A carboxylesterase-selective ratiometric fluorescent two-photon probe and its application to hepatocytes and liver tissues

Carboxylesterases (CEs) are widely distributed enzymes in the human body that catalyze hydrolysis of various endogenous and exogenous substrates. They are directly linked to hepatic drug metabolisms and steatosis, and their regulations are important issues in pharmacological and clinical applications. In this work, we have developed an emission ratiometric two-photon probe (SE1) for quantitatively detecting CE in situ. This probe is based on a translation of intramolecular charge transfer character upon reaction with CE. It shows a sensitive blue-to-yellow emission change in response to human CE activity, easy loading into cells, insensitivity to pH and other metabolites including ROS and RNS, high photostability, and low cytotoxicity. Using live hepatocytes and liver tissues, we found that ratiometric two-photon microscopic imaging with SE1 is an effective tool for monitoring CE activities at the subcellular level in live tissues. This probe will find useful applications in biomedical research, including studies of hepatic steatosis and drug developments.

A Golgi-localized two-photon probe for imaging zinc ions

We report a two-photon fluorescent probe which shows a strong two photon excited fluorescence enhancement in response to Zn(2+), easy loading into the cells, Golgi-localizing ability, low cytotoxicity, and high photostability. Two-photon microscopy imaging revealed that this probe allows for real-time monitoring of the changes in Golgi Zn(2+) as well as their 3D distributions in live cells and tissues.

A quadrupolar two-photon fluorescent probe for in vivo imaging of amyloid-β plaques

A quadrupolar two-photon fluorescent probe for in vivo imaging of amyloid-β plaques is reported.

The formation of beta amyloid (Aβ) plaques in specific brain regions is one of the early pathological hallmarks of Alzheimer's disease (AD). To enable the early detection of AD and related applications, a method for real-time, clear 3D visualization of Aβ plaques in vivo is highly desirable. Two-photon microscopy (TPM) which utilizes two near-infrared photons is an attractive tool for such applications. However, this technique needs a sensitive and photostable two-photon (TP) probe possessing bright TP exited fluorescence to impart high signal-to-noise (S/N) visualization of Aβ plaques. Herein, we report a quadrupolar TP fluorescent probe (QAD1) having large TP action cross section (Φδ_max = 420 GM) and its application for in vivo TPM imaging of Aβ plaques. This probe, designed with a centrosymmetric D–A–D motif with a cyclic conjugating bridge and solubilizing unit, displays bright TP excited fluorescence, appreciable water solubility, robust photostability, and high sensitivity and selectivity for Aβ plaques. Using the real-time TPM imaging of transgenic 5XFAD mice after intravenous injection of QAD1, we show that this probe readily enters the blood brain barrier and provides high S/N ratio images of individual Aβ plaques in vivo. We also used QAD1 in dual-color TPM imaging for 3D visualization of Aβ plaques along with blood vessels and cerebral amyloid angiopathy (CAA) inside living mouse brains. These findings demonstrate that this probe will be useful in biomedical applications including early diagnosis and treatments of AD.

Inhibition of breast cancer invasion by TIS21/BTG2/Pc3-Akt1-Sp1-Nox4 pathway targeting actin nucleators, mDia genes

The mammalian homolog of Drosophila diaphanous (mDia), actin nucleator, has been known to participate in the process of invasion and metastasis of cancer cells via regulating a number of actin-related biological processes. We have previously reported that tumor suppressor TIS21(/BTG2/Pc3) (TIS21) inhibits invadopodia formation by downregulating reactive oxygen species (ROS) in MDA-MB-231 cells. We herein report that TIS21(/BTG2/Pc3) downregulates diaphanous-related formin (DRF) expression via reducing NADPH oxidase 4 (Nox4)-derived ROS generation by Akt1 activation and subsequently impairs invasion activity of the highly invasive breast cancer cells. Knockdown of Akt1 by RNA interference recovered the TIS21(/BTG2/Pc3)-inhibited F-actin remodeling and ROS generation by recovering Nox4 expression. Furthermore, Sp1-mediated Nox4 transcription was downregulated by TIS21(/BTG2/Pc3)-Akt1 signals, leading to the inhibition of cancer cell invasion via F-actin remodeling by mDia genes. To our best knowledge, this is the first study to show that TIS21(/BTG2/Pc3)-Akt1 inhibited Sp1-Nox4-ROS cascade, subsequently reducing invasion activity via inhibition of mDia family genes.

A ratiometric two-photon probe for quantitative imaging of mitochondrial pH values

Mitochondrial pH (pHmito) is known to be alkaline (near 8.0) and has emerged as a potential factor for mitochondrial function and disorder. We have developed a ratiometric two-photon probe (CMP1) for quantitative analysis of pHmito in live cells and tissues. This probe is designed to function by controlling the intramolecular charge transfer from 2-naphthol, having an ideal pKa value (7.86 ± 0.05) in the cells to monitor pHmito. This transition results in a marked yellow to red emission color change in response to pH alterations from 6.0 to 9.0. CMP1 exhibits easy loading, selective and robust staining ability of mitochondria, low cytotoxicity, and bright two-photon excited fluorescence in situ, thereby allowing quantitative imaging of the pHmito in live cells and tissues. The ratiometric TPM imaging clearly reveals that subcellular distribution of the pHmito values is heterogeneous, with the pHmito values in the perinuclear region being higher than those at the periphery of the cells. The changes of pHmito values on carbonyl cyanide m-chlorophenyl hydrazone (CCCP) treatment and autophagic processes were also investigated along with their morphological alterations at specific subcellular positions. We also used CMP1 to visualize the pHmito values of Parkinson's disease model astrocytes as well as living hippocampal tissues. Our results demonstrate that CMP1 will be useful as a quantitative imaging probe to study pHmito in biomedical research.

A cysteamine-selective two-photon fluorescent probe for ratiometric bioimaging

We report a two-photon fluorescent probe for ratiometric imaging of cysteamine in situ. This probe can detect the levels of endogenous cysteamine with statistical significance in live cells and brain hippocampal tissues, revealing that cysteamine is localized mainly in the perikaria of the pyramidal neurons and the granule cells.

Mechanism of Cisplatin-Induced Cytotoxicity Is Correlated to Impaired Metabolism Due to Mitochondrial ROS Generation

The chemotherapeutic use of cisplatin is limited by its severe side effects. In this study, by conducting different omics data analyses, we demonstrated that cisplatin induces cell death in a proximal tubular cell line by suppressing glycolysis- and tricarboxylic acid (TCA)/mitochondria-related genes. Furthermore, analysis of the urine from cisplatin-treated rats revealed the lower expression levels of enzymes involved in glycolysis, TCA cycle, and genes related to mitochondrial stability and confirmed the cisplatin-related metabolic abnormalities. Additionally, an increase in the level of p53, which directly inhibits glycolysis, has been observed. Inhibition of p53 restored glycolysis and significantly reduced the rate of cell death at 24 h and 48 h due to p53 inhibition. The foremost reason of cisplatin-related cytotoxicity has been correlated to the generation of mitochondrial reactive oxygen species (ROS) that influence multiple pathways. Abnormalities in these pathways resulted in the collapse of mitochondrial energy production, which in turn sensitized the cells to death. The quenching of ROS led to the amelioration of the affected pathways. Considering these observations, it can be concluded that there is a significant correlation between cisplatin and metabolic dysfunctions involving mROS as the major player.

Low skeletal muscle mass associates with low femoral neck strength, especially in older Korean women: the Fourth Korea National Health and Nutrition Examination Survey (KNHANES IV)

SUMMARY

Data gathered from a nationally representative cohort demonstrated that subject with low skeletal muscle mass had consistently low femoral neck composite strength indices for compression, bending, and impact, especially in older women, supporting the highly integrated nature of skeletal muscle and bone.

INTRODUCTION

Skeletal muscle and bone interact mechanically and functionally. The present study was performed to investigate the association between muscle mass and femoral neck composite strength indices using a nationally representative cohort.

METHODS

This is a population-based, cross-sectional study from Korea National Health and Nutrition Examination Surveys, including 1,275 Koreans (674 women and 601 men) aged 50 years or older. Femoral neck axis length and width were measured by hip DXA scans and were combined with BMD, body weight, and height to create composite indices of femoral neck strength relative to load in three different failure modes: compression, bending, and impact. Presarcopenia was defined as an appendicular skeletal muscle mass (ASM) divided by body weight that was less than 1 SD below the sex-specific mean for young adults.

RESULTS

After adjusting for confounders, women with presarcopenia had consistently lower indices for compression strength (CSI), bending strength (BSI), and impact strength (ISI) than women without this condition. Men with presarcopenia had a lower ISI value than men without presarcopenia. Multiple regression analyses revealed that lower relative skeletal muscle mass (ASM/weight) associated significantly with lower values for all three femoral neck composite indices in women and with lower CSI and ISI in men.

CONCLUSIONS

These findings provide the first clinical evidence for the notion that age-related low muscle mass may increase the risk of osteoporotic hip fractures by decreasing femoral neck strength relative to load, especially in older women, and support the highly integrated nature of skeletal muscle and bone.

Intraocular pharmacokinetics of intravitreal vascular endothelial growth factor-Trap in a rabbit model

PURPOSE

To determine intraocular pharmacokinetic properties of intravitreally injected vascular endothelial growth factor (VEGF)-Trap in a rabbit model.

METHODS

VEGF-Trap was intravitreally injected in 18 rabbit eyes. Eyes were enucleated 1 h and 1, 2, 5, 14, and 30 days after injections and immediately frozen at -80 °C. Concentration of VEGF-Trap in vitreous, aqueous humor, and retina/choroid was determined using an indirect enzyme-linked immunosorbent assay and analyzed to obtain pharmacokinetic properties.

RESULTS

Maximum concentration of VEGF-Trap was achieved at 1 h in all three tissues. A one-compartment model of distribution was selected as the final model for all tissues studied. Estimated half-life of VEGF-Trap in vitreous, aqueous humor, and retinal/choroid was 87.1, 36.8, and 35.0 h, respectively, and estimated mean residence time was 125.7, 53.1, and 50.5 h, respectively. Area under the curve from time 0 to the end point was 10009.8, 3945.1, and 1189.3, respectively. Total exposure of the aqueous humor and retina/choroid to VEGF-Trap was 39.4% and 11.9% of vitreous exposure, respectively.

CONCLUSION

The vitreous half-life of VEGF-Trap is 3.63 days. This is shorter than that of bevacizumab (6.99 days) and longer than that of ranibizumab (2.51 days), as shown in studies using the same experimental settings. The concentration of VEGF-Trap peaked at 1 h after injections in all eye tissues studied.

A hexaphenylbenzene based AIEE active two photon probe for the detection of hydrogen sulfide with tunable self-assembly in aqueous media and application in live cell imaging

AIEE active HPB based TPE probe exhibited modulation of self-assembled architecture in presence of H₂S and was utilized for TPM imaging for detection of H₂S in HeLa cells.

Biochemical indicators of implantation success of tissue-engineered oral mucosa

Real-time (RT) determination of the health of in vitro tissue-engineered constructs prior to grafting is essential for prediction of success of the implanted tissue-engineered graft. In addition, the US Food and Drug Administration requires specific release criteria in RT prior to the release of tissue-engineered devices for human use. In principle, assessing the viability and functionality of the cellular component can be achieved by quantifying the secretion of growth factors and chemokines of tissue-engineered constructs. Ex vivo-produced oral mucosa equivalents (EVPOMEs) were fabricated under thermally stressed conditions at 43 °C for 24 h to create a functionally compromised EVPOME. We used microchannel enzyme-linked immunosorbent assay to evaluate the functionality of the cellular component, oral keratinocytes, of stressed and unstressed EVPOMEs by measuring the release of vascular endothelial growth factor (VEGF), interleukin-8 (IL-8), human β-defensin 1 (hBD-1), and tissue inhibitor of metalloproteinase 1 and 2 (TIMP-1 and -2) into the spent medium, which was collected on the same day prior to graft implantation into severe combined immunodeficiency mice. Implanted EVPOMEs' histology on the seventh postimplantation day was used to correlate outcomes of grafting to secreted amounts of IL-8, hBD-1, VEGF, TIMP-1, and TIMP-2 from corresponding EVPOMEs. Our findings showed that significantly higher levels of IL-8, hBD-1, and TIMP-2 were secreted from controls than from thermally stressed EVPOMEs. We also found a direct correlation between secreted VEGF and IL-8 and blood vessel counts of implanted EVPOMEs. We concluded that measuring the constitutive release of these factors can be used as noninvasive predictors of healthy tissue-engineered EVPOMEs in RT, prior to their implantation.

A small molecule two-photon fluorescent probe for intracellular sodium ions

We report a small-molecule two-photon fluorescent probe (ANa2) for Na(+) that shows a strong TPEF enhancement in response to Na(+) and can be easily loaded into live cells and can real time monitor the fluctuation of [Na]i in live cells and living tissue at more than 100 μm depth.

Quinoline-based two-photon fluorescent probe for nitric oxide in live cells and tissues

A two-photon fluorescent probe (QNO) for nitric oxide is reported. The probe is designed with a photoinduced electron transfer (PeT) mechanism and shows 12-fold fluorescence enhancement toward NO. Adopting a quinoline derivative as the fluorophore, QNO has a large two-photon action cross section value of 52 GM and long-wavelength emission. It also features high selectivity, low cytotoxicity, and pH insensitivity. By utilizing two-photon microscopy (TPM), QNO can detect NO in live cells and live tissues at a depth of 90-180 μm.