High-throughput 3D imaging of single cells with light-sheet fluorescence microscopy on chip

Single-cell analysis techniques are fundamental to study the heterogeneity of cellular populations, which is the basis to understand several biomedical mechanisms. Light-sheet fluorescence microscopy is a powerful technique for obtaining high-resolution imaging of individual cells, but the complexity of the setup and the sample mounting procedures limit its overall throughput. In our work, we present an optofluidic microscope-on-chip with integrated microlenses for light-sheet shaping and with a fluidic microchannel that allows the automatic and continuous delivery of samples of a few tens of microns in size. The device is used to perform dual-color fluorescence analysis and 3D reconstruction of xenograft-derived mouse breast cancer cells.

Describing the Process and Tools Adopted to Cocreate a Smartphone App for Obesity Prevention in Childhood: Mixed Method Study

Background

Childhood obesity prevention is a public health priority in industrialized countries. The Reggio Emilia Local Health Authority has implemented a program involving primary and secondary prevention as well as the care of obese children. There are many health-promoting mobile apps, but few are targeted to children and very few are sponsored by public health agencies.

Objective

The goal of the research was to describe the process and tools adopted to cocreate a mobile app sponsored by the Reggio Emilia Local Health Authority to be installed in parents’ phones aimed at promoting child health and preventing obesity.

Methods

After stakeholder mapping, a consulting committee including relevant actors, stakeholders, and users was formed. Key persons for childhood obesity prevention were interviewed, focus groups with parents and pediatricians were conducted, and community reporting storytelling was collected. The results of these activities were presented to the consulting committee in order to define the functionalities and contents of the mobile app.

Results

Three key trends emerged from community reporting: being active, playing, and being outdoors; time for oneself, family, and friends; and the pressures of life and work and not having time to be active and socialize. In focus groups, interviews, and labs, mothers showed a positive attitude toward using an app to manage their children's weight, while pediatricians expressed concerns that the app could increase their workload. When these findings were explored by the consulting committee, four key themes were extracted: strong relationships with peers, family members, and the community; access to safe outdoor spaces; children’s need for age-appropriate independence; and professional support should be nonjudgmental and stigma-free. It should be a dialogue that promotes family autonomy. The app functions related to these needs include the following: (1) newsletter with anticipatory guidance, recipes, and vaccination and well-child visit reminders; (2) regional map indicating where physical activity can be done; (3) information on how to manage emergencies (eg, falls, burns, fever); (4) module for reinforcing the counseling intervention conducted by pediatricians for overweight children; and (5) a function to build a balanced daily diet.

Conclusions

The pilot study we conducted showed that cocreation in health promotion is feasible, with the consulting committee being the key co-governance and cocreation tool. The involvement of stakeholders in this committee made it possible to expand the number of persons and institutions actively contributing to the project.

Hidden phase-retrieved fluorescence tomography

Fluorescence tomography is a well-established methodology able to provide structural and functional information on the measured object. At optical wavelengths, the unpredictable scattering of light is often considered a problem to overcome, rather than a feature to exploit. Advances in disordered photonics have shed new light on possibilities offered by opaque materials, treating them as autocorrelation lenses able to create images and focus light. In this Letter, we propose tomography through disorder, introducing a modified Fourier-slice theorem, the cornerstone of the computed tomography, aiming to reconstruct a three-dimensional fluorescent sample hidden behind an opaque curtain.

Glycogen storage in a zebrafish Pompe disease model is reduced by 3-BrPA treatment

Pompe disease (PD) is an autosomal recessive muscular disorder caused by deficiency of the glycogen hydrolytic enzyme acid α-glucosidase (GAA). The enzyme replacement therapy, currently the only available therapy for PD patients, is efficacious in improving cardiomyopathy in the infantile form, but not equally effective in the late onset cases with involvement of skeletal muscle. Correction of the skeletal muscle phenotype has indeed been challenging, probably due to concomitant dysfunctional autophagy. The increasing attention to the pathogenic mechanisms of PD and the search of new therapeutic strategies prompted us to generate and characterize a novel transient PD model, using zebrafish. Our model presented increased glycogen content, markedly altered motor behavior and increased lysosome content, in addition to altered expression of the autophagy-related transcripts and proteins Beclin1, p62 and Lc3b. Furthermore, the model was used to assess the beneficial effects of 3-bromopyruvic acid (3-BrPA). Treatment with 3-BrPA induced amelioration of the model phenotypes regarding glycogen storage, motility behavior and autophagy-related transcripts and proteins. Our zebrafish PD model recapitulates most of the defects observed in human patients, proving to be a powerful translational model. Moreover, 3-BrPA unveiled to be a promising compound for treatment of conditions with glycogen accumulation.

Spatially modulated illumination allows for light sheet fluorescence microscopy with an incoherent source and compressive sensing

Light sheet fluorescence microscopy has become one of the most widely used techniques for three-dimensional imaging due to its high speed and low phototoxicity. Further improvements in 3D microscopy require limiting the light exposure of the sample and increasing the volumetric acquisition rate. We hereby present an imaging technique that allows volumetric reconstruction of the fluorescent sample using spatial modulation on a selective illumination volume. We demonstrate that this can be implemented using an incoherent LED source, avoiding shadowing artifacts, typical of light sheet microscopy. Furthermore, we show that spatial modulation allows the use of Compressive Sensing, reducing the number of modulation patterns to be acquired. We present results on zebrafish embryos which prove that selective spatial modulation can be used to reconstruct relatively large volumes without any mechanical movement. The technique yields an accurate reconstruction of the sample anatomy even at significant compression ratios, achieving higher volumetric acquisition rate and reducing photodamage biological samples.

Novel time-resolved camera based on compressed sensing

Time-resolved cameras with high temporal resolution (down to ps) enable a huge set of novel applications ranging from biomedicine and environmental science to material and device characterization. In this work, we propose, and experimentally validate, a novel detection scheme for time-resolved imaging based on a compressed sampling approach. The proposed scheme unifies into a single element all the required operations, i.e. space modulation, space integration and time-resolved detection, paving the way to dramatic cost reduction, performance improvement and ease of use.

Combined pulsed dye laser and Q-switched Nd:YAG laser intraumatic facial tattoo removal: A case series

Traumatic tattoos can be treated with several methods, including mechanical and chemical devices. However, they are rarely used due to the high risk of permanent side effects such as scarring and depigmentation. Recently, laser devices, especially the Q-switched (QS) laser and the pulsed dye laser (PDL), applied in combination, have achieved complete clearance of the lesions without any risk of side effects. Herein, we reported three cases of traumatic facial tattoos successfully treated with combined PDL and QS Nd:YAG laser.

Real time dynamics of β-catenin expression during Hydra development, regeneration and Wnt signalling activation

Understanding the dynamic cellular behaviours driving morphogenesis and regeneration is a long-standing challenge in biology. Live imaging, together with genetically encoded reporters, may provide the necessary tool to address this issue, permitting the in vivo monitoring of the spatial and temporal expression dynamics of a gene of interest during a variety of developmental processes. Canonical Wnt/β-catenin signalling controls a plethora of cellular activities during development, regeneration and adulthood throughout the animal kingdom. Several reporters have been produced in animal models to reveal sites of active Wnt signalling. In order to monitor in vivo Wnt/β-catenin signalling activity in the freshwater polyp Hydra vulgaris, we generated a β-cat-eGFP transgenic Hydra, in which eGFP is driven by the Hydra β-catenin promoter. We characterized the expression dynamics during budding, regeneration and chemical activation of the Wnt/β-cat signalling pathway using light sheet fluorescence microscopy. Live imaging of the β-cat-eGFP lines recapitulated the previously reported endogenous expression pattern of β-catenin and revealed the dynamic appearance of novel sites of Wnt/β-catenin signalling, that earlier evaded detection by mean of in situ hybridization. By combining the Wnt activity read-out efficiency of the β-catenin promoter with advanced imaging, we have created a novel model system to monitor in real time the activity of Hydra β-cat regulatory sequences in vivo, and open the path to reveal β-catenin modulation in many other physiological contexts.

In Vivo Light Sheet Fluorescence Microscopy of Calcium Oscillations in Arabidopsis thaliana

Calcium imaging in plants requires a high-resolution microscope, able to perform volumetric acquisition in a few seconds, inducing as low photobleaching and phototoxicity as possible to the sample. Light sheet fluorescence microscopy offers these capabilities, with the further chance to mount the sample in vertical position, mimicking the plant's growth and physiological conditions.A protocol for plant preparation and mounting in a light sheet microscope is presented. First, the growth of Arabidopsis thaliana in a sample holder compatible with light sheet microscopy is described. Then, the requirements for sample alignment and image acquisition are detailed. Finally, the image processing steps to analyze calcium oscillations are discussed, with particular emphasis on ratiometric calcium imaging in Arabidopsis root hairs.

Optofluidic lab-on-chips for high throughput 3D imaging of cells and tissues

Optofludic lab-on-chips are compact microsystems that allow the manipulation, the analysis and the imaging of cells with high throughput even at the single cell level. The optofluidic microscopes on chip here presented are fabricated by femtosecond laser micromachining followed by chemical etching. The technique is ideally suited for rapid prototyping and allows 3D geometries and perfect alignment between microfluidic and optical components networks. The devices have been validated on cancer cell lines by imaging in three dimensions both clusters of cells growing on spheres and single cells.