医学

Inflammatory bowel disease (IBD) is highly prevalent globally and, in the majority of cases, remains asymptomatic during its initial stages. The gastrointestinal microbiota secretes volatile organic compounds (VOCs), and their composition alters in IBD. The examination of VOCs could prove beneficial in complementing diagnostic techniques to facilitate the early identification of IBD risk. In this protocol, a model of sodium dextran sulfate (DSS)-induced colitis in rats was successfully implemented for the non-invasive metabolomic assessment of different stages of inflammation. Headspace–gas chromatography–mass spectrometry (HS–GC–MS) was used as a non-invasive method for inflammation assessment at early and remission stages. The disease activity index (DAI) and histological method were employed to assess intestinal inflammation. The HS–GC–MS method demonstrated high sensitivity to intestine inflammation, confirmed by DAI and histology assay, in the acute and remission stages, identifying changes in the relative content of VOCs in stools. HS–GC–MS may be a useful and non-invasive method for IBD diagnostics and therapy effectiveness control.

Fuchs endothelial corneal dystrophy (FECD) is a rare and multifactorial disorder leading to cell death in the innermost layer of the cornea, i.e., the endothelium; UV radiation is reported as the major environmental risk for the disease. Establishing an animal model for this disease has remained challenging in FECD research. We have developed a detailed protocol for the establishment of a UVA-induced FECD mouse model and removal of corneal endothelium from the eye for further molecular and histological studies by taking references from previous studies. UVA light of 500 J/cm² was focused on the C57BL/6J female mouse cornea and kept for an observation period of 90 days. The animal developed corneal scarring by the end of three months. Slit-lamp microscopy and alizarin red–trypan blue staining confirmed endothelial cell death and formation of corneal guttae in the endothelium. Surgical removal of the endothelial layer was successfully done in the diseased mouse, and the result was confirmed by immunofluorescence. This study is relevant for in-depth research using a FECD mouse model, which will surpass the limitation of human tissue scarcity and can be used for in vivo drug targeting to develop therapeutics to cure FECD.

Human induced pluripotent stem (iPS) cell lines harboring mutations in disease-related genes serve as invaluable in vitro models for unraveling disease mechanisms and accelerating drug discovery efforts. Introducing mutations into iPS cells using traditional gene editing approaches based on the CRISPR-Cas9 endonuclease often encounters challenges such as unintended insertions/deletions (indels) and off-target effects. To address these limitations, we present a streamlined protocol for introducing highly accurate gene mutations into human iPS cells using prime editing, a “search-and-replace” genome-editing technology that combines unwanted indel-minimized CRISPR-Cas9 nickase with reverse transcriptase. This protocol encompasses the design of prime editing guide RNAs (pegRNAs) required for binding and replacement at target loci, construction of prime editor and pegRNA expression vectors, gene transfer into iPS cells, and cell line selection. This protocol allows for the efficient establishment of disease-associated gene variants within 6–8 weeks while preserving critical genomic context.

Micro-computed tomography (micro-CT) is a powerful, non-destructive imaging technique that creates high-resolution 3D images of the internal structures of small animal models such as mice and rats. Familiarizing oneself with micro-CT imaging and data analysis can be overwhelming without easy-to-follow, clear instructions. Training on new instruments is often a task exclusive to a select subset of researchers, leaving the majority of potential trainees without a technical grasp of how to navigate the instructions. This protocol on the use of micro-CT aims to bridge that gap by providing a clear, step-by-step guide to acquire and analyze micro-CT images from mice for quantitative data. By exclusively detailing the necessary procedural steps from start to finish and overcoming complex user interfaces during imaging operations and analysis, this protocol will equip new micro-CT users with the ability to measure mouse body composition (bone, body fat, and lean muscle mass) and identify and quantify lung fibrosis. This approach applies to researchers with a basic understanding of medical imaging, animal care, and software analysis.

Interstitial fluid (ISF) is a promising diagnostic sample due to its extensive biomolecular content while being safer and less invasive to collect than blood. However, existing ISF sampling methods are time-consuming, require specialized equipment, and yield small amounts of fluid (<5 μL). We have recently reported a simple and minimally invasive technique for rapidly sampling larger quantities of dermal ISF using a microneedle (MN) array to generate micropores in the skin from which ISF is extracted using a vacuum-assisted skin patch. Here, we present step-by-step protocols for fabricating the MN array and skin patch, as well as for using them to sample ISF from human skin. Using this technique, an average of 20.8 μL of dermal ISF can be collected within 25 min, which is a ∼6-fold improvement over existing ISF sampling methods. Furthermore, the technique is well-tolerated and does not require the use of expensive or specialized equipment. The ability to collect ample volumes of ISF in a quick and minimally invasive manner will facilitate the analysis of ISF for biomarker discovery and its use for diagnostic testing.

Animal infection models play significant roles in the study of bacterial pathogenic mechanisms and host–pathogen interactions, as well as in evaluating drug and vaccine efficacies. Chlamydia trachomatis is responsible for infections in various mucosal tissues, including the eyes and urogenital, respiratory, and gastrointestinal tracts. Chronic infections can result in severe consequences such as trachoma-induced blindness, ectopic pregnancy, and infertility. While intravaginal inoculation of C. muridarum mimics the natural route of sexual transmission between individuals, transcervical inoculation allows the organisms to directly infect endometrial epithelial cells without interference from host responses triggered by chlamydial contact or infection of vaginal and cervical cells. Therefore, in this study, we used mouse models to visualize pathologies in both the endometrium and oviduct following C. muridarum inoculation.

Pulpitis is an important and prevalent disease within the oral cavity. Thus, animal models are necessary tools for basic research focused on pulpitis. Researchers worldwide often use dogs and miniature pigs to construct animal models of pulpitis. However, gene editing in miniature pigs is difficult, the surgical modeling process is complex, and tooth demineralization time is lengthy. Although some researchers have attempted to establish a mouse model of pulpitis, most models have involved direct exposure of dental pulp. However, the causes of pulpitis vary considerably among individuals, hindering effective research. In this study, we established a mouse model of pulpitis by accessing the pulp cavity, exposing the pulp to lipopolysaccharide (LPS), and then filling the tooth. One day after surgery, we observed many necrotic tissues and extensive inflammatory exudate, including neutrophils, around the coronal cavity preparation. Additionally, we noted many more neutrophils and a small amount of chronic inflammatory cell infiltrates at the junction between inflamed and normal tissue. These findings indicated that our model can be used to explore the early stage of pulpitis. Ten days after surgery, we observed vacuolar degeneration in some fibroblasts and proliferation in others at the distal end of the inflamed tissue. We also noted dilation and congestion of the pulp blood vessels. Therefore, our model can also be used to explore the middle and later stages of pulpitis. Thirty days after surgery, we observed necrosis in the coronal pulp cavity and upper half of the root pulp, indicating that our model can also be used to explore the end stage of pulpitis. This model is easy to establish, shows pulpitis progression in the dental pulp, exhibits a clear inflammatory phenotype, and can be readily combined with gene editing techniques. Accordingly, it is suitable for basic research focused on pulpitis and has substantial practical value.

The bone is a highly dynamic organ that undergoes continuous remodeling through an intricate balance of bone formation and degradation. Hyperactivation of the bone-degrading cells, the osteoclasts (OCs), occurs in disease conditions and hormonal changes in females, resulting in osteoporosis, a disease characterized by altered microarchitecture of the bone tissue, and increased bone fragility. Thus, building robust assays to quantify OC resorptive activity to examine the molecular mechanisms underlying bone degradation is critical. Here, we establish an in vitro model to investigate the effect of estrogen withdrawal on OCs derived from the mouse macrophage RAW 264.7 cell line in a bone biomimetic microenvironment. This simple and robust model can also be adapted to examine the effect of drugs and genetic factors influencing OC resorptive activity in addition to being compatible with fluorescent imaging.

The quality of cellular products used in biological research can impact the accuracy of results. Epstein–Barr virus (EBV) is a latent virus that spreads extensively worldwide, and cell lines used in experiments may carry EBV and pose an infection risk. The presence of EBV in a single cell line can contaminate other cell lines used in the same laboratory, affecting experimental results. Existing tests to detect EBV can be divided into three categories: nucleic acid assays, serological assays, and in situ hybridization assays. However, most methods are time-consuming, expensive, and not conducive to high-volume clinical screening. Therefore, a simple system that allows for the rapid detection of EBV in multiple contexts, including both cell culture and tissue samples, remains necessary. In our research, we developed EBV detection systems: (1) a polymerase chain reaction (PCR)-based detection system, (2) a recombinase polymerase amplification (RPA)-based detection system, and (3) a combined RPA-lateral flow assay (LFA) detection system. The minimum EBV detection limits were 1 × 10³ copy numbers for the RPA-based and RPA-LFA systems and 1 × 10⁴ copy numbers for the PCR-based system. Both the PCR and RPA detection systems were applied to 192 cell lines, and the results were consistent with those of the assays specified in industry standards. A total of 10 EBV-positive cell lines were identified. The combined RPA-LFA system is simple to operate, allowing for rapid result visualization. This system can be implemented in laboratories and cell banks as part of a daily quality control strategy to ensure cell quality and experimental safety and may represent a potential new technique for the rapid detection of EBV in clinical samples.

Adipose tissue is crucial for medical applications such as tissue reconstruction, cosmetic procedures, and correcting soft tissue deformities. Significant advances in the use of adipose tissue have been achieved through Coleman’s studies in fat grafting, which gained widespread acceptance due to its effectiveness and safety. Despite its benefits, adipose tissue grafting faces several limitations, including high absorption rates due to insufficient support or anchorage, replacement by fibrous tissue, migration from the intended site, and loss of the initial desired morphology post-administration. To counteract these constraints, there is a need for improved grafting techniques that enhance the predictability and consistency of outcomes. Biomaterials are extensively used in tissue engineering to support cell adhesion, proliferation, and growth. Both natural and synthetic materials have shown promise in creating suitable microenvironments for adipose tissue regeneration. PLGA, a synthetic copolymer, is particularly notable for its biocompatibility, biodegradability, and tunable mechanical properties. Here, we describe a protocol using milled electrospun poly(lactic-co-glycolic acid) (PLGA) fibers combined with lipoaspirated tissue to create a fibrous slurry for injection. By pulverizing PLGA fiber mats to create fiber fragments with increased pore size and porosity, we can influence key cellular responses and enhance the success of adipose tissue–grafting procedures. This approach improves anchorage and support for adipocytes, thereby increasing cell viability. This method aims to enhance vascularity, perfusion, and volume retention in adipose tissue grafts, which addresses many of the limitations of current approaches to adipose tissue grafting and holds promise for more consistent and successful outcomes.