Regulation of alternative polyadenylation by the C2H2-zinc-finger protein Sp1.

Alternative polyadenylation (APA) enhances gene regulatory potential by increasing the diversity of mRNA transcripts. 3' UTR shortening through APA correlates with enhanced cellular proliferation and is a widespread phenomenon in tumor cells. Here, we show that the ubiquitously expressed transcription factor Sp1 binds RNA in vivo and is a common repressor of distal poly(A) site usage. RNA sequencing identified 2,344 genes (36% of the total mapped mRNA transcripts) with lengthened 3' UTRs upon Sp1 depletion. Sp1 preferentially binds the 3' UTRs of such lengthened transcripts and inhibits cleavage at distal sites by interacting with the subunits of the core cleavage and polyadenylation (CPA) machinery. The 3' UTR lengths of Sp1 target genes in breast cancer patient RNA-seq data correlate with Sp1 expression levels, implicating Sp1-mediated APA regulation in modulating tumorigenic properties. Taken together, our findings provide insights into the mechanism for dynamic APA regulation by unraveling a previously unknown function of the DNA-binding transcription factor Sp1.

Establishment of orthotopic osteosarcoma animal models in immunocompetent rats through muti-rounds of in-vivo selection.

Immunodeficient murine models are usually used as the preclinical models of osteosarcoma. Such models do not effectively simulate the process of tumorigenesis and metastasis. Establishing a suitable animal model for understanding the mechanism of osteosarcoma and the clinical translation is indispensable. The UMR-106 cell suspension was injected into the marrow cavity of Balb/C nude mice. Tumor masses were harvested from nude mice and sectioned. The tumor fragments were transplanted into the marrow cavities of SD rats immunosuppressed with cyclosporine A. Through muti-rounds selection in SD rats, we constructed orthotopic osteosarcoma animal models using rats with intact immune systems. The primary tumor cells were cultured in-vitro to obtain the immune-tolerant cell line. VX2 tumor fragments were transplanted into the distal femur and parosteal radius of New Zealand white rabbit to construct orthotopic osteosarcoma animal models in rabbits. The rate of tumor formation in SD rats (P1 generation) was 30%. After four rounds of selection and six rounds of acclimatization in SD rats with intact immune systems, we obtained immune-tolerant cell lines and established the orthotopic osteosarcoma model of the distal femur in SD rats. Micro-CT images confirmed tumor-driven osteolysis and the bone destruction process. Moreover, the orthotopic model was also established in New Zealand white rabbits by implanting VX2 tumor fragments into rabbit radii and femurs. We constructed orthotopic osteosarcoma animal models in rats with intact immune systems through muti-rounds in-vivo selection and the rabbit osteosarcoma model.

Premetastatic Niche Mimicking Bone-On-A-Chip: A Microfluidic Platform to Study Bone Metastasis in Cancer Patients.

Primary cancer modulates the bone microenvironment to sow the seeds of dormancy and metastasis in tumor cells, leading to multiple organ metastasis and death. In this study, 3D printing and bone-on-a-chip (BOC) are combined to develop a BOC platform that mimics the pre-metastatic niches (PMNs) and facilitates elucidation of the interactions between bone-resident cells and metastatic tumor cells under the influence of primary cancer. Photocrosslinkable gelatin methacrylate (GelMA) is used as a 3D culturing hydrogel to encapsulate cells, and circulate tumor culture medium (CM) adjacent to the hydrogel to verify the critical role of mesenchymal stem cells (MSCs) and osteoclasts (RAW264.7s). Three niches: the dormancy niche, the perivascular niche, and the "vicious cycle" niche, are devised to recapitulate bone metastasis in one chip with high cell viability and excellent nutrient exchange. With respect to tumor dormancy and reactivation, the invadopodia formation of A549 lung cancer cells in communication with MSCs and RAW264.7 via the cortactin pathway is researched. As a proof of concept, the functionality and practicality of the platform are demonstrated by analyzing the invadopodia formation and the influence of various cells, and the establishment of the dynamic niches paves the way to understanding PMN formation and related drug discovery.

Frequently expressed glypican-3 as a promising novel therapeutic target for osteosarcomas.

Osteosarcoma (OS) is the most common bone malignancy without a reliable therapeutic target. Glypican-3 (GPC3) mutation and upregulation have been detected in multidrug resistant OS, and anti-GPC3 immunotherapy can effectively suppress the growth of organoids. Further profiling of GPC3 mutations and expression patterns in OS is of clinical significance. To address these issues, fresh OS specimens were collected from 24 patients for cancer-targeted next-generation sequencing (NGS) and three-dimensional patient-derived organoid (PDO) culture. A tumor microarray was prepared using 37 archived OS specimens. Immunohistochemical (IHC) staining was performed on OS specimens and microarrays to profile GPC3 and CD133 expression as well as intratumoral distribution patterns. RT-PCR was conducted to semiquantify GPC3 and CD133 expression levels in the OS tissues. Anti-GPC3 immunotherapy was performed on OS organoids with or without GPC3 expression and its efficacy was analyzed using multiple experimental approaches. No OS cases with GPC3 mutations were found, except for the positive control (OS-08). IHC staining revealed GPC3 expression in 73.77% (45/61) of OSs in weak (+; 29/45), moderate (++; 8/45), and strong (+++; 8/45) immunolabeling densities. The intratumoral distribution of GPC3-positive cells was variable in the focal (+; 10%-30%; 8/45), partial (++; 31%-70%; 22/45), and the most positive patterns (+++; >71%; 15/45), which coincided with CD133 immunolabeling (P = 9.89 × 10-10 ). The anti-GPC3 antibody efficiently inhibits Wnt/ß-catenin signaling and induces apoptosis in GPC3-positive PDOs and PDXs, as opposed to GPC3-negative PDOs and PDXs. The high frequency of GPC3 and CD133 co-expression and the effectiveness of anti-wild-type GPC3-Ab therapy in GPC3-positive OS models suggest that GPC3 is a novel prognostic parameter and a promising therapeutic target for osteosarcoma.

SMN and symmetric arginine dimethylation of RNA polymerase II C-terminal domain control termination.

The carboxy-terminal domain (CTD) of the RNA polymerase II (RNAP II) subunit POLR2A is a platform for modifications specifying the recruitment of factors that regulate transcription, mRNA processing, and chromatin remodelling. Here we show that a CTD arginine residue (R1810 in human) that is conserved across vertebrates is symmetrically dimethylated (me2s). This R1810me2s modification requires protein arginine methyltransferase 5 (PRMT5) and recruits the Tudor domain of the survival of motor neuron (SMN, also known as GEMIN1) protein, which is mutated in spinal muscular atrophy. SMN interacts with senataxin, which is sometimes mutated in ataxia oculomotor apraxia type 2 and amyotrophic lateral sclerosis. Because POLR2A R1810me2s and SMN, like senataxin, are required for resolving RNA-DNA hybrids created by RNA polymerase II that form R-loops in transcription termination regions, we propose that R1810me2s, SMN, and senataxin are components of an R-loop resolution pathway. Defects in this pathway can influence transcription termination and may contribute to neurodegenerative disorders.

Multiparameter functional diversity of human C2H2 zinc finger proteins.

C2H2 zinc finger proteins represent the largest and most enigmatic class of human transcription factors. Their C2H2-ZF arrays are highly variable, indicating that most will have unique DNA binding motifs. However, most of the binding motifs have not been directly determined. In addition, little is known about whether or how these proteins regulate transcription. Most of the ∼700 human C2H2-ZF proteins also contain at least one KRAB, SCAN, BTB, or SET domain, suggesting that they may have common interacting partners and/or effector functions. Here, we report a multifaceted functional analysis of 131 human C2H2-ZF proteins, encompassing DNA binding sites, interacting proteins, and transcriptional response to genetic perturbation. We confirm the expected diversity in DNA binding motifs and genomic binding sites, and provide motif models for 78 previously uncharacterized C2H2-ZF proteins, most of which are unique. Surprisingly, the diversity in protein-protein interactions is nearly as high as diversity in DNA binding motifs: Most C2H2-ZF proteins interact with a unique spectrum of co-activators and co-repressors. Thus, multiparameter diversification likely underlies the evolutionary success of this large class of human proteins.

Assessment of a method to characterize antibody selectivity and specificity for use in immunoprecipitation.

Antibodies are used in multiple cell biology applications, but there are no standardized methods to assess antibody quality-an absence that risks data integrity and reproducibility. We describe a mass spectrometry-based standard operating procedure for scoring immunoprecipitation antibody quality. We quantified the abundance of all the proteins in immunoprecipitates of 1,124 new recombinant antibodies for 152 chromatin-related human proteins by comparing normalized spectral abundance factors from the target antigen with those of all other proteins. We validated the performance of the standard operating procedure in blinded studies in five independent laboratories. Antibodies for which the target antigen or a member of its known protein complex was the most abundant protein were classified as 'IP gold standard'. This method generates quantitative outputs that can be stored and archived in public databases, and it represents a step toward a platform for community benchmarking of antibody quality.

Synthesis, crystal structure, and thermal decomposition of the cobalt(II) complex with 2-picolinic acid.

The cobalt(II) complex of 2-picolinic acid (Hpic), namely, [Co(pic)2(H2O)2] · 2H2O, was synthesized with the reaction of cobalt acetate and 2-picolinic acid as the reactants by solid-solid reaction at room temperature. The composition and structure of the complex were characterized by elemental analysis, infrared spectroscopy, single crystal X-ray diffraction, and thermogravimetry-differential scanning calorimetry (TG-DSC). The crystal structure of the complex belongs to monoclinic system and space group P2(1)/n, with cell parameters of a = 9.8468(7) Å, b = 5.2013(4) Å, c = 14.6041(15) Å, ß = 111.745(6)°, V = 747.96(11) ų, Z = 2, D(c) = 1.666 g cm⁻³, R1 = 0.0297, and wR2 = 0.0831. In the title complex, the Co(II) ion is six-coordinated by two pyridine N atoms and two carboxyl O atoms from two 2-picolinic acid anions, and two O atoms from two H2O molecules, and forming a slightly distorted octahedral geometry. The thermal decomposition processes of the complex under nitrogen include dehydration and pyrolysis of the ligand, and the final residue is cobalt oxalate at about 450°C.

Targeting nanoplatform synergistic glutathione depletion-enhanced chemodynamic, microwave dynamic, and selective-microwave thermal to treat lung cancer bone metastasis.

Once bone metastasis occurs in lung cancer, the efficiency of treatment can be greatly reduced. Current mainstream treatments are focused on inhibiting cancer cell growth and preventing bone destruction. Microwave ablation (MWA) has been used to treat bone tumors. However, MWA may damage the surrounding normal tissues. Therefore, it could be beneficial to develop a nanocarrier combined with microwave to treat bone metastasis. Herein, a microwave-responsive nanoplatform (MgFe2O4@ZOL) was constructed. MgFe2O4@ZOL NPs release the cargos of Fe3+, Mg2+ and zoledronic acid (ZOL) in the acidic tumor microenvironment (TME). Fe3+ can deplete intracellular glutathione (GSH) and catalyze H2O2 to generate •OH, resulting in chemodynamic therapy (CDT). In addition, the microwave can significantly enhance the production of reactive oxygen species (ROS), thereby enabling the effective implementation of microwave dynamic therapy (MDT). Moreover, Mg2+ and ZOL promote osteoblast differentiation. In addition, MgFe2O4@ZOL NPs could target and selectively heat tumor tissue and enhance the effect of microwave thermal therapy (MTT). Both in vitro and in vivo experiments revealed that synergistic targeting, GSH depletion-enhanced CDT, MDT, and selective MTT exhibited significant antitumor efficacy and bone repair. This multimodal combination therapy provides a promising strategy for the treatment of bone metastasis in lung cancer patients.

Preparation of soft magnetic Fe-Ni-Pb-B alloy nanoparticles by room temperature solid-solid reaction.

The Fe-Ni-Pb-B alloy nanoparticles was prepared by a solid-solid chemical reaction of ferric trichloride, nickel chloride, lead acetate, and potassium borohydride powders at room temperature. The research results of the ICP and thermal analysis indicate that the resultants are composed of iron, nickel, lead, boron, and PVP, and the component of the alloy is connected with the mole ratio of potassium borohydride and the metal salts. The TEM images show that the resultants are ultrafine and spherical particles, and the particle size is about a diameter of 25 nm. The largest saturation magnetization value of the 21.18 emu g(-1) is obtained in the Fe-Ni-Pb-B alloy. The mechanism of the preparation reaction for the Fe-Ni-Pb-B multicomponent alloys is discussed.

Long noncoding RNA X-inactive specific transcript (lncRNA XIST) inhibits hepatic insulin resistance by competitively binding microRNA-182-5p.

BACKGROUND: What is highlighted in this study refers to the role and molecular mechanism of long noncoding RNA (lncRNA) X-inactive specific transcript (XIST) in cells with insulin resistance (IR). METHODS: In this study, LX-2 cells were applied to establish IR model in vitro. The expressions of lncRNA XIST, phosphoenolpyruvate carboxykinase (PEPCK,) and glucose-6-phosphatase (G6Pase) were quantified by quantitative reverse transcription polymerase chain reaction. The 2-deoxy-d-glucose-6-phosphate (2-DG6P) level was detected utilizing 2-deoxy-d-glucose (2-DG) uptake measurement kit. Western blot was adopted to measure the protein expressions of insulin-like growth factor-1 receptor (IGF-1R), G6Pase, PEPCK, and phosphatidylinositol 3-kinase (PI3K)/Akt pathway-related genes. StarBase was used to predict the targeting relationship between lncRNA XIST or IGF-1R with miR-182-5p, the results of which were verified by dual-luciferase reporter, RNA pull-down, and RNA immunoprecipitation assays. Rescue experiments were conducted to investigate the effect of miR-182-5p on IR cells. Next, low-expressed lncRNA XIST and high-expressed miR-182-5p were observed in IR cells. RESULTS: Upregulation of lncRNA XIST increased IGF-1R and 2-DG6P levels, decreased G6Pase and PEPCK expressions, and promoted PI3K/Akt pathway activation in IR cells. LncRNA XIST sponged miR-182-5p which targeted IGF-1R. MiR-182-5p mimic reversed the above effects of lncRNA XIST overexpression on IR cells. CONCLUSIONS: In conclusion, lncRNA XIST/miR-182-5p axis alleviates hepatic IR in vitro via IGF-1R/PI3K/Akt signaling pathway, which could be the promising therapeutic target.

Generalized joint hypermobility subjects without knee hyperextension have greater walking anterior tibial translation and flexion angle than those with knee hyperextension.

BACKGROUND: The walking knee kinematic results of generalized joint hypermobility (GJH) subjects were controversial in previous studies. We proposed that this could be related to the knee statuses of GJH subjects with/without knee hyperextension (KH) and assumed that there are significant sagittal knee kinematic differences between GJH subjects with/without KH during gait. RESEARCH QUESTION: Do GJH subjects with KH exhibit significantly different kinematic characteristics than those without KH during walking? METHODS: 35 GJH subjects without KH, 34 GJH subjects with KH, and 30 healthy controls were recruited in this study. A three-dimensional gait analysis system was used to record and compare the knee kinematics of the participants. RESULTS: Significant walking knee kinematics differences were found between GJH subjects with/without KH during walking. GJH subjects without KH had greater flexion angles (4.7-6.0°, 24-53 % gait cycle (GC), p < 0.001; 5.1-6.1°, 65-77 % GC, p = 0.008) and anterior tibial translation (ATT) (3.3-4.1 mm, 0-4 % GC, p = 0.015; 3.8-4.3 mm, 91-100 % GC, p = 0.01) than those with KH. Compared to controls, GJH without KH exhibited increased ATT (4.0-5.7 mm, 0-26 % GC, p < 0.001; 5.1-6.7 mm, 78-100 % GC, p < 0.001), and range of motion of ATT (3.3 mm, p = 0.028) whereas GJH with KH only exhibited increased extension angle (6.9-7.3°, 62-66 % GC, p = 0.015) during walking. SIGNIFICANCE: The findings confirmed the hypothesis and suggested that GJH subjects without KH had more walking ATT and flexion angle asymmetries than those with KH. This may raise concerns about the differences in knee health and risk of knee diseases between GJH subjects with/without KH. However, further investigations should be done to explore the exact influence of walking ATT and flexion angle asymmetries in GJH subjects without KH.

Diagnosis of generalized joint hypermobility with gait patterns using a deep neural network.

Generalized joint hypermobility (GJH) describes the situation that the range of joint motion exceeds the normal range. GJH is found to increase the risk of knee-related injury and osteoarthritis, challenging the athletic ability of the population. Gait signals are directly related to hip and knee athletic conditions, and have been shown to have significant changes with GJH by our previous research. But gait data are noisy, and vary with age, gender, weight, and ethnicity, which makes them hard to analyze with traditional statistical methods. In this study, we proposed an end-to-end deep learning model to recognize the patterns of the gait signals. The model consists of convolutional network blocks, residual network blocks, and attention blocks. Our dataset is composed of 452 samples of gait data obtained by a three-dimension motion capture system, with the six-degree-of-freedom kinematic data of hip, knee, and ankle joints during level walking, downhill, and uphill walking. The model achieves 95.77% accuracy and 98.68% specificity with a recall of 76.84% while is more efficient than traditional machine learning methods. The trained model can be run on economical friendly devices, and provide help for immediate and precise diagnosis of GJH. It is also meaningful to consider its application in large-scale GJH screening, which can contribute to sports medicine.

Multifunctional 3D-printed scaffolds eradiate orthotopic osteosarcoma and promote osteogenesis via microwave thermo-chemotherapy combined with immunotherapy.

Tumor recurrence and a lack of bone-tissue integration are two critical concerns in the surgical treatment of osteosarcoma. Thus, an advanced multifunctional therapeutic platform capable of simultaneously eliminating residual tumor cells and promoting bone regeneration is urgently needed for efficient osteosarcoma treatment. Herein, to thoroughly eliminate tumors and simultaneously promote bone regeneration, an intelligent multifunctional therapeutic scaffold has been engineered by integrating microwave-responsive zeolitic imidazolate framework 8 (ZIF-8) nanomaterials loaded with a chemotherapeutic drug and an immune checkpoint inhibitor onto 3D-printed titanium scaffolds. The constructed scaffold features distinct microwave-thermal sensitization and tumor microenvironment-responsive characteristics, which can induce tumor immunogenic death by microwave hyperthermia and chemotherapy. Orthotopic implantation of the nanocomposite scaffold results in an enhanced immune response against osteosarcoma that may effectively inhibit tumor recurrence through synergistic immunotherapy. During long-term implantation, the zinc ions released from the degradation of ZIF-8 can induce the osteogenic differentiation of stem cells. The porous structure and mechanical properties of the 3D-printed titanium scaffolds provide a structural microenvironment for bone regeneration. This study provides a paradigm for the design of multifunctional microwave-responsive composite scaffolds for use as a therapy for osteosarcoma, which could lead to improved strategies for the treatment of the disease.

Comparing the Accuracy of Seven Scoring Systems in Predicting Survival of Lung Cancer Patients With Spinal Metastases: An External Validation From Two Centers.

STUDY DESIGN: Retrospective case series. OBJECTIVE: To investigate the accuracy of seven scoring systems for the prediction of survival in lung cancer patients with spinal metastases (SPM). SUMMARY OF BACKGROUND DATA: Although survival scoring systems have been developed for surgical decision-making, the reliability and validity of these models are unclear for specific cancer types. As the prevalence of patients with lung cancer increases, it is imperative to determine the accuracy of these models for lung cancer patients with SPM. MATERIALS AND METHODS: This is a retrospective study of a cohort of lung cancer patients with SPM who underwent spine surgery between 2019 and 2021 at two centers. The optimal area under the curve (AUC) was calculated to evaluate the accuracy of seven candidate scoring systems at 3, 6, and 12 months. Calibration and decision curve analysis was used for further validation. RESULTS: A total of 166 patients (mean age: 58.98±10.94; 105 males and 61 females) with SPM were included. The median postoperative survival was 12.87±0.93 months. The modified Bauer score, revised Tokuhashi score, Linden score, Tomita score, the Skeletal Oncology Research Group nomogram, and the New England Spinal Metastasis Score in prediction survival at 3, 6, and 12 months showed a slightly weaker AUC (range 0.464-0.659). The AUC of the Katagiri-New score in predicting 1-year survival for lung cancer patients was the highest (0.708; range 0.619-0.798). The decision curve analysis showed that the Katagiri-New score led to a greater net benefit than the strategies of changing management for all patients or none of the patients. CONCLUSIONS: This study suggests that the most commonly used models have limitations in predicting survival in patients undergoing spinal surgery for metastatic lung cancer and underestimate survival. In this sample of lung cancer patients, the Katagiri-New Scoring system score had the best performance in predicting 1-year survival. LEVEL OF EVIDENCE: 4.

External validation of the SORG machine learning algorithms for predicting 90-day and 1-year survival of patients with lung cancer-derived spine metastases: a recent bi-center cohort from China.

BACKGROUND CONTEXT: The survival prediction of lung cancer-derived spinal metastases is often underestimated by several scores. The SORG machine learning (ML) algorithm is considered a promising tool to predict the risk of 90-day and 1-year mortality in patients with spinal metastases, but not been externally validated for lung cancer. PURPOSE: This study aimed to externally validate the SORG ML algorithms on lung cancer-derived spinal metastases patients from two large-volume, tertiary medical centers between 2018 and 2021. STUDY DESIGN/SETTING: Retrospective, cohort study. PATIENT SAMPLE: Patients aged 18 years or older at two tertiary medical centers in China are treated surgically for spinal metastasis. OUTCOME MEASURES: Mortality within 90 days of surgery, mortality within 1 year of surgery. METHODS: The baseline characteristics were compared between the development cohort and our validation cohort. Discrimination (receiver operating curve), calibration (calibration plot, intercept, and slope), the overall performance (Brier score), and decision curve analysis was used to assess the overall performance of the SORG ML algorithms. RESULTS: This study included 150 patients with lung cancer-derived spinal metastases from two medical centers in China. Ninety-day and 1-year mortality rates were 12.9% (19/147) and 51.3% (60/117), respectively. Lung Cancer with targeted therapies had the lowest Hazard Ratio (HR=0.490), showing an optimal protecting factor. The AUC of the SORG ML algorithm for 90-day mortality prediction in lung cancer-derived spinal metastases is 0.714. While the AUC for 1-year mortality prediction is 0.832 (95CI%, 0.758-0.906). The algorithm for 1-year mortality was well-calibrated with an intercept of 0.13 and a calibration slope of 1.00. However, the 90-day mortality prediction was underestimated with an intercept of 0.60 and a slope of 0.37. The SORG ML algorithms for 1-year mortality showed a greater net benefit than the "treats all or no patients" strategies. CONCLUSIONS: In the latest cohort of lung cancer-derived spinal metastases in China, the SORG algorithms for predicting 1-year mortality performed well on external validation. However, 90-day mortality was underestimated. The algorithm should be further validated by single primary tumor-derived metastasis treated with the latest comprehensive treatment in diverse populations.

Morphological feature recognition of different differentiation stages of induced ADSCs based on deep learning.

In order to accurately identify the morphological features of different differentiation stages of induced Adipose Derived Stem Cells (ADSCs) and judge the differentiation types of induced ADSCs, a morphological feature recognition method of different differentiation stages of induced ADSCs based on deep learning is proposed. Using the super-resolution image acquisition method of ADSCs differentiation based on stimulated emission depletion imaging, after obtaining the super-resolution images at different stages of inducing ADSCs differentiation, the noise of the obtained image is removed and the image quality is optimized through the ADSCs differentiation image denoising model based on low rank nonlocal sparse representation; The denoised image is taken as the recognition target of the morphological feature recognition method for ADSCs differentiation image based on the improved Visual Geometry Group (VGG-19) convolutional neural network. Through the improved VGG-19 convolutional neural network and class activation mapping method, the morphological feature recognition and visual display of the recognition results at different stages of inducing ADSCs differentiation are realized. After testing, this method can accurately identify the morphological features of different differentiation stages of induced ADSCs, and is available.

A lentiviral functional proteomics approach identifies chromatin remodeling complexes important for the induction of pluripotency.

Protein complexes and protein-protein interactions are essential for almost all cellular processes. Here, we establish a mammalian affinity purification and lentiviral expression (MAPLE) system for characterizing the subunit compositions of protein complexes. The system is flexible (i.e. multiple N- and C-terminal tags and multiple promoters), is compatible with Gateway cloning, and incorporates a reference peptide. Its major advantage is that it permits efficient and stable delivery of affinity-tagged open reading frames into most mammalian cell types. We benchmarked MAPLE with a number of human protein complexes involved in transcription, including the RNA polymerase II-associated factor, negative elongation factor, positive transcription elongation factor b, SWI/SNF, and mixed lineage leukemia complexes. In addition, MAPLE was used to identify an interaction between the reprogramming factor Klf4 and the Swi/Snf chromatin remodeling complex in mouse embryonic stem cells. We show that the SWI/SNF catalytic subunit Smarca2/Brm is up-regulated during the process of induced pluripotency and demonstrate a role for the catalytic subunits of the SWI/SNF complex during somatic cell reprogramming. Our data suggest that the transcription factor Klf4 facilitates chromatin remodeling during reprogramming.

Oxyhydroxide-Coated PEO-Treated Mg Alloy for Enhanced Corrosion Resistance and Bone Regeneration.

Plasma electrolytic oxidation (PEO) is widely used as a surface modification method to enhance the corrosion resistance of Mg alloy, the most likely applied biodegradable material used in orthopedic implants. However, the pores and cracks easily formed on the PEO surface are unfavorable for long-term corrosion resistance. In this study, to solve this problem, we used simple immersion processes to construct Mn and Fe oxyhydroxide duplex layers on the PEO-treated AZ31 (PEO-Mn/Fe). As control groups, single Mn and Fe oxyhydroxide layers were also fabricated on PEO (denoted as PEO-Mn and PEO-Fe, respectively). PEO-Mn showed a similar porous morphology to the PEO sample. However, the PEO-Fe and PEO-Mn/Fe films completely sealed the pores on the PEO surfaces, and no cracks were observed even after the samples were immersed in water for 7 days. Compared with PEO, PEO-Mn, and PEO-Fe, PEO-Mn/Fe exhibited a significantly lower self-corrosion current, suggesting better corrosion resistance. In vitro C3H10T1/2 cell culture showed that PEO-Fe/Mn promoted the best cell growth, alkaline phosphatase activity, and bone-related gene expression. Furthermore, the rat femur implantation experiment showed that PEO-Fe/Mn-coated Mg showed the best bone regeneration and osteointegration abilities. Owing to enhanced corrosion resistance and osteogenesis, the PEO-Fe/Mn film on Mg alloy is promising for orthopedic applications.

Two Cannulated Screws Provide Sufficient Biomechanical Strength for Prophylactic Fixation in Adult Patients With an Aggressive Benign Femoral Neck Lesion.

Background: Two cannulated screws were proposed for prophylactic fixation in adult patients with an aggressive benign femoral neck lesion in recent literature. However, the biomechanical properties of this intervention have not yet been investigated. Methods: After the evaluation of the heterogeneity of bone mineral density and geometry via quantitative computed tomography, 24 embalmed adult human cadaver femurs were randomized into the control, inferior half of the anterior cortical (25%) bone defect, entire anterior cortical (50%) bone defect, and the 50% bone defect and two cannulated screw group. Biomechanical analysis was conducted to compare the stiffness and failure load among the four groups when mimicking a one-legged stance. A CT-based finite element analysis (FEA) was performed to mimic the cortical and cancellous bone defect and the implantation of two cannulated screws of the four groups. Measurements of the maximal displacement and von Mises stress were conducted with the longitudinal load force and boundary conditions being established for a one-leg-standing status. Results: We noted a significant improvement in the failure load after the insertion of two 6.5 mm cannulated screws in femurs with 50% bone defect (+95%, p = 0.048), and no significant difference was found between the screw group and the intact femur. Similar trends were also found in the measurements of stiffness (+23%, p > 0.05) via biomechanical testing and the von Mises stresses (-71%, p = 0.043) by FEA when comparing the screw group and the 50% bone defect group. Conclusion: Our findings suggest that two cannulated screws provided sufficient biomechanical strength for prophylactic fixation in adult patients with an aggressive benign femoral neck lesion even when the entire anterior cortical bone is involved.