An integrated microfluidics platform with high-throughput single-cell cloning array and concentration gradient generator for efficient cancer drug effect screening

Research on cavity-driven control methods for concentration gradient microdroplets with high precision and stability

Microfluidic chip technology, an emerging interdisciplinary field, enables precise control of fluids at micro- and nano-scales and is widely applied in biomedicine, chemical analysis, and drug screening. This study investigates the effect of the parameters of chip geometry and the flow rate of fluid on the performance of the droplet concentration gradient generator using a cave-based microfluidic chip structure through numerical simulation and experimental verification. Finite element simulation software, equipped with laminar flow, phase field, and dilute substance transfer modules, was employed to analyze the impact of geometric parameters (cavity number, cavity radius, contact length between the cavity and the central channel, and cavity interval length) on the concentration gradient curve. Additionally, the effect of the fluid flow rate on the frequency, size, and concentration of the generated microdroplets was explored. Results indicate that the number, radius, and contact length of cavities significantly affect the concentration gradient curve, while the interval length has a minimal impact. Precise control of droplet concentration, generation frequency, and size can be achieved by adjusting the flow rates of the dispersed phase and the continuous phase. This study provides a theoretical basis for the design and optimization of concentration gradient microfluidic chips and promotes the application of concentration gradient microdroplet technology in high-throughput drug screening, biological detection and chemical analysis.

Single-Cell Analysis with Spatiotemporal Control of Local pH

This work presents an experimental platform combining scanning ion conductance microscopy (SICM) with confocal laser scanning microscopy (CLSM), using intra- and extracellular pH indicator dyes to study the impact of acid delivery on individual HeLa cells within a population. The proton gradient generated by the SICM delivery is highly confined by the action of the media buffer, making the challenge local. Temporal and spatial aspects of the delivery are modeled by simulations, allowing for pH gradients across individual cells, even within a group, to be calculated. We find a strong dependency between the intracellular pH and the extracellular pH gradient imposed by local acid delivery. Postdelivery intracellular pH recovery depends on the extent of the acid challenge, with cells exposed to lower pH not returning to basal intracellular pH values after the extracellular pH recovers. This is a unique method for concentration-gradient challenge studies of cell populations that will have broad applications in cell biology. SICM can be used to deliver different chemicals and enables a wide range of local conditions to be applied across a cell population, for which the effects can be investigated at the single-cell level.

SlipChip Enables the Integration of CRISPR-Cas12a and RPA for Fast and Stand-Alone HPV Detection

Human papillomavirus (HPV) screening is vital for the early detection and prevention of cervical cancer. However, existing methods often face challenges related to speed, simplicity, and multiplexing, especially in resource-limited settings. Here we developed a portable SlipChip-based multiplexed and rapid nucleic acid testing platform, named SMART, designed to simultaneously detect HPV16 and HPV18. SMART allows seamless integration of the RPA and Cas12a assays on the SlipChip and includes a heating membrane to regulate the on-chip assay temperatures. This allows SMART to operate as a stand-alone platform without additional control instruments. The platform also features an All-in-One imaging mode for rapid on-chip data acquisition, enhancing its performance. SMART enables sensitive detection of HPV16 and HPV18 DNA across multiple samples in just 36 min with a detection limit of approximately 6 copies per reaction. Testing of 56 clinical samples at risk of HPV infection validated SMART's performance, showing 97.7% sensitivity and 100% specificity. In summary, SMART offers a stand-alone system capable of rapidly distinguishing between the two most harmful HPV subtypes, showcasing the significant potential for rapid, multiplexed nucleic acid testing in various applications.

Progress in the Application of Organoids-On-A-Chip in Diseases

With the rapid development of the field of life sciences, traditional 2D cell culture and animal models have long been unable to meet the urgent needs of modern biomedical research and new drug development. Establishing a new generation of experimental models and research models is of great significance for deeply understanding human health and disease processes, and developing effective treatment measures. As is well known, long research and development cycles, high risks, and high costs are the "three mountains" facing the development of new drugs today. Organoids and organ-on-chips technology can highly simulate and reproduce the human physiological environment and complex reactions in vitro, greatly improving the accuracy of drug clinical efficacy prediction, reducing drug development costs, and avoiding the defects of drug testing animal models. Therefore, organ-on-chips have enormous potential in medical diagnosis and treatment.

Single-cell and spatial transcriptomics reveal SPP1-CD44 signaling drives primary resistance to immune checkpoint inhibitors in RCC

BACKGROUND

Immune checkpoint inhibitors (ICIs) are a cornerstone therapy for advanced renal cell carcinoma (RCC). However, significant rates of primary resistance hinder their efficacy, and the underlying mechanisms remain poorly understood. This study aims to unravel the tumor-immune interactions and signaling pathways driving primary resistance to ICIs in RCC.

METHODS

We integrated single-cell RNA sequencing, spatial transcriptomics, and clinical sample analysis to investigate the tumor microenvironment and intercellular signaling. Advanced computational methods, including cell-cell communication networks, pseudotime trajectories, and gene set enrichment analysis (GSEA), were employed to uncover the underlying resistance mechanisms.

RESULTS

Compared to the sensitive group, the primary resistance group exhibited a significant increase in SPP1-CD44 signaling-mediated interactions between tumor cells and immune cells. These interactions disrupted antigen presentation in immune effector cells and suppressed key chemokine and cytokine pathways, thereby impairing effective immune responses. In contrast, the sensitive group showed more active antigen presentation and cytokine signaling, which facilitated stronger immune responses. Furthermore, the interaction between SPP1-secreting tumor cells and CD44-expressing exhausted CD8 + T cells activated the MAPK signaling pathway within CD8 + Tex cells, exacerbating T cell exhaustion and driving the development of ICI resistance in RCC.

CONCLUSION

Our findings reveal a potential mechanism by which SPP1-CD44 signaling mediates tumor-immune cell interactions leading to ICI resistance, providing a theoretical basis for targeting and disrupting this signaling to overcome primary resistance in RCC.

A Biomimetic Optical Cardiac Fibrosis-on-a-Chip for High-Throughput Anti-Fibrotic Drug Screening

Cardiac fibrosis has emerged as the primary cause of morbidity, disability, and even mortality in numerous nations. In light of the advancements in precision medicine strategies, substantial attention has been directed toward the development of a practical and precise drug screening platform customized for individual patients. In this study, we introduce a biomimetic cardiac fibrosis-on-a-chip incorporating structural color hydrogels (SCHs) to enable optical high-throughput drug screening. By cocultivating a substantial proportion of cardiac fibroblasts (CFBs) with cardiomyocytes on the SCH, this biomimetic fibrotic microtissue successfully replicates the structural components and biomechanical properties associated with cardiac fibrosis. More importantly, the structural color shift observed in the SCH can be indicative of cardiac contraction and relaxation, making it a valuable tool for evaluating fibrosis progression. By incorporating such fibrotic microtissue into a microfluidic gradient chip, we develop a biomimetic optical cardiac fibrosis-on-a-chip platform that accurately and efficiently screens potential anti-fibrotic drugs. These characteristics suggest that this microphysiological platform possesses the capability to establish a preclinical framework for screening cardiac drugs, and may even contribute to the advancement of precision medicine.

Full-Combinatorial Concentration Gradient Array with 3D Micro/Nanofluidics for Antibiotic Susceptibility Testing

Recent advancements in micro/nanofluidics have facilitated on-chip microscopy of cellular responses in a high-throughput and controlled microenvironment with the desired physicochemical properties. Despite its potential benefits to combination drug discovery, generating a complete combinatorial set of concentration gradients for multiple reagents in an array format remains challenging. The main reason is limited layouts of conventional micro/nanofluidic systems based on two-dimensional channel networks. In this paper, we present a device with three-dimensional (3D) interconnection of micro/nanochannels capable of generating a complete combinatorial set of concentration gradients for two reagents. The device was readily fabricated by laminating a pair of multilayered monolithic films containing a Christmas tree-like mixer, a cell culture chamber array, and through-holes, all within each single film. We assessed the reliable generation of a full-combinatorial concentration gradient array and validated it by using numerical analysis. We applied the proposed device to test the antibiotic susceptibility of bacterial cells in a convenient one-step manner. Furthermore, we explored the potential of the device to accommodate the arrayed complete combinatorial set for two or more drugs, while extending the capabilities of our laminated object manufacturing method for realizing 3D micro/nanofluidic systems.

Construction of multiple concentration gradients for single-cell level drug screening

Isolation and manipulation of single cells play a crucial role in drug screening. However, previously reported single-cell drug screening lacked multiple-dose concentration gradient studies, which limits their ability to predict drug performance accurately. To solve this problem, we constructed a multiconcentration gradient generator in which a Tai Chi-spiral mixer can accelerate solution mixing in a short time and produce a linear concentration gradient. Later, a gradient generator combined with a single-cell capture array was adopted to investigate the effects of single or combined doses of 5-fluorouracil and cisplatin on human hepatoma cells and human breast carcinoma cells (at the single-cell level). The results showed that both drugs were effective in inhibiting the growth of cancer cells, and the combination was more effective for human hepatoma cells. In addition, the relationship between the biomechanical heterogeneity (e.g., deformability and size) of tumor cells and potential drug resistance at the single-cell level was investigated, indicating that small and/or deformable cells were more resistant than large and/or less deformable cells. The device provides a simple and reliable platform for studying the optimal dosage of different drug candidates at the single-cell level and effectively screening single-agent chemotherapy regimens and combination therapies.

Research on Influencing Factors of Satisfaction with the Use of Public Health Internet Platform: Evidence from Ding Xiang Doctor (DXY) Internet Medical Platform

With the rapid development of Internet information technology, Internet medical platforms are gradually entering daily life. Especially after the outbreak of the COVID-19 pandemic, it becomes very difficult for patients to go out for medical treatment, and the Internet medical platform plays an important role. The study of the use and influencing factors of Internet medical platforms has become a new topic. In this study, evidence from the Chinese Internet medical platform Ding Xiang Doctor(DXY) is combined with an integrated approach of hierarchical analysis and the entropy value method to construct evaluation indexes and questionnaires from four dimensions of perceived quality, perceived value, user trust, and user involvement to analyze the factors influencing users' satisfaction with Internet medical platforms. The questionnaires were distributed online, and 556 questionnaires were distributed from June to August 2022; 520 questionnaires were collected; the questionnaires' recovery rate was 93.53%; after excluding some invalid questionnaires, 424 questionnaires remained; the questionnaire efficiency was 81.54%; the Cronbach coefficient was 0.978; the KMO(Kaiser-Meyer-Olkin) value was 0.977; and the reliability performance was good. The study concluded that: (1) Users pay more attention to the content of perceived value, including the cost of time, economy, expense, and effort spent, and emphasize the degree of personal benefit. (2) Users are less satisfied with the information accessibility, design aesthetics, information timeliness, information comprehensiveness, and classification clarity of the DXY platform. (3) Users pay most attention to the protection of personal privacy by the platform side in the dimension of perceived value. (4) Users' trust in the platform is relatively high, their willingness to use the platform in the future is strong, and the dimensions of online interactive discussion, willingness to pay, and paid services are highly recognized.