In vivo imaging of calcium dynamics in zebrafish hepatocytes

Hepatocytes were the first cell-type for which oscillations of cytoplasmic calcium levels in response to hormones were described. Since then, investigation of calcium dynamics in liver explants and culture has greatly increased our understanding of calcium signaling. A bottleneck, however, exists in observing calcium dynamics in a non-invasive manner due to the optical inaccessibility of the mammalian liver. Here we take advantage of the transparency of the zebrafish larvae to develop a setup that allows in vivo imaging of calcium flux in zebrafish hepatocytes at cellular resolution. Using this, we provide quantitative assessment of intracellular calcium dynamics during multiple contexts, including growth, feeding, ethanol-induced stress and cell ablation. Specifically, we show that synchronized calcium oscillations are present in vivo, which are lost upon starvation. Feeding recommences calcium waves in the liver, but in a spatially restricted manner. Further, ethanol treatment as well as cell ablation induces calcium flux, but with different dynamics. The former causes asynchronous calcium oscillations, while the latter leads to a single calcium spike. Overall, we demonstrate the presence of oscillations, waves and spikes in vivo. Thus, our study introduces a platform for observing diverse calcium dynamics while maintaining the native environment of the liver, which will help investigations into the dissection of molecular mechanisms supporting the intra- and intercellular calcium signaling in the liver.

Stable Twisted Conformation Aza-BODIPY NIR-II Fluorescent Nanoparticles with Ultra-large Stokes Shift for Imaging-Guided Phototherapy

Fluorescence imaging in the second near-infrared window (NIR-II, 1000–1700 nm) holds great promise for in vivo imaging and imaging-guided phototherapy with deep penetration and high spatiotemporal resolution. It is very...

Activatable UCL/CT/MR-Enhanced in vivo Imaging-Guided Radiotherapy and Photothermal Therapy

Although sophisticated radiotherapy (RT) technology has been widely applied in clinical oncotherapy, unsatisfactory therapeutic effect resulted by hypoxic tumor microenvironment and complications are still prevalent. Herein, copper sulphide nanoparticles (CuS...

Constructing Firefly Luciferin Bioluminescence Probes for in Vivo Imaging

Bioluminescence imaging (BLI) is a widely applied visual approach for real-time detecting many physiological and pathological processes in a variety of biological systems. Based on the caged strategy, lots of...

A Novel NIR Fluorescent Nanoprobe Targeting HER2-Positive Breast Cancer: Tra-TTR-A

TTRE, a photosensitizer molecule, has excellent biofluorescence imaging performance and effective antitumor properties for breast cancer. However, its application in breast cancer treatment is limited due to poor tumor selectivity and lack of targeting ability. In this study, TTRE and trastuzumab were combined to synthesize Tra-TTR-A, a novel near-infrared fluorescent nanoprobe for HER2 positive breast cancer. The targeting and antitumor abilities of Tra-TTR-A in breast cancer were also investigated. Like TTRE, Tra-TTR-A has a stable structure with remarkable optical properties and in vivo imaging capacity. However, Tra-TTR-A not only inhibits tumor growth by generating reactive oxygen species but also kills tumor cells by trastuzumab. In this study, Tra-TTR-A, a new type of near-infrared fluorescent nanoprobe that targets HER2-positive breast cancer, was successfully synthesized. Tra-TTR-A could be used in in vivo imaging, targeted photodynamic therapy, and diagnosis and treatment for breast cancer.

Local accumbens in vivo imaging during deep brain stimulation reveals a strategy-dependent amelioration of hedonic feeding

Impulsive overeating is a common, disabling feature of eating disorders. Both continuous deep brain stimulation (DBS) and responsive DBS, which limits current delivery to pathological brain states, have emerged as potential therapies. We used in vivo fiber photometry in wild-type, Drd1-cre, and A2a-cre mice to 1) assay subtype-specific medium spiny neuron (MSN) activity of the nucleus accumbens (NAc) during hedonic feeding of high-fat food, and 2) examine DBS strategy-specific effects on NAc activity. D1, but not D2, NAc GCaMP activity increased immediately prior to high-fat food approach. Responsive DBS triggered a GCaMP surge throughout the stimulation period and durably reduced high-fat intake. However, with continuous DBS, this surge decayed, and high-fat intake reemerged. Our results argue for a stimulation strategy-dependent modulation of D1 MSNs with a more sustained decrease in consumption with responsive DBS. This study illustrates the important role in vivo imaging can play in understanding effects of such novel therapies.