Dendritic cell-mimicking scaffolds for ex vivo T cell expansion

We propose an ex vivo T cell expansion system that mimics natural antigen-presenting cells(APCs)for adoptive cell therapy(ACT).Microfiber scaffolds coated with dendritic cell(DC)membrane replicate physicochemical properties of dendritic cells specific for T cell activation such as rapid recognition by T cells,long duration of T cell tethering,and DC-specific co-stimulatory cues.The DC membrane-coated scaffold is first surface-immobilized with T cell stimulatory ligands,anti-CD3(αCD3)and anti-CD28(αCD28)antibodies,followed by adsorption of releasable interleukin-2(IL-2).The scaffolds present both surface and soluble cues to T cells ex vivo in the same way that these cues are presented by natural APCs in vivo.We demonstrate that the DC-mimicking scaffold promotes greater polyclonal expansion of primary human T cells as compared toαCD3/αCD28-func-tionalized Dynabead.More importantly,major histocompatibility complex molecules derived from the DC membrane of the scaffold allow antigen-specific T cell expansion with target cell-specific killing ability.In addition,most of the expanded T cells(~97%)can be harvested from the scaffold by density gradient centri-fugation.Overall,the DC-mimicking scaffold offers a scalable,modular,and customizable platform for rapid expansion of highly functional T cells for ACT.

The O2-ZmGRAS11 transcriptional regulatory network orchestrates the coordination of endosperm cell expansion and grain filling in maize

Maize(Zea mays)endosperm filling is coordinated with cell expansion to enlarge the grain size,but the mechanism coupling the two processes is poorly understood.Starchy endosperm cells basically contain no visible vacuoles for cell expansion.During grain filling,efficient synthesis of storage compounds leads to reduced cytoplasm and thus lowered cell turgor pressure.Although bioactive gibberellins(GAs)are essential for cell expansion,they accumulate at a low level at this stage.In this study,we identified an endosperm-specific GRAS domain-containing protein(ZmGRAS11)that lacks the DELLA domain and promotes cell expansion in the filling endosperm.The zmgras11 loss-of-function mutants showed normal grain filling but delayed cell expansion,thereby resulting in reduced kernel size and weight.Overexpression of ZmGRAS11 led to larger endosperm cells and therefore increased kernel size and weight.Consistent with this,ZmGRAS11 positively regulates the expression of ZmEXPB12,which is essential for cell expansion,at the endosperm filling stage.Moreover,we found that Opaque2(O2),a central transcription factor that regulates endosperm filling,could directly bind to the promoter of ZmGRAS11 and activate its expression.Taken together,these results suggest that endosperm cell expansion is coupled with endosperm filling,which is orchestrated by the O2-ZmGRAS11-centered transcriptional regulatory network.Our findings also provide potential targets for maize yield improvement by increasing the storage capacity of endosperm cells.

Porous polyetheretherketone microcarriers fabricated via hydroxylation together with cellderived mineralized extracellular matrix coatings promote cell expansion and bone regeneration

Porous microcarriers have aroused increasing attention recently by facilitating oxygen and nutrient transfer,supporting cell attachment and growth with sufficient cell seeding density.In this study,porous polyetheretherketone(PEEK)microcarriers coated with mineralized extracellular matrix(mECM),known for their chemical,mechanical and biological superiority,were developed for orthopedic applications.Porous PEEK microcarriers were derived from smooth microcarriers using a simple wet-chemistry strategy involving the reduction of carbonyl groups.This treatment simultaneously modified surface topology and chemical composition.Furthermore,the microstructure,protein absorption,cytotoxicity and bioactivity of the obtained porous microcarriers were investigated.The deposition of mECM through repeated recellularization and decellularization on the surface of porous MCs further promoted cell proliferation and osteogenic activity.Additionally,the mECM coated porous microcarriers exhibited excellent bone regeneration in a rat calvarial defect repair model in vivo,suggesting huge potential applications in bone tissue engineering.

Cell Production and Expansion in the Primary Root of Maize in Response to Low-Nitrogen Stress

Maize plants respond to low-nitrogen stress by enhancing root elongation. The underlying physiological mechanism remains unknown. Seedlings of maize （Zea mays L., cv. Zhengdan 958） were grown in hydroponics with the control （4 mmol L-1） or low-nitrogen （40 μmol L-1） for 12 d, supplied as nitrate. Low nitrogen enhanced root elongation rate by 4.1-fold, accompanied by increases in cell production rate by 2.2-fold, maximal elemental elongation rate （by 2.5-fold）, the length of elongation zone （by 1.5-fold）, and ifnal cell length by 1.8-fold. On low nitrogen, the higher cell production rate resulted from a higher cell division rate and in fact the number of dividing cells was reduced. Consequently, the residence time of a cell in the division zone tended to be shorter under low nitrogen. In addition, low nitrogen increased root diameter, an increase that occurred speciifcally in the cortex and was accompanied by an increase in cell number. It is concluded that roots elongates in response to low-nitrogen stress by accelerating cell production and expansion.

Recent progress in studies of factors that elicil pancreatic β-cell expansion

The loss of or decreased functional pancreatic β-cell is a major cause of type 1 and type 2 diabetes. Previous studies have shown that adult β-cells can maintain their ability for a low level of turnover through replication and neogenesis. Thus, a strategy to prevent and treat dia- betes would be to enhance the ability of β-cells to increase the mass of functionalβ-cells. Consequently, much effort has been devoted to identify factors that can effectively induce β-cell expansion. This review focuses on recent reports on small molecules and protein fac- tors that have been shown to promote β-cell expansion.

The Cross-talk between ROS and p38MAPKα in the Ex Vivo Expanded Human Umbilical Cord Blood CD133^+ Cells

This study investigated the correlation between and compared the effects of reactive oxygen species（ROS） and p38 mitogen-activated protein kinase α（p38MAPKα） in the ex vivo expanded umbilical cord blood（hUCB） CD133＋ cells.hUCB CD133＋ cells were cultured in the hematopoietic stem cells（HSCs） culture medium with N-acetylcysteine（NAC,an anti-oxidant）,p38MAPKα-specific inhibitor（SB203580） or their combination.The levels of ROS and expression of phosphorylated p38MAPKα（p-p38） in CD133＋ cells were flow cytometrically detected.The efficacy of ex vivo expansion was evaluated by the density of CD133＋ cell sub-group colony-forming cells（CFC） and cobblestone area-forming cells（CAFC） assay.Our results showed decreased ROS levels in NAC,SB203580,and their combination treatment groups were almost 37%,48%,and 85%,respectively.Furthermore,SB203580 abrogated the activation of p38MAPKα more obviously than NAC.Moreover,the CD133＋ cells in SB203580 treatment group had a 21.93±1.36-fold increase,and 14.50±1.19-fold increase in NAC treatment group,but only 10.13±0.57-fold increase in control group.In addition,SB203580 treatment led a higher level increase in the number of CFU and CAFC than NAC did.These findings suggested that,in expanded CD133＋ cells,ROS activates p38MAPKα,which,in turn,induces ROS production,and p38MAPKα might be the most suitable regulator in ROS-p38MAPKα pathway for the promotion of HSCs ex vivo expansion.

Human CD34loCD133lo fetal liver cells support the expansion of human CD34hiCD133hi hematopoietic stem cells

We have recently discovered a unique CD34loCD133lo cell population in the human fetal liver （FL） that gives rise to cells in the hepatic lineage. In this study, we further characterized the biological functions of FL CD341~CD133~~ cells. Our findings show that these CD341~CD133I~ cells express markers of both endodermal and mesodermal lineages and have the capability to differentiate into hepatocyte and mesenchymal lineage cells by ex vivo differentiation assays. Furthermore, we show that CD34~~CD 133I~ cel Is express growth factors that are important for human hematopoietic stem cell （HSC） expansion： stem cell factor （SCF）, insulin-like growth factor 2 （IGF2）, C-X-C motif chemokine 12 （CXCL12）, and factors in the angiopoietin-like protein family. Co-culture of autologous FL HSCs and allogenic HSCs derived from cord blood with CD34loCD133lo cells supports and expands both types of HSCs.These findings are not only essential for extending our understanding of the HSC niche during the development of embryonic and fetal hematopoiesis but will also potentially benefit adult stem cell transplantations in clinics because expanded HSCs demonstrate the same capacity as primary cells to reconstitute the human immune system and mediate long-term hematopoiesis in vivo. Together,CD34loCD133lo cells not only serve as stem/progenitor cells for liver development but are also an essential component of the HSC niche in the human FL.

Clustering-based adaptive low-power subframe configuration with load-aware offsetting in dense heterogeneous networks

Heterogeneous Networks(HetNets)and cell densification represent promising solutions for the surging data traffic demand in wireless networks.In dense HetNets,user traffic is steered toward the Low-Power Node(LPN)when possible to enhance the user throughput and system capacity by increasing the area spectral efficiency.However,because of the transmit power differences in different tiers of HetNets and irregular service demand,a load imbalance typically exists among different serving nodes.To offload more traffic to LPNs and coordinate the Inter-Cell Interference(ICI),Third-Generation Partnership Project(3GPP)has facilitated the development of the Cell Range Expansion(CRE),enhanced Inter-Cell Interference Coordination(eICIC)and Further enhanced ICIC(FeICIC).In this paper,we develop a cell clustering-based load-aware offsetting and an adaptive Low-Power Subframe(LPS)approach.Our solution allows the separation of User Association(UA)functions at the User Equipment(UE)and network server such that users can make a simple cell-selection decision similar to that in the maximum Received Signal Strength(max-RSS)based UA scheme,where the network server computes the load-aware offsetting and required LPS periods based on the load conditions of the system.The proposed solution is evaluated using system-level simulations wherein the results correspond to performance changes in different service regions.Results show that our method effectively solves the offloading and interference coordination problems in dense HetNets.

Overexpression of ACL 1 （abaxially curled leaf 1） Increased Bulliform Cells and Induced Abaxial Curling of Leaf Blades in Rice

Understanding the genetic mechanism underlying rice leaf-shape development is crucial for optimizing rice configuration and achieving high yields; however, little is known about leaf abaxial curling. We isolated a rice transferred DNA （T-DNA） insertion mutant, BY240, which exhibited an abaxial leaf curling phenotype that co-segregated with the inserted T-DNA. The T-DNA was inserted in the promoter of a novel gene, ACL1 （Abaxially Curled Leaf 1）, and led to overexpression of this gene in BY240. Overexpression of ACL1 in wild-type rice also resulted in abaxial leaf curling. ACL1 encodes a protein of 116 amino acids with no known conserved functional domains. Overexpression of ACL2, the only homolog of ACL1 in rice, also induced abaxial leaf curling. RT-PCR analysis revealed high expressions of ACLs in leaf sheaths and leaf blades, suggesting a role for these genes in leaf development. In situ hybridization revealed non-tissue-specific expression of the ACLs in the shoot apical meristem, leaf primordium, and young leaf. Histological analysis showed increased number and exaggeration of bulliform cells and expansion of epidermal cells in the leaves of BY240, which caused developmental discoordination of the abaxial and adaxial sides, resulting in abaxially curled leaves. These results revealed an important mechanism in rice leaf development and provided the genetic basis for agricultural improvement.

Cellulose Synthases and Synthesis in Arabidopsis

Plant cell walls are complex structures composed of high-molecular-weight polysaccharides, proteins, and lignins. Among the wall polysaccharides, cellulose, a hydrogen-bonded β-1,4-1inked glucan microfibril, is the main load-bearing wall component and a key precursor for industrial applications. Cellulose is synthesized by large multi-meric cellulose synthase （CesA） complexes, tracking along cortical microtubules at the plasma membrane. The only known components of these complexes are the cellulose synthase proteins. Recent studies have identified tentative interaction partners for the CesAs and shown that the migratory patterns of the CesA complexes depend on phosphorylation status. These advances may become good platforms for expanding our knowledge about cellulose synthesis in the near future. In addition, our current understanding of cellulose chain polymerization in the context of the CesA complex is discussed.

OsGLU3, a Putative Membrane-Bound Endo-1, 4-Beta-Glucanase, Is Required for Root Cell Elongation and Division in Rice （Oryza sativa L.）

Plant roots move through the soil by elongation. This is vital to their ability to anchor the plant and acquire water and minerals from the soil. In order to identify new genes involved in root elongation in rice, we screened an ethyl methane sulfonate （EMS）-mutagenized rice library, and isolated a short root mutant, Osglu3-1. The map-based cloning results showed that the mutant was due to a point mutation in OsGLU3, which encodes a putative membrane-bound endo- 1,4-13-glucanase. Osglu3-1 displayed less crystalline cellulose content in its root cell wall, shorter root cell length, and a slightly smaller root meristem as visualized by restricted expression of OsCYCBI, I：GUS. Exogenous application of glu- cose can suppress both the lower root cell wall cellulose content and short root phenotypes of Osglu3-1. Consistently, OsGLU3 is ubiquitously expressed in various tissues with strong expression in root tip, lateral root, and crown root pri- modia. The fully functional OsGLU3-GFP was detected in plasma membrane, and FM4-64-1abeled compartments in the root meristem and elongation zones. We also found that phosphate starvation, an environmental stress, altered cell wall cel- lulose content to modulate root elongation in a OsGLU3-dependant way.

Control of Cell Wall Extensibility during Pollen Tube Growth

In this review, we address the question of how the tip-growing pollen tube achieves its rapid rate of elongation while maintaining an intact cell wall. Although turgor is essential for growth to occur, the local expansion rate is controlled by local changes in the viscosity of the apical wall. We focus on several different structures and underly- ing processes that are thought to be major participants including exocytosis, the organization and activity of the actin cytoskeleton, calcium and proton physiology, and cellular energetics. We think that the actin cytoskeleton, in particular the apical cortical actin fringe, directs the flow of vesicles to the apical domain, where they fuse with the plasma mem- brane and contribute their contents to the expanding cell wall. While pH gradients, as generated by a proton-ATPase located on the plasma membrane along the side of the clear zone, may regulate rapid actin turnover and new polymeri- zation in the fringe, the tip-focused calcium gradient biases secretion towards the polar axis. The recent data showing that exocytosis of new wall material precedes and predicts the process of cell elongation provide support for the idea that the intussusception of newly secreted pectin contributes to decreases in apical wall viscosity and to cell expansion. Other prime factors will be the localization and activity of the enzyme pectin methyl-esterase, and the chelation of calcium by pectic acids. Finally, we acknowledge a role for reactive oxygen species in the control of wall viscosity.

Focusing on the Focus： What Else beYOnd the Master Switches for Polar Cell Growth？

Cell polarity, often associated with polarized cell expansion/growth in plants, describes the uneven distribution of cellular components, such as proteins, nucleic acids, signaling molecules, vesicles, cytoskeletal elements, and organelles, which may ultimately modulate cell shape, structure, and function. Pollen tubes and root hairs are model cell systems for studying the molecular mechanisms underlying sustained tip growth. The formation of intercalated epidermal pavement cells requires excitatory and inhibitory pathways to coordinate cell expansion within single cells and between cells in contact. Strictly controlled cell expansion is linked to asymmetric cell division in zygotes and stomatal lineages, which require integrated processes of pre-mitotic cellular polarization and division asymmetry. While small GTPase ROPs are recognized as fundamental signaling switches for cell polarity in various cellular and developmental processes in plants, the broader molecular machinery underpinning polarity establishment required for asymmetric division remains largely unknown. Here, we review the widely used ROP signaling pathways in cell polar growth and the recently discovered feedback loops with auxin signaling and PIN effluxers. We discuss the conserved phosphorylation and phospholipid signaling mechanisms for regulating uneven distribution of proteins, as well as the potential roles of novel proteins and MAPKs in the polarity establishment related to asymmetric cell division in plants.

Microanalysis of Plant Cell Wall Polysaccharides

Oligosaccharide Mass Profiling （OLIMP） allows a fast and sensitive assessment of cell wall polymer structure when coupled with Matrix Assisted Laser Desorption Ionisation Time Of Flight Mass Spectrometry （MALDI-TOF MS）. The short time required for sample preparation and analysis makes possible the study of a wide range of plant organs, revealing a high degree of heterogeneity in the substitution pattern of wall polymers such as the cross-linking glycan xyloglucan and the pectic polysaccharide homogalacturonan. The high sensitivity of MALDI-TOF allows the use of small amounts of samples, thus making it possible to investigate the wall structure of single cell types when material is collected by such methods as laser micro-dissection. As an example, the analysis of the xyloglucan structure in the leaf cell types outer epidermis layer, entire epidermis cell layer, palisade mesophyll cells, and vascular bundles were investigated. OLIMP is amenable to in situ wall analysis, where wall polymers are analyzed on unprepared plant tissue itself without first isolating cell walls. In addition, OLIMP enables analysis of wall polymers in Golgi-enriched fractions, the location of nascent matrix polysaccharide biosynthesis, enabling separation of the processes of wall biosynthesis versus post-deposition apoplastic metabolism. These new tools will make possible a semi-quantitative analysis of the cell wall at an unprecedented level.

Overexpression of OsKTN80a, a katanin P80ortholog, caused the repressed cell elongation and stalled cell division mediated by microtubule apparatus defects in primary root in Oryza sativa

Katanin, a microtubule-severing enzyme, consists of two subunits：the catalytic subunit P60, and the regulatory subunit P80. In several species, P80 functions in meiotic spindle organization, the flagella biogenesis, the neuronal development, and the male gamete production. However, the P80 function in higher plants remains elusive. In this study, we found that there are three katanin P80 orthologs （OsKTN80a, OsKTN80b, and OsKTN80c） in Oryza sativa L. Overexpression of OsKTN80a caused the retarded root growth of rice seedlings. Further investigation indicates that the retained root growth was caused by the repressed cell elongation in the elongation zone and the stalled cytokinesis in the division zone in the root tip. The in vivo examination suggests that OsKTN80a acts as a microtubule stabilizer. We＆amp;nbsp;prove that OsKTN80a, possibly associated with OsKTN60, is involved in root growth via regulating the cell elongation and division.

RALF–FERONIA Signaling: Linking Plant Immune Response with Cell Growth

Plants perceive various external and internal signals to self-modulate biological processes through members of the receptor-like kinase(RLK)family,among which Catharanthus roseus receptor-like kinase 1-like(CrRLK1L)proteins with their ligands,rapid alkalinization factor(RALF)peptides,have attracted considerable interest.FERONIA(FER),a CrRLK1L member,was initially reported to act as a major plant cell growth modulator in distinct tissues.Subsequently,the RALF–FER pathway was confirmed to function as an essential regulator of plant stress responses,including but not limited to immune responses.Furthermore,the RALF–FER pathway modulates immune responses and cell growth in a context-specific manner,and the vital roles of this pathway are beginning to be appreciated in crop species.The recent remarkable advances in understanding the functions and molecular mechanisms of the RALF–FER pathway have also raised many interesting questions that need to be answered in the future.This review mainly focuses on the roles of FER and other CrRLK1L members in modulating immune responses in the context of cell growth in response to their RALF peptide ligands and presents a brief outlook for future research.

Arabidopsis ROOT ELONGATION RECEPTOR KINASES negatively regulate root growth putatively via altering cell wall remodeling gene expression

Receptor-like kinases(RLKs)play key roles in regulating various physiological aspects in plant growth and development.In Arabidopsis thaliana,there are at least 223 leucine-rich repeat(LRR)RLKs.The functions of the majority of RLKs in the LRR XI subfamily were previously revealed.Only three RLKs were not characterized.Here we report that two independent triple mutants of these RLKs,named ROOT ELONGATION RECEPTOR KINASES(REKs),exhibit increased cell numbers in the root apical meristem and enhanced cell size in the elongation and maturation zones.The promoter activities of a number of Quiescent Center marker genes are significantly up-regulated in the triple mutant.However,the promoter activities of several marker genes known to control root stem cell niche activities are not altered.RNA-seq analysis revealed that a number of cell wall remodeling genes are significantly up-regulated in the triple mutant.Our results suggest that these REKs play key roles in regulating root development likely via negatively regulating the expression of a number of key cell wall remodeling genes.