Label-free analysis of prostate acini-like 3D structures by lensfree imaging

YAP1 modulation of primary cilia-mediated ciliogenesis in 2D and 3D prostate cancer models

The primary cilium, a non-motile organelle present in most human cells, plays a crucial role in detecting microenvironmental changes and regulating intracellular signaling. Its dysfunction is linked to various diseases, including cancer. We explored the role of ciliated cells in prostate cancer by using Gefitinib and Jasplakinolide compounds to induce ciliated cells in both normal and tumor-like prostate cell lines. We assessed GLI1 and IFT20 expression and investigated YAP1 protein's role, which is implicated in primary cilium regulation. Finally, we examined these compounds in 3D cell models, aiming to simulate in vivo conditions. Our study highlights YAP1 as a potential target for novel genetic models to understand the primary cilium's role in mediating resistance to anticancer treatments.

Simple Imaging System for Label-Free Identification of Bacterial Pathogens in Resource-Limited Settings

Fast, accurate, and affordable bacterial identification methods are paramount for the timely treatment of infections, especially in resource-limited settings (RLS). However, today, only 1.3% of the sub-Saharan African diagnostic laboratories are performing clinical bacteriology. To improve this, diagnostic tools for RLS should prioritize simplicity, affordability, and ease of maintenance, as opposed to the costly equipment utilized for bacterial identification in high-income countries, such as matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). In this work, we present a new high-throughput approach based on a simple wide-field (864 mm2) lensless imaging system allowing for the acquisition of a large portion of a Petri dish coupled with a supervised deep learning algorithm for identification at the bacterial colony scale. This wide-field imaging system is particularly well suited to RLS since it includes neither moving mechanical parts nor optics. We validated this approach through the acquisition and the subsequent analysis of a dataset comprising 252 clinical isolates from five species, encompassing some of the most prevalent pathogens. The resulting optical morphotypes exhibited intra- and interspecies variability, a scenario considerably more akin to real-world clinical practice than the one achievable by solely concentrating on reference strains. Despite this variability, high identification performance was achieved with a correct species identification rate of 91.7%. These results open up some new prospects for identification in RLS. We released both the acquired dataset and the trained identification algorithm in publicly available repositories.

Microfluidic Applications in Prostate Cancer Research

Prostate cancer is a disease in which cells in the prostate, a gland in the male reproductive system below the bladder, grow out of control and, among men, it is the second-most frequently diagnosed cancer (other than skin cancer). In recent years, prostate cancer death rate has stabilized and, currently, it is the second-most frequent cause of cancer death in men (after lung cancer). Most deaths occur due to metastasis, as cancer cells from the original tumor establish secondary tumors in distant organs. For a long time, classical cell cultures and animal models have been utilized in basic and applied scientific research, including clinical applications for many diseases, such as prostate cancer, since no better alternatives were available. Although helpful in dissecting cellular mechanisms, these models are poor predictors of physiological behavior mainly because of the lack of appropriate microenvironments. Microfluidics has emerged in the last two decades as a technology that could lead to a paradigm shift in life sciences and, in particular, controlling cancer. Microfluidic systems, such as organ-on-chips, have been assembled to mimic the critical functions of human organs. These microphysiological systems enable the long-term maintenance of cellular co-cultures in vitro to reconstitute in vivo tissue-level microenvironments, bridging the gap between traditional cell cultures and animal models. Several reviews on microfluidics for prostate cancer studies have been published focusing on technology advancement and disease progression. As metastatic castration-resistant prostate cancer remains a clinically challenging late-stage cancer, with no curative treatments, we expanded this review to cover recent microfluidic applications related to prostate cancer research. The review includes discussions of the roles of microfluidics in modeling the human prostate, prostate cancer initiation and development, as well as prostate cancer detection and therapy, highlighting potentially major contributions of microfluidics in the continuous march toward eradicating prostate cancer.

ZFHX3 acts as a tumor suppressor in prostate cancer by targeting FTO-mediated m6A demethylation

Zinc-finger homeobox 3 (ZFHX3, also known as ATBF1) suppresses prostatic tumorigenesis. ZFHX3 is frequently found to have numerous deletions in human prostate cancer (PCa). However, the underlying molecular function of ZFHX3 during prostatic tumorigenesis is not well understood. N6-methyladenosine (m6A) modification in RNA plays a critical role in the development of cancers; however, the relationship between ZFHX3 and m6A modification is largely unknown in PCa. In this study, we found that ZFHX3 knockdown decreased total m6A levels through enhancing the transcriptional activity of FTO in PCa cells. Importantly, FTO inhibition suppressed cell proliferation and rescued the promoting function of ZFHX3 knockdown on cell proliferation. In vivo, we verified that FTO was upregulated and ZFHX3 was decreased in PCa patients and that a high level of ZFHX3 is indispensable for low FTO expression and is correlated with better patient survival. Through transcriptome sequencing and MeRIP sequencing, we revealed that E2F2 and CDKN2C were the direct targets of FTO-mediated m6A modification and ZFXH3 was required for the regulation of FTO on E2F2 and CDKN2C expression. Unexpectedly, we uncovered that ZFHX3 expression was in return regulated by FTO in an m6A-dependent way. These findings establish a novel crosstalk mechanism between ZFHX3 and FTO in prostatic tumorigenesis.

Lens-free auto-focusing imaging algorithm for the ultra-broadband light source

Auto-focusing is an essential task for lens-free holographic microscopy, which has developed many methods for high precision or fast refocusing. In this work, we derive the relationship among intensity derivation, the derivative of spectral distribution, as well as the distribution of the object, and propose a new auto-focusing criterion, the Robert critical function with axial difference (RCAD), to enhance the accuracy of distance estimation for lens-free imaging with the ultra-broadband light source. This method consists of three steps: image acquisition and preprocessing, axial-difference calculation, and distance estimation with sharpness analysis. The simulations and experiments demonstrate that the accuracy of this metric on auto-focusing with the ultra-broadband spectrum can effectively assist in determining the off-focus distance. The experiments are conducted in an ultra-broad-spectrum on-chip system, where the samples including the resolution target and the cross-section of the Tilia stem are employed to maximize the applicability of this method. We believe that the RCAD criterion is expected to be a useful auxiliary tool for lens-free on-chip microscopes with ultra-broadband spectrum illumination.

KNSTRN, a Poor Prognostic Biomarker, Affects the Tumor Immune Microenvironment and Immunotherapy Outcomes in Pan-Cancer

Kinetochore-localized astrin- (SPAG5-) binding protein (KNSTRN) is mainly involved in mitosis. Somatic mutations in KNSTRN are known to lead to the occurrence and development of certain tumors. However, the role of KNSTRN in the tumor immune microenvironment (TIME) as a tumor prognostic biomarker and potential therapeutic target has not been clarified. Accordingly, in this study, we aimed to investigate the role of KNSTRN in the TIME. mRNA expression, cancer patient prognosis, and correlations between KNSTRN expression and immune component infiltration were analyzed using Genotype-Tissue Expression, The Cancer Genome Atlas, Cancer Cell Line Encyclopedia, Human Protein Atlas, ImmuCellAI, TIMER2.0, and KM-Plotter. The Genomics of Drug Sensitivity in Cancer database was used to evaluate the relationship between KNSTRN expression and the half maximal inhibitory concentration (IC50) of several anticancer drugs, and gene set variation analysis was performed. Data were visualized using R version 4.1.1. KNSTRN expression was upregulated in the majority of cancers and was associated with a worse prognosis. Additionally, KNSTRN expression was highly correlated with the infiltration of multiple immune components in the TIME and was related to a poor prognosis in tumor patients receiving immunotherapy. KNSTRN expression was also positively correlated with the IC50 of various anticancer drugs. In conclusion, KNSTRN may be a significant prognostic biomarker and promising target for oncotherapy in numerous cancers.

Computational Portable Microscopes for Point-of-Care-Test and Tele-Diagnosis

In bio-medical mobile workstations, e.g., the prevention of epidemic viruses/bacteria, outdoor field medical treatment and bio-chemical pollution monitoring, the conventional bench-top microscopic imaging equipment is limited. The comprehensive multi-mode (bright/dark field imaging, fluorescence excitation imaging, polarized light imaging, and differential interference microscopy imaging, etc.) biomedical microscopy imaging systems are generally large in size and expensive. They also require professional operation, which means high labor-cost, money-cost and time-cost. These characteristics prevent them from being applied in bio-medical mobile workstations. The bio-medical mobile workstations need microscopy systems which are inexpensive and able to handle fast, timely and large-scale deployment. The development of lightweight, low-cost and portable microscopic imaging devices can meet these demands. Presently, for the increasing needs of point-of-care-test and tele-diagnosis, high-performance computational portable microscopes are widely developed. Bluetooth modules, WLAN modules and 3G/4G/5G modules generally feature very small sizes and low prices. And industrial imaging lens, microscopy objective lens, and CMOS/CCD photoelectric image sensors are also available in small sizes and at low prices. Here we review and discuss these typical computational, portable and low-cost microscopes by refined specifications and schematics, from the aspect of optics, electronic, algorithms principle and typical bio-medical applications.

A Novel Approach for a Chip-Sized Scanning Optical Microscope

The recent advances in chip-size microscopy based on optical scanning with spatially resolved nano-illumination light sources are presented. This new straightforward technique takes advantage of the currently achieved miniaturization of LEDs in fully addressable arrays. These nano-LEDs are used to scan the sample with a resolution comparable to the LED sizes, giving rise to chip-sized scanning optical microscopes without mechanical parts or optical accessories. The operation principle and the potential of this new kind of microscope are analyzed through three different implementations of decreasing LED dimensions from 20 µm down to 200 nm.

Human stroma and epithelium co-culture in a microfluidic model of a human prostate gland

The prostate is a walnut-sized gland that surrounds the urethra of males at the base of the bladder comprising a muscular portion, which controls the release of urine, and a glandular portion, which secretes fluids that nourish and protect sperms. Here, we report the development of a microfluidic-based model of a human prostate gland. The polydimethylsiloxane (PDMS) microfluidic device, consisting of two stacked microchannels separated by a polyester porous membrane, enables long-term in vitro cocultivation of human epithelial and stromal cells. The porous separation membrane provides an anchoring scaffold for long-term culturing of the two cell types on its opposite surfaces allowing paracrine signaling but not cell crossing between the two channels. The microfluidic device is transparent enabling high resolution bright-field and fluorescence imaging. Within this coculture model of a human epithelium/stroma interface, we simulated the functional development of the in vivo human prostate gland. We observed the successful differentiation of basal epithelial cells into luminal secretory cells determined biochemically by immunostaining with known differentiation biomarkers, particularly androgen receptor expression. We also observed morphological changes where glandlike mounds appeared with relatively empty centers reminiscent of prostatic glandular acini structures. This prostate-on-a-chip will facilitate the direct evaluation of paracrine and endocrine cross talk between these two cell types as well as studies associated with normal vs disease-related events such as prostate cancer.

Comparative study of fully three-dimensional reconstruction algorithms for lens-free microscopy

We propose a three-dimensional (3D) imaging platform based on lens-free microscopy to perform multiangle acquisitions on 3D cell cultures embedded in extracellular matrices. Lens-free microscopy acquisitions present some inherent issues such as the lack of phase information on the sensor plane and a limited angular coverage. We developed and compared three different algorithms based on the Fourier diffraction theorem to obtain fully 3D reconstructions. These algorithms present an increasing complexity associated with a better reconstruction quality. Two of them are based on a regularized inverse problem approach. To compare the reconstruction methods in terms of artefact reduction, signal-to-noise ratio, and computation time, we tested them on two experimental datasets: an endothelial cell culture and a prostate cell culture grown in a 3D extracellular matrix with large reconstructed volumes up to ∼5  mm³ with a resolution sufficient to resolve isolated single cells. The lens-free reconstructions compare well with standard microscopy.

Unconventional methods of imaging: computational microscopy and compact implementations

In the past two decades or so, there has been a renaissance of optical microscopy research and development. Much work has been done in an effort to improve the resolution and sensitivity of microscopes, while at the same time to introduce new imaging modalities, and make existing imaging systems more efficient and more accessible. In this review, we look at two particular aspects of this renaissance: computational imaging techniques and compact imaging platforms. In many cases, these aspects go hand-in-hand because the use of computational techniques can simplify the demands placed on optical hardware in obtaining a desired imaging performance. In the first main section, we cover lens-based computational imaging, in particular, light-field microscopy, structured illumination, synthetic aperture, Fourier ptychography, and compressive imaging. In the second main section, we review lensfree holographic on-chip imaging, including how images are reconstructed, phase recovery techniques, and integration with smart substrates for more advanced imaging tasks. In the third main section we describe how these and other microscopy modalities have been implemented in compact and field-portable devices, often based around smartphones. Finally, we conclude with some comments about opportunities and demand for better results, and where we believe the field is heading.

Lensfree diffractive tomography for the imaging of 3D cell cultures

New microscopes are needed to help realize the full potential of 3D organoid culture studies. In order to image large volumes of 3D organoid cultures while preserving the ability to catch every single cell, we propose a new imaging platform based on lensfree microscopy. We have built a lensfree diffractive tomography setup performing multi-angle acquisitions of 3D organoid culture embedded in Matrigel and developed a dedicated 3D holographic reconstruction algorithm based on the Fourier diffraction theorem. With this new imaging platform, we have been able to reconstruct a 3D volume as large as 21.5 mm (3) of a 3D organoid culture of prostatic RWPE1 cells showing the ability of these cells to assemble in 3D intricate cellular network at the mesoscopic scale. Importantly, comparisons with 2D images show that it is possible to resolve single cells isolated from the main cellular structure with our lensfree diffractive tomography setup.

Lensless Imaging and Sensing

High-resolution optical microscopy has traditionally relied on high-magnification and high-numerical aperture objective lenses. In contrast, lensless microscopy can provide high-resolution images without the use of any focusing lenses, offering the advantages of a large field of view, high resolution, cost-effectiveness, portability, and depth-resolved three-dimensional (3D) imaging. Here we review various approaches to lensless imaging, as well as its applications in biosensing, diagnostics, and cytometry. These approaches include shadow imaging, fluorescence, holography, superresolution 3D imaging, iterative phase recovery, and color imaging. These approaches share a reliance on computational techniques, which are typically necessary to reconstruct meaningful images from the raw data captured by digital image sensors. When these approaches are combined with physical innovations in sample preparation and fabrication, lensless imaging can be used to image and sense cells, viruses, nanoparticles, and biomolecules. We conclude by discussing several ways in which lensless imaging and sensing might develop in the near future.

Time-lapse contact microscopy of cell cultures based on non-coherent illumination

Video microscopy offers outstanding capabilities to investigate the dynamics of biological and pathological mechanisms in optimal culture conditions. Contact imaging is one of the simplest imaging architectures to digitally record images of cells due to the absence of any objective between the sample and the image sensor. However, in the framework of in-line holography, other optical components, e.g., an optical filter or a pinhole, are placed underneath the light source in order to illuminate the cells with a coherent or quasi-coherent incident light. In this study, we demonstrate that contact imaging with an incident light of both limited temporal and spatial coherences can be achieved with sufficiently high quality for most applications in cell biology, including monitoring of cell sedimentation, rolling, adhesion, spreading, proliferation, motility, death and detachment. Patterns of cells were recorded at various distances between 0 and 1000 μm from the pixel array of the image sensors. Cells in suspension, just deposited or at mitosis focalise light into photonic nanojets which can be visualised by contact imaging. Light refraction by cells significantly varies during the adhesion process, the cell cycle and among the cell population in connection with every modification in the tridimensional morphology of a cell.

Facile bench-top fabrication of enclosed circular microchannels provides 3D confined structure for growth of prostate epithelial cells

We present a simple bench-top method to fabricate enclosed circular channels for biological experiments. Fabricating the channels takes less than 2 hours by using glass capillaries of various diameters (from 100 µm up to 400 µm) as a mould in PDMS. The inner surface of microchannels prepared in this way was coated with a thin membrane of either Matrigel or a layer-by-layer polyelectrolyte to control cellular adhesion. The microchannels were then used as scaffolds for 3D-confined epithelial cell culture. To show that our device can be used with several epithelial cell types from exocrine glandular tissues, we performed our biological studies on adherent epithelial prostate cells (non-malignant RWPE-1 and invasive PC3) and also on breast (non-malignant MCF10A) cells We observed that in static conditions cells adhere and proliferate to form a confluent layer in channels of 150 µm in diameter and larger, whereas cellular viability decreases with decreasing diameter of the channel. Matrigel and PSS (poly (sodium 4-styrenesulphonate)) promote cell adhesion, whereas the cell proliferation rate was reduced on the PAH (poly (allylamine hydrochloride))-terminated surface. Moreover infusing channels with a continuous flow did not induce any cellular detachment. Our system is designed to simply grow cells in a microchannel structure and could be easily fabricated in any biological laboratory. It offers opportunities to grow epithelial cells that support the formation of a light. This system could be eventually used, for example, to collect cellular secretions, or study cell responses to graduated hypoxia conditions, to chemicals (drugs, siRNA, …) and/or physiological shear stress.