How cells change their phenotype

Phenotypic switching mechanisms determine the structure of cell migration into extracellular matrix under the 'go-or-grow' hypothesis

A fundamental feature of collective cell migration is phenotypic heterogeneity which, for example, influences tumour progression and relapse. While current mathematical models often consider discrete phenotypic structuring of the cell population, in-line with the 'go-or-grow' hypothesis (Hatzikirou et al., 2012; Stepien et al., 2018), they regularly overlook the role that the environment may play in determining the cells' phenotype during migration. Comparing a previously studied volume-filling model for a homogeneous population of generalist cells that can proliferate, move and degrade extracellular matrix (ECM) (Crossley et al., 2023) to a novel model for a heterogeneous population comprising two distinct sub-populations of specialist cells that can either move and degrade ECM or proliferate, this study explores how different hypothetical phenotypic switching mechanisms affect the speed and structure of the invading cell populations. Through a continuum model derived from its individual-based counterpart, insights into the influence of the ECM and the impact of phenotypic switching on migrating cell populations emerge. Notably, specialist cell populations that cannot switch phenotype show reduced invasiveness compared to generalist cell populations, while implementing different forms of switching significantly alters the structure of migrating cell fronts. This key result suggests that the structure of an invading cell population could be used to infer the underlying mechanisms governing phenotypic switching.

TabDEG: Classifying differentially expressed genes from RNA-seq data based on feature extraction and deep learning framework

Traditional differential expression genes (DEGs) identification models have limitations in small sample size datasets because they require meeting distribution assumptions, otherwise resulting high false positive/negative rates due to sample variation. In contrast, tabular data model based on deep learning (DL) frameworks do not need to consider the data distribution types and sample variation. However, applying DL to RNA-Seq data is still a challenge due to the lack of proper labeling and the small sample size compared to the number of genes. Data augmentation (DA) extracts data features using different methods and procedures, which can significantly increase complementary pseudo-values from limited data without significant additional cost. Based on this, we combine DA and DL framework-based tabular data model, propose a model TabDEG, to predict DEGs and their up-regulation/down-regulation directions from gene expression data obtained from the Cancer Genome Atlas database. Compared to five counterpart methods, TabDEG has high sensitivity and low misclassification rates. Experiment shows that TabDEG is robust and effective in enhancing data features to facilitate classification of high-dimensional small sample size datasets and validates that TabDEG-predicted DEGs are mapped to important gene ontology terms and pathways associated with cancer.

Hallmarks of stemness in mammalian tissues

All adult tissues experience wear and tear. Most tissues can compensate for cell loss through the activity of resident stem cells. Although the cellular maintenance strategies vary greatly between different adult (read: postnatal) tissues, the function of stem cells is best defined by their capacity to replace lost tissue through division. We discuss a set of six complementary hallmarks that are key enabling features of this basic function. These include longevity and self-renewal, multipotency, transplantability, plasticity, dependence on niche signals, and maintenance of genome integrity. We discuss these hallmarks in the context of some of the best-understood adult stem cell niches.

Pancreatic ductal adenocarcinoma with acinar-to-ductal metaplasia-like cancer cells shows increased cellular proliferation

BACKGROUND/OBJECTIVES

Acinar-to-ductal metaplasia (ADM) has been shown to contribute to the development of pancreatic ductal adenocarcinoma (PDAC) in genetically engineered mouse models, but little is known about whether acinar cell plasticity contributes to carcinogenesis in human PDAC. We aimed to assess whether cancer cells that stain positive for amylase and CK19 (ADM-like cancer cells) are present in human resected PDAC and to investigate their role in tumor progression.

METHODS

We immunohistochemically investigated the presence of ADM-like cancer cells, and compared the clinical and histological parameters of PDAC patients with and without ADM-like cancer cells.

RESULTS

ADM-like cancer cells were detected in 16 of 60 (26.7%) PDAC specimens. Positive staining for anterior gradient protein 2 (AGR2) was observed in 14 of 16 (87.5%) PDAC specimens with ADM-like cancer cells. On the other hand, the intensity of AGR2 expression (negative, low/moderate or high) was lower in PDAC with ADM-like cancer cells (9/7) than in PDAC without these cells (11/33) (P = 0.032). The presence of ADM-like cancer cells was significantly correlated with increased cell proliferation (P = 0.012) and tended to be associated with MUC1 expression (P = 0.067).

CONCLUSIONS

These results indicated that acinar cells may act as the origin of human PDAC, and that their presence may be useful for the stratification of human PDAC to predict prognosis.

Biomarkers of aging

Aging biomarkers are a combination of biological parameters to (i) assess age-related changes, (ii) track the physiological aging process, and (iii) predict the transition into a pathological status. Although a broad spectrum of aging biomarkers has been developed, their potential uses and limitations remain poorly characterized. An immediate goal of biomarkers is to help us answer the following three fundamental questions in aging research: How old are we? Why do we get old? And how can we age slower? This review aims to address this need. Here, we summarize our current knowledge of biomarkers developed for cellular, organ, and organismal levels of aging, comprising six pillars: physiological characteristics, medical imaging, histological features, cellular alterations, molecular changes, and secretory factors. To fulfill all these requisites, we propose that aging biomarkers should qualify for being specific, systemic, and clinically relevant.

Role of Cell-Based Therapies in T2D

Type 2 diabetes mellitus (T2D) has become a global epidemic affecting the health of millions of people. T2D is a complex and multifactorial metabolic disease, largely characterized by a combination of impaired insulin secretion from β cells residing within the islets of the pancreas and peripheral insulin resistance. In this article, we discuss the current state and risk factors for T2D, conventional treatment options, and upcoming strategies, including progress in the areas of allogeneic and xenogeneic islet transplantation, with a major focus on stem cell-derived β cells and associated technologies.

Mechanisms and pathophysiology of Barrett oesophagus

Barrett oesophagus, in which a metaplastic columnar mucosa that can predispose individuals to cancer development lines a portion of the distal oesophagus, is the only known precursor of oesophageal adenocarcinoma, the incidence of which has increased profoundly over the past several decades. Most evidence suggests that Barrett oesophagus develops from progenitor cells at the oesophagogastric junction that proliferate and undergo epithelial-mesenchymal transition as part of a wound-healing process that replaces oesophageal squamous epithelium damaged by gastroesophageal reflux disease (GERD). GERD also seems to induce reprogramming of key transcription factors in the progenitor cells, resulting in the development of the specialized intestinal metaplasia that is characteristic of Barrett oesophagus, probably through an intermediate step of metaplasia to cardiac mucosa. Genome-wide association studies suggest that patients with GERD who develop Barrett oesophagus might have an inherited predisposition to oesophageal metaplasia and that there is a shared genetic susceptibility to Barrett oesophagus and to several of its risk factors (such as GERD, obesity and cigarette smoking). In this Review, we discuss the mechanisms, pathophysiology, genetic predisposition and cells of origin of Barrett oesophagus, and opine on the clinical implications and future research directions.

Discrete protein metric (DPM): A new image similarity metric to calculate accuracy of deep learning-generated cell focal adhesion predictions

Understanding cell behaviors can provide new knowledge on the development of different pathologies. Focal adhesion (FA) sites are important sub-cellular structures that are involved in these processes. To better facilitate the study of FA sites, deep learning (DL) can be used to predict FA site morphology based on limited microscopic datasets (e.g., cell membrane images). However, calculating the accuracy score of these predictions can be challenging due to the discrete/point pattern like nature of FA sites. In the present work, a new image similarity metric, discrete protein metric (DPM), was developed to calculate FA prediction accuracy. This metric measures differences in distribution (d), shape/size (s), and angle (a) of FA sites between predicted and ground truth microscopy images. Performance of the DPM was evaluated by comparing it to three other commonly used image similarity metrics: Pearson correlation coefficient (PCC), feature similarity index (FSIM), and Intersection over Union (IoU). A sensitivity analysis was performed by comparing changes in each metric value due to quantifiable changes in FA site location, number, aspect ratio, area, or orientation. Furthermore, accuracy score of DL-generated predictions was calculated using all four metrics to compare their ability to capture variation across samples. Results showed better sensitivity and range of variation for DPM compared to the other metrics tested. Most importantly, DPM had the ability to determine which FA predictions were quantitatively more accurate and consistent with qualitative assessments. The proposed DPM hence provides a method to validate DL-generated FA predictions and has the potential to be used for investigation of other sub-cellular protein aggregates relevant to cell biology.

Pancreatic Transdifferentiation Using β-Cell Transcription Factors for Type 1 Diabetes Treatment

Type 1 diabetes is a chronic illness in which the native beta (β)-cell population responsible for insulin release has been the subject of autoimmune destruction. This condition requires patients to frequently measure their blood glucose concentration and administer multiple daily exogenous insulin injections accordingly. Current treatments fail to effectively treat the disease without significant side effects, and this has led to the exploration of different approaches for its treatment. Gene therapy and the use of viral vectors has been explored extensively and has been successful in treating a range of diseases. The use of viral vectors to deliver β-cell transcription factors has been researched in the context of type 1 diabetes to induce the pancreatic transdifferentiation of cells to replace the β-cell population destroyed in patients. Studies have used various combinations of pancreatic and β-cell transcription factors in order to induce pancreatic transdifferentiation and have achieved varying levels of success. This review will outline why pancreatic transcription factors have been utilised and how their application can allow the development of insulin-producing cells from non β-cells and potentially act as a cure for type 1 diabetes.

The Oxidative Damage and Inflammation Mechanisms in GERD-Induced Barrett's Esophagus

Barrett's esophagus is a major complication of gastro-esophageal reflux disease and an important precursor lesion for the development of Barrett's metaplasia and esophageal adenocarcinoma. However, the cellular and molecular mechanisms of Barrett's metaplasia remain unclear. Inflammation-associated oxidative DNA damage could contribute to Barrett's esophagus. It has been demonstrated that poly(ADP-ribose) polymerases (PARPs)-associated with ADP-ribosylation plays an important role in DNA damage and inflammatory response. A previous study indicated that there is inflammatory infiltration and oxidative DNA damage in the lower esophagus due to acid/bile reflux, and gastric acid could induce DNA damage in culture esophageal cells. This review will discuss the mechanisms of Barrett's metaplasia and adenocarcinoma underlying oxidative DNA damage in gastro-esophageal reflux disease patients based on recent clinical and basic findings.

Clinical significance of pancreatic ductal metaplasia

Pancreatic ductal metaplasia (PDM) is the stepwise replacement of differentiated somatic cells with ductal or ductal-like cells in the pancreas. PDM is usually triggered by cellular and environmental insults. PDM development may involve all cell lineages of the pancreas, and acinar cells with the highest plasticity are the major source of PDM. Pancreatic progenitor cells are also involved as cells of origin or transitional intermediates. PDM is heterogeneous at the histological, cellular, and molecular levels and only certain subsets of PDM develop further into pancreatic intraepithelial neoplasia (PanIN) and then pancreatic ductal adenocarcinoma (PDAC). The formation and evolution of PDM is regulated at the cellular and molecular levels through a complex network of signaling pathways. The key molecular mechanisms that drive PDM formation and its progression into PanIN/PDAC remain unclear, but represent key targets for reversing or inhibiting PDM. Alternatively, PDM could be a source of pancreas regeneration, including both exocrine and endocrine components. Cellular aging and apoptosis are obstacles to PDM-to-PanIN progression or pancreas regeneration. Functional identification of the cellular and molecular events driving senescence and apoptosis in PDM and its progression would help not only to restrict the development of PDM into PanIN/PDAC, but may also facilitate pancreatic regeneration. This review systematically assesses recent advances in the understanding of PDM physiology and pathology, with a focus on its implications for enhancing regeneration and prevention of cancer. © 2022 The Pathological Society of Great Britain and Ireland.

Molecular signaling in pancreatic ductal metaplasia: emerging biomarkers for detection and intervention of early pancreatic cancer

Pancreatic ductal metaplasia (PDM) is the transformation of potentially various types of cells in the pancreas into ductal or ductal-like cells, which eventually replace the existing differentiated somatic cell type(s). PDM is usually triggered by and manifests its ability to adapt to environmental stimuli and genetic insults. The development of PDM to atypical hyperplasia or dysplasia is an important risk factor for pancreatic intraepithelial neoplasia (PanIN) and pancreatic ductal adenocarcinoma (PDA). Recent studies using genetically engineered mouse models, cell lineage tracing, single-cell sequencing and others have unraveled novel cellular and molecular insights in PDM formation and evolution. Those novel findings help better understand the cellular origins and functional significance of PDM and its regulation at cellular and molecular levels. Given that PDM represents the earliest pathological changes in PDA initiation and development, translational studies are beginning to define PDM-associated cell and molecular biomarkers that can be used to screen and detect early PDA and to enable its effective intervention, thereby truly and significantly reducing the dreadful mortality rate of PDA. This review will describe recent advances in the understanding of PDM biology with a focus on its underlying cellular and molecular mechanisms, and in biomarker discovery with clinical implications for the management of pancreatic regeneration and tumorigenesis.

Acinar to ductal cell trans-differentiation: A prelude to dysplasia and pancreatic ductal adenocarcinoma

Pancreatic cancer (PC) is the deadliest neoplastic epithelial malignancies and is projected to be the second leading cause of cancer-related mortality by 2024. Five years overall survival being ~10%, mortality and incidence rates are disturbing. Acinar to ductal cell metaplasia (ADM) encompasses cellular reprogramming and phenotypic switch-over, making it a cardinal event in tumor initiation. Differential cues and varied regulatory factors drive synchronous functions of metaplastic cell populations leading to multiple cell fates and physiological outcomes. ADM is a precursor for developing early pre-neoplastic lesions further progressing into PC due to oncogenic signaling. Hence delineating molecular events guiding tumor initiation may provide cues for regenerative medicine and precision onco-medicine. Therefore, understanding PC pathogenesis and early diagnosis are crucial. We hereby provide a timely overview of the current progress in this direction and future perspectives we foresee unfolding in the best interest of patient well-being and better clinical management of PC.

A Brief Review of the Mechanisms of β-Cell Dedifferentiation in Type 2 Diabetes

Diabetes is a metabolic disease characterized by hyperglycemia. Over 90% of patients with diabetes have type 2 diabetes. Pancreatic β-cells are endocrine cells that produce and secrete insulin, an essential endocrine hormone that regulates blood glucose levels. Deficits in β-cell function and mass play key roles in the onset and progression of type 2 diabetes. Apoptosis has been considered as the main contributor of β-cell dysfunction and decrease in β-cell mass for a long time. However, recent studies suggest that β-cell failure occurs mainly due to increased β-cell dedifferentiation rather than limited β-cell proliferation or increased β-cell death. In this review, we summarize the current advances in the understanding of the pancreatic β-cell dedifferentiation process including potential mechanisms. A better understanding of β-cell dedifferentiation process will help to identify novel therapeutic targets to prevent and/or reverse β-cell loss in type 2 diabetes.

Tp63-expressing adult epithelial stem cells cross lineages boundaries revealing latent hairy skin competence

The formation of hair follicles, a landmark of mammals, requires complex mesenchymal–epithelial interactions and it is commonly believed that embryonic epidermal cells are the only cells that can respond to hair follicle morphogenetic signals in vivo. Here, we demonstrate that epithelial stem cells of non-skin origin (e.g. that of cornea, oesophagus, vagina, bladder, prostate) that express the transcription factor Tp63, a master gene for the development of epidermis and its appendages, can respond to skin morphogenetic signals. When exposed to a newborn skin microenvironment, these cells express hair-follicle lineage markers and contribute to hair follicles, sebaceous glands and/or epidermis renewal. Our results demonstrate that lineage restriction is not immutable and support the notion that all Tp63-expressing epithelial stem cells, independently of their embryonic origin, have latent skin competence explaining why aberrant hair follicles or sebaceous glands are sometimes observed in non-skin tissues (e.g. in cornea, vagina or thymus).

Adult stem cells are thought to be fate restricted to lineages distinct to their tissue of origin. Here, the authors demonstrate that Tp63 expressing epithelial stem cells from several disparate tissues can respond to skin morphogenetic signals and contribute to hair follicles, sebaceous glands and/or epidermis.

On the correlation between material-induced cell shape and phenotypical response of human mesenchymal stem cells

Learning rules by which cell shape impacts cell function would enable control of cell physiology and fate in medical applications, particularly, on the interface of cells and material of the implants. We defined the phenotypic response of human bone marrow-derived mesenchymal stem cells (hMSCs) to 2176 randomly generated surface topographies by probing basic functions such as migration, proliferation, protein synthesis, apoptosis, and differentiation using quantitative image analysis. Clustering the surfaces into 28 archetypical cell shapes, we found a very strict correlation between cell shape and physiological response and selected seven cell shapes to describe the molecular mechanism leading to phenotypic diversity. Transcriptomics analysis revealed a tight link between cell shape, molecular signatures, and phenotype. For instance, proliferation is strongly reduced in cells with limited spreading, resulting in down-regulation of genes involved in the G2/M cycle and subsequent quiescence, whereas cells with large filopodia are related to activation of early response genes and inhibition of the osteogenic process. In this paper we were aiming to identify a universal set of genes that regulate the material-induced phenotypical response of human mesenchymal stem cells. This will allow designing implants that can actively regulate cellular, molecular signalling through cell shape. Here we are proposing an approach to tackle this question.

Mutation of MEDIATOR 18 and chromate trigger twinning of the primary root meristem in Arabidopsis

Plants adapt to soil injury and biotic stress via cell regeneration. In Arabidopsis, root tip damage by genotoxic agents, antibiotics, UV light and cutting induces a program that recovers the missing tissues through activation of stem cells and involves ethylene response factor 115 (ERF115), which triggers cell replenishment. Here, we show that mutation of the gene encoding an MED18 subunit of the transcriptional MEDIATOR complex and chromate [Cr(VI)], an environmental pollutant, synergistically trigger a developmental program that enables the splitting of the meristem in vivo to produce twin roots. Expression of the quiescent centre gene marker WOX5, auxin-inducible DR5:GFP reporter and the ERF115 factor traced the changes in cell identity during the conversion of single primary root meristems into twin roots and were induced in an MED18 and chromate-dependent manner during the root twinning events, which also required auxin redistribution and signalling mediated by IAA14/SOLITARY ROOT (SLR1). Splitting of the root meristem allowed dichotomous root branching in Arabidopsis, a poorly understood process in which stem cells may act to enable whole organ regeneration.

SINC: a scale-invariant deep-neural-network classifier for bulk and single-cell RNA-seq data

MOTIVATION

Scaling by sequencing depth is usually the first step of analysis of bulk or single-cell RNA-seq data, but estimating sequencing depth accurately can be difficult, especially for single-cell data, risking the validity of downstream analysis. It is thus of interest to eliminate the use of sequencing depth and analyze the original count data directly.

RESULTS

We call an analysis method 'scale-invariant' (SI) if it gives the same result under different estimates of sequencing depth and hence can use the original count data without scaling. For the problem of classifying samples into pre-specified classes, such as normal versus cancerous, we develop a deep-neural-network based SI classifier named scale-invariant deep neural-network classifier (SINC). On nine bulk and single-cell datasets, the classification accuracy of SINC is better than or competitive to the best of eight other classifiers. SINC is easier to use and more reliable on data where proper sequencing depth is hard to determine.

AVAILABILITY AND IMPLEMENTATION

This source code of SINC is available at https://www.nd.edu/∼jli9/SINC.zip.

SUPPLEMENTARY INFORMATION

Supplementary data are available at Bioinformatics online.

Rat mesenchymal stem cell cultures as a model to elucidate the cellular and molecular pathogenesis of bone metaplasia induced by Solanum glaucophyllum intoxication

The hypothesis of this experiment is that mesenchymal stem cells (MSCs) are involved in the genesis of the bone metaplasia caused by Solanum glaucophyllum intoxication. We determined using liquid chromatography that 1 mL of plant extract contained 3.8 μl of 1,25(OH)₂D₃. The ability of 100 μL, 1 mL and 5 mL of extract/L, containing 1 nM (0.4 μg/L), 10 nM (4 μg/L) and 50 nM (20 μg/L) of 1,25(OH)₂D_3, respectively, in inducing the osteogenic differentiation in bone marrow MSCs from rats was tested. At the concentrations of 1 and 5 mL of extract/L of culture medium without osteogenesis-inducing factors, the plant extract induced the osteogenic differentiation of the MSCs, as was evidenced by the greater synthesis of mineralized matrix. At the higher concentration (5 mL of extract/L), an increase in the relative expression of BMP-2 gene was observed. It was concluded that rat bone marrow MSC culture is a good model for studying the effects of the S. glaucophyllum extract on the osteogenic differentiation of undifferentiated cells. Also, S. glaucophyllum extracts containing 10 nM (4 μg/L) and 50 nM (20 μg/L) of 1,25(OH)₂D₃ induce the osteogenic differentiation of MSCs, suggesting that this is one of the mechanisms by which S. glaucophyllum causes bone metaplasia.

Pathogenesis and Cells of Origin of Barrett's Esophagus

In patients with Barrett's esophagus (BE), metaplastic columnar mucosa containing epithelial cells with gastric and intestinal features replaces esophageal squamous mucosa damaged by gastroesophageal reflux disease. This condition is estimated to affect 5.6% of adults in the United States, and is a major risk factor for esophageal adenocarcinoma. Despite the prevalence and importance of BE, its pathogenesis is incompletely understood and there are disagreements over the cells of origin. We review mechanisms of BE pathogenesis, including transdifferentiation and transcommitment, and discuss potential cells of origin, including basal cells of the squamous epithelium, cells of esophageal submucosal glands and their ducts, cells of the proximal stomach, and specialized populations of cells at the esophagogastric junction (residual embryonic cells and transitional basal cells). We discuss the concept of metaplasia as a wound-healing response, and how cardiac mucosa might be the precursor of the intestinal metaplasia of BE. Finally, we discuss shortcomings in current diagnostic criteria for BE that have important clinical implications.

Glyco-conjugated bile acids drive the initial metaplastic gland formation from multi-layered glands through crypt-fission in a murine model

Bile acid reflux is known to be associated with the development of Barrett’s esophagus and esophageal adenocarcinoma (EAC), yet the role of specific bile acids and the mechanism behind the metaplastic changes is unclear. Here, we demonstrate that multi-layered glandular structures at the squamo-columnar junction in mice contain multiple cell lineages, which resemble the human esophageal submucosal gland ducts. Exposing mice to patient’s refluxates induced expansion of multi-layered glandular structures and development of columnar metaplasia at the squamo-columnar junction. The glycine conjugated bile acids induced an intestinal type of metaplasia more typical for Barrett’s esophagus. Through lineage tracing, we excluded the involvement of K5⁺, DCLK1⁺, and LGR5⁺ progenitor cells as the primary source in the development of the glandular metaplastic epithelium. We show that the mechanism behind development of metaplasia involves crypt fission and may be independent of stem cell proliferation. Our findings support the hypothesis that in humans, BE arises from non-squamous cells residing in submucosal gland ducts and that induction of intestinal type of metaplasia is most effectively induced by glycine-conjugated bile acids. These novel insights may lead to more effective strategies to prevent development of Barrett’s esophagus and esophageal adenocarcinoma.

Progress in research into spinal cord injury repair: Tissue engineering scaffolds and cell transdifferentiation

As with all tissues of the central nervous system, the low regeneration ability of spinal cord tissue after injury decreases the potential for repair and recovery. Initially, in spinal cord injuries (SCI), often the surgeon can only limit further damage by early surgical decompression. However, with the development of basic science, especially the development of genetic engineering, molecular biology, tissue engineering, and materials science, some promising progress has been made in promoting the repair of central nervous system injuries. For example, transplantation of neural stem cells (NSCs), olfactory ensheathing cells (OECs), and gene- mediated transdifferentiation to repair central nervous system injury. This paper summarizes the progress and prospects of SCI repair with tissue engineering scaffold and cell transdifferentiation from an extensive literatures.

The Pluripotent Microvascular Pericytes Are the Adult Stem Cells Even in the Testis

The pericytes of the testis are part of the omnipresent population of pericytes in the vertebrate body and are the only true pluripotent adult stem cells able to produce structures typical for the tree primitive germ layers: ectoderm, mesoderm, and endoderm. They originate very early in the embryogenesis from the pluripotent epiblast. The pericytes become disseminated through the whole vertebrate organism by the growing and differentiating blood vessels where they remain in specialized periendothelial vascular niches as resting pluripotent adult stem cells for tissue generation, maintenance, repair, and regeneration. The pericytes are also the ancestors of the perivascular multipotent stromal cells (MSCs). The variable appearance of the pericytes and their progeny reflects the plasticity under the influence of their own epigenetic and the local environmental factors of the host organ. In the testis the pericytes are the ancestors of the neuroendocrine Leydig cells. After activation the pericytes start to proliferate, migrate, and build transit-amplifying cells that transdifferentiate into multipotent stromal cells. These represent progenitors for a number of different cell types in an organ. Finally, it becomes evident that the pericytes are a brilliant achievement of the biological nature aiming to supply every organ with an omnipresent population of pluripotent adult stem cells. Their fascinating features are prerequisites for future therapy concepts supporting cell systems of organs.

Sewing up the wounds : The epithelial morphogenesis as a central mechanism of calcaronean sponge regeneration

Sponges (Porifera) demonstrate prominent regeneration abilities and possess a wide variety of mechanisms, used during this process. In the current study, we combined in vivo observations with histological, immunohistochemical, and ultrastructural technics to elucidate the fine cellular mechanisms of the regeneration in the calcareous sponge Leucosolenia cf. variabilis. The regeneration of Leucosolenia cf. variabilis ends within 4-6 days. The crucial step of the process is the formation of the transient regenerative membrane, formed by the epithelial morphogenesis-spreading of the intact exopinacoderm and choanoderm. The spreading of the choanoderm is accompanied by the transdifferentiation of the choanocytes. The regenerative membrane develops without any contribution of the mesohyl cells. Subsequently, the membrane gradually transforms into the body wall. The cell proliferation is neither affected nor contributes to the regeneration at any stage. Thus, Leucosolenia cf. variabilis regeneration relies on the remodeling of the intact tissues through the epithelial morphogenesis, accompanied by the transdifferentiation of some differentiated cell types, which makes it similar to the regeneration in homoscleromorphs and eumetazoans.

A novel mechanism of gland formation in zebrafish involving transdifferentiation of renal epithelial cells and live cell extrusion

Transdifferentiation is the poorly understood phenomenon whereby a terminally differentiated cell acquires a completely new identity. Here, we describe a rare example of a naturally occurring transdifferentiation event in zebrafish in which kidney distal tubule epithelial cells are converted into an endocrine gland known as the Corpuscles of Stannius (CS). We find that this process requires Notch signalling and is associated with the cytoplasmic sequestration of the Hnf1b transcription factor, a master-regulator of renal tubule fate. A deficiency in the Irx3b transcription factor results in ectopic transdifferentiation of distal tubule cells to a CS identity but in a Notch-dependent fashion. Using live-cell imaging we show that CS cells undergo apical constriction en masse and are then extruded from the tubule to form a distinct organ. This system provides a valuable new model to understand the molecular and morphological basis of transdifferentiation and will advance efforts to exploit this rare phenomenon therapeutically.

Pink Adipocytes

Adipocytes are lipid-rich parenchymal cells contained in a very plastic organ, whose composition can undergo striking physiologic changes. In standard conditions the organ contains white and brown adipocytes which play opposite roles: lipid storage to meet metabolic requirements and lipid burning for thermogenesis, respectively. During chronic cold exposure, white adipocytes transdifferentiate to brown, to increase thermogenesis, whereas in conditions of chronic positive energy balance brown adipocytes transdifferentiate to white, to increase energy stores. During pregnancy, lactation, and post-lactation, subcutaneous white adipocytes convert to milk-producing glands formed by lipid-rich elements that can be defined as pink adipocytes. Recent fate-mapping data support the conversion of pink to brown adipocytes and the reversible conversion of brown adipocytes to myoepithelial cells of alveoli.

Are Gastric and Esophageal Metaplasia Relatives? The Case for Barrett's Stemming from SPEM

Chronic injury and inflammation in the esophagus can cause a change in cellular differentiation known as metaplasia. Most commonly, the differentiation changes manifest as Barrett's esophagus (BE), characterized by the normal stratified squamous epithelium converting into a cuboidal-columnar, glandular morphology. BE cells can phenotypically resemble specific normal cell types of the stomach or intestine, or they can have overlapping phenotypes in disorganized admixtures. The stomach can also undergo metaplasia characterized by aberrant gastric or intestinal differentiation patterns. In both organs, it has been argued that metaplasia may represent a recapitulation of the embryonic or juvenile gastrointestinal tract, as cells access a developmental progenitor genetic program that can help repair damaged tissue. Here, we review the normal development of esophagus and stomach, and describe how BE represents an intermixing of cells resembling gastric pseudopyloric (SPEM) and intestinal metaplasia. We discuss a cellular process recently termed "paligenosis" that governs how mature, differentiated cells can revert to a proliferating progenitor state in metaplasia. We discuss the "Cyclical Hit" theory in which paligenosis might be involved in the increased risk of metaplasia for progression to cancer. However, somatic mutations might occur in proliferative phases and then be warehoused upon redifferentiation. Through years of chronic injury and many rounds of paligenosis and dedifferentiation, eventually a cell with a mutation that prevents dedifferentiation may arise and clonally expand fueling stable metaplasia and potentially thereafter acquiring additional mutations and progressing to dysplasia and cancer.

The Path of Most Resistance: Transdifferentiation Underlies Exceptional Nonresponses to Androgen Receptor Pathway Inhibition in Prostate Cancer

<b/> In this issue of Cancer Discovery, Zou and colleagues describe a mechanism involving cellular transdifferentiation that promotes exceptional resistance to antiandrogen therapy in prostate cancer. A background of coinactivation of Trp53 and Pten increased the frequency of the transdifferentiated neuroendocrine phenotype. These findings have implications for developing approaches to repress cellular plasticity and overcome treatment resistance. Cancer Discov; 7(7); 673-4. ©2017 AACRSee related article by Zou et al., p. 736.

How to make a tumour: cell type specific dissection of Ustilago maydis-induced tumour development in maize leaves

The biotrophic fungus Ustilago maydis causes smut disease on maize (Zea mays), which is characterized by immense plant tumours. To establish disease and reprogram organ primordia to tumours, U. maydis deploys effector proteins in an organ-specific manner. However, the cellular contribution to leaf tumours remains unknown. We investigated leaf tumour formation at the tissue- and cell type-specific levels. Cytology and metabolite analysis were deployed to understand the cellular basis for tumourigenesis. Laser-capture microdissection was performed to gain a cell type-specific transcriptome of U. maydis during tumour formation. In vivo visualization of plant DNA synthesis identified bundle sheath cells as the origin of hyperplasic tumour cells, while mesophyll cells become hypertrophic tumour cells. Cell type-specific transcriptome profiling of U. maydis revealed tailored expression of fungal effector genes. Moreover, U. maydis See1 was identified as the first cell type-specific fungal effector, being required for induction of cell cycle reactivation in bundle sheath cells. Identification of distinct cellular mechanisms in two different leaf cell types and of See1 as an effector for induction of proliferation of bundle sheath cells are major steps in understanding U. maydis-induced tumour formation. Moreover, the cell type-specific U. maydis transcriptome data are a valuable resource to the scientific community.

New role of endoplasmic reticulum chaperones in regulating metaplasia during tumorigenesis

Metaplasia is emerging as a key process in tumorigenesis. We discovered that 2 essential endoplasmic reticulum (ER) chaperones, 78-kilodalton glucose-regulated protein (GRP78) and 94-kilodalton glucose-regulated protein (GRP94) have a role in metaplasia. Grp78 haploinsufficiency in the mouse pancreas impairs acinar-to-ductal metaplasia, whereas in the uterus, Grp94 loss induces squamous cell metaplasia; both resulting in tumor suppression.

Reflux esophagitis and its role in the pathogenesis of Barrett's metaplasia

Reflux esophagitis damages the squamous epithelium that normally lines the esophagus, and promotes replacement of the damaged squamous lining by the intestinal metaplasia of Barrett's esophagus, the precursor of esophageal adenocarcinoma. Therefore, to prevent the development of Barrett's metaplasia and esophageal adenocarcinoma, the pathogenesis of reflux esophagitis must be understood. We have reported that reflux esophagitis, both in a rat model and in humans, develops as a cytokine-mediated inflammatory injury (i.e., cytokine sizzle), not as a caustic chemical injury (i.e., acid burn), as traditionally has been assumed. Moreover, reflux induces activation of hypoxia inducible factor (HIF)-2α, which enhances the transcriptional activity of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) causing increases in pro-inflammatory cytokines and in migration of T lymphocytes, an underlying molecular mechanism for this cytokine-mediated injury. In some individuals, reflux esophagitis heals with Barrett's metaplasia. A number of possibilities exist for the origin of the progenitor cells that give rise to this intestinal metaplasia including those of the esophagus, the proximal stomach, or the bone marrow. However, intestinal cells are not normally found in the esophagus, the stomach, or the bone marrow. Thus, the development of Barrett's intestinal metaplasia must involve some molecular reprogramming of key developmental transcription factors within the progenitor cell, a process termed transcommitment, which may be initiated by the noxious components of the gastric refluxate. This review will highlight recent studies on the pathogenesis of reflux esophagitis and on reflux-related molecular reprogramming of esophageal squamous epithelial cells in the pathogenesis of Barrett's metaplasia.

Barrett's metaplasia develops from cellular reprograming of esophageal squamous epithelium due to gastroesophageal reflux

Gastroesophageal reflux disease (GERD) clinically predisposes to columnar Barrett's metaplasia (BM) in the distal esophagus. We demonstrate evidence supporting the cellular origin of BM from reprograming or transcommitment of resident normal esophageal squamous (NES) epithelial cells in response to acid and bile (A + B) exposure using an in vitro cell culture model. The hTERT-immortalized NES cell line NES-B10T was exposed 5 min/day to an A + B mixture for 30 wk. Morphological changes, mRNA, and protein expression levels for the inflammatory marker cyclooxygenase-2; the lineage-determining transcription factors TAp63 (squamous), CDX2, and SOX9 (both columnar); and the columnar lineage markers Villin, Muc-2, CK8, and mAb Das-1 (incomplete phenotype of intestinal metaplasia) were assessed every 10 wk. Markers of columnar lineage and inflammation increased progressively, while squamous lineage-determining transcriptional factors were significantly decreased both at the mRNA and/or protein level in the NES-B10T cells at/after A + B treatment for 30 wk. Distinct modifications in morphological features were only observed at/after 30 wk of A + B exposure. These changes acquired by the NES-B10T 30-wk cells were retained even after cessation of A + B exposure for at least 3 wk. This study provides evidence that chronic exposure to the physiological components of gastric refluxate leads to repression of the discernable squamous transcriptional factors and activation of latent columnar transcriptional factors. This reflects the alteration in lineage commitment of the precursor-like biphenotypic, NES-B10T cells in response to A + B exposure as the possible origin of BM from the resident NES cells.NEW & NOTEWORTHY This study provides evidence of the origins of Barrett's metaplasia from lineage transcommitment of resident esophageal cells after chronic exposure to gastroesophageal refluxate. The preterminal progenitor-like squamous cells alter their differentiation and develop biphenotypic characteristics, expressing markers of incomplete-type columnar metaplasia. Development of these biphenotypic precursors in vitro is a unique model to study pathogenesis of Barrett's metaplasia and esophageal adenocarcinoma.

Evaluation of the Effects of Airborne Particulate Matter on Bone Marrow-Mesenchymal Stem Cells (BM-MSCs): Cellular, Molecular and Systems Biological Approaches

Particulate matter (PM) contains heavy metals that affect various cellular functions and gene expression associated with a range of acute and chronic diseases in humans. However, the specific effects they exert on the stem cells remain unclear. Here, we report the effects of PM collected from the city of Jeddah on proliferation, cell death, related gene expression and systems of biological analysis in bone marrow mesenchymal stem cells (BM-MSCs), with the aim of understanding the underlying mechanisms. PM_2.5 and PM₁₀ were tested in vitro at various concentrations (15 to 300 µg/mL) and durations (24 to 72 h). PMs induced cellular stress including membrane damage, shrinkage and death. Lower concentrations of PM_2.5 increased proliferation of BM-MSCs, while higher concentrations served to decrease it. PM₁₀ decreased BM-MSCs proliferation in a concentration-dependent manner. The X-ray fluorescence spectrometric analysis showed that PM contains high levels of heavy metals. Ingenuity Pathway Analysis (IPA) and hierarchical clustering analyses demonstrated that heavy metals were associated with signaling pathways involving cell stress/death, cancer and chronic diseases. qRT-PCR results showed differential expression of the apoptosis genes (BCL2, BAX); inflammation associated genes (TNF-α and IL-6) and the cell cycle regulation gene (p53). We conclude that PM causes inflammation and cell death, and thereby predisposes to chronic debilitating diseases.

Shift of microRNA profile upon glioma cell migration using patient-derived spheroids and serum-free conditions

Glioblastoma multiforme (GBM) is the most frequent malignant primary brain tumor. A major reason for the overall median survival being only 14.6 months is migrating tumor cells left behind after surgery. Another major reason is tumor cells having a so-called cancer stem cell phenotype being therefore resistant towards traditional chemo- and radiotherapy. A group of novel molecular targets are microRNAs (miRNAs). MiRNAs are small non-coding RNAs exerting post-transcriptional regulation of gene expression. The aim of this study was to identify differentially expressed miRNAs in migrating GBM cells using serum-free stem cell conditions. We used patient-derived GBM spheroid cultures for a novel serum-free migration assay. MiRNA expression of migrating tumor cells isolated at maximum migration speed was compared with corresponding spheroids using an OpenArray Real-Time PCR System. The miRNA profiling revealed 30 miRNAs to be differentially expressed. In total 13 miRNAs were upregulated and 17 downregulated in migrating cells compared to corresponding spheroids. The three most deregulated miRNAs, miR-1227 (up-regulated), miR-32 (down-regulated) and miR-222 (down-regulated), were experimentally overexpressed. A non-significantly increased migration rate was observed after miR-1227 overexpression. A significantly reduced migration rate was observed after miR-32 and miR-222 overexpression. In conclusion a shift in microRNA profile upon glioma cell migration was identified using an assay avoiding serum-induced migration. Both the miRNA profiling and the functional validation suggested that miR-1227 may be associated with increased migration and miR-32 and miR-222 with decreased migration. These miRNAs may represent potential novel targets in migrating glioma cells.

Metaplastic changes in the epithelium of radicular cysts: A series of 711 cases

Background

This study was aimed to evaluate the prevalence of metaplastic changes in the epithelium of radicular cysts and to investigate how they relate to the clinical and radiographic characteristics of the cysts, based on a large series of radicular cysts.

Material and Methods

Biopsies of cysts of endodontic origin that were examined at the Department of Oral Pathology between 2004 and 2011 have been re-evaluated for this study. Only cases that were re-confirmed with clinical and histological diagnoses of a radicular or residual radicular cyst were included. The included cases were evaluated for the prevalence of metaplastic changes in the form of mucous secreting cells (MSC) or ciliated cells (CC). The relations between the metaplastic changes and the cyst type (radicular or residual radicular), as well as demographic, clinical and radiographic parameters, were statistically evaluated using Fischer and chi-square tests. Significance was set at p<0.05.

Results

A total of 711 cysts were included: 677 were radicular cysts (95%) and 34 (5%) were residual radicular cysts. 23 cases had histopathological diagnoses other than radicular or residual radicular cysts and were excluded from the study. MSC were present in 47 (6.6%) cysts. MSC were significantly more common in residual radicular cysts than in radicular cysts [8 (23.5%) and 39 (5.8%), respectively; p<0.001]. MSC-containing cysts were commonly found in asymptomatic patients (10.5%, p<0.001), and usually presented with well-defined radiographic borders (7.2%, p<0.05). CC were present in 34 (4.8%) cysts, with a markedly high prevalence in the maxillary molar sextant (15%, p<0.001).

Conclusions

In the epithelium of radicular and residual radicular cysts the presence of specific metaplastic changes may be related to cyst type, symptomatology, radiographic findings and tooth location.

Key words:Radicular cyst, metaplasia, mucous secreting cells, ciliated cells.

Notch1 is associated with the differentiation of human bone marrow‑derived mesenchymal stem cells to cardiomyocytes

Notch signaling is involved in the early process of differentiation to determine the fate of stem cells. However, the precise role of Notch in human bone marrow-derived mesenchymal stem cells (hBMSCs) remains unclear. The present study aimed to investigate the involvement of Notch signalling during the course of hBMSC differentiation into cardiomyocytes using hBMSCs, with multilineage differentiation ability, isolated and purified from human bone marrow. Flow cytometric analysis revealed that CD29, CD44 and CD90 were highly expressed on the surface of cells in their fifth passage, whereas detection of CD34, CD45, CD54 and HLA-DR was negative. Visualization of morphological changes, western blotting, immunocytochemistry and reverse transcription-quantitative polymerase chain reaction (RT-qPCR) demonstrated that hBMSCs differentiate into cardiomyocytes through treatment with 5-azacytidine (5-aza). Transmission electron microscopy revealed ultramicroscopic details of differentiated hBMSCs. Western blotting and immunocytochemistry demonstrated increased protein expression levels of α-actin and cardiac troponin T expression, and RT-qPCR revealed increased mRNA expression of Notch1 early in the process of differentiation (days 1, 4 and 7), and increased mRNA expression levels of the transcription factors GATA binding protein-4 and NK2 homeobox 5 at day 28 day. In conclusion, differentiation of hBMSCs into cardiomyocytes was induced in vitro by 5-aza, and was associated with upregulation of Notch1, GATA binding protein-4 and Nkx2.5 expression. Overexpression of the Notch1 signaling pathway may represent a potential mechanism underlying the differentiation of hBMSCs.

Neuronal Trans-Differentiation in Prostate Cancer Cells

BACKGROUND

Neuroendocrine (NE) differentiation in prostate cancer (PCa) is an aggressive phenotype associated with therapy resistance. The complete phenotype of these cells is poorly understood. Clinical classification is based predominantly on the expression of standard NE markers.

METHODS

We analyzed the phenotype of NE carcinoma of the prostate utilizing in vitro methods, in silico, and immunohistochemical analyses of human disease.

RESULTS

LNCaP cells, subjected to a variety of stressors (0.1% [v/v] fetal bovine serum, cyclic AMP) induced a reproducible phenotype consistent with neuronal trans-differentiation. Cells developed long cytoplasmic processes resembling neurons. As expected, serum deprived cells had decreased expression in androgen receptor and prostate specific antigen. A significant increase in neuronal markers also was observed. Gene array analysis demonstrated that LNCaP cells subjected to low serum or cAMP showed statistically significant manifestation of a human brain gene expression signature. In an in silico experiment using human data, we identified that only hormone resistant metastatic prostate cancer showed enrichment of the "brain profile." Gene ontology analysis demonstrated categories involved in neuronal differentiation. Three neuronal markers were validated in a large human tissue cohort.

CONCLUSION

This study proposes that the later stages of PCa evolution involves neuronal trans-differentiation, which would enable PCa cells to acquire independence from the neural axis, critical in primary tumors. Prostate 76:1312-1325, 2016. © 2016 Wiley Periodicals, Inc.

ICRP Publication 131: Stem Cell Biology with Respect to Carcinogenesis Aspects of Radiological Protection

This report provides a review of stem cells/progenitor cells and their responses to ionising radiation in relation to issues relevant to stochastic effects of radiation that form a major part of the International Commission on Radiological Protection's system of radiological protection. Current information on stem cell characteristics, maintenance and renewal, evolution with age, location in stem cell 'niches', and radiosensitivity to acute and protracted exposures is presented in a series of substantial reviews as annexes concerning haematopoietic tissue, mammary gland, thyroid, digestive tract, lung, skin, and bone. This foundation of knowledge of stem cells is used in the main text of the report to provide a biological insight into issues such as the linear-no-threshold (LNT) model, cancer risk among tissues, dose-rate effects, and changes in the risk of radiation carcinogenesis by age at exposure and attained age. Knowledge of the biology and associated radiation biology of stem cells and progenitor cells is more developed in tissues that renew fairly rapidly, such as haematopoietic tissue, intestinal mucosa, and epidermis, although all the tissues considered here possess stem cell populations. Important features of stem cell maintenance, renewal, and response are the microenvironmental signals operating in the niche residence, for which a well-defined spatial location has been identified in some tissues. The identity of the target cell for carcinogenesis continues to point to the more primitive stem cell population that is mostly quiescent, and hence able to accumulate the protracted sequence of mutations necessary to result in malignancy. In addition, there is some potential for daughter progenitor cells to be target cells in particular cases, such as in haematopoietic tissue and in skin. Several biological processes could contribute to protecting stem cells from mutation accumulation: (a) accurate DNA repair; (b) rapidly induced death of injured stem cells; (c) retention of the DNA parental template strand during divisions in some tissue systems, so that mutations are passed to the daughter differentiating cells and not retained in the parental cell; and (d) stem cell competition, whereby undamaged stem cells outcompete damaged stem cells for residence in the niche. DNA repair mainly occurs within a few days of irradiation, while stem cell competition requires weeks or many months depending on the tissue type. The aforementioned processes may contribute to the differences in carcinogenic radiation risk values between tissues, and may help to explain why a rapidly replicating tissue such as small intestine is less prone to such risk. The processes also provide a mechanistic insight relevant to the LNT model, and the relative and absolute risk models. The radiobiological knowledge also provides a scientific insight into discussions of the dose and dose-rate effectiveness factor currently used in radiological protection guidelines. In addition, the biological information contributes potential reasons for the age-dependent sensitivity to radiation carcinogenesis, including the effects of in-utero exposure.

Barrett's Esophagus: A Comprehensive and Contemporary Review for Pathologists

This review provides a summary of our current understanding of, and the controversies surrounding, the diagnosis, pathogenesis, histopathology, and molecular biology of Barrett's esophagus (BE) and associated neoplasia. BE is defined as columnar metaplasia of the esophagus. There is worldwide controversy regarding the diagnostic criteria of BE, mainly with regard to the requirement to histologically identify goblet cells in biopsies. Patients with BE are at increased risk for adenocarcinoma, which develops in a metaplasia-dysplasia-carcinoma sequence. Surveillance of patients with BE relies heavily on the presence and grade of dysplasia. However, there are significant pathologic limitations and diagnostic variability in evaluating dysplasia, particularly with regard to the more recently recognized unconventional variants. Identification of non-morphology-based biomarkers may help risk stratification of BE patients, and this is a subject of ongoing research. Because of recent achievements in endoscopic therapy, there has been a major shift in the treatment of BE patients with dysplasia or intramucosal cancer away from esophagectomy and toward endoscopic mucosal resection and ablation. The pathologic issues related to treatment and its complications are also discussed in this review article.

Migrating glioma cells express stem cell markers and give rise to new tumors upon xenografting

Glioblastoma (GBM) is the most frequent and malignant brain tumor with an overall survival of only 14.6 months. Although these tumors are treated with surgery, radiation and chemotherapy, recurrence is inevitable. A critical population of tumor cells in terms of therapy, the so-called cancer stem cells (CSCs), has been identified in gliomas and many other cancers. These tumor cells have a stem cell-like phenotype and are suggested to be responsible for tumor growth, chemo- and radio-resistance as well as recurrence. However, functional evidence for migrating glioma cells having a stem cell-like phenotype is currently lacking. In the present study, the aim was to characterize the phenotype of migrating tumor cells using a novel migration assay based on serum-free stem cell medium and patient-derived spheroid cultures. The results showed pronounced migration of five different GBM spheroid cultures, but not of the commercial cell line U87MG. An in vitro limiting dilution assay showed preserved but reduced spheroid formation capacity of migrating cells. Orthotopic xenografting in mice showed preserved but reduced tumorigenic capacity. Profiling of mRNAs revealed no significant deregulation of 16 predefined CSC-related genes and the HOX-gene list in migrating cells compared to spheroids. Determination of GBM molecular subtypes revealed that subtypes of spheroids and migrating cells were identical. In conclusion, migrating tumor cells preserve expression of stem cell markers and functional CSC characteristics. Since CSCs are reported to be highly resistant to therapy, these results emphasize that the CSC phenotype should be taken into consideration in future treatment of GBMs.

Circulating Tumor Cells in the Adenocarcinoma of the Esophagus

Circulating tumor cells (CTCs) are elements of indisputable significance as they seem to be responsible for the onset of metastasis. Despite this, research into CTCs and their clinical application have been hindered by their rarity and heterogeneity at the molecular and cellular level, and also by a lack of technical standardization. Esophageal adenocarcinoma (EAC) is a highly aggressive cancer that is often diagnosed at an advanced stage. Its incidence has increased so much in recent years that new diagnostic, prognostic and predictive biomarkers are urgently needed. Preliminary findings suggest that CTCs could represent an effective, non-invasive, real-time assessable biomarker in all stages of EAC. This review provides an overview of EAC and CTC characteristics and reports the main research results obtained on CTCs in this setting. The need to carry out further basic and translational research in this area to confirm the clinical usefulness of CTCs and to provide oncologists with a tool to improve therapeutic strategies for EAC patients was herein highlighted.

Astrocytes Can Adopt Endothelial Cell Fates in a p53-Dependent Manner

Astrocytes respond to a variety of CNS injuries by cellular enlargement, process outgrowth, and upregulation of extracellular matrix proteins that function to prevent expansion of the injured region. This astrocytic response, though critical to the acute injury response, results in the formation of a glial scar that inhibits neural repair. Scar-forming cells (fibroblasts) in the heart can undergo mesenchymal-endothelial transition into endothelial cell fates following cardiac injury in a process dependent on p53 that can be modulated to augment cardiac repair. Here, we sought to determine whether astrocytes, as the primary scar-forming cell of the CNS, are able to undergo a similar cellular phenotypic transition and adopt endothelial cell fates. Serum deprivation of differentiated astrocytes resulted in a change in cellular morphology and upregulation of endothelial cell marker genes. In a tube formation assay, serum-deprived astrocytes showed a substantial increase in vessel-like morphology that was comparable to human umbilical vein endothelial cells and dependent on p53. RNA sequencing of serum-deprived astrocytes demonstrated an expression profile that mimicked an endothelial rather than astrocyte transcriptome and identified p53 and angiogenic pathways as specifically upregulated. Inhibition of p53 with genetic or pharmacologic strategies inhibited astrocyte-endothelial transition. Astrocyte-endothelial cell transition could also be modulated by miR-194, a microRNA downstream of p53 that affects expression of genes regulating angiogenesis. Together, these studies demonstrate that differentiated astrocytes retain a stimulus-dependent mechanism for cellular transition into an endothelial phenotype that may modulate formation of the glial scar and promote injury-induced angiogenesis.