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Secreted protein acidic and rich in cysteine (SPARC) shows a specific colocalization with limbal epithelial stem cells (LESCs) in vivo; however, the inherent relationship between SPARC and LESCs is still unclear. This study investigated the effects of SPARC on the maintenance of LESC stemness and corneal wound healing. To test the influence of different concentration of exogenous SPARC on the proliferation of LESCs, cell counting kit-8 assay and 5-ethynyl-2′-deoxyuridine staining were performed and the results indicated that 1 μg/mL SPARC was the optimum concentration for enhanced LESC proliferation. Compared with a control group, SPARC-treated group showed a higher expression of LESC-positive markers p63α, ABCG-2, and Bmi-1, and a lower level of differentiation marker cytokeratin-3 (CK3), thereby suggesting that SPARC could maintain LESC characteristic phenotype and suppress spontaneous epithelial differentiation in vitro. In vivo, exogenous SPARC accelerated the wound-healing process by both the enhancement of LESC proliferation and promoting the migration of the proliferating cells. However, the intact epithelium impaired this function of SPARC by contact inhibition. [ABSTRACT FROM AUTHOR]

Cells migrate collectively to form tissues and organs during morphogenesis. Contact inhibition of locomotion (CIL) drives collective migration by inhibiting lamellipodial protrusions at cell–cell contacts and promoting polarization at the leading edge. Here, we report a CIL-related collective cell behavior of myotubes that lack lamellipodial protrusions, but instead use filopodia to move as a cohesive cluster in a formin-dependent manner. We perform genetic, pharmacological and mechanical perturbation analyses to reveal the essential roles of Rac2, Cdc42 and Rho1 in myotube migration. These factors differentially control protrusion dynamics and cell–matrix adhesion formation. We also show that active Rho1 GTPase localizes at retracting free edge filopodia and that Rok-dependent actomyosin contractility does not mediate a contraction of protrusions at cell–cell contacts, but likely plays an important role in the constriction of supracellular actin cables. Based on these findings, we propose that contact-dependent asymmetry of cell–matrix adhesion drives directional movement, whereas contractile actin cables contribute to the integrity of the migrating cell cluster. Contact stimulation of migration drives tissue morphogenesis. Here the authors report that filopodia-based contact-dependent asymmetry of cell–matrix adhesion drives directional movement, whereas contractile actin cables contribute to the integrity of the migrating cell cluster in the myotubes of Drosophila developing testes. [ABSTRACT FROM AUTHOR]

Classical r- vs. K -selection theory describes the trade-offs between high reproductive output and competitiveness and guides research in evolutionary ecology. While its impact has waned in the recent past, cancer evolution may rekindle it. Herein, we impose r - or K -selection on cancer cell lines to obtain strongly proliferative r cells and highly competitive K cells to test ideas on life-history strategy evolution. RNA-seq indicates that the trade-offs are associated with distinct expression of genes involved in the cell cycle, adhesion, apoptosis, and contact inhibition. Both empirical observations and simulations based on an ecological competition model show that the trade-off between cell proliferation and competitiveness can evolve adaptively. When the r and K cells are mixed, they exhibit strikingly different spatial and temporal distributions. Due to this niche separation, the fitness of the entire tumor increases. The contrasting selective pressure may operate in a realistic ecological setting of actual tumors. [ABSTRACT FROM AUTHOR]

Pioglitazone (PIO), an oral hypoglycemic agent, is used in the treatment of type 2 diabetes. Some studies have suggested that an increased risk of bladder cancer with PIO exposure, while the others reported there is no such relationship. Therefore, it is doubtful whether PIO can increase the risk of bladder cancer. The effects of PIO on DNA damage and/or transformation of human bladder cells are not fully known. We investigated the effects of PIO on cytotoxicity, DNA single and double strand breaks and repair and neoplastic transformation in human bladder cells (hTU1) treated with 10, 20, and 40 μM PIO for 24, 48 and 72 hr. PIO decreased cell viability in a concentration‐dependent manner. Increased levels of comet parameters showed that PIO and its metabolites can significantly induce DNA double strand breaks at all concentrations tested. PIO also significantly induced the formation of phosphorylated H2AX and p53 binding protein 1 foci. DNA damage was not repaired in a 24 hr recovery period. PIO can also induce malignant transformation of human bladder cells exhibiting loss of contact inhibition and anchorage independent growth. This is the first study to indicate that PIO can induce DNA damage and malignant transformation, reduce or alter the DNA repair capacity in human bladder cells. From these results, we suggest that patients with diabetes treated with PIO may have an increased risk of bladder cancer. [ABSTRACT FROM AUTHOR]

Intracellular pathogens have evolved to utilize normal cellular processes to complete their replicative cycles. Pathogens that interface with proliferative cell signaling pathways risk infections that can lead to cancers, but the factors that influence malignant outcomes are incompletely understood. Human papillomaviruses (HPVs) predominantly cause benign hyperplasia in stratifying epithelial tissues. However, a subset of carcinogenic or "high-risk" HPV (hr-HPV) genotypes are etiologically linked to nearly 5% of all human cancers. Progression of hr-HPV-induced lesions to malignancies is characterized by increased expression of the E6 and E7 oncogenes and the oncogenic functions of these viral proteins have been widely studied. Yet, the mechanisms that regulate hr-HPV oncogene transcription and suppress their expression in benign lesions remain poorly understood. Here, we demonstrate that EGFR/MEK/ERK signaling, influenced by epithelial contact inhibition and tissue differentiation cues, regulates hr-HPV oncogene expression. Using monolayer cells, epithelial organotypic tissue models, and neoplastic tissue biopsy materials, we show that cell-extrinsic activation of ERK overrides cellular control to promote HPV oncogene expression and the neoplastic phenotype. Our data suggest that HPVs are adapted to use the EGFR/MEK/ERK signaling pathway to regulate their productive replicative cycles. Mechanistic studies show that EGFR/MEK/ERK signaling influences AP-1 transcription factor activity and AP-1 factor knockdown reduces oncogene transcription. Furthermore, pharmacological inhibitors of EGFR, MEK, and ERK signaling quash HPV oncogene expression and the neoplastic phenotype, revealing a potential clinical strategy to suppress uncontrolled cell proliferation, reduce oncogene expression and treat HPV neoplasia. Author summary: Human papillomavirus (HPV) infections occur in differentiating squamous epithelium and induce hyperplasia during the viral replicative cycle. Although HPV oncogene expression is necessary to promote cellular proliferation for viral genome amplification in the middle epithelial layers, oncogene levels are thereafter suppressed to permit differentiation-induced late gene expression in the uppermost epithelial cells. Yet, the mechanisms responsible for controlling HPV oncogene expression are not well understood. Here, we demonstrate that EGFR/MEK/ERK signaling, which is subject to the normal cellular cues of contact inhibition and epithelial tissue differentiation, is a critical regulator of hr-HPV oncogene expression. We found that extrinsic activation of ERK overrides cellular control to promote oncogene expression and the neoplastic phenotype. Many epidemiologically defined risk factors activate the EGFR/MEK/ERK pathway, suggesting a common mechanism whereby they may promote HPV persistence and disease progression. Lastly, we show that HPV oncogene transcription and protein expression remain susceptible to MEK/ERK control in early neoplastic tissues and tumor cells and that targeted inhibition of MEK/ERK signaling might be exploited therapeutically for HPV-induced infections and tumors. [ABSTRACT FROM AUTHOR]

Cells that collide with each other repolarize away from contact, in a process called contact inhibition of locomotion (CIL), which is necessary for correct development of the embryo. CIL can occur even when cells make a micron-scale contact with a neighbor-much smaller than their size. How precisely can a cell sense cell-cell contact and repolarize in the correct direction? What factors control whether a cell recognizes it has contacted a neighbor? We propose a theoretical model for the limits of CIL where cells recognize the presence of another cell by binding the protein ephrin with the Eph receptor. This recognition is made difficult by the presence of interfering ligands that bind nonspecifically. Both theoretical predictions and simulation results show that it becomes more difficult to sense cell-cell contact when it is difficult to distinguish ephrin from the interfering ligands, or when there are more interfering ligands, or when the contact width decreases. However, the error of estimating contact position remains almost constant when the contact width changes. This happens because the cell gains spatial information largely from the boundaries of cell-cell contact. We study using statistical decision theory the likelihood of a false-positive CIL event in the absence of cell-cell contact, and the likelihood of a false negative where CIL does not occur when another cell is present. Our results suggest that the cell is more likely to make incorrect decisions when the contact width is very small or so large that it nears the cell's perimeter. However, in general, we find that cells have the ability to make reasonably reliable CIL decisions even for very narrow (micron-scale) contacts, even if the concentration of interfering ligands is ten times that of the correct ligands.

Cells in a tumor are heterogeneous, often including a small number of tumor-initiating cells (TICs) and the majority of cancerous and non-cancerous cells. We have previously reported that constitutive activation of Notch signaling in adipocytes of mice leads to dedifferentiated liposarcoma (DDLPS), an aggressive liposarcoma (LPS) with no effective treatment. Here, we explored the role of Notch signaling in cellular heterogeneity of LPS. We performed serial transplantations to enrich for TICs, and derived cells exhibiting sustained Notch activation (mLPS1 cells) and cells with normal Notch activity (mLPS2 cells). Both mLPS1 and mLPS2 cells proliferated rapidly, and neither exhibited contact inhibition. However, only the mLPS1 cells exhibited tumorigenicity and gave rise to LPS upon engraftment into mice. The mLPS1 cells also highly expressed markers of cancer stem cells (Cd133) , mesenchymal stem cells (Cd73 , Cd90 , Cd105, Dlk1) and the long non-coding RNA Rian. By contrast, the mLPS2 cells accumulated lipid droplets and expressed mature adipocyte markers when induced to differentiate. Most importantly, CRISPR-mediated disruption of Notch abrogated the tumorigenic properties of mLPS1 cells. These results reveal a key role of Notch signaling in maintaining TICs in LPS. Image 1 • Liposarcomas are heterogeneous and contain tumor-initiating cells (TICs). • Serial transplantation of liposarcomas efficiently enrich TICs. • Notch activation is a signature of TICs in liposarcoma. • Liposarcoma TICs express genes of cancer and mesenchymal stem cells. [ABSTRACT FROM AUTHOR]

Purpose: Corneal endothelial dystrophies are characterized by endothelial cell loss and dysfunction. Recent evidence suggests that corneal endothelial cells (CECs) can regenerate although they do not do so under normal conditions. This work sought to test whether CECs can be stimulated to proliferate in organ culture by wounding and/or by treatment with the engineered human fibroblast growth factor 1 (FGF1) derivative TTHX1114. Methods: Human donor corneas obtained from eye banks were maintained in organ culture in the presence or absence of TTHX1114. Wounds in the corneas were created by quartering the corneas. The CEC monolayer was identified as a regular layer by Hoechst staining of the nuclear DNA with cell outlines delineated by immunohistochemical identification of ZO-1. Nuclei and nuclei incorporating 5-ethynyl-2'-deoxyuridine (EdU) were counted using ImageJ. Results: CECs in normal corneas in undisturbed monolayers had low, but measurable, rates of proliferation. CECs at the edge of a wound had higher rates of proliferation, probably due to the release of contact inhibition. TTHX1114 increased proliferation at wound edges. After 7 days of culture, proliferating CECs formed contiguous groups of labeled cells that did not migrate away from one another. TTHX1114-treated cells, including the EdU labeled proliferating cells, retained normal morphology, including cell/cell junction ZO-1 staining. Conclusions: Proliferation of CECs in organ-cultured corneas is low, but can be stimulated by wounding or by the administration of TTHX1114 with the effects of each being additive. The CEC monolayer appears to have a population of progenitor cells that are susceptible to stimulation. [ABSTRACT FROM AUTHOR]

This chapter discusses our current knowledge on the major segregation events that lead to the individualization of the building blocks of vertebrate organisms, starting with the segregation between "outer" and "inner" cells, the separation of the germ layers and the maintenance of their boundaries during gastrulation, and finally the emergence of the primary axial structure, the notochord. The amphibian embryo is used as the prototypical model, to which fish and mouse development are compared. This comparison highlights a striking conservation of the basic processes. It suggests that simple principles may account for the formation of divergent structures. One of them is based on the non-adhesive nature of the apical domain of epithelial cells, exploited to segregate superficial and deep cell populations as a result of asymmetric division. The other principle involves differential expression of contact cues, such as ephrins and protocadherins, to build up high tension along adhesive interfaces, which efficiently creates sharp boundaries. [ABSTRACT FROM AUTHOR]

Research results on the formation and structuring of disperse jet fuel systems of fuel TS-1 in contact with icing inhibition liquids and without them with water and the formation of an aggregated disperse phase, which is one of the causes of fuel system failures of aircraft, are presented. [ABSTRACT FROM AUTHOR]

Collective migration, themovement of groups inwhich individuals affect the behaviour of one another, occurs at practically every scale, from bacteria up to whole species' populations. Universal principles of collective movement can be applied at all levels. In this review, we will describe the rules governing collectivemotility, with a specific focus on the neural crest, an embryonic stem cell population that undergoes extensive collective migration during development. We will discuss howthe underlying principles of individual cell behaviour, and those that emerge from a supracellular scale, can explain collective migration. [ABSTRACT FROM AUTHOR]

C3A is a subclone of the human hepatoblastoma HepG2 cell line with strong contact inhibition of growth. We fortuitously found that C3A was more susceptible to human coronavirus HCoV-OC43 infection than HepG2, which was attributed to the increased efficiency of virus entry into C3A cells. In an effort to search for the host cellular protein(s) mediating the differential susceptibility of the two cell lines to HCoV-OC43 infection, we found that ArfGAP with dual pleckstrin homology (PH) domains 2 (ADAP2), gamma-interferon-inducible lysosome/endosome-localized thiolreductase (GILT), and lymphocyte antigen 6 family member E (LY6E), the three cellular proteins identified to function in interference with virus entry, were expressed at significantly higher levels in HepG2 cells. Functional analyses revealed that ectopic expression of LY6E, but not GILT or ADAP2, in HEK 293 cells inhibited the entry of HCoV-O43. While overexpression of LY6E in C3A and A549 cells efficiently inhibited the infection of HCoV-OC43, knockdown of LY6E expression in HepG2 significantly increased its susceptibility to HCoV-OC43 infection. Moreover, we found that LY6E also efficiently restricted the entry mediated by the envelope spike proteins of other human coronaviruses, including the currently pandemic SARS-CoV-2. Interestingly, overexpression of serine protease TMPRSS2 or amphotericin treatment significantly neutralized the IFN-inducible transmembrane 3 (IFITM3) restriction of human coronavirus (CoV) entry, but did not compromise the effect of LY6E on the entry of human coronaviruses. The work reported herein thus demonstrates that LY6E is a critical antiviral immune effector that controls CoV infection and pathogenesis via a mechanism distinct from other factors that modulate CoV entry. [ABSTRACT FROM AUTHOR]

Homogenization of the initial cell distribution is essential for effective cell development. However, there are few previous reports on efficient cell seeding methods, even though the initial cell distribution has a large effect on cell proliferation. Dense cell regions have an inverse impact on cell development, known as contact inhibition. In this study, we developed a method to homogenize the cell seeding density using secondary flow, or Ekman transportation, induced by orbital movement of the culture dish. We developed an orbital shaker device that can stir the medium in a 35-mm culture dish by shaking the dish along a circular orbit with 2 mm of eccentricity. The distribution of cells in the culture dish can be controlled by the rotational speed of the orbital shaker, enabling dispersion of the initial cell distribution. The experimental results indicated that the cell density became most homogeneous at 61 rpm. We further evaluated the cell proliferation after homogenization of the initial cell density at 61 rpm. The results revealed 36% higher proliferation for the stirred samples compared with the non-stirred control samples. The present findings indicate that homogenization of the initial cell density by Ekman transportation contributes to the achievement of higher cell proliferation. [ABSTRACT FROM AUTHOR]

Glioblastoma is a deadly cancer, with no effective therapies. Better understanding and identification of selective targets are urgently needed. We found that advillin (AVIL) is overexpressed in all the glioblastomas we tested including glioblastoma stem/initiating cells, but hardly detectable in non-neoplastic astrocytes, neural stem cells or normal brain. Glioma patients with increased AVIL expression have a worse prognosis. Silencing AVIL nearly eradicated glioblastoma cells in culture, and dramatically inhibited in vivo xenografts in mice, but had no effect on normal control cells. Conversely, overexpressing AVIL promoted cell proliferation and migration, enabled fibroblasts to escape contact inhibition, and transformed immortalized astrocytes, supporting AVIL being a bona fide oncogene. We provide evidence that the tumorigenic effect of AVIL is partly mediated by FOXM1, which regulates LIN28B, whose expression also correlates with clinical prognosis. AVIL regulates the cytoskeleton through modulating F-actin, while mutants disrupting F-actin binding are defective in its tumorigenic capabilities. Genes that modulate the cytoskeleton have been associated with increased cell proliferation and migration. Here, the authors show that AVIL, an actin regulatory protein, is overexpressed in glioblastomas and mediates oncogenic effects through regulation of FOXM1 stability and LIN28B expression. [ABSTRACT FROM AUTHOR]

p27Kip1, a member of the Cip/Kip family of cyclin-dependent kinase (CDK) inhibitors, is now known as a multifunctional protein that plays crucial roles in cell architecture and migration by regulating rearrangements of the actin cytoskeleton and microtubules. The intracellular level of p27Kip1 is increased by anti-proliferative stimuli, such as mitogen deprivation and contact inhibition, which also induce formation of primary cilia, microtubule-based membranous organelles that protrude from the cell surface. However, it remains unknown whether p27Kip1 is associated with ciliogenesis. Here, we have generated p27Kip1-knockout hTERT-immortalized human retinal pigment epithelial cells, and found that ciliogenesis is almost completely disrupted in p27Kip1-knockout cells. The defect of ciliogenesis is rescued by the exogenous expression of wild-type p27Kip1 and, surprisingly, its 86–140 amino acid region, which is neither responsible for CDK inhibition nor remodeling of the actin cytoskeleton and microtubules. Moreover, transmission electron microscopy and immunofluorescence analyses reveal that p27Kip1 abrogation impairs one of the earliest events of ciliogenesis, docking of the Ehd1-associated preciliary vesicles to the distal appendages of the basal body. Our findings identify a novel CDK-independent function of p27Kip1 in primary cilia formation. • Primary cilia formation is impaired in p27Kip1 knockout cells. • The cyclin/CDK-, RhoA-, and stathmin-binding properties of p27Kip1 are dispensable for ciliogenesis. • The 86–140 amino acid region of p27Kip1 is required for ciliogenesis. • p27Kip1 is required for preciliary vesicle docking to the basal body during ciliogenesis. [ABSTRACT FROM AUTHOR]

We consider a mathematical model describing population dynamics of normal and abnormal cell densities with contact inhibition of cell growth from a theoretical point of view. In the first part of this paper, we discuss the global existence of a solution satisfying the segregation property in one space dimension for general initial data. Here, the term segregation property means that the different types of cells keep spatially segregated when the initial densities are segregated. The second part is devoted to singular limit problems for solutions of the PDE system and traveling wave solutions, respectively. Actually, the contact inhibition model considered in this paper possesses quite similar properties to those of the Fisher-KPP equation. In particular, the limit problems reveal a relation between the contact inhibition model and the Fisher-KPP equation. [ABSTRACT FROM AUTHOR]

Contact inhibition is a cell property that limits the migration and proliferation of cells in crowded environments. Here we investigate the growth dynamics of a cell colony composed of migrating and proliferating cells on a substrate using a minimal model that incorporates the mechanisms of contact inhibition of locomotion and proliferation. We find two distinct regimes. At early times, when contact inhibition is weak, the colony grows exponentially in time, fully characterised by the proliferation rate. At long times, the colony boundary moves at a constant speed, determined only by the migration speed of a single cell and independent of the proliferation rate. Further, the model demonstrates how cell-cell alignment speeds up colony growth. Our model illuminates how simple local mechanical interactions give rise to contact inhibition, and from this, how cell colony growth is self-organised and controlled on a local level. [ABSTRACT FROM AUTHOR]

Uterine fibroids (UFs) are benign myometrial neoplasms. The mechanical environment activates signaling through the Hippo pathway effectors Yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding domain (TAZ) in other fibrotic disorders. Here, we assess the differences in YAP/TAZ responsiveness to signals in UF compared with myometrium (Myo). Matched samples of UF and Myo were collected. Atomic force microscopy (AFM) was used to determine in situ stiffness. Cells were plated sparsely on hydrogels or at confluence. Ten nanomolars of estradiol (E2) and 100 nM progesterone (P4) were used. Immunostaining for YAP/TAZ and extracellular matrix (ECM) proteins was performed. Cells were incubated with control or YAP1 (YAP)/WWTR1 (TAZ) small interfering RNA (siRNA). Real time qPCR was completed for connective tissue growth factor (CTGF). Cells were treated with verteporfin (a YAP inhibitor) or Y27632 (a ROCK inhibitor), and ECM gene expression was analyzed. Paired t test and Wilcoxon sign-rank test were used. AFM-measured tissue stiffness and YAP/TAZ nuclear localization in situ and in confluent cells were higher in UF compared with Myo (p < 0.05). Decreasing substrate stiffness reduced YAP/TAZ nuclear localization for both Myo and UF (p = 0.05). Stimulating cells with E2 or P4 increased YAP/TAZ nuclear localization, but only in Myo (p = 0.01). UFs had increased FN, COLI, and COLIII deposition. Following siRNA targeting, CTGF was found to be statistically decreased. Verteporfin treatment reduced cell survival and reduced FN deposition. Treatment with Y27632 demonstrated better cell tolerance and a reduction in ECM deposition. The mechanosensitive pathway may be linked to YAP/TAZ function and involved in transducing fibroid growth. [ABSTRACT FROM AUTHOR]

Cancer is a complex phenomenon, and the sheer variation in behaviour across different types renders it difficult to ascertain underlying biological mechanisms. Experimental approaches frequently yield conflicting results for myriad reasons, and mathematical modelling of cancer is a vital tool to explore what we cannot readily measure, and ultimately improve treatment and prognosis. Like experiments, models are underpinned by certain biological assumptions, variation of which can lead to divergent predictions. An outstanding and important question concerns contact inhibition of proliferation (CIP), the observation that proliferation ceases when cells are spatially confined by their neighbours. CIP is a characteristic of many healthy adult tissues, but it remains unclear to which extent it holds in solid tumours, which exhibit regions of hyper-proliferation, and apparent breakdown of CIP. What precisely occurs in tumour tissue remains an open question, which mathematical modelling can help shed light on. In this perspective piece, we explore the implications of different hypotheses and available experimental evidence to elucidate the implications of these scenarios. We also outline how erroneous conclusions about the nature of tumour growth may be arrived at by looking selectively at biological data in isolation, and how this might be circumvented. [ABSTRACT FROM AUTHOR]

Cell migration is crucial for many physiological and pathological processes. During embryogenesis, neural crest cells undergo coordinated epithelial to mesenchymal transformations and migrate towards various forming organs. Here we develop a computational model to understand how mutual interactions between migrating neural crest cells (NCs) and the surrounding population of placode cells (PCs) generate coordinated migration. According to experimental findings, we implement a minimal set of hypotheses, based on a coupling between chemotactic movement of NCs in response to a placode-secreted chemoattractant (Sdf1) and repulsion induced from contact inhibition of locomotion (CIL), triggered by heterotypic NC–PC contacts. This basic set of assumptions is able to semi-quantitatively recapitulate experimental observations of the characteristic multispecies phenomenon of "chase-and-run", where the colony of NCs chases an evasive PC aggregate. The model further reproduces a number of in vitro manipulations, including full or partial disruption of NC chemotactic migration and selected mechanisms coordinating the CIL phenomenon. Finally, we provide various predictions based on altering other key components of the model mechanisms. [ABSTRACT FROM AUTHOR]

Malignant peritoneal mesothelioma (MPeM) is a rare and aggressive form of malignant mesothelioma. Sufficient biological tools for studying the functional characteristics of this cancer have not been developed. Therefore, in this study, a novel human cancer cell line, KOG-1, was established from ascites fluids isolated from a 39-year-old Japanese woman with pemetrexed-resistant MPeM. Cells were dendritic or linear immediately after thawing, showed a jigsaw puzzle-like and spindle arrangement during growth, and formed monolayers without contact inhibition in two-dimensional (2D) culture. The population doubling time was 13.7 h. Karyotypic and molecular genetic analyses showed that chromosome numbers ranged from 62 to 142, with a peak of 73 with complicated copy number alterations. No germline BAP1 pathogenic variant was detected. Cells expressed various tumor markers of mesothelioma, such as calretinin, podoplanin, and Wilms tumor 1 (WT-1). Drug sensitivity and resistance testing with a set of 36 drugs using 2D and three-dimensional (3D) culture models demonstrated that KOG-1 cells showed high and low sensitivity to pemetrexed under 2D and 3D culture conditions, respectively, whereas control ovarian cancer cell lines showed low sensitivity to pemetrexed under both culture conditions. This newly established cell line will be a valuable biological resource to expand the feasibility of functional studies as well as drug testing for potential therapeutic purposes in MPeM. [ABSTRACT FROM AUTHOR]

The molecular mechanisms by which lymphatic vessels induce cell contact inhibition are not understood. Here, we identify the cGMP-dependent phosphodiesterase 2A (PDE2A) as a selective regulator of lymphatic but not of blood endothelial contact inhibition. Conditional deletion of Pde2a in mouse embryos reveals severe lymphatic dysplasia, whereas blood vessel architecture remains unaltered. In the absence of PDE2A, human lymphatic endothelial cells fail to induce mature junctions and cell cycle arrest, whereas cGMP levels, but not cAMP levels, are increased. Loss of PDE2A-mediated cGMP hydrolysis leads to the activation of p38 signaling and downregulation of NOTCH signaling. However, DLL4-induced NOTCH activation restores junctional maturation and contact inhibition in PDE2A-deficient human lymphatic endothelial cells. In postnatal mouse mesenteries, PDE2A is specifically enriched in collecting lymphatic valves, and loss of Pde2a results in the formation of abnormal valves. Our data demonstrate that PDE2A selectively finetunes a crosstalk of cGMP, p38, and NOTCH signaling during lymphatic vessel maturation. [Display omitted] • The phosphodiesterase 2A is enriched in lymphatic endothelial cells • Loss of lymphatic PDE2A prevents contact inhibition and junctional maturation • PDE2A controls p38 and Notch signaling in a cGMP-dependent manner • Postnatal mesenteric lymphatic valves are defective in the absence of PDE2A Carlantoni et al. demonstrate that loss of lymphatic PDE2A prevents the formation of mature lymphatic junctions, and this results in continuous proliferation and lymphatic dysfunction in human primary cells and mouse models. Lymphatic PDE2A exerts its function by controlling p38 and NOTCH signaling via cGMP modulation. [ABSTRACT FROM AUTHOR]

Microbial life in extreme environments, such as deserts and deep oceans, is thought to have evolved to overcome constraints of nutrient availability, temperature, and suboptimal hygiene environments. Isolation of probiotic bacteria from such niche may provide a competitive edge over traditional probiotics. Here, we tested the survival, safety, and antimicrobial effect of a recently isolated and potential novel strain of Bacillus subtilis (CP9) from desert camel in vitro. Antimicrobial assays were performed via radial diffusion, agar spot, and co-culture assays. Cytotoxic analysis was performed using pig intestinal epithelial cells (IPEC-J2). Real time-PCR was performed for studying the effect on ETEC virulence genes and metabolomic analysis was performed using LC-MS. The results showed that CP9 cells were viable in varied bile salts and in low pH environments. CP9 showed no apparent cytotoxicity in IPEC-J2 cells. CP9 displayed significant bactericidal effect against Enterotoxic E. coli (ETEC), Salmonella Typhimurium, and Methicillin-resistant Staphylococcus aureus (MRSA) in a contact inhibitory fashion. CP9 reduced the expression of ETEC virulent genes during a 5 h co-culture. Additionally, a unique emergent metabolic signature in co-culture samples was observed by LC-MS analysis. Our findings indicate that CP9 exhibits a strong antibacterial property and reveals potential mechanisms behind.

Many bacteria kill competitors using short-range weapons, such as the Type VI secretion system and contact dependent inhibition (CDI). Although these weapons can deliver powerful toxins, they rely on direct contact between attacker and target cells. We hypothesized that movement enables attackers to contact more targets and thus greatly empower their weapons. To explore this, we developed individual-based and continuum models of contact-dependent combat which show that motility greatly improves toxin delivery through two underlying processes. First, genotypic mixing increases the inter-strain contact probability of attacker and sensitive cells. Second, target switching ensures attackers constantly attack new cells, instead of repeatedly hitting the same cell. We test our predictions with the pathogen Pseudomonas aeruginosa, using genetically engineered strains to study the interaction between CDI and twitching motility. As predicted, we find that motility works synergistically with CDI, in some cases increasing weapon efficacy up to 10,000-fold compared with non-motile scenarios. Moreover, we demonstrate that both mixing processes occur using timelapse single-cell microscopy and quantify their relative importance by combining experimental data with our model. Our work shows how bacteria can combine cell movement with contact-based weapons to launch powerful attacks on their competitors., (© The Author(s) 2024. Published by Oxford University Press on behalf of the International Society for Microbial Ecology.)

A complete hydatidiform mole (CHM) is androgenetic in origin and characterized by enhanced trophoblastic proliferation and the absence of fetal tissue. In 15 to 20% of cases, CHMs are followed by malignant gestational trophoblastic neoplasms including choriocarcinoma. Aberrant genomic imprinting may be responsible for trophoblast hypertrophy in CHMs, but the detailed mechanisms are still elusive, partly due to the lack of suitable animal or in vitro models. We recently developed a culture system of human trophoblast stem (TS) cells. In this study, we apply this system to CHMs for a better understanding of their molecular pathology. CHM-derived TS cells, designated as TSmole cells, are morphologically similar to biparental TS (TSbip) cells and express TS-specific markers such as GATA3, KRT7, and TFAP2C. Interestingly, TSmole cells have a growth advantage over TSbip cells only after they reach confluence. We found that p57KIP2, a maternally expressed gene encoding a cyclin-dependent kinase inhibitor, is strongly induced by increased cell density in TSbip cells, but not in TSmole cells. Knockout and overexpression studies suggest that loss of p57KIP2 expression would be the major cause of the reduced sensitivity to contact inhibition in CHMs. Our findings shed light on the molecular mechanism underlying the pathogenesis of CHMs and could have broad implications in tumorigenesis beyond CHMs because silencing of p57KIP2 is frequently observed in a variety of human tumors. [ABSTRACT FROM AUTHOR]

Collective cell migration is the coordinated movement of a physically connected group of cells and is a prominent driver of development and metastasis. Interactions between cells within migrating collectives, and between migrating cells and other cells in the environment, play key roles in stimulating motility, steering and sometimes promoting cell survival. Similarly, diverse heterotypic interactions and collective behaviors likely contribute to tumor metastasis. Here, we describe a sampling of cells that migrate collectively in vivo, including well-established and newer examples. We focus on the under-appreciated property that many - perhaps most - collectively migrating cells move as cooperating groups of distinct cell types. [ABSTRACT FROM AUTHOR]

Models of tissue growth are now well established, in particular, in relation to their applications to cancer. They describe the dynamics of cells subject to motion resulting from a pressure gradient generated by the death and birth of cells, itself controlled primarily by pressure through contact inhibition. In the compressible regime, pressure results from the cell densities and when two different populations of cells are considered, a specific difficulty arises; the equation for each cell density carries a hyperbolic character, and the equation for the total cell density has a degenerate parabolic property. For that reason, few a priori estimates are available and discontinuities may occur. Therefore the existence of solutions is a difficult problem. Here, we establish the existence of weak solutions to the model with two cell populations which react similarly to the pressure in terms of their motion but undergo different growth/death rates. In opposition to the method used in the recent paper of Carrillo et al., our strategy is to ignore compactness of the cell densities and to prove strong compactness of the pressure gradient. For that, we propose a new version of Aronson–Bénilan estimate, working in L2 rather than We improve known results in three directions; we obtain new estimates, we treat dimensions higher than 1 and we deal with singularities resulting from vacuum. [ABSTRACT FROM AUTHOR]

We consider a nonlinear system of partial differential equations which describes the dynamics of two types of cell densities with contact inhibition. After a change of variables the system turns out to be parabolic-hyperbolic and admits travelling wave solutions which solve a 3D dynamical system. Compared to the scalar Fisher-KPP equation, the structure of the travelling wave solutions is surprisingly rich and to unravel part of it is the aim of the present paper. In particular, we consider a parameter regime where the minimal wave velocity of the travelling wave solutions is negative. We show that there exists a branch of travelling wave solutions for any nonnegative wave velocity, which is not connected to the travelling wave solution with minimal wave velocity. The travelling wave solutions with nonnegative wave velocity are strictly positive, while the solution with minimal one is segregated in the sense that the product uv vanishes. [ABSTRACT FROM AUTHOR]

Cell migration plays an important role in physiology and pathophysiology. It was observed in the experiments that cells, such as fibroblast, leukocytes, and cancer cells, exhibit a wide variety of migratory behaviors, such as persistent random walk, contact inhibition of locomotion, and ordered behaviors. To identify biophysical mechanisms for these cellular behaviors, we developed a rigorous computational model of cell migration on a two-dimensional non-deformable substrate. Cells in the model undergo motion driven by mechanical interactions between cellular protrusions and the substrate via the balance of tensile forces. Properties of dynamic formation of lamellipodia induced the persistent random walk behavior of a migrating cell. When multiple cells are included in the simulation, the model recapitulated the contact inhibition of locomotion between cells at low density without any phenomenological assumptions or momentum transfer. Instead, the model showed that contact inhibition of locomotion can emerge via indirect interactions between the cells through their interactions with the underlying substrate. At high density, contact inhibition of locomotion between numerous cells gave rise to confined motions or ordered behaviors, depending on cell density and how likely lamellipodia turn over due to contact with other cells. Results in our study suggest that various collective migratory behaviors may emerge without more restrictive assumptions or direct cell-to-cell biomechanical interactions. [ABSTRACT FROM AUTHOR]

Although anticoagulation without hemorrhage is a primary aim, this vision has remained as yet out of reach. Even despite the superior safety profile of the direct oral anticoagulants, hemorrhage remains a major risk of anticoagulation. Selective inhibition of the contact pathway of coagulation, specifically coagulation factor XI (FXI) and/or factor XII (FXII), has now substantial epidemiologic and preclinical data supporting the notion that these factors contribute to pathologic thrombosis and are yet primarily dispensable for in vivo hemostasis. In this way, targeting FXI and FXII may revolutionize the future anticoagulation landscape. Several drugs are under development for this purpose, including: ISIS 416858, a FXI antisense oligonucleotide which impairs hepatic synthesis of FXI; MAA868, a monoclonal antibody that binds the procoagulant enzymatic site of both zymogen and activated FXI (FXIa); BAY 1213790, a monoclonal antibody that binds the procoagulant enzymatic site of FXIa only; and AB023, a monoclonal antibody that inhibits activated FXII-mediated activation of FXI, along with two small molecules in clinical trials. Each of these drugs have demonstrated favorable safety profiles in their phases 1 and 2 studies to date, with preclinical data also supporting efficacy of abrogating thrombosis in various animal models. Other benefits of some of these drugs include once-monthly dosing and safety in patients with renal or hepatic impairment, while others offer quickly metabolized parenteral options, thus providing more convenient and widely available anticoagulation options. Though still far from the marketplace, drugs targeting FXI and FXII have the potential to usher in a new era of anticoagulation therapy. [ABSTRACT FROM AUTHOR]

Interactions between different cell types can induce distinct contact inhibition of locomotion (CIL) responses that are hypothesised to control population-wide behaviours during embryogenesis. However, our understanding of the signals that lead to cell-type specific repulsion and the precise capacity of heterotypic CIL responses to drive emergent behaviours is lacking. Using a new model of heterotypic CIL, we show that fibrosarcoma cells, but not fibroblasts, are actively repelled by epithelial cells in culture.We show that knocking down EphB2 or ERK in fibrosarcoma cells specifically leads to disruption of the repulsion phase of CIL in response to interactions with epithelial cells. We also examine the population-wide effects when these various cell combinations are allowed to interact in culture. Unlike fibroblasts, fibrosarcoma cells completely segregate fromepithelial cells and inhibiting their distinctCIL response by knocking down EphB2 or ERK family proteins also disrupts this emergent sorting behaviour. These data suggest that heterotypic CIL responses, in conjunction with processes such as differential adhesion, may aid the sorting of cell populations. [ABSTRACT FROM AUTHOR]

Previous work has shown that expression of the extracellular signal-regulated kinase (ERK) is decreased by high density in normal fibroblast cells, and this was correlated with increased expression of mitogen-activated protein kinase phosphatases. Because of these differences in ERK regulation upon contact inhibition, it is likely that other cellular responses may be influenced by the attainment of a contact-inhibited state. Expression of matrix metalloproteinase-9 and cadherin cleavage were both found to be decreased upon reaching high culture density. Inhibition of ERK activity with the MEK inhibitor PD98059 resulted in increased expression of cadherins, while constitutive activation of ERK through the use of expression of an ERK construct with a D319N sevenmaker mutation resulted in decreased expression of cadherins and enhanced colony formation of HT-1080 fibrosarcoma cells. Taken together, these results corroborate a role for the regulation of ERK upon the attainment of a contact-inhibited state with increased expression of cadherins. [ABSTRACT FROM AUTHOR]

Maintaining the homogeneity of a stem cell population is one of the challenges in bioprocessing prior to therapeutic applications of stem cells. Concerning human induced pluripotent stem cell (hiPSC) colonies cultured on feeder cells, cells at the peripheral region of the colony were found to have a higher average movement rate than cells at the central region of the colony. This spatial difference in average movement rate might lead to spatial heterogeneity of cell fate decision in the colony. We have developed a kinetic model to clarify the origin of this phenomenon which was difficult to understand by in vitro studies alone. Using a kinetic model based on a cellular automaton, we described fundamental cell behaviors including cell division, contact inhibition, cell migration, cell–cell connections, and cell–substrate connections. With all parameter values estimated from experimental data, the appropriateness of our kinetic model was indicated by good agreement between simulated and experimental data. Using the kinetic model, the average cell movement rate in a colony became homogenous after cell division stopped, implying that cell division was the main cause of the observed spatial heterogeneity. The result also showed a directly proportional relationship between the frequency of cell pushing and cell movement rate in the colony, confirming the role of cell division. Our kinetic model is expected to be useful for studying behaviors of hiPSCs and proposing good strategies to improve hiPSC bioprocessing. [ABSTRACT FROM AUTHOR]

Fasciola hepatica is one of the etiological agents of fasciolosis, a widespread disease in domestic animals and occasionally in humans. Fasciolosis may be reduced by blocking the parasite transmission through its intermediate hosts. In the present work, different monosaccharides have been tested for their ability to impact on ligand/receptor interactions at the interface between the parasite and the intermediate host. Laboratory snails were subjected to miracidia in the presence of methyl-α-D-mannopyranoside (MetMan), α-D-glucose (Glc), N-acetyl-D-glucosamine (GlcNAc), D-(+)-galactose (Gal), N-acetyl-D-galactosamine (GalNAc) or L-(−)-fucose (Fuc), in 10 mM concentration. The snail survival rates and the prevalence of infection were determined after 50 days. Survived snails in the study groups varied from 78% to 97%. A remarkable reduction in the number of parasite-infected snails was observed in groups subjected to MetMan, Glc, or GlcNAc – 36.9%, 10.9%, and 11.9%, respectively, compared to 92.7% in the control group. Other tested monosaccharides had a low impact on snail infection. The results point to the implication that surface carbohydrate/receptor interactions are among the determining factors concerning the transmission of F. hepatica by the specific vector Galba truncatula. Biological recognition between the two organisms can be interfered with appropriate monosaccharides and this can be used to develop an alternative method for control of fasciolosis at the intermediate host level. [ABSTRACT FROM AUTHOR]

Human trabecular meshwork (hTM) cell isolation in academic settings utilizes the motile nature of these cells, allowing them to migrate away from the explant and proliferate on distal regions of the culture substrate. Corneoscleral rims used for transplantation are a potential source of explants for the establishment of hTM cell cultures. However, cell isolation and the initiation of primary cell cultures from ocular tissues stored in Optisol-GS medium for an extended period of time (>6 days) has proven difficult, since Optisol-GS remarkably reduces cell viability and cellularity. Therefore, explants obtained from ocular tissues stored in Optisol-GS do not often provide adequate cell yield to initiate primary cell cultures if conventional culture techniques are used. Therefore, the majority of the research on primary hTM cell isolation has been accomplished using donor tissue obtained within 72 h postmortem. The goal of this study was to develop an hTM cell isolation procedure from nontransplantable ocular materials, utilizing the anchorage dependency of TM cells. This procedure yielded functionally viable cells, efficiently dissociated from the trabecular meshwork. Isolated cells demonstrated typical hTM cell characteristics including monolayer formation, contact inhibition, phagocytosis, and responses to glucocorticoid exposure. To the best of our knowledge, this is the first time an expired explant has been utilized in the successful isolation of hTM cells. Our results clearly demonstrate the advantage of increasing the anchor points of hTM cells for enhanced cell migration out from the explants, which have limited cell proliferative capacity. [ABSTRACT FROM AUTHOR]

The neural crest cells (NCCs) are transient migratory multipotent cells that emerge at the interface between the prospective epidermis of a developing embryo and neuroepithelium due to its multipotency, long-range migration through embryo and its capacity to generate a prodigious number of differentiated cell types. For these reasons, though it derived from the ectoderm, the NC has been called the fourth germ layer. For induction and formation of NCCs, non-neural ectoderm, the neural plate, and the underlying mesoderm play an important role. There are a number of signaling molecules essential for the formation, epithelialmesenchymal transition, delamination, migration, and localization of NCC. Once NCCs formed, it starts migrating from the neuroepithelium and quickly splitting into distinct streams. NCCs are differentiated into multiple cell types, ranging from neurons and glial cells of the peripheral nervous system to pigment cells, fibroblasts to smooth muscle cells, and odontoblasts to adipocytes. NCCs migrate in larger numbers which are regulated by different mechanisms, including chemotaxis, contact inhibition of locomotion, and cell sorting. Hence, this reviews to discuss about NC formation, differentiation, and migration. [ABSTRACT FROM AUTHOR]

Preterm-born individuals are at risk for poorer executive functions. Longitudinal studies investigating whether preterm-born individuals present persistent cognitive deficits, or a transient delay of development are scarce. We assessed developmental trajectories of executive functions (inhibition, working memory, cognitive flexibility) in 29 very preterm-born individuals (<32 weeks' gestation) and 25 term-born controls longitudinally over two time points, namely in childhood (7-12 years of age, TP1) and adolescence (13-16 years of age, TP2). Individual changes in executive functions were examined using relative difference scores (TP2 - TP1) / TP1). There was a significantly stronger improvement of inhibition (U = 477, p = .024) and cognitive flexibility (U = 312, p = .029) between childhood and adolescence in very preterm-born individuals than in term-born controls. Preterm-born individuals improved their performance in the domain of cognitive flexibility significantly more often (76%) between childhood and adolescence than controls (31%, χ2 = 8.6, p = .003). Controls worsened significantly more often (36%) in the domain of inhibition than the preterm group (14%, χ2 = 4.8, p = .028). Results indicate that healthy preterm-born individuals show prolonged development of executive functions throughout childhood up into adolescence. [ABSTRACT FROM AUTHOR]

Osteosarcoma is the most common primary malignant bone tumor type in children and adolescents under 20 years of age. Biological characteristics include invasiveness, metastasis, abnormal differentiation and loss of contact inhibition. microRNAs (miRNAs) are involved in the transcriptional and post-transcriptional regulation of target mRNAs. Previous studies have demonstrated that miR-218 inhibits tumor formation and progression in glioma, colon cancer and renal cell carcinoma; however, the mechanism of action of miR-218 in osteosarcoma has not been completely determined. In the present study, it was demonstrated that miR-218 exhibited low expression and targeted E2F2 in osteosarcoma cells. Additionally, overexpression of miR-218 inhibited osteosarcoma cell proliferation, with the opposite result occurring following the knockdown of miR-218. Furthermore, it was determined that miR-218 inhibited tumor formation and reduced the expression of E2F2 and proliferating cell nuclear antigen in nude mice. Collectively, the present data demonstrated that miR-218 serves an important role in suppressing the proliferation of osteosarcoma cells, potentially regulated by E2F2, which may provide a novel protein marker for the treatment of osteosarcoma. [ABSTRACT FROM AUTHOR]

Objective. Rat liver stem-like epithelial cells (WB-F344) that under certain conditions may differentiate into hepatocyte and biliary lineages were subjected to acute X-irradiation with the aim to examine cell cycle peculiarities during the course of survival. Materials and methods. Suspensions of WB-F344 cells that grew as a monolayer and reached sub-confluence were irradiated with 1, 5, and 10 Gy of X-rays (2 Gy/min). As an intact control, sham-irradiated cells were used. After irradiation, cells were plated into 25-cm2 tissue culture flasks to culture them for over several days without reaching contact inhibition. On days 1, 2, 3, and 5 post-irradiation, cells were harvested and examined for nuclear morphology and DNA ploidy by stoichiometric toluidine blue reaction and image cytometry. On days 7 and 9 post-irradiation, only heavily irradiated (10 Gy) cells were examined. Also, 10 Gy-irradiated cells were chosen for immunofluorescence staining to monitor persistence of DNA lesions (γ-H2AX), cell proliferation (Ki-67), and self-renewal factors characteristic for stem cells (OCT4 and NANOG). Results. Radioresistance of WB-F344 cells was evidenced by the findings that they do not undergo rapid and massive cell death that in fact was weakly manifested as apoptotic even in heavily irradiated cells. Instead, there was cell cycle progression delay accompanied by polyploidization (via Ki-67-positive mitotic slippage or via impaired cytokinesis) and micronucleation in a dose-dependent manner, although micronucleation to some extent went ahead of polyploidization. Polyploid cells amenable for recovering from DNA damage can mitotically depolyploidize. Many micronuclei contained γ-H2AX clusters, suggesting isolation of severely damaged DNA fragments. Both factors, OCT4 and NANOG, were expressed in the intact control, but became enhanced after irradiation. Conclusions. Although the fact of micronucleation is indicative of genotoxic effect, WB-F344 cells can probably escape cell death via sorting of damaged DNA by micronuclei. Induction of polyploidy in these cells can be adaptive to promote cell survival and tissue regeneration with possible involvement of self-renewal mechanism. [ABSTRACT FROM AUTHOR]

Background To prepare new calcium based intracanal medicament from egg shell and sea shell powder mixed with pure coconut oil then evaluate the antibacterial activity of the new prepared materials and compare the result with Metapex intracanal medicament. Materials and Methods Calcium based intracanal medicament have been prepared from local egg shell and from seashell (Cowrie) in a form of nano calcium oxide powder; each powder was mixed separately with locally made pure coconut oil to form two experimental materials. Antimicrobial activity was evaluated by direct contact inhibition zone test of each experimental material and control with Enterococcus faecalis, after 24 hours of incubation at 37°C, zone of bacterial growth was observed and measured. Results The results showed that both of the prepared materials have antibacterial effect, these results were statistically analyzed using One-way ANOVA & Duncan>s Multiple Range test at p=0.01 levels. Conclusion Results have shown that both egg and sea shells contain many types of metal oxides in different concentration that might have antibacterial action in addition to the lauric acid from the coconut oil which clinically proven to have antibacterial activity that aided the experimental materials to have an acceptable antibacterial activity. [ABSTRACT FROM AUTHOR]

Malignant transformation of fibroblast and epithelial cells is accompanied by increased beta 1-6 N-acetylglucosaminyltransferase V (GlcNAc-TV) activity, a Golgi N-linked oligosaccharide processing enzyme. Herein, we report that expression of GlcNAc-TV in Mv1Lu cells, an immortalized lung epithelial cell line results in loss of contact-inhibition of cell growth, an effect that was blocked by swainsonine, an inhibitor of Golgi processing enzyme alpha-mannosidase II. In serum-deprived and high density monolayer cultures, the GlcNAc-TV transfectants formed foci, maintained microfilaments characteristic of proliferating cells, and also experienced accelerated cell death by apoptosis. Injection of the GlcNAc-TV transfectants into nude mice produced a 50% incidence of benign tumors, and progressively growing tumors in 2:12 mice with a latency of 6 mo, while no growth was observed in mice injected with control cells. In short term adhesion assays, the GlcNAc-TV expressing cells were less adhesive on surfaces coated with fibronectin and collagen type IV, but no changes were observed in levels of cell surface alpha 5 beta 1 or alpha v beta 3 integrins. The larger apparent molecular weights of the LAMP-2 glycoprotein and integrin glycoproteins alpha 5, alpha v and beta 1 in the transfected cells indicates that their oligosaccharide chains are substrates for GlcNAc-TV. The results suggest that beta 1-6GlcNAc branching of N-linked oligosaccharides contributes directly to relaxed growth controls and reduce substratum adhesion in premalignant epithelial cells.

Purpose: To report the explantation of a detached and opaque donor disc as an alternative to secondary keratoplasty in a case of persistent graft detachment followed by spontaneous clearance of the recipient cornea after non-Descemet stripping automated endothelial keratoplasty (non-DSAEK). Methods: A 57-year-old man with cataract and bullous keratopathy after herpes simplex virus endotheliitis of the right eye and best spectacle-corrected visual acuity (BSCVA) of 0.1 underwent simultaneous phacoemulsification and non-DSAEK. Due to early detachment of the donor disc, two additional intracameral air injections were necessary in order to achieve graft attachment. However, the donor disc gradually detached and became fibrotic while the recipient cornea anterior to the detached graft became transparent and without any edema. Therefore, a mere explantation of the DSAEK graft was performed. Results: Four months after graft explantation, BSCVA was 0.5 and endothelial cell density (ECD) was 1,221 cells/mm2. After 13 months, BSCVA was still 0.6 while ECD had fell to 800, and 2 years later, the endothelium decompensated. BSCVA was 0.3 and ECD was not measurable. Conclusions: To our knowledge this is the first report of explantation of an endothelial graft as an alternative to re-keratoplasty in a case of spontaneous corneal clearance. This minimally invasive treatment may be considered in similar cases. However, due to the ongoing loss of endothelial cells after endothelial keratoplasty, a re-keratoplasty may still be needed in the long term.

The effects of randomness, an unavoidable feature of intracellular environments, are observed at higher hierarchical levels of living matter organization, such as cells, tissues, and organisms. Additionally, the many compounds interacting as a well-orchestrated network of reactions increase the difficulties of assessing these systems using only experiments. This limitation indicates that elucidation of the dynamics of biological systems is a complex task that will benefit from the establishment of principles to help describe, categorize, and predict the behavior of these systems. The theoretical machinery already available, or ones to be discovered to help solve biological problems, might play an important role in these processes. Here, we demonstrate the application of theoretical tools by discussing some biological problems that we have approached mathematically: fluctuations in gene expression and cell proliferation in the context of loss of contact inhibition. We discuss the methods that have been employed to provide the reader with a biologically motivated phenomenological perspective of the use of theoretical methods. Finally, we end this review with a discussion of new research perspectives motivated by our results.