Objective To establish a rat model of Alzheimer's disease (AD) expressing human triple mutant amyloid precursor protein (APP) in the hippocampus, and to provide a model for the study of disease mechanisms and drug development. Methods Twenty-four 12-week-old SPF-grade female SD rats were randomly divided into a blank control group, a virus control group and an experimental group, with eight rats in each group; among them, the experimental group received a stereotaxic injection of adeno-associated virus (AAV) carrying the human triple mutant APP and NanoLuc luciferase genes into the hippocampus. In vivo imaging was used to observe viral expression in the brains of rats in each group, the novel object recognition test was used to assess the recognition memory of the rats in each group, real-time fluorescent quantitative PCR was used to detect the expression level of the APP gene, HE staining was used to examine the brain histopathology, Nissl staining was used to assess the hippocampal lesions, and immunohistochemistry was used to detect the deposition of amyloid β-protein (Aβ). Results In vivo imaging showed that reporter fluorescence was detected in the brains of rats in both experimental and virus control groups. Fluorescence quantitative PCR showed that the expression level of the APP gene was significantly increased in the brains of rats in the experimental group (P<0.01). Novel object recognition test revealed that the recognition memory of rats in the experimental group was significantly reduced compared with that of the blank control group (P<0.01). Six months after recombinant AAV virus infection, HE staining and Nissl staining of brain tissues showed that the number of neurons and Nissl bodies in the CA1 region of the hippocampus in the experimental group was reduced and disorganized; immuno-histochemistry testing of the CA1 region of the hippocampus and the pyramidal cell layer of the experimental group revealed prominent brown deposits, indicating Aβ protein deposition. Conclusion The rat model successfully established by stereotaxic injection and AAV-mediated delivery of human triple mutant APP gene exhibits typical AD features, providing a valuable animal model for studying AD pathology and developing drug therapies targeting Aβ protein deposition.

Objective To establish a rat model of Alzheimer's disease (AD) expressing human triple mutant amyloid precursor protein (APP) in the hippocampus, and to provide a model for the study of disease mechanisms and drug development. Methods Twenty-four 12-week-old SPF-grade female SD rats were randomly divided into a blank control group, a virus control group and an experimental group, with eight rats in each group; among them, the experimental group received a stereotaxic injection of adeno-associated virus (AAV) carrying the human triple mutant APP and NanoLuc luciferase genes into the hippocampus. In vivo imaging was used to observe viral expression in the brains of rats in each group, the novel object recognition test was used to assess the recognition memory of the rats in each group, real-time fluorescent quantitative PCR was used to detect the expression level of the APP gene, HE staining was used to examine the brain histopathology, Nissl staining was used to assess the hippocampal lesions, and immunohistochemistry was used to detect the deposition of amyloid β-protein (Aβ). Results In vivo imaging showed that reporter fluorescence was detected in the brains of rats in both experimental and virus control groups. Fluorescence quantitative PCR showed that the expression level of the APP gene was significantly increased in the brains of rats in the experimental group (P<0.01). Novel object recognition test revealed that the recognition memory of rats in the experimental group was significantly reduced compared with that of the blank control group (P<0.01). Six months after recombinant AAV virus infection, HE staining and Nissl staining of brain tissues showed that the number of neurons and Nissl bodies in the CA1 region of the hippocampus in the experimental group was reduced and disorganized; immuno-histochemistry testing of the CA1 region of the hippocampus and the pyramidal cell layer of the experimental group revealed prominent brown deposits, indicating Aβ protein deposition. Conclusion The rat model successfully established by stereotaxic injection and AAV-mediated delivery of human triple mutant APP gene exhibits typical AD features, providing a valuable animal model for studying AD pathology and developing drug therapies targeting Aβ protein deposition.

Human naïve pluripotent stem cells (PSCs) hold great promise for embryonic development studies. Existing induction and culture strategies for these cells, heavily dependent on MEK inhibitors, lead to widespread DNA hypomethylation, aberrant imprinting loss, and genomic instability during extended culture. Here, employing high-content analysis alongside a bifluorescence reporter system indicative of human naïve pluripotency, we screened over 1,600 chemicals and identified seven promising candidates. From these, we developed four optimized media-LAY, LADY, LUDY, and LKPY-that effectively induce and sustain PSCs in the naïve state. Notably, cells reset or cultured in these media, especially in the LAY system, demonstrate improved genome-wide DNA methylation status closely resembling that of pre-implantation counterparts, with partially restored imprinting and significantly enhanced genomic stability. Overall, our study contributes advancements to naïve pluripotency induction and long-term maintenance, providing insights for further applications of naïve PSCs.
Humans ; DNA Methylation/drug effects* ; Genomic Instability ; Pluripotent Stem Cells/metabolism* ; Cell Culture Techniques/methods* ; Cells, Cultured

Senecavirus A (SVA) is a major viral pathogen causing disease in pigs, and effective monitoring of SVA infection is critical for disease control. In this study, we aimed to develop a reliable ELISA method for rapidly detecting neutralizing antibodies against SVA. We used HEK293F cells to express an SVA-specific porcine Fab antibody and verified the biological activity of the Fab antibody by indirect ELISA, immunofluorescence assay, virus neutralization test, and Western blotting. The Fab antibody was biotinylated and used as a competitive antibody to establish a competitive ELISA (C-ELISA) for detecting neutralizing antibodies against SVA. We then evaluated the C-ELISA in terms of sensitivity, specificity, repeatability, and result agreement rate with the VNT. The results showed that we successfully prepared an SVA-specific porcine Fab antibody, which showed high affinity for SVA. We named this antibody 1M33Fab and designated it as Bio-1M33Fab after biotin labeling. The assay conditions were optimized as follows: the coating concentration of SVA particles being 1 μg/mL, the working concentration of Bio-1M33Fab being 0.5 μg/mL, the optimal serum dilution of 1:10, and the optimal dilution of enzyme-labeled avidin being 1:30 000. At a percent inhibition (PI) of 47%, the assay demonstrated the highest sensitivity (96.88%) and specificity (100%), with no cross-reactivity observed with the positive sera of major porcine viral diseases. The intra-assay coefficient of variation ranged from 1.12% to 7.34%, while the inter-assay coefficient of variation ranged from 1.10% to 8.97%, indicating good repeatability. In the detection of 224 clinical pig serum samples, C-ELISA and VNT showed a result agreement rate of 93.75%. In conclusion, we successfully develop a C-ELISA method for detecting neutralizing antibodies against SVA by using a porcine-derived Fab antibody, which lays a foundation for the development of detection kits.
Animals ; Swine ; Antibodies, Neutralizing/immunology* ; Enzyme-Linked Immunosorbent Assay/methods* ; Immunoglobulin Fab Fragments/immunology* ; Antibodies, Viral/immunology* ; Picornaviridae/immunology* ; Humans ; HEK293 Cells ; Swine Diseases/diagnosis* ; Picornaviridae Infections/diagnosis*

ObjectiveTo investigate the role of sphingosine-1-phosphate （S1P） in abnormal ossification in ankylosing spondylitis （AS）， clarify the relationship between S1P and “angiogenesis-osteogenesis” coupling， and provide new strategies for AS treatment. MethodsFemoral heads from AS patients and patients undergoing routine hip replacement were collected for immunohistochemical （IHC） staining to evaluate osteogenesis and H-type vessel formation. In vitro， ELISA was used to quantify the synthesis of S1P and analyze the expression changes of S1P signaling pathway-related molecules during the osteogenic differentiation of mesenchymal stem cells derived from patients with ankylosing spondylitis （ASMSCs） and those from healthy donors （HDMSCs）， to evaluate the activation status of S1P pathway during osteogenesis. Sphingosine kinase 1 （SK1） expression was knocked down in MSCs， and the S1P receptor inhibitor FTY720 was applied to block S1P signaling. Alkaline phosphatase （ALP） activity and Alizarin Red S （ARS） quantification were used to assess the effect of S1P on ASMSCs osteogenesis. Conditioned medium from osteogenically induced MSCs was used to treat human umbilical vein endothelial cells （HUVECs） to evaluate the effect of S1P on angiogenesis. An AS mouse model （SKG mice） was treated with FTY720 or the SK1 inhibitor PF-543 citrate. IHC staining and micro-CT scanning were used to assess abnormal ossification and spinal fusion， and immunofluorescence was used to evaluate H-type vessel formation. ResultsCompared with Osteonecrosis of the Femoral Head（ONFH） patients， AS patients exhibited excessive osteogenesis and H-type vessel formation （OCN P＜0.001， CD31 P＜0.001， EMCN P＜0.001）. During osteogenic differentiation， S1P expression and secretion were significantly higher in ASMSCs than in HDMSCs （P=0.0179）. Inhibition of S1P signaling with FTY720 or SK1 knockdown significantly suppressed osteogenic differentiation （compared with ASMSC， ARS： HDMSC P=0.001 8， FTY720 P＜0.001， si-SK1 P＜0.001； ALP： HDMSC P=0.032 8， FTY720 P=0.001 6， si-SK1 P＜0.001） of ASMSCs and the angiogenesis of HUVEC（compared with ASMSC， cell-covered area， total loops， total tube length and total branch points P＜0.001）. Treatment with FTY720 or PF-543 markedly inhibited abnormal ossification and spinal fusion（compared with Curdlan， arthritis index score， P＜0.001； OCN：control P=0.002， PF-543 P=0.010 7， FTY720 P=0.015 9 ） in AS mice and reduced H-type vessel formation （CD31⁺EMCN⁺： compared with curdlan， control P＜0.001， PF-543 P=0.001 7， FTY720 P=0.002 1）. ConclusionIncreased S1P synthesis in ASMSCs promotes osteogenic differentiation via autocrine mechanisms and further enhances ossification by facilitating H-type angiogenesis. Inhibiting S1P secretion in ASMSCs significantly suppresses abnormal ossification in AS.

BACKGROUND:The distribution of the necrotic area plays an important role in hip preservation treatment.At present,there are few studies on whether the difference in the three-dimensional spatial distribution of osteonecrosis of the femoral head affects the clinical outcome of fibular support. OBJECTIVE:To explore the relationship between the spatial distribution and clinical outcome at the sites of osteonecrosis of the femoral head and fibular support using CT three-dimensional reconstruction so as to provide a basis for optimizing the applicable conditions of fibular support and improving the hip preservation effect of fibular support. METHODS:Eighty patients with osteonecrosis of the femoral head who were treated with fibular support for hip preservation from January 2010 to January 2021 were selected as the study subjects according to the inclusion criteria.They were followed up for at least 2 years.According to the clinical outcome,the patients were divided into the successful hip preservation group(n=55)and the failure hip preservation group(n=25).3D reconstruction was performed according to the preoperative and postoperative CT images of the patients.According to the three-column theory,the femoral head was divided into outer nine areas,middle nine areas and inner nine areas(L1-9,C1-9,and M1-9)to explore the spatial distribution of necrotic area of the femoral head and fibular support area and its relationship with clinical outcome. RESULTS AND CONCLUSION:(1)Before operation,the necrotic area of the femoral head was mainly distributed in L1,L2,L4,L5,C1,C2,C4,and C5(the upper and middle part of the anterior part of the outer ninth area and the middle part of the middle ninth area).After operation,the fibular support area was mainly distributed in L5,L6,C5,and C6(the middle and lower part of the outer ninth area and the middle and lower part of the middle ninth area).(2)There were significant differences in the distribution of osteonecrosis of the femoral head between the successful hip preservation group and the failure hip preservation group in L8(the posterior middle part of the outer ninth area),C3(the anterior lower part of the middle ninth area),C6(the lower middle part of the middle part of the inner ninth area)and M2(the anterior middle part of the inner ninth area)(P<0.05).There was a significant difference in the distribution of fibular support in L5 and L6(middle and lower part of outer nine)(P<0.05).Among them,the L8 region could be used as an independent predictor of hip preservation failure in fibular support surgery.The area under the curve of the L8 single factor prediction model was 0.698[95%CI(0.575,0.822)];the sensitivity was 76%,and the specificity was 63.6%.(3)It turns out,when the necrotic area involves L8,C3,C6,and M2,especially L8,the failure of fibular support may increase,and when the fibular support involves L5 and L6,the effect of hip preservation is often not ideal.

BACKGROUND:The appearance of the crescent sign in femoral head necrosis is a"turning point"in the progression of the disease,and repairing and stabilizing the bone-cartilage interface is particularly important in preventing further progression and collapse of the femoral head.Tissue engineering offers potential advantages in the simultaneous repair and integration of the bone-cartilage interface. OBJECTIVE:To review potentially suitable techniques addressing the subchondral separation in femoral head necrosis. METHODS:Relevant articles from January 1970 to April 2023 were searched in PubMed,Web of Science,and China National Knowledge Infrastructure(CNKI)using English search terms"femoral head necrosis,avascular necrosis of femoral head,osteonecrosis of femoral head"and Chinese search terms"femoral head necrosis,subchondral bone,cartilage,integration of cartilage and subchondral bone".A total of 114 articles were included for review and analysis. RESULTS AND CONCLUSION:(1)Structural defects,ischemic and hypoxic environment,inflammatory factors,and stress concentration may cause subchondral separation in osteonecrosis of the femoral head.Subchondral bone collapse and failure of hip-preserving surgery may be associated.Integration of tissue engineering scaffolds with the bone-cartilage interface is one potential approach for treating subchondral separation in osteonecrosis of the femoral head.(2)Current literature suggests that multiphase scaffolds,gradient scaffolds,and composite materials have shown improvements in promoting cell adhesion,proliferation,and deposition of bone and cartilage matrix.These advancements aid in the integration of scaffolds with the bone-cartilage interface and have implications for the treatment of subchondral separation in osteonecrosis of the femoral head.(3)Surface modifications of scaffolds can enhance interface integration efficiency,but they have their advantages and disadvantages.Scaffolds providing different environments can induce differentiation of mesenchymal stem cells and facilitate integration between different interfaces.(4)Future scaffolds for subchondral separation in osteonecrosis of the femoral head are expected to be composite materials with gradient and differentiated biomimetic structures.Surface modifications and stem cell loading can promote integration between the bone-cartilage interface and scaffolds for therapeutic purposes,but further experimental verification is still needed.Challenges include synchronizing scaffold degradation rate with repair progress and ensuring stability between different interfaces.

BACKGROUND:Bone has bioelectric effects.However,bone defects can lead to loss of endogenous bioelectricity in bone.The implantation of bone tissue engineering scaffolds with bioelectric effect into bone defects will replenish the missing electrical signals and accelerate the repair of bone defects. OBJECTIVE:To introduce the bioelectric effect of bone tissue and expound the repair effect of electrical stimulation on bone defects,summarize the research progress of bioelectric effect applied to bone tissue engineering,in order to provide new ideas for the research of bone tissue engineering. METHODS:Relevant articles were searched on CNKI,WanFang,PubMed,Web of Science and ScienceDirect databases,using"bioelectrical effect,bioelectrical materials,electrical stimulation,bone tissue engineering,bone scaffold,bone defect,bone repair,osteogenesis"as the English and Chinese search terms.Finally,87 articles were included for analysis. RESULTS AND CONCLUSION:(1)Bioelectrical effect combined with ex vivo electrical stimulation to design bone tissue engineering scaffolds is an ideal and feasible approach,and the main materials involved include metallic materials,graphene materials,natural bio-derived materials,and synthetic biomaterial.At present,the most widely used conductive material is graphene material,which benefits from its super conductivity,large specific surface area,good biocompatibility with cells and bones,and excellent mechanical properties.(2)Graphene materials are mainly introduced into the scaffold as modified materials to enhance the conductivity of the overall scaffold,while its large surface area and rich functional groups can promote the loading and release of bioactive substances.(3)However,there are still some major challenges to overcome for bioelectrically effective bone tissue engineering scaffolds:not only electrical conductivity but also the overall performance of the bracket needs to be considered;lack of uniform,standardized preparation of bioelectrically effective bone tissue engineering scaffolds;extracorporeal electrical stimulation intervention systems are not yet mature enough;lack of individualized guidance on stent selection to enable the selection and design of the most appropriate stent for patients with different pathologies.(4)When designing conductive scaffolds,researchers have to deeply consider the comprehensive effects of the scaffolds,such as biocompatibility,mechanical properties,and biodegradability.This combination of properties can be achieved by combining multiple materials.(5)Beyond that,clinical translation should be the ultimate consideration for conductive stent design.On the basis of evaluating the safe current threshold for electrical stimulation to act on the human body and facilitate the repair of bone defects,animal experiments as well as basic experiments are designed and then applied to the clinic to achieve the ultimate goal of applying bioelectrical effect bone tissue engineering scaffolds in the clinic.