The most outstanding actual trends delineated include the diminishment of toxicity via surface functionalization, cell targeting, tagging and tracking via controlled binding and uptake, hybrid INP treatments, magnetic guidance, combined drug and gene delivery, use as adjuvants in inhalable vaccines, and other. Many of the understudied research directions, which have been accomplished by the nanostructured organic polymers in the pulmonary niche, are discussed. The progress in the use of INPs as inhalable diagnostics or therapeutics has been hampered by their well-recognized inflammatory potential and toxicity in the respiratory tract. However, the annual numbers of methodologically innovative studies have been on the rise throughout the past two decades, suggesting that this is a prolific direction of research, its comparatively poor commercial takings notwithstanding. Still, the lack of consensus on the effects of many INP compositions at low but therapeutically effective doses, the plethora of contradictory reports on ostensibly identical chemical compositions and NP properties, and the many cases of antagonism in combinatorial NP treatments imply that the rational design of inhalable medical devices based on INPs must rely on qualitative principles for the most part and embrace a partially stochastic approach as well. At the same time, the fact that the most studied INPs for pulmonary applications have been those with some of the thickest records of pulmonary toxicity, e.g., carbon, silver, gold, silica and iron oxide, is a silent call for the expansion of the search for new inorganic compositions for use in inhalable therapies to new territories.

ZC3H4 regulates infiltrating monocytes, attenuating pulmonary fibrosis through IL-10

Silicosis is a pulmonary fibrosis-associated disease caused by the inhalation of large amounts of free silicon dioxide (SiO₂) that mainly manifests as early inflammation and late pulmonary fibrosis. As macrophage precursors, monocytes accumulate in the lung during early inflammation, but their role in the development of silicosis is unclear. Single-cell sequencing (cell numbers = 25,002), Western blotting, quantitative real-time PCR, ELISA and cell functional experiments were used to explore the specific effects of monocytes on fibroblasts. The CRISPR/Cas9 system was used to specifically knock down ZC3H4, a novel member of the CCCH zinc finger protein family, and was combined with pharmacological methods to explore the mechanism by which ZC3H4 affects chemokine and cytokine secretion. The results indicated that (1) SiO₂ induced an infiltrating phenotype in monocytes; (2) infiltrating monocytes inhibited the activation, viability and migration of fibroblasts by regulating IL-10 but not IL-8; and (3) SiO₂ downregulated IL-10 via ZC3H4-induced autophagy. This study revealed that ZC3H4 regulated the secretion function of monocytes, which, in turn, inhibited fibroblast function in early inflammation through autophagy signaling, thereby reducing pulmonary fibrosis. These findings provide a new idea for the clinical treatment of silicosis.

The Advances and Biomedical Applications of Imageable Nanomaterials

Nanomedicine shows great potential in screening, diagnosing and treating diseases. However, given the limitations of current technology, detection of some smaller lesions and drugs’ dynamic monitoring still need to be improved. With the advancement of nanotechnology, researchers have produced various nanomaterials with imaging capabilities which have shown great potential in biomedical research. Here, we summarized the researches based on the characteristics of imageable nanomaterials, highlighted the advantages and biomedical applications of imageable nanomaterials in the diagnosis and treatment of diseases, and discussed current challenges and prospects.

Recent Advances in Fluorescence Imaging of Pulmonary Fibrosis in Animal Models

Pulmonary fibrosis (PF) is a lung disease that may cause impaired gas exchange and respiratory failure while being difficult to treat. Rapid, sensitive, and accurate detection of lung tissue and cell changes is essential for the effective diagnosis and treatment of PF. Currently, the commonly-used high-resolution computed tomography (HRCT) imaging has been challenging to distinguish early PF from other pathological processes in the lung structure. Magnetic resonance imaging (MRI) using hyperpolarized gases is hampered by the higher cost to become a routine diagnostic tool. As a result, the development of new PF imaging technologies may be a promising solution. Here, we summarize and discuss recent advances in fluorescence imaging as a talented optical technique for the diagnosis and evaluation of PF, including collagen imaging, oxidative stress, inflammation, and PF-related biomarkers. The design strategies of the probes for fluorescence imaging (including multimodal imaging) of PF are briefly described, which can provide new ideas for the future PF-related imaging research. It is hoped that this review will promote the translation of fluorescence imaging into a clinically usable assay in PF.

FITC characterization of a cathepsin B-responsive nanoprobe for report of differentiation of HL60 cells into macrophages

A cathepsin B (Cat B)-responsive optical nanoprobe is designed and prepared for report of HL60 differentiation into macrophage. A peptide sequence FRFK is linked to fluorescein (FITC) via the distant amino group of its lysine and N-terminated with acrylic acid (AA) to yield a molecular fluorescent probe AA-FRFK (FITC). The molecular probe is further embedded in poly(lactic-co-glycolic acid) (PLGA) to form a fluorescent nanoprobe AA-FRFK (FITC)@PLGA. The resultant optical nanoprobe is degradable by lysosomal Cat B, which is expressed in macrophages with a level of 5-10 times of that in HL60 cells. As a result, a significant decrease in fluorescence intensity is associated with the differentiation process of HL60 to macrophage and can be used as an indication of the differentiation process. The findings may pave a way toward the development of a universal in vitro labeling strategy of exogenous stem cells for report of in vivo cell differentiation by a dual-mode imaging modality involving optical imaging and magnetic resonance imaging.

pH-Triggered Aggregation of Gold Nanoparticles for Enhanced Labeling and Long-Term CT Imaging Tracking of Stem Cells in Pulmonary Fibrosis Treatment

Gold nanoparticles (AuNPs) pose a great challenge in the development of nanotracers that can self-adaptively alter their properties in response to certain cellular environments for long-term stem cell tracking. Herein, pH-sensitive Au nanotracers (CPP-PSD@Au) are fabricated by sequential coupling of AuNPs with sulfonamide-based polymer (PSD) and cell-penetrating peptide (CPP), which can be efficiently internalized by mesenchymal stem cells (MSCs) and undergo pH-induced self-assembly in endosomes, facilitating long-term computed tomography (CT) imaging tracking MSCs in a murine model of idiopathic pulmonary fibrosis (IPF). Using the CPP-PSD@Au, the transplanted MSCs for the first time can be monitored with CT imaging for up to 35 days after transplantation into the lung of IPF mice, clearly elucidating the migration process of MSCs in vivo. Moreover, we preliminarily explored the mechanism of the CPP-PSD@Au labeled MSCs in the alleviation of IPF, including recovery of alveolar integrity, decrease of collagen deposition, as well as down-regulation of relevant cytokine level. This work facilitates our understanding of the behavior and effect of MSCs in the therapy of IPF, thereby providing an important insight into the stem cell-based treatment of lung diseases.

Nanoparticles for Stem Cell Tracking and the Potential Treatment of Cardiovascular Diseases

Stem cell-based therapies have been shown potential in regenerative medicine. In these cells, mesenchymal stem cells (MSCs) have the ability of self-renewal and being differentiated into different types of cells, such as cardiovascular cells. Moreover, MSCs have low immunogenicity and immunomodulatory properties, and can protect the myocardium, which are ideal qualities for cardiovascular repair. Transplanting mesenchymal stem cells has demonstrated improved outcomes for treating cardiovascular diseases in preclinical trials. However, there still are some challenges, such as their low rate of migration to the ischemic myocardium, low tissue retention, and low survival rate after the transplantation. To solve these problems, an ideal method should be developed to precisely and quantitatively monitor the viability of the transplanted cells in vivo for providing the guidance of clinical translation. Cell imaging is an ideal method, but requires a suitable contrast agent to label and track the cells. This article reviews the uses of nanoparticles as contrast agents for tracking MSCs and the challenges of clinical use of MSCs in the potential treatment of cardiovascular diseases.

Mesenchymal stem cells ameliorate silica-induced pulmonary fibrosis by inhibition of inflammation and epithelial-mesenchymal transition

Silicosis is a devastating occupational disease caused by long-term inhalation of silica particles, inducing irreversible lung damage and affecting lung function, without effective treatment. Mesenchymal stem cells (MSCs) are a heterogeneous subset of adult stem cells that exhibit excellent self-renewal capacity, multi-lineage differentiation potential and immunomodulatory properties. The aim of this study was to explore the effect of bone marrow-derived mesenchymal stem cells (BMSCs) in a silica-induced rat model of pulmonary fibrosis. The rats were treated with BMSCs on days 14, 28 and 42 after perfusion with silica. Histological examination and hydroxyproline assays showed that BMSCs alleviated silica-induced pulmonary fibrosis in rats. Results from ELISA and qRT-PCR indicated that BMSCs inhibited the expression of inflammatory cytokines TNF-α, IL-1β and IL-6 in lung tissues and bronchoalveolar lavage fluid of rats exposed to silica particles. We also performed qRT-PCR, Western blot and immunohistochemistry to examine epithelial-mesenchymal transition (EMT)-related indicators and demonstrated that BMSCs up-regulate E-cadherin and down-regulate vimentin and extracellular matrix (ECM) components such as fibronectin and collagen Ⅰ. Additionally, BMSCs inhibited the silica-induced increase in TGF-β1, p-Smad2 and p-Smad3 and decrease in Smad7. These results suggested that BMSCs can inhibit inflammation and reverse EMT through the inhibition of the TGF-β/Smad signalling pathway to exhibit an anti-fibrotic effect in the rat silicosis model. Our study provides a new and meaningful perspective for silicosis treatment strategies.

Mesenchymal stem/stromal cell-based therapy: mechanism, systemic safety and biodistribution for precision clinical applications

Mesenchymal stem/stromal cells (MSCs) are a promising resource for cell-based therapy because of their high immunomodulation ability, tropism towards inflamed and injured tissues, and their easy access and isolation. Currently, there are more than 1200 registered MSC clinical trials globally. However, a lack of standardized methods to characterize cell safety, efficacy, and biodistribution dramatically hinders the progress of MSC utility in clinical practice. In this review, we summarize the current state of MSC-based cell therapy, focusing on the systemic safety and biodistribution of MSCs. MSC-associated risks of tumor initiation and promotion and the underlying mechanisms of these risks are discussed. In addition, MSC biodistribution methodology and the pharmacokinetics and pharmacodynamics of cell therapies are addressed. Better understanding of the systemic safety and biodistribution of MSCs will facilitate future clinical applications of precision medicine using stem cells.

Pneumoconiosis: current status and future prospects

ABSTRACT

Pneumoconiosis refers to a spectrum of pulmonary diseases caused by inhalation of mineral dust, usually as the result of certain occupations. The main pathological features include chronic pulmonary inflammation and progressive pulmonary fibrosis, which can eventually lead to death caused by respiratory and/or heart failure. Pneumoconiosis is widespread globally, seriously threatening global public health. Its high incidence and mortality lie in improper occupational protection, and in the lack of early diagnostic methods and effective treatments. This article reviews the epidemiology, safeguard procedures, diagnosis, and treatment of pneumoconiosis, and summarizes recent research advances and future research prospects.

Near-infrared photothermal liposomal nanoantagonists for amplified cancer photodynamic therapy

Photodynamic therapy (PDT) has been demonstrated to be a promising strategy for the treatment of cancer, while its therapeutic efficacy is often compromised due to excessive concentrations of glutathione (GSH) as a reactive oxygen species (ROS) scavenger in cancer cells. Herein, we report the development of near-infrared (NIR) photothermal liposomal nanoantagonists (PLNAs) for amplified PDT through through the reduction of intracellular GSH biosynthesis. Such PLNAs were constructed via encapsulating a photosensitizer, indocyanine green (ICG) and a GSH synthesis antagonist, l-buthionine sulfoximine (BSO) into a thermal responsive liposome. Under NIR laser irradiation at 808 nm, PLNAs generate mild heat via a ICG-mediated photothermal conversion effect, which leads to the destruction of thermal responsive liposomes for a controlled release of BSO in a tumor microenvironment, ultimately reducing GSH levels. This amplifies intracellular oxidative stresses and thus synergizes with PDT to afford an enhanced therapeutic efficacy. Both in vitro and in vivo data verify that PLNA-mediated phototherapy has an at least 2-fold higher efficacy in killing cancer cells and inhibiting tumor growth compared to sole PDT. This study thus demonstrates a NIR photothermal drug delivery nanosystem for amplified photomedicine.

Enhanced and long-term CT imaging tracking of transplanted stem cells labeled with temperature-responsive gold nanoparticles

Gold nanoparticles (AuNPs) have been extensively employed for computed tomography (CT) imaging in cell labeling and tracking because of their strong X-ray attenuation coefficient and excellent biocompatibility. However, the design and synthesis of stimuli-responsive AuNPs to modulate their endocytosis and exocytosis for optimal cell labeling and tracking are promising but challenging. Herein, we report an innovative labeling strategy based on temperature-responsive AuNPs (TRAuNPs) with high cell labeling efficiency and extended intracellular retention duration. We have manifested that the TRAuNP labeling imposes a negligible adverse effect on the function of human mesenchymal stem cells (hMSCs). Further experiment with idiopathic pulmonary fibrosis (IPF) model mice has demonstrated the feasibility of TRAuNP labeling for long time CT imaging tracking of transplanted hMSCs. What's more, the survival of transplanted hMSCs could also be monitored simultaneously using bioluminescence imaging after the expression of luciferase reporter genes. Therefore, we believe that this dual-modal labeling and tracking strategy enables visualization of the transplanted hMSCs in vivo, which may provide an important insight into the role of stem cells in the IPF therapy.

microRNA-186 in extracellular vesicles from bone marrow mesenchymal stem cells alleviates idiopathic pulmonary fibrosis via interaction with SOX4 and DKK1

Background

Previous reports have identified that human bone marrow mesenchymal stem cell-derived extracellular vesicles (BMSC-EVs) with their cargo microRNAs (miRNAs) are a promising therapeutic approach for the treatment of idiopathic pulmonary fibrosis (IPF). Therefore, we explored whether delivery of microRNA-186 (miR-186), a downregulated miRNA in IPF, by BMSC EVs could interfere with the progression of IPF in a murine model.

Methods

In a co-culture system, we assessed whether BMSC-EVs modulated the activation of fibroblasts. We established a mouse model of PF to evaluate the in vivo therapeutic effects of BMSC-EVs and determined miR-186 expression in BMSC-EVs by polymerase chain reaction. Using a loss-of-function approach, we examined how miR-186 delivered by BMSC-EVs affected fibroblasts. The putative relationship between miR-186 and SRY-related HMG box transcription factor 4 (SOX4) was tested using luciferase assay. Next, we investigated whether EV-miR-186 affected fibroblast activation and PF by targeting SOX4 and its downstream gene, Dickkopf-1 (DKK1).

Results

BMSC-EVs suppressed lung fibroblast activation and delayed IPF progression in mice. miR-186 was downregulated in IPF but enriched in the BMSC-EVs. miR-186 delivered by BMSC-EVs could suppress fibroblast activation. Furthermore, miR-186 reduced the expression of SOX4, a target gene of miR-186, and hence suppressed the expression of DKK1. Finally, EV-delivered miR-186 impaired fibroblast activation and alleviated PF via downregulation of SOX4 and DKK1.

Conclusion

In conclusion, miR-186 delivered by BMSC-EVs suppressed SOX4 and DKK1 expression, thereby blocking fibroblast activation and ameliorating IPF, thus presenting a novel therapeutic target for IPF.

Synthesis of heteronanostructures for multimodality molecular imaging-guided photothermal therapy

Here, a heteronanostructure (Au-Fe₃O₄@PDA-PEG-DTPA-Gd) has been constructed for multimodality molecular imaging (T₁-/T₂-weighted MRI and CT imaging)-guided PTT of cancer by combination of Au-Fe₃O₄, PDA shell and DTPA-Gd into one nanoplatform.

The Efficacy of Mesenchymal Stem Cells in Therapy of Acute Kidney Injury Induced by Ischemia-Reperfusion in Animal Models

Mesenchymal stem cells (MSCs), discovered and isolated from the bone marrow in the 1960s and with self-renewal capacity and multilineage differentiation potential, have valuable immunomodulatory abilities. Acute kidney injury (AKI) refers to rapid renal failure, which exhibits as quickly progressive decreasing excretion in few hours or days. This study was performed to assess the efficacy of MSCs in the treatment of AKI induced by ischemia-reperfusion using a meta-analysis method. A literature search using corresponding terms was performed in the following databases: Embase, Cochrane Library, PubMed, and ISI Web of Science databases up to Dec 31, 2019. Data for outcomes were identified, and the efficacy of MSCs for AKI was assessed using Cochrane Review Manager Version 5.3. Nineteen studies were eligible and recruited for this meta-analysis. MSC treatment can reduce the Scr levels at 1 day, 2 days, 3 days, 5 days, and >7 days (1 day: WMD = -0.56, 95% CI: -0.78, -0.34, P < 0.00001; 2 days: WMD = -0.58, 95% CI: -0.89, -0.28, P = 0.0002; 3 days: WMD = -0.65, 95% CI: -0.84, -0.45, P < 0.00001; 5 days: WMD = -0.35, 95% CI: -0.54, -0.16, P = 0.0003; and >7 days: WMD = -0.22, 95% CI: -0.36, -0.08, P = 0.002) and can reduce the levels of BUN at 1 day, 2 days, 3 days, and 5 days (1 day: WMD = -11.72, 95% CI: -18.80, -4.64, P = 0.001; 2 days: WMD = -33.60, 95% CI: -40.15, -27.05, P < 0.00001; 3 days: WMD = -21.14, 95% CI: -26.15, -16.14, P < 0.00001; and 5 days: WMD = -8.88, 95% CI: -11.06, -6.69, P < 0.00001), and it also can reduce the levels of proteinuria at 3 days and >7 days and alleviate the renal damage in animal models of AKI. In conclusion, MSCs might be a promising therapeutic agent for AKI induced by ischemia-reperfusion.