CRISPR/Cas-Based Techniques for Live-Cell Imaging and Bioanalysis

CRISPR/Cas bioimaging: From whole body biodistribution to single-cell dynamics

This review explores the transformative role of CRISPR/Cas systems in optical bioimaging, emphasizing how advancements in nanoparticle (NP) technologies are revolutionizing the visualization of gene-editing processes both in vitro and in vivo. Optical imaging techniques, such as near-infrared (NIR) and fluorescence imaging, have greatly benefited from the integration of nanoformulated contrast agents, improving resolution, sensitivity, and specificity. CRISPR/Cas systems, originally developed just for gene editing, are now being coupled with these imaging modalities to enable real-time monitoring and quantitative measurements of metabolites, vitamins, proteins, nucleic acids and other entities in specific areas of the body, as well as tracking of CRISPR/Cas delivery, editing efficiency, and potential off-target effects. The development of CRISPR/Cas-loaded NPs allows for enhanced imaging and precise monitoring across multiple scales with multiplexed and multicolor imaging in complex settings, including potential in vivo diagnostics. CRISPR/Cas therapeutics as well as diagnostics are hindered by the lack of efficient and targeted delivery tools. Biomimetic NPs have emerged as promising tools for improving biocompatibility, enhancing targeting capabilities, and overcoming biological barriers, facilitating more efficient delivery and bioimaging of CRISPR/Cas systems in vivo. As the design of these NPs and delivery mechanisms improves, alongside advancements in endolysosomal escape, CRISPR/Cas-based bioimaging will continue to advance, offering unprecedented possibilities in precision medicine and theranostic applications.

Method development and clinical validation of LAMP-CRISPR/Cas12a for rapid detection of respiratory pathogens in children

Background

Respiratory tract infections pose a substantial health burden, particularly among pediatric populations globally. The timely and accurate identification of pathogens such as Streptococcus pneumoniae (SP) and Mycoplasma pneumoniae (MP) is critical for effective clinical management.

Methods

In this study, a novel diagnostic approach combining loop-mediated isothermal amplification (LAMP) with CRISPR-Cas12a technology was developed for detecting SP and MP in clinical respiratory samples. A total of 23 specimens, including bronchoalveolar lavage fluid and nasopharyngeal swab samples, were assessed to evaluate the feasibility and performance of the method. After nucleic acid extraction, samples underwent LAMP amplification followed by CRISPR-Cas12a-mediated fluorescence detection.

Results

The LAMP-CRISPR/Cas12a method demonstrated high sensitivity and specificity for SP detection. It exhibited excellent sensitivity for SP and promising specificity for MP. Comparative analysis with standard diagnostic methods highlighted its potential to enhance diagnostic accuracy and efficiency. The assay provided results within 1 h, which is suitable for rapid point-of-care testing.

Conclusion

The integrated LAMP-CRISPR/Cas12a approach represents a significant advancement in detecting respiratory pathogens in clinical settings. It offers a rapid, sensitive, and specific diagnostic tool for identifying SP and MP, which is crucial for guiding precision therapies and improving patient outcomes. Future research aims to optimize assay sensitivity, streamline workflow to minimize contamination risks, and expand its detection scope so that other types of pathogens and mutation resistance genes can be detected. This molecular diagnostic strategy holds promise for the management of respiratory infections by enabling early and precise pathogen identification.

CRISPR/Cas System-Based Fluorescent Sensor for Analysis and Detection

Fluorescent sensor is an important tool to reliaze qualitative or quantitative detection of target analyte based on the fluorescence principle. Clustered regularly interspaced short palindromic repeats/CRISPR-associated protein (CRISPR/Cas) has been utilized to develop as a precise, efficient, and highly sensitive molecular diagnostic tool due to its efficient targeting and gene editing ability. At present, CRISPR/Cas system-based fluorescent sensors have shown excellent performance in the field of analysis and detection, and have received widespread attention. Therefore, this paper reviews the mechanism of the CRISPR/Cas system, the characteristics of different Cas proteins, and the principle and characteristics of the fluorescent sensor, with a focus on summarizing the application of the CRISPR/Cas system-based fluorescent sensor for analysis and detection.

CRISPR in clinical diagnostics: bridging the gap between research and practice

CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) has transformed molecular biology through its precise gene-editing capabilities. Beyond its initial applications in genetic modification, CRISPR has emerged as a powerful tool in diagnostics and biosensing. This review explores its transition from genome editing to innovative detection methods, including nucleic acid identification, single nucleotide polymorphism (SNP) analysis, and protein sensing. Advanced technologies such as SHERLOCK and DETECTR demonstrate CRISPR's potential for point-of-care diagnostics, enabling rapid and highly sensitive detection. The integration of chemical modifications, CRISPR-Chip technology, and enzymatic systems like Cas12a and Cas13a enhances signal amplification and detection efficiency. These advancements promise decentralized, real-time diagnostic solutions with significant implications for global healthcare. Furthermore, the fusion of CRISPR with artificial intelligence and digital health platforms is paving the way for more accessible, cost-effective, and scalable diagnostic approaches, ultimately revolutionizing precision medicine.

Live Cell Painting: image-based profiling in live cells using Acridine Orange

Image-based profiling has been used to analyze cell health, drug mechanism of action, CRISPR-edited cells, and overall cytotoxicity. Cell Painting is a broadly used image-based assay that uses morphological features to capture how cells respond to treatments. However, this method requires cell fixation for staining, which prevents examining live cells. To address this limitation, here we present Live Cell Painting (LCP), a high-content method based on Acridine orange, a metachromatic dye that labels different organelles and cellular structures. We began by showing that LCP can be applied to follow acidic vesicle redistribution of cells exposed to acidic vesicles inhibitors. Next, we show that LCP can identify subtle changes in cells exposed to silver nanoparticles that are not detected by techniques such as MTT assay. In drug treatments, LCP was helpful in assessing the dose-response relationship and creating profiles that allow clustering of drugs that cause liver injury. Here, we present an affordable and easy-to-use image-based assay capable of assessing overall cell health and showing promise for use in various applications such as assessing drugs and nanoparticles. We envisage the use of Live Cell Painting as an initial screening of overall cell health while providing insights into new biological questions.

A Comparison of Two Versions of the CRISPR-Sirius System for the Live-Cell Visualization of the Borders of Topologically Associating Domains

In recent years, various technologies have emerged for the imaging of chromatin loci in living cells via catalytically inactive Cas9 (dCas9). These technologies facilitate a deeper understanding of the mechanisms behind the chromatin dynamics and provide valuable kinetic data that could not have previously been obtained via FISH applied to fixed cells. However, such technologies are relatively complicated, as they involve the expression of several chimeric proteins as well as sgRNAs targeting the visualized loci, a process that entails many technical subtleties. Therefore, the effectiveness in visualizing a specific target locus may be quite low. In this study, we directly compared two versions of a previously published CRISPR-Sirius method based on the use of sgRNAs containing eight MS2 or PP7 stem loops and the expression of MCP or PCP fused to fluorescent proteins. We assessed the visualization efficiency for several unique genomic loci by comparing the two approaches in delivering sgRNA genes (transient transfection and lentiviral transduction), as well as two CRISPR-Sirius versions (with PCP and with MCP). The efficiency of visualization varied among the loci, and not all loci could be visualized. However, the MCP-sfGFP version provided more efficient visualization in terms of the number of cells with signals than PCP-sfGFP for all tested loci. We also showed that lentiviral transduction was more efficient in locus imaging than transient transfection for both CRISPR-Sirius systems. Most of the target loci in our study were located at the borders of topologically associating domains, and we defined a set of TAD borders that could be effectively visualized using the MCP-sfGFP version of the CRISPR-Sirius system. Altogether, our study validates the use of the CRISPR-Sirius technology for live-cell visualization and highlights various technical details that should be considered when using this method.