医学

Retinopathy of prematurity (ROP), a retinovascular disease, is a leading cause of childhood blindness worldwide. Given the constraints of studying molecular mechanisms in preterm infants, reproducible animal models are important to understand ROP pathophysiology. Mouse and rat oxygen-induced retinopathy (OIR) models are the most commonly used and recapitulate key vascular features seen in ROP. However, these models are susceptible to inherent variability that limits reproducibility, including inter-litter variability, consistency of oxygen delivery across experiments, retinal dissection technique, and immunohistochemistry. Here, we describe a comprehensive protocol for performing the most common mouse and rat OIR models, and procedures such as eye enucleation, retinal dissection and flat mounting, isolectin GS-IB4 staining, whole retina stitched fluorescence imaging from Z-stacks, and quantification of vascular features. This protocol provides important materials and procedural details to increase the reproducibility of the mouse and rat OIR models.

Isolation of adult mouse ventricular myocytes is essential for studying cardiac physiology and cellular function. Traditional methods commonly rely on Langendorff perfusion systems, which provide continuous retrograde coronary perfusion but require specialized equipment and can be complex to operate. Here, we describe a simplified Langendorff-based protocol that uses a syringe pump–driven system to achieve constant-flow retrograde aortic perfusion during enzymatic digestion. The setup incorporates an inline heater for precise temperature control and uses widely available laboratory components, enabling consistent delivery of digestion enzymes. This approach maintains stable perfusion despite changes in coronary resistance and reduces variability associated with conventional gravity-driven systems. The protocol yields high-quality adult ventricular myocytes suitable for downstream functional analyses, including electrophysiology, contractility, and calcium imaging. Compared with traditional systems, this method is more accessible, reduces technical complexity, and improves reproducibility, facilitating adoption in laboratories without dedicated isolated-heart perfusion infrastructure.

When the function of cardiac capillaries is impaired, cardiac function declines, and the risk of disease increases. No reliable assay has been developed to detect or evaluate the level of material exchange of capillaries deep within healthy heart tissue. In this study, we develop a new method to detect and evaluate molecules leaking from capillaries in cardiac tissue. By administering fluorescent dextran to mice via the tail vein, followed by rapid processing of the heart tissue, we have detected leaking fluorescent material from intracardiac microvessels. By comparing the detected images with those taken during the negative-control administration, using the image processing software LAS X and ImageJ, we detected trace amounts of fluorescent material that had leaked from the capillaries. We calculated the area of tissue where fluorescence was detected to perform a quantitative assessment, which we used as an indicator of capillary permeability. This new method of indexing will provide a different perspective on the factors contributing to the decline in cardiac function and the increased risk of disease with aging.

Fluorescence in situ hybridization (FISH) can be employed to study the expression and subcellular localization of nucleic acids by using labeled antisense strands that hybridize with the target RNA or DNA molecules. Likewise, immunofluorescence antibody staining (IF) takes advantage of the specific interaction between a fluorophore-labeled antibody and its corresponding antigen. This protocol reports the combination of RNA-FISH and IF antibody staining for simultaneous detection of both RNA transcripts and proteins of interest in routine formalin-fixed paraffin-embedded (FFPE) bone marrow biopsy samples. Herein, we provide a detailed description of the methodology that we have developed and optimized to study the spatial expression of two transcripts—TGFB1 and PDGFA1—in human hematopoietic (CD45⁺) and non-hematopoietic (CD271⁺) cells in the bone marrow of patients with acute lymphoblastic leukemia (ALL).

The rising global incidence of pancreatitis, pancreatic cancer, and diabetes has increased the need for efficient in vivo gene manipulation approaches to study the pancreas and develop new therapies. Although transgenic mouse models are widely used, they are time-consuming and costly to generate and maintain. Systemic viral delivery methods offer greater flexibility but often lack pancreatic specificity and require high viral doses. Here, we describe a streamlined protocol for intrapancreatic ductal delivery of adeno-associated viruses (AAVs) for targeted gene delivery. Our protocol requires standard surgical equipment and can be implemented in most laboratories. Specifically, we adopted a clamping strategy at the hepatopancreatic duct near the liver, as well as beneath the major duodenal papilla at the duodenum. This strategy exposes the duodenal papilla, facilitating viral delivery, preventing backflow, and enabling efficient pancreatic transduction at lower viral doses. Overall, this method provides a fast, simple, and effective approach for pancreas-targeted gene manipulation, facilitating preclinical studies of pancreatic biology and disease.

Extracellular vesicles (EVs) circulating in blood serve as non-invasive “liquid biopsies,” carrying molecular cargo that reflects the physiological and pathological state of distant cells. Their analysis is crucial for understanding disease mechanisms and discovering novel biomarkers. Clinically, blood EVs hold significant promise for early disease diagnosis, prognostic assessment, and monitoring treatment response in diverse areas such as organ transplantation, cancer, and neurological disorders. Current EV isolation techniques, beyond ultracentrifugation, include size exclusion chromatography (separation by size for high purity) and immunoaffinity capture (using antibodies for high specificity). Here, we present a simplified, rapid, and reproducible method for isolating EVs from small-volume blood samples. This protocol consistently yields a concentrated EV pellet covering 50–300 nm EVs, amenable to direct downstream analysis. Developed and validated in our laboratory using human, porcine, and murine blood samples, this method has proven instrumental in identifying EV-based biomarkers for predicting outcomes related to organ transplantation. The protocol’s adaptability and reliance on readily prepared, cost-effective reagents further enhance its utility. This scalable approach can be further integrated with subsequent purification or enrichment steps to optimize sample preparation for protein and nucleic acid assays.

Organoids are self-organizing 3D tissues representing an innovative technology with interesting implications and potential for the study of tumor biology. They can be developed from fine-needle biopsies or resection material from healthy or tumor tissues. Patient-derived organoids are able to retain most of the histological characteristics, the expression profile, and the genomic landscape of the corresponding primary tissues, making them suitable for translational studies and for the identification of molecular alterations in the field of personalized medicine. Here, we describe a detailed protocol for the preparation and in vitro expansion of tumor and non-tumor organoids from surgical resections or needle biopsies of patients with hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (iCCA), enabling subsequent testing of small-molecule VDAC1 antagonists at different doses. In parallel, we developed a hepatic steatosis model by treating healthy liver organoids with oleic acid, recapitulating key features of lipid accumulation and metabolic dysfunction in vitro. This protocol enables the generation of patient-derived liver organoids that preserve the histological and molecular characteristics of their original tissue, providing a robust and versatile platform for translational studies, personalized drug testing, and the exploration of novel therapeutic strategies targeting tumor metabolism.

Obtaining articular cartilage-derived cells (chondroprogenitors) by explant methodology is a reliable approach for isolating migratory progenitor cells that retain strong chondrogenic potential. This method allows cells to emerge naturally from small cartilage fragments without enzymatic digestion. The procedure consists of plating cartilage explants on a plastic surface with culture medium, from which cells subsequently migrate and adhere to the substrate. Compared with enzymatic isolation, the explant approach minimizes cellular stress and better reproduces the physiological microenvironment of cartilage tissue. This protocol can be applied to both osteoarthritic and non-osteoarthritic samples, enabling comparative studies on disease-related phenotypic differences. Overall, this technique offers a reproducible, straightforward, and minimally invasive strategy for obtaining functional chondroprogenitor cells suitable for cartilage regeneration research.

The pancreatic islet, the only type of tissue that secretes insulin in response to elevated blood glucose, plays a vital role in diabetes development and treatment. While various islet vascularization strategies have been developed, they have been hindered by major limitations such as relying on pre-patterning and the inability to span long distances. Furthermore, few strategies have demonstrated robust enough vascularization in vivo to support therapeutic subcutaneous islet transplantation. Using adaptive endothelial cells (ECs) reprogrammed by transient expression of the ETS Variant Transcription Factor 2 (ETV-2) gene, we have physiologically vascularized human islets within a generic microchamber and have achieved functional engraftment of human islets in the subcutaneous space of mice. Such adaptive ECs, which we term reprogrammed vascular ECs (R-VECs), have been proven to be a suitable tool for both in vitro disease modeling and in vivo transplantation of not only islets but also other organoids.

Intravenous hemostats have shown significant promise in prolonging survival for severe noncompressible and internal injuries in preclinical animal models. Existing approaches include the use of liposomes with or without procoagulant enzymes, as well as polymer nanoparticles or soluble biopolymers. While these methods predominantly target or mimic tissue components that are present during coagulation, such as activated platelets and collagen, they may not account for the loss of fibrinogen, which is not only key to clot formation but also the first protein to fall below critical levels in dilutional coagulopathy. This protocol describes the synthesis and in vitro or ex vivo characterization of a crosslinkable nanoparticle system that seeks to address dilutional coagulopathy by leveraging the critical gelation concentration and bioorthogonal click chemistry. The system was shown to only gel at high nanoparticle and crosslinker concentrations, increase the rate of platelet recruitment, and decrease the rate of clot degradation in a low-fibrinogen environment, providing a platform for treating severe hemorrhage in a coagulopathic environment. Ultimately, the contents of this protocol may assist researchers in the in vitro characterization and screening of other crosslinkable nanoparticle systems or hemostats, with potential expansions to other categories of coagulation dysfunction, such as embolism treatment.