We present an easy-to-use, disposable, thermoplastic microwell chip designed to support screening and high-resolution imaging of single-cell behavior in two- and three-dimensional (2D and 3D) cell cultures. We show that the chip has excellent optical properties and provide simple protocols for efficient long-term cell culture of suspension and adherent cells, the latter grown either as monolayers or as hundreds of single, uniformly sized spheroids. We then demonstrate the applicability of the system for single-cell analysis by correlating the dynamic cytotoxic response of single immune cells grown under different metabolic conditions to their intracellular cytolytic load at the end of the assay. Additionally, we illustrate highly multiplex cytotoxicity screening of tumor spheroids in the chip, comparing the effect of environment cues characteristic of the tumor microenvironment on natural killer (NK)-cell-induced killing. Following the functional screening, we perform high-resolution 3D immunofluorescent imaging of infiltrating NK cells within the spheroid volumes.

Natural killer (NK) cells can protect from tumor-transformed cells using a fine-tuned machinery of activating and inhibiting receptors. An important activating receptor is Fc gamma receptor IIIa (FcγRIIIA or CD16A), which can trigger antibody-dependent cellular cytotoxicity (ADCC) when recognizing antibody-opsonized target cells. One strategy to boost ADCC responses may be achieved by inhibiting activation-induced shedding of CD16A from the NK cell surface. However, previous preclinical studies have shown contrasting results regarding the effectiveness and limitations of this approach. Here, microchip-based live cell-imaging was used to assess the consequences of CD16A shedding inhibition on the dynamics of NK cell cytotoxicity. The bispecific innate cell engager acimtamig (AFM13) was superior to IgG1 monoclonal antibodies in ADCC and in increasing the fraction of cytotoxic NK cells and serial killers. Under conditions where CD16A shedding was inhibited, acimtamig still triggered ADCC; however, the ability to promote serial killing was reduced and associated with impaired NK cell detachment from target cells. These results demonstrate that CD16A shedding represents an intrinsic feature of NK cell biology that is critical to sustain the antitumoral cytotoxicity of NK cells. This has implications for CD16A engineering of NK cell products and their combination with CD16A-directed NK cell engagers.

The development of new immunotherapeutic drugs and combinatorial strategies requires the implementation of novel methods to test their efficacy in vitro. Here, we present a series of miniaturized in vitro assays to assess immune cell cytotoxic activity, infiltration, and phenotype in renal carcinoma spheroids with the use of a recently developed multichambered microwell chip. We provide protocols for tumor spheroid formation, NK cell culture, fluorescence labelling and imaging of live or fixed cells directly in the chip together with data analysis.

γδ T cells play a pivotal role in protection against various types of infections and tumours, from early childhood on and throughout life. They consist of several subsets characterised by adaptive and innate-like functions, with Vγ9Vδ2 being the largest subset in human peripheral blood. Although these cells show signs of cytotoxicity, their modus operandi remains poorly understood. Here we explore, using live single-cell imaging, the cytotoxic functions of γδ T cells upon interactions with tumour target cells with high temporal and spatial resolution. While γδ T cell killing is dominated by degranulation, the availability of lytic molecules appears tightly regulated in time and space. In particular, the limited co-occurrence of granzyme B and perforin restrains serial killing of tumour cells by γδ T cells. Thus, our data provide new insights into the cytotoxic arsenal and functions of γδ T cells, which may guide the development of more efficient γδ T cell based adoptive immunotherapies.

Miniaturization of cell culture substrates enables controlled analysis of living cells in confined micro-scale environments. This is particularly suitable for imaging individual cells over time, as they can be monitored without escaping the imaging field-of-view (FoV). Glass materials are ideal for most microscopy applications. However, with current methods used in life sciences, glass microfabrication is limited in terms of either freedom of design, quality, or throughput. In this work, we introduce laser-induced deep etching (LIDE) as a method for producing glass microwell arrays for live single cell imaging assays. We demonstrate novel microwell arrays with deep, high-aspect ratio wells that have rounded, dimpled or flat bottom profiles in either single-layer or double-layer glass chips. The microwells are evaluated for microscopy-based analysis of long-term cell culture, clonal expansion, laterally organized cell seeding, subcellular mechanics during migration and immune cell cytotoxicity assays of both adherent and suspension cells. It is shown that all types of microwells can support viable cell cultures and imaging with single cell resolution, and we highlight specific benefits of each microwell design for different applications. We believe that high-quality glass microwell arrays enabled by LIDE provide a great option for high-content and high-resolution imaging-based live cell assays with a broad range of potential applications within life sciences. 

Here, we present a methodology based on multiplexed fluorescence screening of two-or three-dimensional cell cultures in a newly designed multichambered microwell chip, allowing direct assessment of drug or im-mune cell cytotoxic efficacy. We establish a framework for cell culture, formation of tumor spheroids, fluores-cence labeling, and imaging of fixed or live cells at various magnifications directly in the chip together with data analysis and interpretation. The methodology is demonstrated by drug cytotoxicity screening using ovarian and non-small cell lung cancer cells and by cellular cytotoxicity screening targeting tumor spheroids of renal carcinoma and ovarian carcinoma with natural killer cells from healthy donors. The miniaturized format allowing long-term cell culture, efficient screening, and high-quality imaging of small sample volumes makes this methodology promising for individualized cytotoxicity tests for precision medicine.

Despite advancements in analytical technologies, their complexity and cost have largely restricted their application in scalable online or multiplexed measurements. Here we report a quartz crystal resonator (QCR)-based method for detection of macromolecules that allows immensely simpler and faster measurements by employing for the first time a fixed frequency drive (FFD) and analytical expressions of acoustic parameters. Using human immunoglobulin E (hIgE) as an exemplar macromolecule and an anti-hIgE aptamer functionalised on a QCR, quantitative accuracy was benchmarked against the traditional impedance analysis method. The ability of FFD to capture data over longer observation periods at significantly higher acquisition rates at a fixed amplitude showed improvement in the QCR's sensitivity and specificity of transduction. The foundations for low-cost and low power online integration and large-scale multiplexability are also discussed.

Glass materials have excellent optical and chemical properties for microscopy-based live cell assays but state-of-the-art methods for microfabrication of Lab-on-Chip (LoC) devices are often limited by either complex manufacturing and/or low quality results. In this work, we have evaluated glass microwell array chips produced using a recently introduced laser-based microfabrication method. Three different types of microwell designs have been tested for imaging and screening of on-chip cell cultures and live cell assays.

Tuberculosis (TB) infects about 25% of the world population and claims more human lives than any other infectious disease. TB is spread by inhalation of aerosols containing viable Mycobacterium tuberculosis expectorated or exhaled by patients with active pulmonary disease. Air-sampling technology could play an important role in TB control by enabling the detection of airborne M. tuberculosis, but tools that are easy to use and scalable in TB hotspots are lacking. We developed an electrostatic air sampler termed the TB Hotspot DetectOR (THOR) and investigated its performance in laboratory aerosol experiments and in a prison hotspot of TB transmission. We show that THOR collects aerosols carrying microspheres, Bacillus globigii spores and M. bovis BCG, concentrating these microparticles onto a collector piece designed for subsequent detection analysis. The unit was also successfully operated in the complex setting of a prison hotspot, enabling detection of a molecular signature for M. tuberculosis in the cough of inmates. Future deployment of this device may lead to a measurable impact on TB case-finding by screening individuals through the aerosols they generate.

Cell therapy manufacturing is limited by lack of online tools capable of realtime in-process monitoring, particularly of simultaneous changes in multiple orthogonal (mutually independent) parameters. Here, we studied changes in CD36 expression, number density and size (area) of erythroblasts through different stages of erythropoiesis in vitro using a quartz crystal resonator (QCR), integrated with a microscope, and flow cytometry in parallel. An analytical model was developed extending the Kanazawa-Gordon theory. Based on this model, independent correlations were established between changes in each QCR parameter, dissipation (ΔΓ) and resonance frequency (−Δf0), and CD36 expression (from flow cytometry) and cell area (from microscope). The correlation functions were used to derive an acoustic signature (−ΔΓ/Δf0) of the differentiation process that uniquely mapped the relative changes in CD36 expression and late-stage enucleation-related deviations. A method to quantify relative changes in cell area purely from the acoustic parameters was also proposed. This work demonstrated for the first time the potential of an electromechanical tool for online monitoring of concurrently varying orthogonal phenotypic parameters in cell therapy manufacturing.