Animal models and experimental medicine最新文献

Background: Skeletal tuberculosis (TB) remains a persistent clinical and research challenge due to its chronic course, osteolytic destruction, and the limitations of existing animal models, which often require high-level biosafety containment or fail to replicate human skeletal pathology.

Methods: This study developed a biosafe, accessible, and versatile murine model of skeletal TB using Mycobacterium smegmatis, a fast-growing, nonpathogenic mycobacterial species with high genomic homology to Mycobacterium tuberculosis. Three infection routes-subperiosteal calvarial injection, intratibial injection, and intracardiac inoculation-were systematically evaluated for their ability to induce localized versus disseminated bone infection under standard biosafety level (BSL)-1 conditions.

Results: Subperiosteal calvarial and intratibial injection of M. smegmatis induced localized bone lesions characterized by osteolysis, sequestrum formation, granulomatous inflammation, and increased osteoclast activity. Intratibial infection additionally triggered compartment-specific immune responses, including neutrophil and macrophage expansion, transient B-cell depletion, and activation of interferon-γ⁺ (IFN-γ⁺) T cells, reflecting active immune remodeling at the infection site. Systemic dissemination via intracardiac injection reproducibly generated progressive vertebral and tibial bone destruction with organized granuloma formation and immune cell infiltration but without prominent sequestrum formation. Compared to intratibial infection, intracardiac delivery exhibited lower intragroup variability and more closely recapitulated the diffuse progression of extrapulmonary skeletal tuberculosis.

Conclusions: This M. smegmatis-based murine model provides a straightforward, reliable, and immunopathologically relevant platform for exploring host-pathogen dynamics, immune-driven bone destruction, and early-stage therapeutic testing in skeletal TB, all within standard BSL-1 laboratories. This model fills a critical gap by enabling BSL-1 research into skeletal TB mechanisms and drug development.

Background: Rats are often used to prepare skin defect models. However, the skin defect sizes of the models prepared by researchers are different, and the lack of consensus on the critical-size defect makes it difficult to compare their research results.

Methods: The time for wound closure was evaluated and recorded through gross observation. The regression equation between the healing time and the diameter of skin defect was established, which can be used to predict the healing time for a certain skin defect size in rats. Histochemical and immunohistochemical staining was used to observe the regeneration and reconstruction of skin appendages, and the functional skin repair was quantitatively scored.

Results: The critical-size defect of rats was determined based on the maximum capacity of structural skin repair, and the functional skin repair was quantitatively scored based on the regeneration and reconstruction of skin appendages. The allowable range of critical-size skin defect of SD rats lies between 45 and 50 mm in diameter. The concept of structural repair and the category of functional repair of injured skin are put forward. The regression equation between the structural skin healing time and defect diameters is established.

Conclusion: The allowable range of skin critical-size defect of SD rats lies between 45 and 50 mm in diameter. The regression equation between the structural skin healing time and defect diameters can be used to predict the healing time for a certain skin defect size in rats.

Knee osteoarthritis (KOA) is a chronic degenerative disease. Monosodium iodoacetate (MIA) induction is the most commonly used therapeutic effect evaluation and mechanism of action research model; we observed a lack of standardization and uniformity in current model building methods, which led us to conduct this study.

Background: The aim was to investigate the time- and dose-related changes in the behavioral and pathological characteristics in the MIA-induced KOA model rat.

Methods: MIA (40, 50, and 60 mg/mL) was injected into the left joint of male Sprague-Dawley rats. After 2 weeks, the changes in the KOA rat model were observed by behavioral evaluation, imaging-level evaluation, and histological-level evaluation. The changes were also compared after 40-mg/mL MIA injection for 2 and 6 weeks.

Results: MIA-induced bone surface defects, osteophyte hyperplasia around the articular rim, increased subchondral bone density, thinning of the sparse trabecular bone, structural disorder, and local clustering were observed. The degree of injury gradually increased with the increase in MIA concentration. After 6 weeks, subchondral bone density and sparse trabecular bone increased in the KOA model.

Conclusions: The severity of the model also increased significantly with the changes in dose and time. In dose-dependent experiments, this study revealed that 40 mg/mL was the optimal dose to induce significant pathological changes without causing undue discomfort or death in animals. This dose may induce pathological changes stably and is suitable for long-term observation.

Background: In recent decades, the global incidence of dengue fever has been steadily increasing, with continuous geographical expansion. Researchers have successfully modeled most clinical symptoms of human dengue fever using interferon type I (IFN-I) or combined IFN-I/II receptor knockout mice infected with dengue virus (DENV). However, this model requires further optimization to better support related studies.

Methods: This study aimed to establish a stable dengue infection model by evaluating the effects of different genetic backgrounds and injection routes on DENV infection in interferon receptor knockout mice. We first infected various strains of interferon receptor-deficient mice with DENV and compared their susceptibility based on clinical symptoms, viremia levels, organ indices, histopathological findings, and vascular leakage markers. Subsequently, we selected the most susceptible strain to further investigate the impact of different injection methods on infection outcomes.

Results: We found that BALB/c background mice with type 1 interferon receptor knockout(IFNAR) had the most obvious symptoms. Subsequently, we selected IFNAR-/-BALB/c mice to further explore the effects of different injection methods on dengue virus infection. The results showed that the intraperitoneal injection group had the most severe clinical symptoms, the longest duration of viremia, and the most obvious degree of organ damage.

Conclusion: Through systematic screening and optimization, we established a robust animal model of dengue virus infection via intraperitoneal injection in IFNAR-/- BALB/c mice. This model offers a valuable tool for future dengue research.

Background: Biological osteosynthesis preserves blood supply and promotes rapid healing by aligning fracture fragments without direct surgical exposure. Pedicle screws are primarily designed for internal fixation in spinal procedures. A key objective of many orthopedic studies is to assess the biocompatibility of implants with bone and adjacent soft tissue. This study aims to evaluate the biocompatibility and effects of the Pedicle screw-Rod configuration as a novel external fixation method in canine tibial osteotomy.

Methods: With ethics approval, eight healthy, intact male dogs, aged 10-12 months and weighing between 20 and 22 kg, underwent a minimally invasive medial tibial approach for surgical fixation of tibial osteotomy using a Pedicle screw-Rod configuration. Postoperative evaluations included ultrasound assessments at the osteotomy site and histological evaluations at the bone-screw interface.

Results: B-mode ultrasound evaluation indicated healing progress at all osteotomy sites. The color Doppler examination revealed an initial increase in signals in the surrounding soft tissue during the first 4 weeks post-operation, followed by a decrease in signals within the adjacent soft tissue between the 5th and 8th weeks. During this latter period, the signals were primarily concentrated on the bone surface and the callus. The bone-screw interface at various screw sites exhibited similar histological changes, indicating effective integration of the newly formed woven bone into the screw threads.

Conclusions: Fixation of non-articular tibial osteotomy with Pedicle screw-Rod configuration resulted in secondary bone healing, characterized by abundant callus formation and neovascularization. This implant demonstrated favorable biocompatibility with bone and surrounding soft tissue, without significant complications.

Background: Mastitis seriously affects the mammary health of humans and animals. Studies have found that inflammation and oxidative stress play key roles in the occurrence and development of mastitis. Therefore, in-depth research on related molecular mechanisms is of great significance.

Methods: Postpartum mice were anesthetized with pentobarbital and administered lipopolysaccharide to develop the mouse mastitis model. Proteomic analysis was performed to compare protein expression in mitochondria-associated endoplasmic reticulum membranes (MAM) from two mouse mammary gland groups. Western blot was used to detect the expression of MAM-related proteins in mitochondria. AlphaFold3 was used to predict the molecular structures of phosphofurin acidic cluster sorting protein 2 (PACS2) and mitofusin 2 (MFN2) and their interaction levels. The MFN2-PACS2 interaction was investigated using co-immunoprecipitation and small interfering RNA.

Results: The results showed that the inflammation level in the mammary gland tissue of mice with mastitis significantly increased, the total antioxidant capacity decreased, and the expression of MAM-related proteins MFN2 and PACS2 was significantly downregulated. In cell experiments, overexpression of MFN2 can inhibit inflammation and oxidative stress responses, and promote the interaction between MFN2 and PACS2 to affect the formation of MAMs.

Conclusion: In summary, this study suggests that mastitis can alter the expression of MAM-related proteins in mouse breast tissue. The interaction between MFN2 and PACS2 regulates the formation of MAMs. Overexpression of MFN2 can promote the formation of MAMs and inhibit inflammation and oxidative stress response in mammary epithelial cells. Our results provided a new theoretical basis and potential therapeutic targets for the prevention and treatment of mastitis.

Background: The aim of the study was to develop a non-human primate model of metabolic dysfunction in Macaca fascicularis using chronic high-fat diet (HFD) to mimic clinical disease progression.

Methods: Thirty-five male macaques aged 10-15 years underwent an 18-month HFD intervention. Physiological parameters (BMI, BP, hematology), liver fat fraction (evaluated by ultrasound/MRI), cardiac function (assessed by echocardiography), and histopathology (using liver biopsy) were measured before and after the intervention. Serum proteomics with KEGG/STRING analyses identified molecular mechanisms.

Results: Within 6 months, HFD induced dyslipidemia (elevated TG, TCHO, HDL-C, LDL-C). After 18 months, metabolic dysfunction-associated steatohepatitis (MASH) was confirmed by histopathology in 57.14% (16/28) of macaques, diabetes (elevated FPG/HbA1c) in 17.86% (5/28), and myocardial hypertrophy (elevated LVMass/LAD) in 46.43% (13/28). Proteomics identified Bile acid-CoA: amino acid N-acyltransferase (BAAT) as a MASH hallmark protein, the level of which was inversely correlated with the degree of fibrosis. For diabetes, citrate synthase (CS) and malate dehydrogenase 1 (MDH1) impaired glucose oxidation via the TCA cycle, while hexose-6-phosphate dehydrogenase (H6PD) disrupted gluconeogenesis. Myocardial hypertrophy was associated with the downregulation of SRC proto-oncogene, non-receptor tyrosine kinase (SRC), mitogen-activated protein kinase 14 (MAPK14), emerin (EMD), and integrin subunit beta 1 (ITGB1).

Conclusions: An 18-month HFD successfully established a translational M. fascicularis model replicating key metabolic disorders (MASH, diabetes, cardiac hypertrophy). BAAT, CS/MDH1/H6PD, and SRC/MAPK14/EMD/ITGB1 were identified as mechanistic biomarkers for these conditions.

Background: An arterial stiffness is an indicator of many cardiovascular diseases. The temporal position of systolic blood pressure (BP) on aorta pulse waveform is assumed to gradually shift on the waveform in response to increasing/decreasing vascular stiffness. The animal model of rats and invasive methods that cannot be used in humans was applied to test the assumption on arterial pulse waveform (APW) of anesthetized rat. The aim of this study was to characterize the temporal movement of diastolic and systolic pressures on the APW of anesthetized rats during increasing/decreasing vascular stiffness.

Methods: The right jugular vein of anesthetized normotensive and spontaneously hypertensive rats was cannulated for intravascular administration of vascularly active compounds to alter systolic pressure and vascular stiffness. The left carotid artery was cannulated to detect APW, from which numerous APW parameters were evaluated.

Results: During increases/decreases in systolic BP or stiffness, the temporal position of diastolic BP of individual heartbeats di-gitally shifted on the APW between two temporal positions ~8-12 ms apart, and the temporal position of systolic BP on the APW did not gradually shift during increases/decreases in vascular stiffness, as expected, but oscillated between constant di-gital, tri-gital, or tetra-gital temporal positions.

Conclusions: Introducing new APW parameters, n-gital systolic BP fluctuations on rat APW were found. Fluctuations in n-gital were approximately constant during large changes in systolic pressure despite significant changes in augmentation index and cardiovascular stiffness, which may challenge the assumption of a gradual temporal location of systolic pressure on rat APW under these conditions.

Graft procurement in adult living donor liver transplantation (LDLT) faces persistent challenges in balancing volumetric adequacy and donor safety. This study introduces two-stage portal vein ligation and reperfusion for graft procurement in LDLT (PVLR-LT), which aims to expand the left lateral lobe for achieving adequate grafts, thereby circumventing technical and anatomical limitations of conventional approaches. In a rat model, the PVLR-LT group underwent selective portal vein ligation (step I) to induce targeted hypertrophy, followed by reperfusion and transplantation (step II). Outcomes were compared among PVLR-LT, negative controls, and standard-volume controls. Staged portal flow modulation effectively redistributed hepatic mass allocation, yielding grafts with graft recipient weight ratio approximately double that of negative controls and equivalent to standard-volume controls. Donors experienced no mortality, with only transient enzyme elevation. Recipient survival in the PVLR-LT group significantly exceeded that of the negative control group and was non-inferior to that of the standard-volume control group, while hepatic enzyme peaks were markedly lower than those in standard-volume control recipients. This study provides a promising proof of concept, establishing the feasibility of using PVLR-LT to convert the surgically straightforward left lateral segment into right lobe-sized grafts through staged portal flow modulation and demonstrating the translational potential for laparoscopic LDLT.

The current anesthetic standard for laryngoscopy in rats utilizes injectable intraperitoneal anesthesia. Injectable anesthesia is suboptimal for short procedures due to variability in anesthesia duration and anesthetic side effects. Conversely, inhalational gas anesthesia offers precise titration with a rapid onset and offset. However, its use during laryngoscopy has not been documented due to existing administration techniques obstructing direct visualization of the larynx. The technique described here allows real-time visualization of the rat larynx with concurrent administration of inhaled anesthetic gas. This method is particularly well-suited for recurrent laryngeal nerve or vocal fold pathology studies, where repeat visualization of the larynx is necessary.