Precursor Cells Research Articles

N-cadherin facilitates trigeminal sensory neuron outgrowth and target tissue innervation.

Our findings are significant because they demonstrate how neurons derived from two distinct cell populations, neural crest and placode cells, coordinate the outgrowth of their axons in time and space to generate the trigeminal ganglion using the cell adhesion molecule N-cadherin. Notably, our results provide evidence for the existence of subpopulations of neurons within the trigeminal ganglion that differentially require N-cadherin to facilitate axon outgrowth, and hint at the possibility that trigeminal pioneer neurons are derived from placode cells while followers arise from both placode and neural crest cells. These studies provide new insight into trigeminal gangliogenesis that will likely be translatable to other cranial ganglia and vertebrate species.

Blockade of Discoidin Domain Receptor Signaling with Sitravatinib Reveals DDR2 as a Mediator of Neuroblastoma Pathogenesis and Metastasis.

Oncogene-driven expression and activation of receptor tyrosine kinases (RTK) promotes tumorigenesis and contributes to drug resistance. Increased expression of the kinases DDR2 (Discoid Domain Receptor 2), RET, PDGFRA, KIT, MET, and ALK (Anaplastic Lymphoma Kinase) independently correlate with decreased overall survival (OS) and event free survival (EFS) of pediatric neuroblastoma. The multikinase inhibitor sitravatinib targets DDR2, RET, PDGFRA, KIT and MET with low nanomolar activity and we therefore tested its efficacy against orthotopic and syngeneic tumor models. Sitravatinib markedly reduced cell proliferation and migration in vitro independently of MYCN (N-Myc proto-oncogene), ALK, or MYC (c-Myc proto-oncogene) status, and inhibited proliferation and metastasis of human orthotopic xenografts. Oral administration of sitravatinib to homozygous Th-MYCN transgenic mice (Th-MYCN+/+) after tumor initiation completely arrested further tumor development with no mice dying of disease while maintained on sitravatinib treatment (control cohort 57 days median time to sacrifice). Among these top kinases, DDR2 expression has the strongest correlation with poor survival and high stage at diagnosis, and the highest sensitivity to the drug. We confirmed on-target inhibition of collagen-mediated activation of DDR2. Genetic knockdown of DDR2 partially phenocopies Sitravatinib treatment, limiting tumor development and metastasis across tumor models. Analysis of single cell sequencing data demonstrated that DDR2 is restricted to mesenchymal-type tumor subpopulations and is enriched in Schwann Cell Precursor (SCP) subpopulations found in high-risk disease. These data define an unsuspected role for sitravatinib as a therapeutic agent in neuroblastoma and reveal a novel function for DDR2 as a driver of tumor growth and metastasis.

Schwannian and Perineuriomatous Differentiation in a Series of Giant Congenital Melanocytic Nevi.

Close relationship between melanocytes and neural cells is accepted to reflect their common derivation from the neural crest and tumors combining both elements. We present a series of 10 patients with giant congenital melanocytic nevi (CMN) in which a secondary proliferation (11 lesions) with schwannian and/or perineuriomatous differentiation developed in the course of the disease. The age of the patients (4 male and 6 female) at the time of surgery and histological assessment varied from 3 months to 57 years. Histopathologically, the following subgroups were delineated: (1) nodular/tumoriform "neurotization" in CMN, (2) diffuse neurofibroma-like proliferation within CMN, (3) plexiform neurofibroma-like proliferation within CMN, and (4) diffuse perineuriomatous (hybrid schwannomatous-perineuriomatous) differentiation in CMN. We review the pertinent literature, including the role of recently identified Schwann cell precursors which are believed to represent the nerve-associated state of neural crest-like cells that persists into later developmental stages.

Loss of ninein interferes with osteoclast formation and causes premature ossification.

Ninein is a centrosome protein that has been implicated in microtubule anchorage and centrosome cohesion. Mutations in the human NINEIN gene have been linked to Seckel syndrome and to a rare form of skeletal dysplasia. However, the role of ninein in skeletal development remains unknown. Here, we describe a ninein knockout mouse with advanced endochondral ossification during embryonic development. Although the long bones maintain a regular size, the absence of ninein delays the formation of the bone marrow cavity in the prenatal tibia. Likewise, intramembranous ossification in the skull is more developed, leading to a premature closure of the interfrontal suture. We demonstrate that ninein is strongly expressed in osteoclasts of control mice, and that its absence reduces the fusion of precursor cells into syncytial osteoclasts, whereas the number of osteoblasts remains unaffected. As a consequence, ninein-deficient osteoclasts have a reduced capacity to resorb bone. At the cellular level, the absence of ninein interferes with centrosomal microtubule organization, reduces centrosome cohesion, and provokes the loss of centrosome clustering in multinucleated mature osteoclasts. We propose that centrosomal ninein is important for osteoclast fusion, to enable a functional balance between bone-forming osteoblasts and bone-resorbing osteoclasts during skeletal development.

Integrated systems biology analysis of acute lymphoblastic leukemia: unveiling molecular signatures and drug repurposing opportunities.

Acute lymphoblastic leukemia (ALL) is a hematological malignancy characterized by aberrant proliferation and accumulation of lymphoid precursor cells within the bone marrow. The tyrosine kinase inhibitor (TKI), imatinib mesylate, has played a significant role in the treatment of Philadelphia chromosome-positive ALL (Ph + ALL). However, the achievement of durable and sustained therapeutic success remains a challenge due to the development of TKI resistance during the clinical course.The primary objective of this investigation is to propose a novel and efficacious treatment approach through drug repositioning, targeting ALL and its Ph + subtype by identifying and addressing differentially expressed genes (DEGs). This study involves a comprehensive analysis of transcriptome datasets pertaining to ALL and Ph + ALL in order to identify DEGs associated with the progression of these diseases to identify possible repurposable drugs that target identified hub proteins.The outcomes of this research have unveiled 698 disease-related DEGs for ALL and 100 for Ph + ALL. Furthermore, a subset of drugs, specifically glipizide for Ph + ALL, and maytansine and isoprenaline for ALL, have been identified as potential candidates for therapeutic intervention. Subsequently, cytotoxicity assessments were performed to confirm the in vitro cytotoxic effects of these selected drugs on both ALL and Ph + ALL cell lines.In conclusion, this study offers a promising avenue for the management of ALL and Ph + ALL through drug repurposed drugs. Further investigations are necessary to elucidate the mechanisms underlying cell death, and clinical trials are recommended to validate the promising results obtained through drug repositioning strategies.

Microbiota regulates the TET1-mediated DNA hydroxymethylation program in innate lymphoid cell differentiation

Innate lymphoid cell precursors (ILCPs) develop into distinct subsets of innate lymphoid cells (ILCs) with specific functions. The epigenetic program underlying the differentiation of ILCPs into ILC subsets remains poorly understood. Here, we reveal the genome-wide distribution and dynamics of the DNA methylation and hydroxymethylation in ILC subsets and their respective precursors. Additionally, we find that the DNA hydroxymethyltransferase TET1 suppresses ILC1 but not ILC2 or ILC3 differentiation. TET1 deficiency promotes ILC1 differentiation by inhibiting TGF-β signaling. Throughout ILCP differentiation at postnatal stage, gut microbiota contributes to the downregulation of TET1 level. Microbiota decreases the level of cholic acid in the gut, impairs TET1 expression and suppresses DNA hydroxymethylation, ultimately resulting in an expansion of ILC1s. In adult mice, TET1 suppresses the hyperactivation of ILC1s to maintain intestinal homeostasis. Our findings provide insights into the microbiota-mediated epigenetic programming of ILCs, which links microbiota-DNA methylation crosstalk to ILC differentiation.

Sequential‐dip‐coating processed mixed organic and inorganic perovskite film from halide‐free lead precursor for efficient perovskite solar cells

AbstractA novel all‐sequential‐dip‐coated (SDC) deposited FA1MA1−yPbI3−xBrx perovskite films have been synthesized from an aqueous non‐halide lead precursor towards an environmentally benign, cost‐effective, and efficient approach for high‐performance perovskite solar cells (PrSCs). The mixed‐cationic FA1MA1−yPbI3−xBrx perovskite layers ensure the fractional incorporation of Br into the perovskite crystal lattice. The insertion of Br contents was regulated by modulating the FABr concentration into the FABr/MAI mixed‐cationic precursor solution. The incorporation of minor FABr into MAI helps to improve the surface coverage and crystallinity of the synthesized per‐ovskite layer in contrast to the other perovskite films prepared with higher FABr content under the same environment. The PrSCs with these FA1MA1−yPbI3−xBrx perovskite layers displayed good de‐vice performances and stability with a PCE of 11.1%. These outcomes reveal that the synthesis of FA1MA1−yPbI3−xBrx perovskite films with the SDC approach is more efficient because of the use of environmentally benign solvents for synthesizing lead and perovskite layers.

NRF2 Plays a Crucial Role in the Tolerogenic Effect of Ethyl Pyruvate on Dendritic Cells.

Ethyl pyruvate (EP) is a redox-active compound that has been previously shown to be effective in restraining immune hyperactivity in animal models of various autoimmune and chronic inflammatory diseases. Importantly, EP has also been proven to have a potent tolerogenic effect on dendritic cells (DCs). Here, the influence of EP on the signaling pathways in DCs relevant for their tolerogenicity, including anti-inflammatory NRF2 and pro-inflammatory NF-κB, was explored. Specifically, the effects of EP on DCs obtained by GM-CSF-directed differentiation of murine bone marrow precursor cells and matured under the influence of lipopolysaccharide (LPS) were examined via immunocytochemistry and RT-PCR. EP counteracted LPS-imposed morphological changes and down-regulated the LPS-induced expression of pro-inflammatory mediators in DCs. While it reduced the activation of NF-κB, EP potentiated NRF2 and downstream antioxidative molecules, thus implying the regulation of NRF2 signaling pathways as the major reason for the tolerizing effects of EP on DCs.

Remyelination-oriented clemastine treatment attenuates neuropathies of optic nerve and retina in glaucoma.

As one of the top causes of blindness worldwide, glaucoma leads to diverse optic neuropathies such as degeneration of retinal ganglion cells (RGCs). It is widely accepted that the level of intraocular pressure (IOP) is a major risk factor in human glaucoma, and reduction of IOP level is the principally most well-known method to prevent cell death of RGCs. However, clinical studies show that lowering IOP fails to prevent RGC degeneration in the progression of glaucoma. Thus, a comprehensive understanding of glaucoma pathological process is required for developing new therapeutic strategies. In this study, we provide functional and histological evidence showing that optic nerve defects occurred before retina damage in an ocular hypertension glaucoma mouse model, in which oligodendroglial lineage cells were responsible for the subsequent neuropathology. By treatment with clemastine, an Food and Drug Administration (FDA)-approved first-generation antihistamine medicine, we demonstrate that the optic nerve and retina damages were attenuated via promoting oligodendrocyte precursor cell (OPC) differentiation and enhancing remyelination. Taken together, our results reveal the timeline of the optic neuropathies in glaucoma and highlight the potential role of oligodendroglial lineage cells playing in its treatment. Clemastine may be used in future clinical applications for demyelination-associated glaucoma.

Revealing and targeting metabolic drivers contributing to treatment escape in diffuse midline glioma.

10038 Background: Diffuse midline glioma (DMG) is an aggressive pediatric brain tumor that predominately affects children, with a median survival of 9-11 months. DMGs are driven by self-renewing, stem-like glioma cells that have been stalled in an oligodendrocyte precursor cell (OPC)-like state and that highly express PDGFRA. This overexpression of PDGFRA has been shown to be pivotal in DMG development. Thus, targeting PDGFRA may serve as a viable treatment approach for DMG. In our previous studies, we revealed that avapritinib, a next generation tyrosine kinase inhibitor of PDGFRA, is highly effective in DMG cells. While a subset of patients receiving treatment with avapritinib experienced a promising clinical response, all patients eventually experienced tumor progression due to treatment escape. In this study, we investigated which mechanisms DMG cells use to escape avapritinib treatment, and how we can therapeutically exploit these resistance mechanisms. Methods: Transcriptomic profiling and functional assays were performed on patient-derived DMG cell lines. A combinatorial drug screening identified drug candidates evaluated in this study. Results: Bulk RNA sequencing analysis of two patient derived DMG cell lines revealed an upregulation of genes associated with both fatty acid metabolism and oxidative phosphorylation (OXPHOS) following avapritinib treatment. Functional assays confirmed elevated OXPHOS in avapritinib-treated cells with significant increases in mitochondrial energy transduction, palmitate- (a product of fatty acid metabolism) driven oxygen consumption rates, and incorporation of palmitate-derived carbons into the tricarboxylic acid (TCA) cycle. CRISPR-Cas9-mediated knockout of PDGFRAin one DMG cell line confirmed the metabolic changes observed following avapritinib treatment. Analysis of bulk RNA sequencing data revealed an upregulation of key fatty acid- related transcription factors in avapritinib-treated DMG cells. Specifically, Peroxisome Proliferator-Activated Receptor alpha (PPAR-alpha), Sterol Regulatory Binding Element Binding Transcription Factors 1 and 2, and Fatty Acid Synthase (FASN) were most prominently upregulated. To determine which therapies could target the dependency of avapritinib-treated cells on fatty acid metabolism, we performed a combinatorial drug screening and found three lipid pathway inhibitors that have synergistic cytotoxic effects with avapritinib. Specifically, a FASN inhibitor, cholesterol pathway inhibitor, and PPAR-alpha inhibitor. Conclusions: In this study, we revealed metabolic drivers that may contribute to avapritinib resistance in DMG cells, and identified compounds capable of inhibiting these drivers that demonstrate synergy with avapritinib. We now intend on testing these combination therapies in vivo as we aim to provide a long-term clinical benefit to DMG patients receiving avapritinib.

Small extracellular vesicles as a novel liquid biopsy approach for glioblastoma.

2073 Background: Glioblastoma (GBM) remains the most common and aggressive primary malignant brain tumor, and afflicted patients have limited options and poor overall survival. Diagnosis, prognosis, and assessment of treatment effectiveness is hampered by the absence of readily available sensitive, tumor specific, non-invasive blood-based assays which could be followed serially. Small extracellular vesicles (sEV) are nano-sized (≤200 nm) membrane bound bodies secreted by all cells, encapsulating cargo reflective of their parent cells. sEV have emerged as promising molecular indicator of a disease condition. Here, we report the feasibility of isolating glioma specific sEV (sEVglioma) from the plasma and characterizing those for GBM specific molecular biomarkers. Methods: Plasma samples were collected from patients (n=31) diagnosed with adult gliomas (including grade 3 and 4 GBM, grade 2 and 3 astrocytoma) and healthy individuals (n=9). Total sEV (TE) population was isolated from plasma by a modified precipitation (ExoQuick) method. Next, sEVglioma were isolated from the TE by an immunoprecipitation approach employing specific surface markers targeting cellular origin of gliomas, including astrocyte (GLAST and EAAT2), oligodendrocyte precursor cell (OSP and MOG), and neural stem cell (CD133). sEVglioma were characterized for size and concentration by nanoparticle tracking analyses; surface expression of glioma specific biomarkers by nano-flow cytometry and confocal microscopy; and the expression of a panel of specific miRNAs by RT-PCR. Lastly, sEVglioma were assessed by digital PCR for IDH1 status (wild type or mutated). Results: The average size of isolated sEVglioma was less than 200nm. Importantly, compared to TE, sEVglioma showed significant enrichment for glioma specific biomarkers such as ephrin type-A receptor 2 (14.7-fold), tenascin C (22.7-fold), and glial fibrillary acidic protein (8.4-fold) by nano-flow cytometry. Similarly, sEVglioma, but not TE, demonstrated high expression of EGFRvIII (3.6-fold), a known biomarker for GBM. These results were confirmed by confocal microscopy. Interestingly, expression of specific miRNAs (miR-9a-5p, miR-16-5p, miR-21-5p) in sEVglioma was higher in glioma patients with shorter survival (<12 months) compared to patients with longer survival (>20 months). Lastly, we successfully detected the existence of wild type IDH1 and absence of mutated IDH1 R132H in sEVglioma from GBM patients. This approach was validated in sEV isolated from the conditioned media of IDH1-wild type GBM cell lines (A172 and T98G) and a IDH1-mutated cell line (BT54). Conclusions: We present a novel approach to isolate sEVglioma from blood that could serve as a liquid biopsy, offering valuable molecular and genetic information. This approach promises early detection, potential to distinguish pseudo-progression, and assessment of treatment effectiveness with remarkable precision.

Role of NEDD9 expression in non-metastatic HER2-positive breast cancer.

e12645 Background: Neural Precursor Cell Expressed Developmentally Downregulated Protein 9 (NEDD9) is a member of the associated substrate family. Our previous studies demonstrated the role of NEDD9 overexpression in early tumorigenesis in HER2-positive (HER2+) breast cancer in vivo. Tissue microarray-based analysis showed a strong correlation between NEDD9 mRNA and relapse-free survival (RFS) and pathologic complete response (pCR) rate in HER2+ breast cancers. In this study, NEDD9 expression in non-metastatic HER2+ breast cancer was evaluated by tissue microarray. Methods: A total of 64 patients with non-metastatic HER2+ cancer of the breast who had received neoadjuvant chemotherapy and had sufficient pathology specimens were included in the study. NEDD9 was stained by tissue microarray, and the expression was subclassified as low, intermediate, and high based on the NEDD9 expression score. The correlations of NEDD9 expression with the clinical/biological characteristics, treatment, and treatment response were analyzed by Fisher Exact test. Results: A total of 64 patients were included in the study, with a medium follow-up duration of 4.6 years. The median age was 54, 1 patient was male, 79.3% of patients had stage 2 disease, 1 patient had inflammatory breast cancer, and 37.5% of patients had ER/PR negative disease. The most common neoadjuvant chemotherapy regimen was TCHP (82.5%), 44.4% of patients underwent lumpectomy, and 67.7% of patients underwent axillary lymph node dissection (ALND). 54% of patients achieved complete pathologic response (pCR), all patients received adjuvant anti-HER2 treatment, 85.7% received adjuvant radiotherapy, and 74.6% received adjuvant endocrine therapy. The NEDD9 expression distribution for low, intermediate, and high were 37.5%, 50.0%, and 12.5%, respectively. NEDD9-high patients had higher tumor stage and grade than NEDD9-low/ intermediate patients (p = 0.004, p= 0.041). More NEDD9-high patients underwent ALND compared to NEDD9- low/intermediate patients (p = 0.09). There is no statistically significant difference in pCR rate between NEDD9 expression groups, although numerically more NEDD9-high patients achieved pCR (75%, 56.2%, and 43.5% in NEDD9-high, intermediate, and low patients). Conclusions: In non-metastatic HER2+ breast cancer, NEDD9 expression is associated with more advanced tumor grade and stage. There is no statistically significant difference in pCR rate between groups, although more patients achieved pCR with a higher level of NEDD9 expression. The sample size limits our study. Additional study is needed to evaluate the correlation between NEDD9 expression and pCR rate following neoadjuvant chemotherapy in HER2+ breast cancer.

Enhanced electrophysiological activity and neurotoxicity screening of environmental chemicals using 3D neurons from human neural precursor cells purified with PSA-NCAM

The assessment of neurotoxicity for environmental chemicals is of utmost importance in ensuring public health and environmental safety. Multielectrode array (MEA) technology has emerged as a powerful tool for assessing disturbances in the electrophysiological activity. Although human embryonic stem cell (hESC)-derived neurons have been used in MEA for neurotoxicity screening, obtaining a substantial and sufficiently active population of neurons from hESCs remains challenging. In this study, we successfully differentiated neurons from a large population of human neuronal precursor cells (hNPC) purified using a polysialylated neural cell adhesion molecule (PSA-NCAM), referred to as hNPCPSA-NCAM+. The functional characterization demonstrated that hNPCPSA-NCAM+-derived neurons improve functionality by enhancing electrophysiological activity compared to total hNPC-derived neurons. Furthermore, three-dimensional (3D) neurons derived from hNPCPSA-NCAM+ exhibited reduced maturation time and enhanced electrophysiological activity on MEA. We employed subdivided population analysis of active mean firing rate (MFR) based on electrophysiological intensity to characterize the electrophysiological properties of hNPCPSA-NCAM+-3D neurons. Based on electrophysiological activity including MFR and burst parameters, we evaluated the sensitivity of hNPCPSA-NCAM+-3D neurons on MEA to screen both inhibitory and excitatory neuroactive environmental chemicals. Intriguingly, electrophysiologically active hNPCPSA-NCAM+-3D neurons demonstrated good sensitivity to evaluate neuroactive chemicals, particularly in discriminating excitatory chemicals. Our findings highlight the effectiveness of MEA approaches using hNPCPSA-NCAM+-3D neurons in the assessment of neurotoxicity associated with environmental chemicals. Furthermore, we emphasize the importance of selecting appropriate signal intensity thresholds to enhance neurotoxicity prediction and screening of environmental chemicals.

Anti-tumor activity of niclosamide-mediated oxidative stress against acute lymphoblastic leukemia.

Acute lymphoblastic leukemia (ALL) is a heterogeneous clonal disease originated from B- or T-cell lymphoid precursor cells. ALL is often refractory or relapses after treatment. Novel treatments are anxiously needed in order to achieve a better response and prolonged overall survival in ALL patients. In the present study, we aimed at examining the anti-tumor effect of niclosamide on ALL. We investigated the effects of niclosamide on the proliferation and apoptosis in vitro, the growth of ALL cells in xenografted NCG mice. The results showed that niclosamide treatment potently inhibited the growth of ALL cells and induced apoptosis via elevating the levels of reactive oxygen species (ROS) and activating TP53. These findings suggest that niclosamide may be a promisingly potential agent for ALL therapy.

Targeted suppression of siRNA biogenesis in Arabidopsis pollen promotes triploid seed viability

In plants, small-interfering RNAs (siRNAs) mediate epigenetic silencing via the RNA-directed DNA methylation (RdDM) pathway, which is particularly prominent during reproduction and seed development. However, there is limited understanding of the origins and dynamics of reproductive siRNAs acting in different cellular and developmental contexts. Here, we used the RNaseIII-like protein RTL1 to suppress siRNA biogenesis in Arabidopsis pollen, and found distinct siRNA subsets produced during pollen development. We demonstrate that RTL1 expression in the late microspore and vegetative cell strongly impairs epigenetic silencing, and resembles RdDM mutants in their ability to bypass interploidy hybridization barriers in the seed. However, germline-specific RTL1 expression did not impact transgenerational inheritance of triploid seed lethality. These results reveal the existence of multiple siRNA subsets accumulated in mature pollen, and suggest that mobile siRNAs involved in the triploid block are produced in germline precursor cells after meiosis, or in the vegetative cell during pollen mitosis.

Cedrol alleviates postmenopausal osteoporosis in rats through inhibiting the activation of the NF-κB signaling pathway.

Pharmacological studies have shown that Cedrol (CE) exhibits extensive biological activities, including anti-inflammatory and analgesic. Moreover, it can inhibit the NF-κB pathway and the expression of various associated proteins. This study aimed to investigate the role of CE in postmenopausal osteoporosis. The results showed that intragastric administration of CE (10 and 20mg/kg) significantly improved the bone microstructure damage and increased bone mineral density, trabecular bone volume, and bone trabecular thickness in ovariectomized (OVX) rats (p < 0.05). CE treatment additionally made a well-organized arrangement of bone trabeculae and improved its thickness and density. Compared with the OVX group, the levels of tartrate-resistant acid phosphatase from 5b and C-terminal telopeptide of type I collagen were significantly reduced by 42.75% and 49.27% in the OVX + CE rats (p < 0.05). TRAP staining visually showed that the number of osteoclasts in the femur tissue of CE-treated rats was less than that of the OVX group. The expressions of nuclear factor of activated T-cells, cytoplasmic 1, acid phosphatase 5, and cathepsin K in OVX + CE rats were significantly decreased by 51.61%, 46.07%, and 50.34% compared to the OVX group (p < 0.01). In addition, CE intervention effectively reduced the phosphorylation levels of P65 and IκBα and inhibited the NF-κB signaling pathway. Meanwhile, CE diminished the number of multinucleated osteoclasts induced by receptor activator for nuclear factor-κB ligand and hindered cell fusion as well as nuclear translocation of osteoclast precursor cells P65. In conclusion, CE inhibits osteoclastogenesis by suppressing the activation of the NF-κB signaling pathway, thereby alleviating postmenopausal osteoporosis.

Somatic epigenetic drift during shoot branching: a cell lineage-based model.

Plant architecture is shaped by the production of new organs, most of which emerge post-embryonically. This process includes the formation of new lateral branches along existing shoots. Current evidence supports a detached meristem model as the cellular basis of lateral shoot initiation. In this model, a small number of undifferentiated cells are sampled from the periphery of the shoot apical meristem (SAM) to act as precursors for axillary buds, which eventually develop into new shoots. Repeated branching thus creates cellular bottlenecks (i.e. somatic drift) that affect how de novo (epi)genetic mutations propagate through the plant body during development. Somatic drift could be particularly relevant for stochastic DNA methylation gains and losses (i.e. spontaneous epimutations), as they have been shown to arise rapidly with each cell division. Here, we formalize a special case of the detached meristem model, where precursor cells are randomly sampled from the SAM periphery in a way that maximizes cell lineage independence. We show that somatic drift during repeated branching gives rise to a mixture of cellular phylogenies within the SAM over time. This process is dependent on the number of branch points, the strength of drift as well as the epimutation rate. Our model predicts that cell-to-cell DNA methylation heterogeneity in the SAM converges to non-zero states during development, suggesting that epigenetic variation is an inherent property of the SAM cell population. Our insights have direct implications for empirical studies of somatic (epi)genomic diversity in long-lived perennial and clonal species using bulk or single-cell sequencing approaches.

Preparation and efficacy of antibacterial methacrylate monomer-based polymethyl methacrylate bone cement containing N-halamine compounds.

Our objective in this study was to prepare a novel type of polymethyl methacrylate (PMMA) bone cement, analyze its material properties, and evaluate its safety and antibacterial efficacy. A halamine compound methacrylate antibacterial PMMA bone cement containing an N-Cl bond structure was formulated, and its material characterization was determined with Fourier transform infrared spectroscopy (FT-IR) and 1H-NMR. The antibacterial properties of the material were studied using contact bacteriostasis and releasing-type bacteriostasis experiments. Finally, in vitro and in vivo biocompatibility experiments were performed to analyze the toxic effects of the material on mice and embryonic osteoblast precursor cells (MC3T3-E1). Incorporation of the antibacterial methacrylate monomer with the N-halamine compound in the new antibacterial PMMA bone cement significantly increased its contact and releasing-type bacteriostatic performance against Staphylococcus aureus. Notably, at 20% and 25% additions of N-halamine compound, the contact and releasing-type bacteriostasis rates of bone cement samples reached 100% (p < 0.001). Furthermore, the new antibacterial bone cement containing 5%, 10%, and 15% N-halamine compounds showed good biocompatibility in vitro and in vivo. In this study, we found that the novel antibacterial PMMA bone cement with N-halamine compound methacrylate demonstrated good contact and releasing-type bacteriostatic properties against S. aureus. In particular, bone cement containing a 15% N-halamine monomer exhibited strong antibacterial properties and good in vitro and in vivo biocompatibility.

Biofabrication of Tissue-Engineered Cartilage Constructs Through Faraday Wave Bioassembly of Cell-Laden Gelatin Microcarriers.

Acoustic biofabrication is an emerging strategy in tissue engineering due to its mild and fast manufacturing process. Herein, tissue-engineered cartilage constructs with high cell viability are fabricated from cell-laden gelatin microcarriers (GMs) through Faraday wave bioassembly, a typical acoustic "bottom-up" manufacturing process. Assembly modules are first prepared by incorporating cartilage precursor cells, the chondrogenic cell line ATDC5, or bone marrow-derived mesenchymal stem cells (BMSCs), into GMs. Patterned structures are formed by Faraday wave bioassembly of the cell-laden GMs. Due to the gentle and efficient assembly process and the protective effects of microcarriers, cells in the patterned structures maintain high activity. Subsequently, tissue-engineered cartilage constructs are obtained by inducing cell differentiation of the patterned structures. Comprehensive evaluations are conducted to verify chondrocyte differentiation and the formation of cartilage tissue constructs in terms of cell viability, morphological analysis, gene expression, and matrix production. Finally, implantation studies with a rat cartilage defect model demonstrate that these tissue-engineered cartilage constructs are beneficial for the repair of articular cartilage damage in vivo. This study provides the first biofabrication of cartilage tissue constructs using Faraday wave bioassembly, extending its application to engineering tissues with a low cell density.

Exploring biological mechanisms in orthodontic tooth movement: Bridging the gap between basic research experiments and clinical applications – A comprehensive review

ObjectivesThe molecular mechanisms behind orthodontic tooth movements (OTM) were investigated by clarifying the role of chemical messengers released by cells. MethodsUsing the Cochrane library, Google scholar, and PubMed databases, a literature search was conducted, and studies published from 1984 to 2024 were considered. ResultsBoth bone growth and remodeling may occur when a tooth is subjected to mechanical stress. These chemicals have a significant effect on the stimulation and regulation of osteoblasts, osteoclasts, and osteocytes during alveolar bone remodeling. This regulation can take place in pathological conditions, such as periodontal diseases, or during OTM alone. This comprehensive review outlines key molecular mechanisms underlying OTM and explores various clinical assumptions associated with specific molecules and their functional domains during this process. Furthermore, clinical applications of certain molecules such as relaxin, prostaglandin E (PGE), and interleukin-1β (IL-1β) in accelerating OTM have been reported. Our findings underscore the existing gap between OTM clinical applications and basic research investigations. ConclusionA comprehensive understanding of orthodontic treatment is enriched by insights into biological systems. We reported the activation of osteoblasts, osteoclast precursor cells, osteoclasts, and osteocytes in response to mechanical stress, leading to targeted cellular and molecular interventions and facilitating rapid and regulated alveolar bone remodeling during tooth movement. Despite the shortcomings of clinical studies in accelerating OTM, this review highlights the crucial role of biological agents in this process and advocates for prioritizing high-quality human studies in future research to gain further insights from clinical trials.