ROS-activatable nanocomposites for CT imaging tracking and antioxidative protection of mesenchymal stem cells in idiopathic pulmonary fibrosis therapy.

Mesenchymal stem cell (MSC) transplantation is emerging as a promising approach in the treatment of idiopathic pulmonary fibrosis (IPF), while it is still impeded by several challenges, including unsatisfactory treatment outcomes due to the poor survival of transplanted MSCs, and the lack of non-invasive and long-term imaging modality for tracking the behavior of MSCs. Herein, copper-based nanozyme (CuxO NPs) and gold nanoparticles (Au NPs) were encapsulated in oxidation-sensitive dextran (Oxi-Dex), a dextran derivative with reactive oxygen species (ROS)-responsiveness, forming a kind of novel nanocomposites (assigned as RSNPs) to act as ROS scavengers and computer tomography (CT) imaging tracers. After being internalized by MSCs, RSNPs enabled continuous CT imaging tracking of the transplanted MSCs for 21 days in IPF treatment, obtaining the location and distribution of the transplanted MSCs. Once MSCs were attacked by oxidative stress, the intracellular RSNPs could activate ROS clearance on demand by releasing CuxO NPs, thereby enhancing the therapeutic efficacy against IPF by improving cell survival. Taken together, a novel multifunctional RSNP was fabricated to label MSCs for CT imaging tracking and clearing superfluous ROS, presenting a promising high-efficient IPF therapy.

ROS-Responsive Janus Au/Mesoporous Silica Core/Shell Nanoparticles for Drug Delivery and Long-Term CT Imaging Tracking of MSCs in Pulmonary Fibrosis Treatment.

Mesenchymal stem cell (MSC) therapy has been proven to be a potentially effective approach for idiopathic pulmonary fibrosis (IPF) treatment. However, this strategy is currently limited by the poor curative effect and an insufficient comprehension of the in vivo condition of the transplanted MSCs in the remedy of IPF. To address these issues, herein, a nanosystem composed of Janus Au/mesoporous silica core/shell nanoparticles (Janus NPs) is designed for effective therapeutic and real-time tracing of MSCs in MSC-based IPF therapy. The Janus NPs consist of a Au core and a pirfenidone (PFD)-loaded mesoporous silica shell asymmetrically decorated with two targeting moieties: one is reactive oxygen species (ROS)-sensitive thioketal grafted methoxy poly(ethylene glycol) (mPEG-TK), and the other is 1,2-distearoyl-sn-glycero-3-phosphoethanolamine (DSPE). The asymmetric decoration on each side of the particle allows long-term anchoring of the Janus NPs on the cell membrane to facilitate the responsive release of PFD in the ROS environment of the fibrotic lung, thereby enhancing the therapeutic efficacy of the transplanted MSCs by improving the microenvironment. Following drug release, the Janus NPs quickly enter into MSCs, achieving long-term computed tomography (CT) imaging tracing of MSCs in IPF model mice for an in-depth comprehension of the cell therapy mechanism. Overall, this work reports on Janus Au/PFD-loaded mesoporous silica core/shell NPs that combine the drug delivery and imaging tracking of MSCs, which may provide a strategy for the stem cell-based treatment of IPF.

Functional Au nanoparticles for engineering and long-term CT imaging tracking of mesenchymal stem cells in idiopathic pulmonary fibrosis treatment.

Idiopathic pulmonary fibrosis (IPF) therapy has always been a big and long-standing challenge in clinical practice due to the lack of miraculous medicine. Mesenchymal stem cells (MSCs)-based therapy has recently emerged as a promising candidate for redefining IPF therapy. Enhancing the therapeutic efficacy of MSCs and understanding of their growth, migration and differentiation in harsh lung microenviroments are two keys to improving the stem cell-based IPF treatment. Herein, a non-viral dual-functional nanocarrier is fabricated by a one-pot approach, using protamine sulfate stabilized Au nanoparticles (AuPS), to genetically engineer MSCs for simultaneous IPF treatment and monitoring the biological behavior of the MSCs. AuPS exhibits superior cellular uptake ability, which results in efficient genetic engineering of MSCs to overexpress hepatocyte growth factor for enhanced IPF therapy. In parallel, the intracellular accumulation of AuPS improves the CT imaging contrast of MSCs, allowing visual tracking of the therapeutic engineered MSCs up to 48 days. Overall, this work has described for the first time a novel strategy for enhanced therapeutic efficacy and long-term CT imaging tracking of transplanted MSCs in IPF therapy, providing great prospect for stem cell therapy of lung disease.

Ferromagnetic Vortex Iron Oxide Nanorings Modified with Integrin ß1 Antibody for Targeted MRI Tracking of Human Mesenchymal Stem Cells.

Mesenchymal stem cells (MSCs) have demonstrated great potential for tissue engineering and regenerative medicine applications. Noninvasive and real-term tracking of transplanted MSCs in vivo is crucial for studying the distribution and migration of MSCs, and their role in tissue injury repair. This study reports on the use of ferrimagnetic vortex iron oxide (FVIO) nanorings modified with anti-human integrin ß1 for specific recognition and magnetic resonance imaging (MRI) tracking of human MSCs (hMSCs). Integrin ß1 is highly expressed at all stem cell proliferation and differentiation stages. Therefore, the anti-integrin ß1 antibody (Ab) introduced in FVIO targets integrin ß1, thus enabling FVIO to target stem cells at any stage. This is unlike the traditional MRI-based monitoring of transplanted stem cells, which usually requires pre-labeling the stem cells with tracers before injection. Because of the ability to recognize hMSCs, the Ab-modified FVIO nanotracers (FVIO-Ab) have the advantage of not requiring pre-labeling before stem cell transplantation. Furthermore, the FVIO-Ab nanotracers have high T*2 contrast resulting from the unique magnetic properties of FVIO which can improve the MRI tracking efficiency of stem cells. This work may provide a new way for stem cell labeling and in vivo MRI tracking, thus reducing the risks associated with stem cell transplantation and promoting clinical translation.

In vivo MRI tracking and therapeutic efficacy of transplanted mesenchymal stem cells labeled with ferrimagnetic vortex iron oxide nanorings for liver fibrosis repair.

Mesenchymal stem cells (MSCs) have showed promising effects in the treatment of liver fibrosis. Long-term and noninvasive in vivo tracking of transplanted MSCs is essential for understanding the therapeutic mechanism of MSCs during the therapy of liver fibrosis. In this study, we report the development of a ferrimagnetic vortex iron oxide nanoring (FVIO)-based nanotracer for the long-term visualization of transplanted human MSCs (hMSCs) by magnetic resonance imaging (MRI). The FVIOs were prepared by a hydrothermal reaction followed by hydrogen reduction. To endow the FVIOs with biocompatibility, polyethylene glycol amine (mPEG-NH2) was covalently coupled on the surface of FVIOs, forming FVIO@PEG nanotracers with high contrast enhancement and intracellular uptake. The hMSCs labeled with FVIO@PEG nanotracers exhibited enhanced MRI contrast than those labeled with a commercial contrast agent, and could be continuously monitored by MRI in liver fibrosis mice for 28 days after transplantation, clearly clarifying the migration behavior of hMSCs in vivo. Moreover, we explored the therapeutic mechanism of the FVIO@PEG labeled hMSCs in the amelioration of liver fibrosis, including the reduction in inflammation and oxidative stress, the inhibition of hepatic fibrosis-caused histopathological damage, as well as the down-regulation of the expression of relevant cytokines. The results obtained in this work may deepen our understanding of the behavior and role of hMSCs in the treatment of liver fibrosis, which is key to the clinical application of stem cells in the therapy of liver diseases.

CT/bioluminescence dual-modal imaging tracking of stem cells labeled with Au@PEI@PEG nanotracers and RfLuc in nintedanib-assisted pulmonary fibrosis therapy.

Mesenchymal stem cells (MSCs) are promising in idiopathic pulmonary fibrosis (IPF) therapy. However, low survival rate and ambiguous behavior of MSCs after transplantation impede their clinical translation. To this end, we have developed a new strategy to improve the survival rate and monitor the behavior of the transplanted MSCs simultaneously. In our strategy, nintedanib, a tyrosine kinase inhibitor, is employed to protect the human MSCs (hMSCs) from excessive oxidative stress responses and inflammatory environment in the damaged lung. Moreover, by labeling of the transplanted hMSCs with a computed tomography (CT) nanotracer, Au nanoparticles functionalized with polyethylenimine (PEI) and polyethylene glycol (PEG) (Au@PEI@PEG), in combination with red-emitting firefly luciferase (RfLuc), in vivo CT/bioluminescence (BL) dual-modal imaging tracking of the location, distribution, and survival of the transplanted hMSCs in presence of nintedanib were achieved, which facilitates the profound understanding of the role the stem cells play in IPF therapy.

DNA-coated gold nanoparticles for tracking hepatocyte growth factor secreted by transplanted mesenchymal stem cells in pulmonary fibrosis therapy.

The identification of paracrine factors secreted by transplanted mesenchymal stem cells (MSCs) during the treatment of idiopathic pulmonary fibrosis (IPF) is essential for understanding the role of MSCs in therapy. Herein, we report a facile and efficient strategy for in vivo tracking the secretion of hepatocyte growth factor (HGF) in MSCs during IPF therapy. In our strategy, a novel nanoflare tracer consisting of gold nanoparticles (AuNPs), complementary sequences and dye-labeled recognition sequences is developed. Briefly, the AuNPs are functionalized with oligonucleotide complementary sequences hybridized to the organic dye-labeled recognition sequences, where the organic fluorophores are in close proximity to the AuNPs. In the absence of targets, the dye and AuNPs are separated from each other, inducing the quenching of the fluorescence signal. However, in the presence of targets, the recognition sequences gradually fall off from the AuNPs, causing the fluorescence signal to rise. In brief, in vivo monitoring of the dynamic expression of HGF mRNA in transplanted MSCs during IPF therapy in the current work may provide new insight into the paracrine process of the transplanted MSCs, thereby advancing the MSC-based IPF therapy toward clinical applications.

Facile engineering of ECM-mimetic injectable dual crosslinking hydrogels with excellent mechanical resilience, tissue adhesion, and biocompatibility.

Injectable hydrogels have aroused ever-increasing interest for their cell/biomaterial delivery ability through minimally invasive procedures. Nevertheless, it is still a challenge to simply fabricate natural biopolymer-based injectable hydrogels possessing satisfactory mechanical properties, bioadhesion, and cell delivery ability. Herein, we describe a facile dual crosslinking (DC) strategy for preparing extracellular matrix (ECM) mimetic hydrogels with desirable comprehensive performance. The chondroitin sulfate (CS)- and gelatin (Gel)-based single crosslinked (SC) hydrogels were first developed via reversible borate ester bonds, and further strengthened through the Michael-addition crosslinking reaction or visible-light initiated photopolymerization with thiol-containing polyethylene glycol (PEG) crosslinkers. The dynamic SC hydrogels showed good injectability, pH-sensitive gel-sol transformation, and self-adhesion ability to various biological tissues such as skin, liver, and intervertebral disc. The mechanically tough DC hydrogels displayed tunable stiffness, and resilience to compression load (up to 90% strain) owing to the effective energy dissipation mechanism. The formed DC hydrogels after subcutaneous injection well integrated with surrounding tissues and exhibited fast self-recovery properties. Moreover, the photoencapsulation of human mesenchymal stem cells (hMSCs) within the developed DC hydrogels was achieved and has been proved to be biocompatible, highlighting the great potential of the photopolymerized DC hydrogels in cell delivery and three-dimensional (3D) cell culture. This biomimetic, mechanically resilient, adhesive, and cytocompatible injectable DC hydrogel could serve as a promising candidate for tissue engineering.

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.

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.

Near-infrared-persistent luminescence/bioluminescence imaging tracking of transplanted mesenchymal stem cells in pulmonary fibrosis.

Human mesenchymal stem cells (hMSCs) are promising in the treatment of pulmonary fibrosis (PF). However, the behavior of hMSCs after transplantation, including dynamic translocation, location and survival, impeding the clinical application of hMSCs in PF is still ambiguous. Herein, we report an effective dual-labeling strategy combining endogenous bioluminescence imaging (BLI) and exogenous near-infrared-persistent luminescence (NIR-PL) imaging for in situ visualization of the transplanted stem cells. The long persistent luminescence nanoparticles (LPLNPs), Zn1.1Ga1.8Ge0.1O4:Cr3+,Eu3+, were developed to track the dynamic translocation, position and distribution of the transplanted hMSCs, taking advantage of their long-lasting NIR-PL imaging ability and minimal autofluorescence background interference. Moreover, in virtue of their ability to express red-emitting firefly luciferase (RfLuc), the living stem cells after transplantation could be discriminated from the dead cells by BLI. This facile pattern contributes to the in situ monitoring of stem cells regarding their spontaneous behavior in vivo and therefore deepening our knowledge in the role played by the transplanted hMSCs in PF therapy.

CT/MR Dual-Modality Imaging Tracking of Mesenchymal Stem Cells Labeled with a Au/GdNC@SiO2 Nanotracer in Pulmonary Fibrosis.

Mesenchymal stem cells (MSCs) have shown potential as an innovative treatment for pulmonary fibrosis (PF), due to their capability to ameliorate the inflammation and moderate the deterioration of PF. The fate of the stem cells transplanted into the lung, including survival, migration, homing, and functions, however, has not been fully understood yet. In this paper, we report the development of a computed tomography/magnetic resonance (CT/MR) dual-modal nanotracer, gold/gadolinium nanoclusters overcoated with a silica shell (Au/GdNC@SiO2), for noninvasive labeling and tracking of the transplanted human MSCs (hMSCs) in a PF model. The Au/GdNC@SiO2 nanotracer exhibits good colloidal and chemical stability, high biocompatibility, enhanced longitudinal MR relaxivity, and superior X-ray attenuation property. The hMSCs can be effectively labeled with Au/GdNC@SiO2, resulting in a significantly increased cellular CT/MR imaging contrast, without any obvious adverse effect on the function, including proliferation and differentiation of the labeled stem cells. Moreover, by using the Au/GdNC@SiO2 nanotracer, the hMSCs transplanted in the lung can be tracked for 7 d via in vivo CT/MR dual-modality imaging. This work may provide an insight into the role the transplanted hMSCs play in PF therapy, thus promoting the stem cell-based regenerative medicine.

Long-term in vivo CT tracking of mesenchymal stem cells labeled with Au@BSA@PLL nanotracers.

Human mesenchymal stem cells (hMSCs) transplantation has attracted considerable interest for the treatment of pulmonary injury. Noninvasive and long-term tracking of hMSCs after transplantation in vivo, which is important for our understanding of the stem cell therapy, still remains a big challenge. Herein, we report on the development of a novel gold nanoparticle-based nanotracer to track by CT imaging the transplantation of hMSCs in vivo. Gold nanoparticles (AuNPs) were synthesized on bovine serum albumin (BSA) via an in situ growth method and modified with a poly-l-lysine (PLL) layer, yielding Au@BSA@PLL nanotracers with enhanced biocompatibility and intracellular uptake. Au@BSA@PLL nanotracers were explored for in vitro and in vivo tracking of hMSCs with computer tomography (CT). Our results showed that the endocytosis of Au@BSA@PLL by hMSCs was as high as ∼293 pg per cell. Meanwhile, the nanotracers had a negligible influence on the viability, proliferation, and osteogenic and adipogenic differentiation of the labeled hMSCs. Using a pulmonary fibrosis injury mouse model induced by bleomycin, the labeled hMSCs could be tracked by CT imaging up to 23 d after transplanted in vivo, suggesting the feasibility of Au@BSA@PLL as a potential cellular nanotracer for noninvasive and long-term CT tracking of hMSCs in lung tissue repair.

CT/Bioluminescence Dual-Modal Imaging Tracking of Mesenchymal Stem Cells in Pulmonary Fibrosis.

Human mesenchymal stem cells (hMSCs), due to their immune regulation and collateral secretion effects, are currently explored for potential therapy of idiopathic pulmonary fibrosis (IPF). Understanding the migration, homing, functions, and survival of transplanted hMSCs in vivo is critical to successful IPF treatment. Therefore, it is highly desired to develop noninvasive and effective imaging technologies to track the transplanted hMSCs, providing experimental basis for improving the efficacy of hMSCs in the treatment of IPF. The rational design and development of a dual-labeling strategy are reported by integrating gold nanoparticle (AuNP)-based computed tomography (CT) nanotracers and red-emitting firefly luciferase (RfLuc)-based bioluminescence (BL) tags for CT/BL multimodal imaging tracking of the transplanted hMSCs in a murine model of IPF. In this approach, the CT nanotracer is prepared by sequential coupling of AuNPs with polyethylene glycol and trans-activator of transcription (TAT) peptide (Au@TAT), and employed it to monitor the location and distribution of the transplanted hMSCs in vivo by CT imaging, while RfLuc is used to monitor hMSCs viability by BLI. This facile strategy allows for visualization of the transplanted hMSCs in vivo, thereby enabling profound understanding of the role of hMSCs in the IPF treatment, and advancing stem cell-based regenerative medicine.