Hypoxia preconditioning increases Notch1 activity by regulating DNA methylation in vitro and in vivo.

BACKGROUND: Our previous research has demonstrated that hypoxic preconditioning (HPC) can improve spatial learning and memory abilities in adult mice. Adult hippocampal neurogenesis has been associated with learning and memory. The Neurogenic locus notch homolog protein (Notch) was involved in adult hippocampal neurogenesis, as well as in learning and memory. It is currently unclear whether the Notch pathway regulates hippocampal neuroregeneration by modifying the DNA methylation status of the Notch gene following HPC. METHOD: The HPC animal model and cell model were established through repeated hypoxia exposure using mice and the mouse hippocampal neuronal cell line HT22. Step-down test was conducted on HPC mice. Real-time PCR and Western blot analysis were used to assess the mRNA and protein expression levels of Notch1 and hairy and enhancer of split1 (HES1). The presence of BrdU-positive cells and Notch1 expression in the hippocampal dental gyrus (DG) were examined with confocal microscopy. The methylation status of the Notch1 was analyzed using methylation-specific PCR (MS-PCR). HT22 cells were employed to elucidate the impact of HPC on Notch1 in vitro. RESULTS: HPC significantly improved the step-down test performance of mice with elevated levels of mRNA and protein expression of Notch1 and HES1 (P < 0.05). The intensities of the Notch1 signal in the control group, the H group and the HPC group were 2.62 ± 0.57 × 107, 2.87 ± 0.84 × 107, and 3.32 ± 0.14 × 107, respectively, and the number of BrdU (+) cells in the hippocampal DG were 1.83 ± 0.54, 3.71 ± 0.64, and 7.29 ± 0.68 respectively. Compared with that in C and H group, the intensity of the Notch1 signal and the number of BrdU (+) cells increased significantly in HPC group (P < 0.05). The methylation levels of the Notch1 promoter 0.82 ± 0.03, 0.65 ± 0.03, and 0.60 ± 0.02 in the C, H, and HPC groups, respectively. The methylation levels of Notch1 decreased significantly (P < 0.05). The effect of HPC on HT22 cells exhibited similarities to that observed in the hippocampus. CONCLUSION: HPC may confer neuroprotection by activating the Notch1 signaling pathway and regulating its methylation level, resulting in the regeneration of hippocampal neurons.

Three-Dimensional Bioprinting of Decellularized Extracellular Matrix-Based Bioinks for Tissue Engineering.

Three-dimensional (3D) bioprinting is one of the most promising additive manufacturing technologies for fabricating various biomimetic architectures of tissues and organs. In this context, the bioink, a critical element for biofabrication, is a mixture of biomaterials and living cells used in 3D printing to create cell-laden structures. Recently, decellularized extracellular matrix (dECM)-based bioinks derived from natural tissues have garnered enormous attention from researchers due to their unique and complex biochemical properties. This review initially presents the details of the natural ECM and its role in cell growth and metabolism. Further, we briefly emphasize the commonly used decellularization treatment procedures and subsequent evaluations for the quality control of the dECM. In addition, we summarize some of the common bioink preparation strategies, the 3D bioprinting approaches, and the applicability of 3D-printed dECM bioinks to tissue engineering. Finally, we present some of the challenges in this field and the prospects for future development.

Polydopamine-Encapsulated Perfluorocarbon for Ultrasound Contrast Imaging and Photothermal Therapy.

Biomedical nanoplatforms have been widely investigated for ultrasound (US) imaging and cancer therapy. Herein, perfluorocarbon (PFC) is encapsulated into biocompatible polydopamine (PDA) to form a theranostic nanosystem, followed by the modification of polyethylene glycol (PEG) to stabilize the nanoparticle via a facile one-pot method. Under 808 nm near-infrared laser irradiation, PDA can generate hyperthermia to transform PFC droplets to bubbles with high US imaging sensitivity. The US imaging detection of the PFC-PDA-PEG nanosystem is achievable in a time span of up to 25 min in vitro at a low US frequency and mechanical index, manifesting a US imaging performance for in vivo application. Moreover, tumor cells incubated with the nanosystem are ablated effectively under laser irradiation at 808 nm. The results illustrate the potential of the PDA-based theranostic agent in US imaging-guided photothermal therapy of tumor.

Assessment of tissue oxygenation of periodontal inflammation in patients with coronary artery diseases using optical spectroscopy.

BACKGROUND: We have recently developed a non-invasive periodontal diagnostic tool that was validated in periodontitis patients without systemic disorders like coronary artery disease (CAD). The purpose of present study is to verify whether this optical instrument can also be used in periodontitis patients with CAD. METHODS: A total of 62 periodontitis patients with CAD were recruited along with a control group consisting of 59 age and gender matched periodontitis volunteers without systemic disorders. Using a portable optical near-infrared spectrometer, optical spectra were obtained, processed and evaluated from the two groups. A modified Beer-Lambert unmixing model that incorporates a nonparametric scattering loss function was used to determine the relative contribution of deoxygenated hemoglobin (Hb) and oxygenated hemoglobin (HbO2) to the overall spectrum. The balance between tissue oxygen delivery and utilization in periodontal tissues was then assessed. RESULTS: Tissue oxygen saturation was significantly decreased in the periodontitis sites (p < 0.01), compared to the healthy sites in those individuals with CAD. There was a trend towards increased concentration of Hb and decreased concentration of HbO2 from healthy to diseased sites, without statistical significance (p > 0.05). No statistical differences were found in tissue oxygen saturation between the CAD and control groups either in periodontal healthy or inflammatory sites. CONCLUSION: This study supports the hypothesis that optical spectroscopy can determine the periodontal inflammation in patients with certain systemic disorders like CAD. And the overall periodontal oxygenation profiles in CAD patients resemble those in non-CAD individuals either in healthy or inflammatory sites.

Liposome-quantum dot complexes enable multiplexed detection of attomolar DNAs without target amplification.

Sensitive detection of DNA usually relies on target amplification approaches such as polymerase chain reaction and rolling circle amplification. Here we describe a new approach for sensitive detection of low-abundance DNA using liposome-quantum dot (QD) complexes and single-particle detection techniques. This assay allows for detection of single-stranded DNA at attomolar concentrations without the involvement of target amplification. Importantly, this strategy can be employed for simultaneous detection of multiple DNA targets.

Study on galactosylated sodium alginate for enhancing HepG2 Cells adhesion and 3D printability.

Sodium alginate is a polyanionic natural polysaccharide polymer widely used in tissue engineering. However, the lack of binding domains for interaction with cells limits its application in regenerative medicine. This study designed a kind of galactosylated sodium alginate (G-SA) material with improved galactose grafting rate by EDC/NHS activation of carboxyl groups in MES buffer and subsequently cross-linking by Ca2+ aims to enhance the adherence behavior of HepG2 cells on alginate substrate. The synthesized G-SA was characterized by Fourier transform infrared spectra and nuclear magnetic resonance spectroscopy. G-SA exhibited good biocompatibility and significantly enhanced the adhesion behavior of HepG2 cells on its surface. Furthermore, we demonstrated that the effect of G-SA concentration in enhancing cell adhesion was diminished at higher than 2% w/v. Finally, the suitability of G-SA material is investigated for 3D printing, demonstrating that HepG2 cells could maintain high viability and excellent printability in the interior of the gel. In addition, cells could multiply and grow into cell spheroids with an average size of 200 µm in G-SA scaffolds. These results indicated that galactosylated sodium alginate material could be used as a 3D culture system that could be effective for engineering liver cancer models.

Oriented synthesis of one-dimensional polypyrrole molecule chains in a metal-organic framework.

We report for the first time the preparation of single polypyrrole (PPy) molecule chains using a "metal-organic framework" with 1 nm channels as a template. The obtained one-dimensional (1-D) PPy has highly structure order and excellent conductivity, which has improved by as much as five orders of magnitude in comparison with that of 2-D PPy.

In-situ synthesis of covalent organic polymer thin film integrates with palladium nanoparticles for the construction of a cathodic photoelectrochemical cytosensor.

Sensitive detection of cancer cells is essential to early clinic diagnosis, and the photoelectrochemical (PEC) sensors with high sensitivity and good selectivity may provide new approaches for cytosensing. Herein, we demonstrate the development of a new cathodic PEC cytosensor based on the integration of covalent organic polymer (COP) with palladium nanoparticles (PdNPs). The COP films are in-situ grown at room temperature on the transparent indium tin oxide-coated glass substrates, and they subsequently assemble with PdNPs to immobilize aptamers via palladium-sulfur chemistry. PdNPs can catalyze the oxidation of dopamine to produce aminochrome and its derivative, which may function as the electron acceptors of COP for the generation of an enhanced photocurrent. In the absence of cancer cells, the electrons on the conduction band of COP on the electrode transfer to the aminochrome and O2, while the electrons on the electrode transfer to the hole of valence band, resulting in a high cathodic photocurrent. In the presence of cancer cells, the trapped cancer cells efficiently cover the electrode to reduce the surface of COP/PdNPs, resulting in the decrease of catalytic precipitation on the electrode and consequently the generation of a low PEC signal. This PEC cytosensor exhibits high sensitivity with a detection limit of 8 cells mL-1 and a large dynamic range from 10 to 106 cells mL-1. Moreover, this PEC cytosensor has distinct advantages of high selectivity, good reproducibility and excellent stability, and it can be extended to directly detect various cancer cells through the integration with corresponding specific aptamers.

Modulation of Tumor Hypoxia by pH-Responsive Liposomes to Inhibit Mitochondrial Respiration for Enhancing Sonodynamic Therapy.

BACKGROUND AND PURPOSE: Sonodynamic therapy (SDT) has been widely used for the noninvasive treatment of solid tumors, but the hypoxic tumor microenvironment limits its therapeutic effect. The current methods of reoxygenation to enhance SDT have limitations, prompting reconsideration of the design of therapeutic approaches. Here, we developed a tumor microenvironment-responsive nanoplatform by reducing oxygen consumption to overcome hypoxia-induced resistance to cancer therapy. METHODS: A pH-responsive drug-loaded liposome (MI-PEOz-lip) was prepared and used to reduce oxygen consumption, attenuating hypoxia-induced resistance to SDT and thereby improving therapeutic efficiency. Photoacoustic imaging (PAI) and fluorescence imaging (FI) of MI-PEOz-lip were evaluated in vitro and in breast xenograft tumor models. The pH-sensitive functionality of MI-PEOz-lip was applied for pH-triggered cargo release, and its capacity was evaluated. The MI-PEOz-lip-mediated SDT effect was compared with other treatments in vivo. RESULTS: MI-PEOz-lip was demonstrated to specifically accumulate in tumors. Metformin molecules in liposomes selectively accumulate in tumors by pH-responsive drug release to inhibit the mitochondrial respiratory chain while releasing IR780 to the tumor area. These pH-responsive liposomes demonstrated PAI and FI imaging capabilities in vitro and in vivo, providing potential for treatment guidance and monitoring. In particular, the prepared MI-PEOz-lip combined with ultrasound irradiation effectively inhibited breast tumors by producing toxic reactive singlet oxygen species (ROS), while the introduction of metformin inhibited mitochondrial respiration and reduced tumor oxygen consumption, resulting in excellent sonodynamic therapy performance compared with other treatments. CONCLUSION: In this study, we present a novel strategy to achieve high therapeutic efficacy of SDT by the rational design of multifunctional nanoplatforms. This work provides a new strategy that can solve the current problems of inefficient oxygen delivery strategies and weaken resistance to various oxygen-dependent therapies.

Highly uniform and stable cerasomal microcapsule with good biocompatibility for drug delivery.

Efforts to improve the stability of liposomes have recently led to the development of organic-inorganic liposomal cerasomes. However, the uncontrollable size of cerasomes has greatly limited their biomedical applications. In this study, a novel strategy was introduced to fabricate hybrid liposomal cerasomes with high stability and uniform size. The hybrid lipids were first deposited onto CaCO3 microspheres through electrostatic interactions and self-assembly, and then the CaCO3 core was removed to obtain hollow microcapsules, i.e. the cerasomes. The species of the lipid oligomers was detected by MALDI-TOF-MS, which demonstrates the existence of siloxane network on microcapsules' surface. Anticancer drug doxorubicin hydrochloride (DOX) loaded cerasomal microcapsule (DLCM) exhibited an initial burst release behavior followed by the sustained release and remarkably high stability towards surfactant solubilization and long term storage. The DLCM displayed a pH-dependent and sustained DOX release profile in vitro, which can be well explained using a well established mathematical model. Our results indicate that these novel cerasomal microcapsules have great potential to be applied as drug delivery system in cancer therapy.

Stable cerasomes for simultaneous drug delivery and magnetic resonance imaging.

Magnetic liposomes have been frequently used as nanocarriers for targeted drug delivery and magnetic resonance imaging in recent years. Despite great potentials, their morphological/structural instability in the physiological environment still remains an intractable challenge for clinical applications. In this study, stable hybrid liposomal cerasomes (ie, liposomes partially coated with silica) which can co-encapsulate Fe3O4 nanoparticles and the anticancer drug paclitaxel were developed using thin film hydration method. Compared with the drug loaded liposomes, the paclitaxel-loaded magnetic cerasomes (PLMCs) exhibited much higher storage stability and better sustained release behavior. Cellular uptake study showed that the utilization of an external magnetic field significantly facilitated the internalization of PLMCs into cancer cells, resulting in potentiated drug efficacy of killing tumor cells. The T2 relaxivity (r2) of our PLMCs was much higher than that of free Fe3O4 nanoparticles, suggesting increased sensitivity in T2-weighted imaging. Given its excellent biocompatibility also shown in the study, such dual functional PLMC is potentially a promising nanosystem for effective cancer diagnosis and therapy.