Jove-Journal of Visualized Experiments最新文献

Osteosarcopenia (OS), a complex degenerative disorder, is characterized by the concurrent decline in skeletal muscle mass and bone mineral density (BMD), posing an enormous health hazard for the elderly population. Despite its clinical relevance, the pathophysiological mechanisms underlying OS are not fully understood, underscoring the necessity for a deeper comprehension of its etiology to facilitate effective treatment strategies. The development of a reliable animal model is pivotal in this endeavor. This study presents a refined protocol for the induction of postmenopausal osteosarcopenia in rats through bilateral ovariectomy, a method known to accelerate the onset of age-related muscle and bone loss. In this study, rats aged 12 weeks were stratified by body weight and randomly assigned to either a sham operation group or an ovariectomized (OVX) group. Tissue samples from the quadriceps and triceps muscles of the left hind limb, as well as the left femur, were systematically collected at 4, 8, and 12 weeks post-surgery. This methodical approach ensures a comprehensive evaluation of the effects of ovariectomy on muscle and bone health. Histological evaluation of muscle fiber atrophy and femoral morphology was conducted using hematoxylin and eosin (HE) staining, while bone mineral density was quantified using dual-energy X-ray absorptiometry (DXA). The temporal progression of OS was meticulously monitored at the aforementioned intervals, providing insights into the dynamic interplay between muscle and bone degeneration. This model not only accurately reflects the clinical manifestations of OS but also serves as a robust platform for investigating novel therapeutic approaches and their underlying mechanisms.

Natural killer (NK) cells are innate immune cells that play a crucial role in the body's defense against tumors and viral infections. The generation of human induced pluripotent stem cell (iPSC)-derived chimeric antigen receptor (CAR) expressing NK cells has emerged as a promising avenue for "off the shelf" cancer immunotherapy. Here, we utilized an NK cell-optimized CAR construct that includes the transmembrane domain of NKG2D, the 2B4 co-stimulatory domain, and the CD3ζ signaling domain, which has been demonstrated to stimulate robust antigen-specific NK cell-mediated antitumor activity. The use of iPSCs for CAR NK cell generation offers several advantages, including homogenous CAR expression, scalability, reproducibility, and the potential for clinical application. This detailed step-by-step protocol from cell engineering to differentiation enables the generation of NK cell-optimized iPSC-derived CAR-expressing NK cells, providing a standardized and targeted cancer immunotherapy with improved antitumor activity and highlighting their potential as a promising treatment option for various malignancies.

With their remarkable capacity to generate both ectodermal and mesenchymal derivatives, cranial neural crest cells (CNCC) have attracted a lot of interest in studying the mechanisms regulating cell fate decisions and plasticity. Originating in the dorsal neuroepithelium, this cell population is transient and relatively rare in the developing embryo - making functional tests, genomic screens, and biochemistry assays challenging to perform in vivo. To overcome these limitations, several methods have been developed to model CNCC development in vitro. Neurosphere (NS) based culturing methods provide a complex microenvironment that recapitulates the developing anterior neuroepithelium in 3D. These systems allow the growth of many NS in the same plate to generate a large amount of CNCC, but the produced NS present a high variability in shape, size, and number of CNCC formed - making quantitative assays difficult to perform. This protocol outlines a reproducible method for generating NS from mouse embryonic stem cells (mESC) in a 96-well format. NS generated in 96-well plates produce cranial neural crest cells (CNCC), which can be further cultured. By controlling the number of starting cells, this approach reduces variability in the size and shape between NS and increases reproducibility across experiments. Finally, this culture system is adaptable to several applications and offers a higher degree of flexibility, making it highly customizable and suitable for multiplexing experimental conditions.

Transmission of iatrogenic prion disease has occurred from contaminated neurosurgical tools, transplant materials, and occupational exposure to prion-contaminated laboratory tools. Prions cause disease by the templated misfolding of the normal cellular form of the prion protein, PrP^C, into the misfolded and pathogenic form PrP^Sc and are invariably fatal. Reducing iatrogenic and occupational prion transmission is challenging. First, prions can bind to and persist on surfaces for long periods of time. Second, prions are highly resistant to inactivation. Given this, surfaces can retain infectivity for long periods of time following ineffective decontamination. Not only can this pose a potential occupational risk for prion laboratory workers, but it could potentially cross-contaminate laboratory experiments utilizing sensitive prion amplification techniques. The protocol described here for a prion safety laboratory swipe test includes steps for the identification and documentation of high-traffic laboratory areas, recommended swabbing controls to ensure the validity of results, steps to identify proper responses to positive surface swabbing sites, representative results from prion swipe testing, as well as potential artifactual results. Overall, the prion safety laboratory swipe test can be implemented as part of a broader prion safety program to assess decontamination of surfaces, monitor common spaces for prion contamination, and implement the documentation of prion decontamination status.

Intrathecal catheterization has been widely applied in animal experiments, especially those on neuropathic pain. However, the traditional methods still have several limitations. Although some investigators have attempted to improve the traditional methods, the available methods still need to be modified. Herein, we introduce a modified method for intrathecal catheterization in rats. This method uses a 20 cm long stainless-steel wire (0.2 mm in diameter), a 15 cm long plastic PE10 tube, a self-made sealing cap, and a 0.3 cm × 0.5 cm anti-allergic band. Our modified method for intrathecal catheterization has several advantages. First, introducing a stainless-steel wire to PE10 tube increases the elasticity of the tube, improves the success rate of intrathecal catheterization, reduces the amount of space required for the operation, and minimizes the damage to the tissues around the lumbar spine. Second, the length of PE10 tube is determined before the surgery, and catheter indwelling time can be longer than one week. Third, the PE10 tube is fixed by a figure-8 suture, 4 times, which prevents tube movement and retraction when the animal moves. Fourth, a self-made sealing cap is used to seal the PE10 tube, which not only prevents cerebrospinal fluid leakage but also reduces the need for repeated cutting of PE10 tube. Finally, the extracorporeal end of PE10 tube is tied with a band, which prevents tube retraction when the animal moves. This method can increase the catheterization success rate in rats, as approximately 80% of PE10 tubes remained in place even 28 days after surgery. Thus, this modified method may represent a simple, convenient, and reliable approach for repetitive intrathecal drug administration.

Interbody fusion of the lumbar spine is a standard procedure for symptomatic degenerative lumbar spine disease if conservative treatment fails. Surgical decompression and fusion of the segment can be achieved using several different techniques. Over the last decades, minimally invasive techniques, such as lateral interbody fusion (LLIF), have been developed to reduce tissue damage and complications and allow quicker patient recovery. With growing popularity, indications for LLIF have expanded to treat spinal deformities and foraminal/central stenosis. Mechanically, it allows for an unsurpassed fixation through the left-to-right apophyseal ring placement of the cage. LLIF utilizes a minimally disruptive retroperitoneal corridor and includes both trans-psoas and pre-psoas approaches. For the pre-psoas approach, the risk of damage from manipulation of the intramuscular lumbar plexus is reduced compared to a trans-psoas approach. However, increased risks of major vascular, ureteral, bowel injury and sympathetic plexus damage are reported. This article aims to provide a detailed and comprehensive guide on stand-alone lateral trans-psoas interbody fusion, including its indications, surgical procedure, potential complications, and outcomes based on a decade of experience from a single center.

The precise and real-time measurement of oxygen partial pressure (pO2) brings valuable information in many pathologies, including cancer. Low tumor pO2 (i.e., hypoxia) is connected to tumor aggressiveness and poor response to therapy. The quantification of tumor pO2 allows the evaluation of treatment effectiveness. Electron Paramagnetic Resonance Imaging (EPRI), particularly Pulse EPRI, has emerged as an advanced three-dimensional (3D) method of assessing tissue oxygenation in vivo. This innovation was enabled by the technological developments in EPR (Electron Paramagnetic Resonance) and the application of the water-soluble oximetric spin probes from the triaryl family, offering fast and sensitive oxygenation data. The relaxation time of the spin probe (T1 and/or T2) provides accurate information about pO2 in selected voxels. Human glioblastoma LN229 tumors were grown in the interscapular fad pad of BALB/c nude mice. Ultrasound (US) imaging was used as a reference for tumor anatomical information. To image tissue pO2, the animals were placed in a fixed position in the animal bed with fiducials, enabling registration between the imaging modalities. After the OX071 contrast agent was administered, EPRI was performed, followed by US B-mode. Because of the low spin probe toxicity, the procedure can be repeated during tumor growth or treatment. Following imaging, the registration process was carried out using software written in MATLAB. Ultimately, the hypoxic fraction can be calculated for a specific tumor, and the histogram of pO2 tissue distribution can be compared over time. EPRI combined with ultrasound is an excellent tool for oxygen mapping of tumors in the preclinical setting.

Antibiotic persistence is a phenomenon in which a small number of bacterial cells in a genetically susceptible population survive antibiotic treatment that kills the other genetically identical cells. Bacterial persisters can resume replication once antibiotic treatment ends and are commonly thought to underlie clinical treatment failure. Recent work harnessing the power of time-lapse fluorescence microscopy, in which bacteria are labeled with fluorescent transcriptional reporters, translational reporters, and/or dyes for a variety of cellular features, has advanced our understanding of Escherichia coli persisters beyond what could be learned from population-level antibiotic survival assays. Such single-cell approaches, rather than bulk population assays, are essential for delineating the mechanisms of persister formation, damage response, and survival. However, methods for studying persisters in other important pathogenic species at this level of detail remain limited. This study provides an adaptable approach for time-lapse imaging of Pseudomonas aeruginosa (a gram-negative rod) and Staphylococcus aureus (a gram-positive coccus) during antibiotic treatment and recovery. We discuss molecular genetic approaches to introduce fluorescent reporters into these bacteria. Using these reporters, as well as dyes, we can track the phenotypic changes, morphological features, and fates of individual cells in response to antibiotic treatment. Additionally, we are able to observe the phenotypes of individual persisters as they resuscitate following treatment. In all, this work serves as a resource for those interested in tracking the survival and gene expression of individual antibiotic-treated cells, including persisters, both during and after treatment, in clinically important pathogens.

The development of midbrain organoids (MOs) from human pluripotent stem cells (hPSCs) represents a significant advancement in understanding brain development, facilitating precise disease modeling, and advancing therapeutic research. This protocol outlines a method for generating midbrain-specific organoids using induced pluripotent stem cells (iPSCs), employing a strategic differentiation approach. Key techniques include dual-SMAD inhibition to suppress SMAD signaling, administration of fibroblast growth factor 8b (FGF-8b), and activation of the Sonic Hedgehog pathway using the agonist purmorphamine, guiding iPSCs towards a midbrain fate. The organoids produced by this method achieve diameters up to 2 mm and incorporate a diverse array of neuroepithelial cell types, reflecting the midbrain's inherent cellular diversity. Validation of these organoids as authentic midbrain structures involves the expression of midbrain-specific markers, confirming their identity. A notable outcome of this methodology is the effective differentiation of iPSCs into dopaminergic neurons, which are characteristic of the midbrain. The significance of this protocol lies in its ability to produce functionally mature, midbrain-specific organoids that closely replicate essential aspects of the midbrain, offering a valuable model for in-depth exploration of midbrain developmental processes and the pathophysiology of related disorders such as Parkinson's disease. Thus, this protocol serves as a crucial resource for researchers seeking to enhance our understanding of the human brain and develop new treatments for neurodegenerative diseases, making it an indispensable tool in the field of neurological research.

Epilepsy is among the most prevalent neurological disorders characterized by recurring spontaneous seizures. Seizures represent a clinical manifestation of uncontrolled, excessively synchronized neural cell activity. The extent of brain damage from seizures depends on their duration and intensity. Regrettably, there is no effective remedy for epilepsy. The aim of this investigation is to assess whether the planaria worm Dugesia dorotocephala could serve as a model to aid in identifying and developing treatments for epilepsy that can target acute seizures. Currently, various models, such as marine models, are used to evaluate antiseizure medications (ASM). However, they are very expensive, and there are ethical concerns. Alternatively, invertebrate models offer a cost-effective research opportunity in the drug discovery process for ASM. Planaria belong to the flatworm family and inhabit marine freshwater and terrestrial environments. Dugesia dorotocephala is the dominant species of aquatic planaria across North America. D. dorotocephala presents as a viable invertebrate model for epilepsy studies due to its cost-effectiveness, vertebrate-like neurons, and quantifiable behaviors, unlike other invertebrates or larger animals. They have been used in various pharmacology and environmental toxicology studies related to age, memory, and regeneration. In this study, planaria were exposed to different concentrations of pilocarpine, a common chemoconvulsant to study their behavior upon exposure. Following the observation, planaria were euthanized and preserved in either formaldehyde or Golgi solution for neurohistological assessment. Six distinct behavioral phenotypes were observed in planaria: dorsal oscillations, head oscillations, tail dorsal expansion, C-shape, head flick, and tail flick. Dorsal oscillation frequencies were significantly increased among experimental groups compared to the control and exhibited dose dependence. Additionally, pilocarpine disrupted the motility of the planaria. Pilocarpine-induced seizures in planaria can serve as a model to evaluate acute seizures and antiseizure medication, which is essential in developing therapeutic interventions for human patients suffering from epilepsy.