Compounding engineered mesenchymal stem cell-derived exosomes: A potential rescue strategy for retinal degeneration.

The prevalence of retinal degenerative diseases, including age-related macular degeneration and retinitis pigmentosa, has been increasing globally and is linked to the aging population and improved life expectancy. These diseases are characterized by chronic, progressive neuronal damage or depletion of the photoreceptor cells in the retina, and limited effective treatment options are currently available. Mesenchymal stem cell-derived exosomes (MSC-EXOs) containing cytokines, growth factors, lipids, mRNA, and miRNA, which act as mediators of intercellular communication transferring bioactive molecules to recipient cells, offer an appealing, non-cellular nanotherapeutic approach for retinal degenerative diseases. However, treatment specificity is compromised due to their high heterogeneity in size, content, functional effects, and parental cellular source. To improve this, engineered MSC-EXOs with increased drug-loading capacity, targeting ability, and resistance to bodily degradation and elimination have been developed. This review summarizes the recent advances in miRNAs of MSC-EXOs as a treatment for retinal degeneration, discussing the strategies and methods for engineering therapeutic MSC-EXOs. Notably, to address the single functional role of engineered MSC-EXOs, we propose a novel concept called "Compound Engineered MSC-EXOs (Co-E-MSC-EXOs)" along with its derived potential therapeutic approaches. The advantages and challenges of employing Co-E-MSC-EXOs for retinal degeneration in clinical applications, as well as the strategies and issues related to them, are also highlighted.

Periodontal Ligament Stem Cell-Derived Exosomes Regulate Muc5ac Expression in Rat Conjunctival Goblet Cells via Regulating Macrophages Toward an Anti-Inflammatory Phenotype.

BACKGROUND: Several studies have reported the protective effects of mesenchymal stem cell-derived exosomes (MSC-Exos) in reducing inflammation and decreasing conjunctival goblet cell (CGC) loss in dry eye disease. However, whether MSC-Exos provide anti-inflammatory profiles in macrophages, thus contributing to CGC protection, has remained elusive. METHODS: Macrophages were incubated with PKH26-labeled periodontal ligament mesenchymal stem cell-derived exosomes (PDLSC-Exos) for 12 h, and uptake of PDLSC-Exos by macrophages was observed by a confocal fluorescence microscope. The mRNA expression of TNF-α, IL-10, and Arg1 was detected by quantitative real-time polymerase chain reaction (qRT-PCR). The protein expression of TNF-α and IL-10 were quantified using western blotting. Then, CGCs were exposed to different macrophage supernatants and qRT-PCR was used to detect the Muc5ac mRNA expression of CGCs in response to or absence of cholinergic stimulation. ELISA was used to determine the Muc5ac secretion of CGCs in response to cholinergic stimulation. RESULTS: The uptake of PDLSC-Exos by M1 macrophages facilitates M2 macrophage polarization with the elevated expressions of IL-10 and Arg1. In macrophage supernatant-treated CGCs systems, PDLSC-Exo-treated M1 macrophage supernatant significantly enhanced the Muc5ac expression of CGCs in response to, or in the absence of, cholinergic stimulation, while the addition of PDLSC-Exos to the control macrophage supernatant did not generate a change in Muc5ac expression. Conversely, the addition of PDLSC-Exos to the diluted control macrophage supernatant induced a significant increase in Muc5ac expression. CONCLUSION: PDLSC-Exos could protect CGCs against M1 macrophage-mediated inflammation, and the protective effects of PDLSC-Exos are partly attributable to their effects on M1 macrophages.

General Strategy for Bioluminescence Sensing of Peptidase Activity In Vivo Based on Tumor-Targeting Probiotic.

The abnormally expressed peptidases in human tissues are associated with many kinds of cancers. Monitoring of endogenous peptidase activity could allow us for pathophysiology elucidation and early clinical diagnosis. Herein, we developed a general strategy for bioluminescence (BL) sensing of peptidase activity in vivo based on tumor-targeting probiotics. The probiotic that harbored a luciferase-encoding plasmid was used to target and colonize tumor and provide luciferase for BL imaging. The peptide-based probes Lc and GPc were applied to track leucine aminopeptidase (LAP) and dipeptidyl peptidase IV (DPPIV) activity, respectively, by simply adding l-leucine and Gly-Pro dipeptides at the N-terminus of d-cysteine, which were specifically controlled by peptidase cleavage and released free d-cysteine to conduct a subsequent click condensation reaction with 2-cyano-6-hydroxybenzothiazole (HCBT) to produce firefly luciferin in situ, giving rise to a strong BL signal. Neither gene modification of cells of interest nor complicated synthesis was required in this BL system. Encouraged by these advantages, we successfully used our probes to monitor LAP and DPPIV activities in vitro and in vivo, respectively. A good linearity between BL and peptidase was obtained in the concentration range of 2.5-40.0 mU/mL with a limit of detection (LOD) of 1.1 mU/mL (55 ng/mL) for LAP and 2.0-40.0 mU/mL with a LOD of 0.78 mU/mL (1.15 ng/mL) for DPPIV, respectively. Additionally, approximately 5-fold (LAP) and 10-fold (DPPIV) differences in the BL signal before and after treatment with a specific inhibitor were also obtained for in vivo BL imaging. All these results reflected the potential application value of our probes in BL sensing of peptidase activity. We envision that our strategy may be a useful approach for monitoring a wide range of peptidases in tumors, especially in primary tumors.

The distinct difference in azido sugar metabolic rate between neural stem cells and fibroblasts and its application for decontamination of chemically induced neural stem cells.

In our report, we found a distinct difference in azido sugar metabolic rate between neural stem cells and fibroblasts, which can be used for selective removal of fibroblasts from neural stem cell mixtures. Chemically induced neural stem cells (ciNSCs) serve as a highly valuable source of NSCs. Incompletely induced fibroblasts could interfere with ciNSC differentiation and become tumorigenic. Herein, we applied our method for the decontamination of ciNSCs and it exhibited excellent selectivity for ciNSCs. The results demonstrate that the ciNSC population can be efficiently purified to 98.1%. As far as we know, this is the highest purity obtained so far. We envision that, in the future, our method could be used as a safe, effective, and chemically-defined tool for decontaminating ciNSCs in both fundamental research and clinical stem cell therapy.

Chemiluminescence of Conjugated-Polymer Nanoparticles by Direct Oxidation with Hypochlorite.

Chemiluminescence (CL) is an advantageous detection tool for in vivo imaging because of the high signal-to-noise ratio of its optical-signal readout, which does not require an external excitation source. Conjugated polymers (CPs) are now used as an energy acceptor in CL nanoparticles to enhance the CL. Here, we demonstrate CL from the direct oxidation of CP backbones in conjugated-polymer nanoparticles (CPNs) by hypochlorite. Such CL CPNs completely avoid the involvement of small-molecule CL donors. The strategy greatly simplifies CL-probes preparation and increases the stability of CL nanoprobes by overcoming the leakage problem of CL donors in nanoparticles. Hypochlorite can oxidize the vinylene bond (C═C) in polyfluorene-vinylene (PFV)/polyphenylenevinylene (PPV) via π2-π2 cycloaddition to form a PFV- or PPV-dioxetane intermediate that is unstable and can spontaneously degrade into PFV- or PPV-aldehyde and generate photons. The dioxetane-intermediate formation was confirmed by UV-vis-absorption, fluorescence, nuclear-magnetic-resonance (1H NMR), and Fourier-transform infrared (FT-IR) spectroscopy. The CL quantum yield (QY) of the brightest CL probe, CPN-poly[(9,9-di(2-ethylhexyl)-9 H-fluorene-2,7-vinylene)- co-(1-methoxy-4-(2-ethylhexyloxy)-2,5-phenylenevinylene)] (90:10 mol ratio, CPN-PFV- co-MEHPV), was 17.79 einsteins/mol (namely, photons per particle). CPN-PFV- co-MEHPV was size-stable, noncytotoxic, selective, and sensitive for hypochlorite detection. The linear range and the LOD of CPN-PFV- co-MEHPV for ClO- detection are 2-30 and 0.47 µM. Thus, CPN-PFV- co-MEHPV was successfully applied for in vivo imaging of endogenously produced ClO- in living animals. We expect that the represented strategy could be extended to construct other CL nanoprobes for bioimaging and disease diagnosis by simply optimizing and transforming CP backbones; such CL CPNs will have a profound impact on the field of bioimaging.

Magnetic nanoporous carbon as an adsorbent for the extraction of phthalate esters in environmental water and aloe juice samples.

In this work, magnetic nanoporous carbon with high surface area and ordered structure was synthesized using cheap commercial silica gel as template and sucrose as the carbon source. The prepared magnetic nanoporous carbon was firstly used as an adsorbent for the extraction of phthalate esters, including diethyl phthalate, diallyl phthalate, and di-n-propyl-phthalate, from lake water and aloe juice samples. Several parameters that could affect the extraction efficiency were optimized. Under the optimum conditions, the limit of detection of the method (S/N = 3) was 0.10 ng/mL for water sample and 0.20 ng/mL for aloe juice sample. The linearity was observed over the concentration range of 0.50-150.0 and 1.0-200.0 ng/mL for water and aloe juice samples, respectively. The results showed that the magnetic nanoporous carbon has a high adsorptive capability toward the target phthalate esters in water and aloe juice samples.