Stem cell plasticity. Plasticity of epithelial stem cells in tissue regeneration

The Chromatin Accessibility Landscape in Cell Plasticity and Reprogramming: Understanding and Overcoming the Barriers

Cell plasticity enables the dynamic changes in cell identities necessary for normal development and tissue repair. Induced cell reprogramming, which leverages this plasticity, holds great promise for regenerative medicine and personalized therapies. However, the success of cell reprogramming is often impeded by various molecular barriers, such as epigenetic marks, cell senescence, and the activation of alternative or refractory routes. In this review, we examine the cell reprogramming events that occur within or between germ layers and adult stem cell lineages and propose that the overall similarity in the pre-existing chromatin accessibility landscape is a major determinant of reprogramming efficiency from one cell type to another. A better understanding of the regulation and control of chromatin accessibility should facilitate the development of new methods and strategies to improve cell reprogramming efficiency and advance translational research.

Epithelial-Immune-Stromal Interactions Define Divergent Repair and Fibrosis Pathways After Acute Kidney Injury in Human Renal Transplants

Acute kidney injury (AKI) is a major cause of early graft dysfunction after kidney transplantation, particularly in recipients of high-risk donor kidneys prone to ischemia-reperfusion injury. However, the cellular mechanisms dictating whether injury resolves or progresses to fibrosis remain unclear. This study combines single-nucleus RNA sequencing and imaging mass cytometry (IMC) analysis of human kidney allograft biopsies collected within eight weeks posttransplant, stratified by long-term functional outcomes. Grafts that recovered function were enriched in regenerative proximal tubular (PT) cells co-expressing PROM1, CD24, and injury markers, consistent with scattered tubular cells (STCs). In contrast, non-recovering grafts contained a unique subpopulation of transitional proximal tubule cells (tPT4) characterized by dedifferentiation, loss of epithelial identity, and acquisition of fibroblast-like features. Fibroblast trajectory analysis revealed a profibrotic lineage, progressing from stromal progenitors to myofibroblasts, exclusive to nonrecovery grafts. Immune profiling showed divergent macrophage (MΦ) polarization, with reparative MΦ2 cells and regulatory dendritic cell (DC)-like signatures in recovering grafts, versus inflammatory MΦ1 and pro-fibrotic DCs in non-recovery. IMC confirmed spatial colocalization of injured tubules, activated fibroblasts, and immune cells in fibrotic regions, validated in an independent cohort. Functional assays demonstrated that ischemic epithelial injury activated monocyte-derived MΦs with mixed inflammatory/reparative profiles and induced fibroblast-related gene expression, while PAX8 knockdown impaired epithelial proliferation and promoted pro-inflammatory signaling. These findings reveal epithelial cell plasticity as a central driver of divergent repair outcomes following renal transplant AKI and highlight epithelial-immune-stromal crosstalk as a therapeutic target to promote recovery and prevent chronic graft injury.

One Sentence Summary

Single-cell and spatial mapping of human kidney transplants reveal regenerative and fibrotic cell programs across tubular, immune, and stromal compartments that determine whether acute injury resolves or progresses to chronic allograft injury.

Transcriptional landscapes underlying Notch-induced lineage conversion and plasticity of mammary basal cells

The mammary epithelium derives from multipotent mammary stem cells (MaSCs) that engage into differentiation during embryonic development. However, adult MaSCs maintain the ability to reactivate multipotency in non-physiological contexts. We previously reported that Notch1 activation in committed basal cells triggers a basal-to-luminal cell fate switch in the mouse mammary gland. Here, we report conservation of this mechanism and found that in addition to the mammary gland, constitutive Notch1 signaling induces a basal-to-luminal cell fate switch in adult cells of the lacrimal gland, the salivary gland, and the prostate. Since the lineage transition is progressive in time, we performed single-cell transcriptomic analysis on index-sorted mammary cells at different stages of lineage conversion, generating a temporal map of changes in cell identity. Combining single-cell analyses with organoid assays, we demonstrate that cell proliferation is indispensable for this lineage conversion. We also reveal the individual transcriptional landscapes underlying the cellular plasticity switching of committed mammary cells in vivo with spatial and temporal resolution. Given the roles of Notch signaling in cancer, these results may help to better understand the mechanisms that drive cellular transformation.

A Visible-Light Photocatalysis/Hydrolysis Hydrogen-Generating Nanoplatform for Dynamic Inflammation Management via Immune Metabolism Orchestration during Wound Repair

Effective management of inflammation is one of the promising strategies to prevent the formation of chronic wounds. Despite hydrogen being a prospective molecule for anti-inflammatory effects, the on-demand delivery of hydrogen that could synchronize with the dynamic inflammation stages has yet remained unaddressed. Moreover, its specific immunomodulatory mechanisms are still veiled. In this study, we introduced ISO-ZIF-8@AB, a hydrogen-generating nanoplatform that integrated visible-light photocatalysis and hydrolysis reactions to achieve controllable hydrogen release on demand, functioning with an initial peak release and following a sustained release. With ISO-ZIF-8@AB further loaded into an aligned ECM-like scaffold, the complex significantly alleviated inflammation and prevented protracted unhealing. The bulk-RNA sequencing combined with single-cell RNA sequencing revealed that hydrogen treatment effectively reduced the excessive aggregation and infiltration of innate immune cells. Specifically, hydrogen reduced the proportion of Ptgs2+Nos2+ pro-inflammatory macrophages (PIMs) by mitigating mitochondrial stress and suppressing HIF-1α-induced glycolysis, the immune-metabolic regulation of which reduced harmful crosstalk between PIMs and hypodermal fibroblasts and facilitated extracellular matrix production accompanied by the ultimate wound repair. Overall, this study presented a strategy for controllable hydrogen release in terms of timing and rate, with further discussions regarding the underlying immune-metabolic regulation mechanisms of hydrogen therapy.

Unlocking regeneration: how partial reprogramming resembles tissue healing

Partial reprogramming achieved by the transient expression of the transcription factors (TFs) Oct4, Sox2, Klf4 and C-Myc (abbreviated OSKM) can erase aging and damage features in cells, leading to increased healthspan, lifespan and tissue regeneration. Recent reports suggest that the mechanisms of partial reprogramming may share some similarities with natural dedifferentiation and regeneration. Both processes appear to involve the transient repression of somatic identity through the sequestration of somatic identity TFs to noncanonical sites, which are opened by the high expression of pioneer TFs, leading to transient dedifferentiation into a fetal-like state. Here, we review the reported benefits of partial reprogramming on tissue regeneration and propose a common mechanism of epigenetic remodeling with natural regeneration after tissue injury.

Safely Targeting Cancer, the Wound That Never Heals, Utilizing CBP/Beta-Catenin Antagonists

Stem cells, both normal somatic (SSC) and cancer stem cells (CSC) exist in minimally two states, i.e., quiescent and activated. Regulation of these two states, including their reliance on different metabolic processes, i.e., FAO and glycolysis in quiescent versus activated stem cells respectively, involves the analysis of a complex array of factors (nutrient and oxygen levels, adhesion molecules, cytokines, etc.) to initiate the epigenetic changes to either depart or enter quiescence. Quiescence is a critical feature of SSC that is required to maintain the genomic integrity of the stem cell pool, particularly in long lived complex organisms. Quiescence in CSC, whether they are derived from mutations arising in SSC, aberrant microenvironmental regulation, or via dedifferentiation of more committed progenitors, is a critical component of therapy resistance and disease latency and relapse. At the beginning of vertebrate evolution, approximately 450 million years ago, a gene duplication generated the two members of the Kat3 family, CREBBP (CBP) and EP300 (p300). Despite their very high degree of homology, these two Kat3 coactivators play critical and non-redundant roles at enhancers and super-enhancers via acetylation of H3K27, thereby controlling stem cell quiescence versus activation and the cells metabolic requirements. In this review/perspective, we discuss the unique regulatory roles of CBP and p300 and how specifically targeting the CBP/β-catenin interaction utilizing small molecule antagonists, can correct lineage infidelity and safely eliminate quiescent CSC.

Long-term expansion of basal cells and the novel differentiation methods identify mechanisms for switching Claudin expression in normal epithelia

Epithelia are tightly connected cellular sheets, that shield our body from the external environment. They are continuously maintained by a pooled population of undifferentiated cells through differentiation. However, the maintenance mechanisms remain incompletely understood due to the difficulty of experimentally observing the differentiation process. To address this issue, we developed a culture method for long-term expansion of primary mammary basal cells with a set of compounds, that includes undifferentiated cells. An effective differentiation method regarding Claudin expression was also developed by simply removing compounds. To verify this differentiation-switching technique, we obtained microarray data comparing each differentiation state. Subsequent cellular analysis confirmed key transcription factors in each state: (1) EGR1 in undifferentiated basal cells is important for suppressing Claudin expression through maintaining the epithelial-mesenchymal transition (EMT) transcription factor TWIST1, (2) ELF3 in differentiated cells is important for actin organization and subsequent Claudin localization at the cell-cell border, that corresponds to the amount of GRHL3, an actin organizer. Their relevance was also observed in tissues and organoids. In summary, we present an effective tool for verifying molecular mechanisms that determine Claudin status in normal basal cell differentiation, that would be beneficial in epithelial cell biology, cancer biology, physiology, and regeneration research.

Sphingolipid metabolism orchestrates establishment of the hair follicle stem cell compartment

Sphingolipids serve as building blocks of membranes to ensure subcellular compartmentalization and facilitate intercellular communication. How cell type-specific lipid compositions are achieved and what is their functional significance in tissue morphogenesis and maintenance has remained unclear. Here, we identify a stem cell-specific role for ceramide synthase 4 (CerS4) in orchestrating fate decisions in skin epidermis. Deletion of CerS4 prevents the proper development of the adult hair follicle bulge stem cell (HFSC) compartment due to altered differentiation trajectories. Mechanistically, HFSC differentiation defects arise from an imbalance of key ceramides and their derivate sphingolipids, resulting in hyperactivation of noncanonical Wnt signaling. This impaired HFSC compartment establishment leads to disruption of hair follicle architecture and skin barrier function, ultimately triggering a T helper cell 2-dominated immune infiltration resembling human atopic dermatitis. This work uncovers a fundamental role for a cell state-specific sphingolipid profile in stem cell homeostasis and in maintaining an intact skin barrier.

Increased levels of lagging strand polymerase α in an adult stem cell lineage affect replication-coupled histone incorporation

Stem cells display asymmetric histone inheritance, while nonstem progenitor cells exhibit symmetric patterns in the Drosophila male germ line. Here, we report that components involved in lagging strand synthesis, DNA polymerases α and δ, have substantially reduced levels in stem cells compared to progenitor cells, and this promotes local asymmetry of parental histone incorporation at the replication fork. Compromising Polα genetically induces the local replication-coupled histone incorporation pattern in progenitor cells to resemble that in stem cells, seen by both nuclear localization patterns and chromatin fibers. This is recapitulated using a Polα inhibitor in a concentration-dependent manner. The local old versus new histone asymmetry is comparable between stem cells and progenitor cells at both S phase and M phase. Together, these results indicate that developmentally programmed expression of key DNA replication components is important to shape stem cell chromatin. Furthermore, manipulating one crucial DNA replication component can induce replication-coupled histone dynamics in nonstem cells to resemble those in stem cells.

Dietary Iron Alleviates Dextran Sodium Sulfate-Induced Intestinal Injury by Regulating Regeneration of Intestinal Stem Cells in Weaned Mice

Iron deficiency is the most common comorbidity of inflammatory bowel disease (IBD), but the effect of iron supplementation on the repair processes of intestinal injury in weaned mice is unknown. This study aimed to evaluate the potential mechanism of dietary iron on intestinal injury and intestinal regeneration in the dextran sodium sulfate (DSS)-induced colitis of the weaned mouse model. The mice were fed either a control diet containing (45.00 mg/kg Fe) or iron supplemental (448.30 mg/kg Fe) diet for 14 days, followed by a 7-day oral administration of 2.5% DSS to all mice. The result showed that at day 0 of the recovery period (0 DRP), the impact of iron on the gut index and intestinal morphology was found to be more significant in weaned mice compared to adult mice. At 3 DRP, the iron diet alleviated inflammation-induced weight loss, shortening of colon length, thickening of the muscle layer, and disruption of gut morphology. At 0, 3, and 7 DRP, we found that an iron diet increased intestinal stem cell (ISC) viability and protected epithelial integrity. Furthermore, FeSO4 significantly enhanced organoid viability and increased mRNA expression of differentiation, ISC, and retinol metabolism-related marker genes in the organoids compared with the control group. Overall, this study demonstrates that the iron diet accelerates intestinal regeneration after intestinal injury in weaned mice by activating the retinol metabolic pathway to regulate the proliferation and differentiation of ISCs.

Recent advances in the role of neuroregulation in skin wound healing

Neuroregulation during skin wound healing involves complex interactions between the nervous system and intricate tissue repair processes. The skin, the largest organ, depends on a complex system of nerves to manage responses to injury. Recent research has emphasized the crucial role of neuroregulation in maximizing wound healing outcomes. Recently, researchers have also explained the interactive contact between the peripheral nervous system and skin cells during the different phases of wound healing. Neurotransmitters and neuropeptides, once observed as simple signalling molecules, have since been recognized as effective regulators of inflammation, angiogenesis, and cell proliferation. The significance of skin innervation and neuromodulators is underscored by the delayed wound healing observed in patients with diabetes and the regenerative capabilities of foetal skin. Foetal skin regeneration is influenced by the neuroregulatory environment, immature immune system, abundant growth factors, and increased pluripotency of cells. Foetal skin cells exhibit greater flexibility and specialized cell types, and the extracellular matrix composition promotes regeneration. The extracellular matrix composition of foetal skin promotes regeneration, making it more capable than adult skin because neuroregulatory signals affect skin regeneration. The understanding of these systems can facilitate the development of therapeutic strategies to alter the nerve supply to the skin to enhance the process of wound healing. Neuroregulation is being explored as a potential therapeutic strategy for enhancing skin wound repair. Bioelectronic strategies and neuromodulation techniques can manipulate neural signalling, optimize the neuroimmune axis, and modulate inflammation. This review describes the function of skin innervation in wound healing, emphasizing the importance of neuropeptides released by sensory and autonomic nerve fibres. This article discusses significant discoveries related to neuroregulation and its impact on skin wound healing.

Stemness in solid malignancies: coping with immune attack

Immunotherapy has become a key new pillar of cancer treatment, and this has sparked interest in understanding mechanisms of cancer immune evasion. It has long been appreciated that cancers are constituted by heterogeneous populations of tumour cells. This feature is often fuelled by specialized cells that have molecular programs resembling tissue stem cells. Although these cancer stem cells (CSCs) have capacity for unlimited self-renewal and differentiation, it is increasingly evident that some CSCs are capable of achieving remarkable immune resistance. Given that most immunotherapy regiments have overlooked CSC-specific immune-evasive mechanisms, many current treatment strategies often lead to cancer relapse. This Review focuses on advancements in understanding how CSCs in solid tumours achieve their unique immune-evasive properties, enabling them to drive tumour regrowth. Moreover, as cancers often arise from tissue stem cells that acquired oncogenic mutations, we discuss how tissue stem cells undergoing malignant transformation activate intrinsic immune-evasive mechanisms and establish close interactions with suppressive immune cells to escape immune surveillance. In addition, we summarize how in advanced disease stages, CSCs often hijack features of normal stem cells to resist antitumour immunity. Finally, we provide insights in how to design a new generation of cancer immunotherapies to ensure elimination of CSCs.

Bridging tissue repair and epithelial carcinogenesis: epigenetic memory and field cancerization

The epigenome coordinates spatial-temporal specific gene expression during development and in adulthood, for the maintenance of homeostasis and upon tissue repair. The upheaval of the epigenetic landscape is a key event in the onset of many pathologies including tumours, where epigenetic changes cooperate with genetic aberrations to establish the neoplastic phenotype and to drive cell plasticity during its evolution. DNA methylation, histone modifiers and readers or other chromatin components are indeed often altered in cancers, such as carcinomas that develop in epithelia. Lining the surfaces and the cavities of our body and acting as a barrier from the environment, epithelia are frequently subjected to acute or chronic tissue damages, such as mechanical injuries or inflammatory episodes. These events can activate plasticity mechanisms, with a deep impact on cells' epigenome. Despite being very effective, tissue repair mechanisms are closely associated with tumour onset. Here we review the similarities between tissue repair and carcinogenesis, with a special focus on the epigenetic mechanisms activated by cells during repair and opted by carcinoma cells in multiple epithelia. Moreover, we discuss the recent findings on inflammatory and wound memory in epithelia and describe the epigenetic modifications that characterise them. Finally, as wound memory in epithelial cells promotes carcinogenesis, we highlight how it represents an early step for the establishment of field cancerization.

Expansion of Human Epidermal Keratinocytes in Co-culture with Human Feeder Cells

The co-culture of human epidermal keratinocytes with mouse 3T3-J2 feeder cells, a method developed by Green and colleagues, has been widely used since the early 1980s to generate skin autografts. Additionally, co-culture with 3T3-J2 cells has been a crucial tool in skin stem cell biology, as it facilitates the evaluation of self-renewal capacity and differentiation of epidermal stem cells. This chapter presents a recent enhancement of the Green method, aimed at further promoting the expansion of human epidermal keratinocytes by utilizing a small molecule inhibitor of TGF-β signaling. This new protocol also enables the rapid expansion of human epidermal keratinocytes in co-culture with human feeder cells, including human dermal fibroblasts and human preadipocytes-two key alternatives to 3T3-J2 cells-with the long-term goal of developing customized Xeno-free skin autografts.

Type III interferons induce pyroptosis in gut epithelial cells and impair mucosal repair

Tissue damage and repair are hallmarks of inflammation. Despite a wealth of information on the mechanisms that govern tissue damage, mechanistic insight into how inflammation affects repair is lacking. Here, we investigated how interferons influence tissue repair after damage to the intestinal mucosa. We found that type III, not type I or type II, interferons delay epithelial cell regeneration by inducing the upregulation of Z-DNA-binding protein 1 (ZBP1). Z-nucleic acids formed following intestinal damage are sensed by ZBP1, leading to caspase-8 activation and the cleavage of gasdermin C (GSDMC). Cleaved GSDMC drives epithelial cell death by pyroptosis and delays repair of the large or small intestine after colitis or irradiation, respectively. The type III interferon/ZBP1/caspase-8/GSDMC axis is also active in patients with inflammatory bowel disease (IBD). Our findings highlight the capacity of type III interferons to delay gut repair, which has implications for IBD patients or individuals exposed to radiation therapies.

Can brain neurons change identity? Lessons from obesity

It has long been thought that the functional identity of mammalian brain neurons is programmed during development and remains stable throughout adult life; however, certain populations of neurons continue to express active regulators of neuronal identity into adulthood. Prolonged exposure to diet-induced metabolic stress induces features of neuronal identity modification in adult mice, and maladaptive changes in neuronal identity maintenance have been linked to cognitive impairment in humans suffering from neurodegenerative diseases often associated with obesity. Here we discuss how, by unraveling the neurological roots of obesity, we may solve the puzzle of whether mammalian brain neurons retain identity plasticity into adulthood, while advancing knowledge of the pathogenic mechanisms at the interface of metabolic and neurodegenerative disorders.

Advances in proteins, polysaccharides, and composite biomaterials for enhanced wound healing via microenvironment management: A review

Wound management is crucial yet imposes substantial social and economic burdens on patients and healthcare systems. The recent rapid advancements in biomaterials and manufacturing technology have created favorable conditions for expediting wound healing. This review examines the latest developments in biomacromolecule-based wound dressings, with a particular focus on proteins and polysaccharides, and their role in modulating the wound microenvironment. The importance of extracellular matrix (ECM)-inspired materials, such as hydrogels and biomimetic dressings, is emphasized. Additionally, this review explores the functionalization of wound dressings, emphasizing properties such as hemostatic capabilities, pain relief, antimicrobial activity, and innovative smart functions like electroceuticals and wound condition monitoring. The study integrates discussions on both the macroscopic healing outcomes and the microscopic pathophysiological mechanisms, highlighting recent advances in managing wound environments to expedite healing. Finally, the review critically assesses the challenges associated with the clinical translation of these wound-healing materials in the future.

JAK/STAT signaling maintains an intermediate cell population during prostate basal cell fate determination

Unipotent basal and luminal stem cells maintain prostate homeostasis, with an intermediate cell population emerging during prostate inflammation or cancer. However, the identities of basal stem cell and intermediate cell population remain unclear. Here we identified a rare intermediate cell population expressing luminal markers (termed Basal-B) with enhanced organoid formation capacity, and a larger basal population (termed Basal-A). Genetic lineage tracing revealed Basal-B cells represented a transient basal stem cell state during prostate homeostasis and androgen-mediated regeneration. Activated JAK/STAT signaling was identified in Basal-B cells, and its inhibition significantly reduced Basal-B markers expression. Inflammation increased Basal-B-to-luminal cell transdifferentiation, but JAK/STAT inhibition notably attenuated this effect. Pten gene deletion increased Nkx3.1-expressing Basal-B-like cell population and led to neoplasia. In humans, h-Basal-B cells were more prevalent in benign prostate hyperplasia. This study reveals the identities of intermediate Basal-B cells and underscores the role of JAK/STAT signaling in prostate cell fate determination.

Cellular Plasticity in Gut and Liver Regeneration

The intestine and liver share a unique regenerative property that sets them apart from other mammalian visceral organs. The intestinal epithelium exhibits rapid renewal, making it one of the fastest renewing tissues in humans. Under physiological conditions, intestinal stem cells within each intestinal crypt continuously differentiate into the different types of intestinal epithelial cells to maintain intestinal homeostasis. However, when exposed to tissue damage or stressful conditions such as inflammation, intestinal epithelial cells in the gastrointestinal tract exhibit plasticity, allowing fully differentiated cells to regain their stem cell properties. Likewise, hepatic epithelial cells possess a remarkable regenerative capacity to restore lost liver mass through proliferation-mediated liver regeneration. When the proliferation-mediated regenerative capacity is impaired, hepatocytes and biliary epithelial cells (BECs) can undergo plasticity-mediated regeneration and replenish each other. The transition of mammalian liver progenitor cells to hepatocytes/BECs can be observed under tightly controlled experimental conditions such as severe hepatocyte injury accompanied by the loss of regenerative capacity. In this review, we will discuss the mechanism by which cellular plasticity contributes to the regeneration process and the potential therapeutic implications of understanding and harnessing cellular plasticity in the gut and liver.

Insights into the molecular changes of adipocyte dedifferentiation and its future research opportunities

Recent studies have challenged the traditional belief that mature fat cells are irreversibly differentiated and revealed they can dedifferentiate into fibroblast-like cells known as dedifferentiated fat (DFAT) cells. Resembling pluripotent stem cells, DFAT cells hold great potential as a cell source for stem cell therapy. However, there is limited understanding of the specific changes that occur following adipocyte dedifferentiation and the detailed regulation of this process. This review explores the epigenetic, genetic, and phenotypic alterations associated with DFAT cell dedifferentiation, identifies potential targets for clinical regulation and discusses the current applications and challenges in the field of DFAT cell research.

The TMEM63B Channel Facilitates Intestinal Motility and Enhances Proliferation of Intestinal Stem Cells

The intestines are in a constant state of motion and self-renewal. The mechanical breakdown of food facilitates intestinal movement and aids digestion. It is believed that mechanical stimulation, triggered by changes in osmotic pressure within the intestines, plays a crucial role in regulating gastrointestinal motility. While TRPs and PIEZO1/2 have been identified as mechanosensitive ion channels involved in this process, there still exist numerous unidentified channels with similar properties. In this study, we demonstrate that the TMEM63B expressed in intestinal stem cells contributes to the regulation of intestinal motility and digestion. The deletion of TMEM63B in intestinal stem cells not only decelerates intestinal motility and impairs digestion but also attenuates the proliferation of intestinal stem cells and exacerbates DSS-induced colitis in mice. Collectively, our findings unveil the pivotal role of TMEM63B in governing optimal digestive function and modulating intestinal motility.

Variations in cell plasticity and proliferation underlie distinct modes of regeneration along the antero-posterior axis in the annelid Platynereis

The capacity to regenerate lost tissues varies significantly among animals. Some phyla, such as the annelids, display substantial regenerating abilities, although little is known about the cellular mechanisms underlying the process. To precisely determine the origin, plasticity and fate of the cells participating in blastema formation and posterior end regeneration after amputation in the annelid Platynereis dumerilii, we developed specific tools to track different cell populations. Using these tools, we find that regeneration is partly promoted by a population of proliferative gut cells whose regenerative potential varies as a function of their position along the antero-posterior axis of the worm. Gut progenitors from anterior differentiated tissues are lineage restricted, whereas gut progenitors from the less differentiated and more proliferative posterior tissues are much more plastic. However, they are unable to regenerate the stem cells responsible for the growth of the worms. Those stem cells are of local origin, deriving from the cells present in the segment abutting the amputation plane, as are most of the blastema cells. Our results favour a hybrid and flexible cellular model for posterior regeneration in Platynereis relying on different degrees of cell plasticity.

Biochemical characterization of the feedforward loop between CDK1 and FOXM1 in epidermal stem cells

The complex network governing self-renewal in epidermal stem cells (EPSCs) is only partially defined. FOXM1 is one of the main players in this network, but the upstream signals regulating its activity remain to be elucidated. In this study, we identify cyclin-dependent kinase 1 (CDK1) as the principal kinase controlling FOXM1 activity in human primary keratinocytes. Mass spectrometry identified CDK1 as a key hub in a stem cell-associated protein network, showing its upregulation and interaction with essential self renewal-related markers. CDK1 phosphorylates FOXM1 at specific residues, stabilizing the protein and enhancing its nuclear localization and transcriptional activity, promoting self-renewal. Additionally, FOXM1 binds to the CDK1 promoter, inducing its expression.We identify the CDK1-FOXM1 feedforward loop as a critical axis sustaining EPSCs during in vitro cultivation. Understanding the upstream regulators of FOXM1 activity offers new insights into the biochemical mechanisms underlying self-renewal and differentiation in human primary keratinocytes.

p21 Regulates Wnt-Notch balance via DREAM/MMB/Rb-E2F1 and maintains intestinal stem cell homeostasis

The crosstalk and balance regulation of Wnt-Notch have been known to be essential for cell fate decision and tissue regeneration, however, how this balance is maintained and how the Wnt-Notch pathways are connected with cell cycle regulation is still not clear. By analyzing the molecular alterations in mouse model with accelerated aging phenotypes due to loss of p21 function in a Werner syndrome background, we observed that Wnt3 and β-Catenin were down-regulated, while Notch1 and Hes1 were up-regulated. This disruption in Wnt-Notch signaling was accompanied by the loss of intestinal stem cell compartment, increase in Bmi1 positive cells, loss of Olfm4/Lgr5 positive cells, and reduced secretory Paneth cells and goblet cells in the intestinal crypts of p21TKO mice. BrdU incorporation, cleaved caspase 3, and Tunel assay results revealed the fast turnover of intestinal epithelia, which may result in abnormal stem cell mobilization and exhaustion of the stem cell reservoir in the intestinal crypts. We further identified shift of DREAM complex towards MMB complex due to the loss of p21 as the cause for faster turnover of intestinal epithelia. Importantly, we identified the E2F1 as the transcriptional regulator for Notch1, which linked the p21-DREAM/MMB/Rb-E2F1 pathway with Wnt-Notch pathway. The overexpression of p21 rescued the DREAM pathway, as well as the imbalance of Wnt-Notch pathway. In summary, our data identify p21 as an important factor in maintaining sequential mobilization, proliferation, and homeostasis of intestinal stem cells.

Dynamic regulation of tissue fluidity controls skin repair during wound healing

During wound healing, different pools of stem cells (SCs) contribute to skin repair. However, how SCs become activated and drive the tissue remodeling essential for skin repair is still poorly understood. Here, by developing a mouse model allowing lineage tracing and basal cell lineage ablation, we monitor SC fate and tissue dynamics during regeneration using confocal and intravital imaging. Analysis of basal cell rearrangements shows dynamic transitions from a solid-like homeostatic state to a fluid-like state allowing tissue remodeling during repair, as predicted by a minimal mathematical modeling of the spatiotemporal dynamics and fate behavior of basal cells. The basal cell layer progressively returns to a solid-like state with re-epithelialization. Bulk, single-cell RNA, and epigenetic profiling of SCs, together with functional experiments, uncover a common regenerative state regulated by the EGFR/AP1 axis activated during tissue fluidization that is essential for skin SC activation and tissue repair.

Answering open questions in biology using spatial genomics and structured methods

Genomics methods have uncovered patterns in a range of biological systems, but obscure important aspects of cell behavior: the shapes, relative locations, movement, and interactions of cells in space. Spatial technologies that collect genomic or epigenomic data while preserving spatial information have begun to overcome these limitations. These new data promise a deeper understanding of the factors that affect cellular behavior, and in particular the ability to directly test existing theories about cell state and variation in the context of morphology, location, motility, and signaling that could not be tested before. Rapid advancements in resolution, ease-of-use, and scale of spatial genomics technologies to address these questions also require an updated toolkit of statistical methods with which to interrogate these data. We present a framework to respond to this new avenue of research: four open biological questions that can now be answered using spatial genomics data paired with methods for analysis. We outline spatial data modalities for each open question that may yield specific insights, discuss how conflicting theories may be tested by comparing the data to conceptual models of biological behavior, and highlight statistical and machine learning-based tools that may prove particularly helpful to recover biological understanding.

Epithelial-mesenchymal transition in tissue repair and degeneration

Epithelial-mesenchymal transitions (EMTs) are the epitome of cell plasticity in embryonic development and cancer; during EMT, epithelial cells undergo dramatic phenotypic changes and become able to migrate to form different tissues or give rise to metastases, respectively. The importance of EMTs in other contexts, such as tissue repair and fibrosis in the adult, has become increasingly recognized and studied. In this Review, we discuss the function of EMT in the adult after tissue damage and compare features of embryonic and adult EMT. Whereas sustained EMT leads to adult tissue degeneration, fibrosis and organ failure, its transient activation, which confers phenotypic and functional plasticity on somatic cells, promotes tissue repair after damage. Understanding the mechanisms and temporal regulation of different EMTs provides insight into how some tissues heal and has the potential to open new therapeutic avenues to promote repair or regeneration of tissue damage that is currently irreversible. We also discuss therapeutic strategies that modulate EMT that hold clinical promise in ameliorating fibrosis, and how precise EMT activation could be harnessed to enhance tissue repair.

Coordinating energy metabolism and signaling pathways in epithelial self-renewal and differentiation

Epidermal stem cells (EPSCs) are essential for maintaining skin homeostasis and ensuring a proper wound healing. During in vitro cultivations, EPSCs give rise to transient amplifying progenitors and differentiated cells, finally forming a stratified epithelium that can be grafted onto patients. Epithelial grafts have been used in clinics to cure burned patients or patients affected by genetic diseases. The long-term success of these advanced therapies relies on the presence of a correct amount of EPSCs that guarantees long-term epithelial regeneration. For this reason, a deeper understanding of self-renewal and differentiation is fundamental to fostering their clinical applications.The coordination between energetic metabolism (e.g., glycolysis, tricarboxylic acid cycle, oxidative phosphorylation, and amino acid synthesis pathways), molecular signalling pathways (e.g., p63, YAP, FOXM1, AMPK/mTOR), and epigenetic modifications controls fundamental biological processes as proliferation, self-renewal, and differentiation. This review explores how these signalling and metabolic pathways are interconnected in the epithelial cells, highlighting the distinct metabolic demands and regulatory mechanisms involved in skin physiology.

Isolation and Characterization of Meniscus Progenitor Cells From Rat, Rabbit, Goat, and Human

OBJECTIVE

Meniscus progenitor cells (MPCs) have been identified as promising candidates for meniscus regeneration, and it is crucial for us to understand meniscus injury repair mechanism at the cellular level. In this study, we investigate the biological properties of MPCs isolated from different species using the differential adhesion to fibronectin (DAF) technique. We aim to characterize MPCs in different species and evaluate the feasibility of these models for future meniscal investigation.

DESIGN

MPCs were isolated from freshly digested meniscus from rat, rabbit, goat, and human cells using DAF. Biological properties, including proliferation, colony-forming, multilineage differentiation, and migration abilities, were compared in MPCs and their corresponding mixed meniscus cell (MCs) population in each species.

RESULTS

MPCs were successfully isolated by the DAF technique in all species. Rat MPCs appeared cobblestone-like, rabbit MPCs were more polygonal, goat MPCs had a spindle-shaped morphology, human MPCs appear more fibroblast-like. Compared with MCs, isolated MPCs showed progenitor cell characteristics, including multilineage differentiation ability and MSC (mesenchymal stem cells) markers (CD166, CD90, CD44, Stro-1) expression. They also highly expressed fibronectin receptors CD49e and CD49c. MPCs also showed greater proliferation capacity and retained colony-forming ability. Except for goat MPCs showed greater migration abilities than MCs, no significant differences were found in the migration ability between MPCs and MCs in other species.

CONCLUSION

Our study shows that DAF is an effective method for isolating MPCs from rat, rabbit, goat, and human. MPCs in these species demonstrated similar characteristics, including greater proliferation ability and better chondrogenic potential.

Customized Proteinaceous Nanoformulation for In Vivo Chemical Reprogramming

Sweat gland (SwG) regeneration is crucial for the functional rehabilitation of burn patients. In vivo chemical reprogramming that harnessing the patient's own cells in damaged tissue is of substantial interest to regenerate organs endogenously by pharmacological manipulation, which could compensate for tissue loss in devastating diseases and injuries, for example, burns. However, achieving in vivo chemical reprogramming is challenging due to the low reprogramming efficiency and an unfavorable tissue environment. Herein, this work has developed a functionalized proteinaceous nanoformulation delivery system containing prefabricated epidermal growth factor structure for on-demand delivery of a cocktail of seven SwG reprogramming components to the dermal site. Such a chemical reprogramming system can efficiently induce the conversion of epidermal keratinocytes into SwG myoepithelial cells, resulting in successful in situ regeneration of functional SwGs. Notably, in vivo chemical reprogramming of SwGs is achieved for the first time with an impressive efficiency of 30.6%, surpassing previously reported efficiencies. Overall, this proteinaceous nanoformulation provides a platform for coordinating the target delivery of multiple pharmacological agents and facilitating in vivo SwG reprogramming by chemicals. This advancement greatly improves the clinical accessibility of in vivo reprogramming and offers a non-surgical, non-viral, and cell-free strategy for in situ SwG regeneration.

Modulating the hAM/PCL Biocomposite for Expedited Wound Healing: A Chemical-Free Approach for Boosting Regenerative Potential

There is an arising need for effective wound dressings that retain the bioactivity of a cellular treatment, but without the high costs and complexities associated with manufacturing, storing, and applying cell-based products. As skin wound recovery is a dynamic and complicated process, a significant obstacle to the healing of skin wounds is the lack of an appropriate wound dressing that can imitate the microenvironment of healthy skin and prevent bacterial infection. It requires the well-orchestrated integration of biological and molecular events. In this study, we have fabricated full-thickness skin graft biocomposite membranes to target full-thickness skin excision wounds. We reinforced human amniotic membrane (hAM) with electrospun polycaprolactone (PCL) to develop composite membranes, namely, PCL/hAM and PCL/hAM/PCL. Composite membranes were compared for physical, biological, and mechanical properties with the native counterpart. PCL/hAM and PCL/hAM/PCL displayed improved stability and delayed degradation, which further synergically improved the rapid wound healing property of hAM, driven primarily by wound closure analysis and histological assessment. Moreover, PCL/hAM displayed a comparable cellular interaction to hAM. On application as a wound dressing, histological analysis demonstrated that hAM and PCL/hAM promoted early epidermis and dermis formation. Studies on in vivo wound healing revealed that although hAM accelerates cell development, the overall wound healing process is similar in PCL/hAM. This finding is further supported by the immunohistochemical analysis of COL-1/COL-3, CD-31, and TGF-β. Overall, this conjugated PCL and hAM-based membrane has considerable potential to be applied in skin wound healing. The facile fabrication of the PCL/hAM composite membrane provided the self-regenerating wound dressing with the desired mechanical strength as an ideal regenerative property for skin tissue regeneration.

Stem-cell states converge in multistage cutaneous squamous cell carcinoma development

Stem cells play a critical role in cancer development by contributing to cell heterogeneity, lineage plasticity, and drug resistance. We created gene expression networks from hundreds of mouse tissue samples (both normal and tumor) and integrated these with lineage tracing and single-cell RNA-seq, to identify convergence of cell states in premalignant tumor cells expressing markers of lineage plasticity and drug resistance. Two of these cell states representing multilineage plasticity or proliferation were inversely correlated, suggesting a mutually exclusive relationship. Treatment of carcinomas in vivo with chemotherapy repressed the proliferative state and activated multilineage plasticity whereas inhibition of differentiation repressed plasticity and potentiated responses to cell cycle inhibitors. Manipulation of this cell state transition point may provide a source of potential combinatorial targets for cancer therapy.

Materiobiomodulated ROS Therapy for De Novo Hair Growth

Hair loss is characterized by the inability of hair follicles (HFs) to enter the telogen-anagen transition (TAT) and lack of de novo HFs. Current pharmaceutical therapies and surgical modalities have been largely limited to regulating hair regrowth efficiently without side effects and lacking treatment compliance. Here, this work proposes a materiobiomodulation therapy (MBMT), wherein polydopamine (PDA) nanoparticles with redox activity can be modulated to have a stoichiometric ROS (H2O2) donating ability. These nanoparticles can intracellularly deliver ROS with high-efficiency via the clathrin-dependent endocytosis process. Utilizing homozygote transgenic HyPerion (a genetically-encoded H2O2 biosensor) mice, this work also achieves in vivo dynamic monitoring of intracellular H2O2 elevation induced by ROS donators. Subcutaneous administration with ROS donators results in rapid onset of TAT and subsequent hair regrowth with a specific ROS "hormesis effect." Mechanistically, ROS activate β-catenin-dependent Wnt signaling, upregulating hair follicle stem cell expression. This work further develops a microneedles patch for transdermal ROS delivery, demonstrating long-term, low-dose ROS release. Unlike photobiomodulation therapy (PBMT), MBMT requires no external stimuli, providing a convenient and efficient approach for clinical hair loss treatment. This material-HF communication implicates new avenues in HF-related diseases, achieving targeted ROS delivery with minimal side effects.

Reduced Levels of Lagging Strand Polymerases Shape Stem Cell Chromatin

Stem cells display asymmetric histone inheritance while non-stem progenitor cells exhibit symmetric patterns in the Drosophila male germline lineage. Here, we report that components involved in lagging strand synthesis, such as DNA polymerase α and δ (Polα and Polδ), have significantly reduced levels in stem cells compared to progenitor cells. Compromising Polα genetically induces the replication-coupled histone incorporation pattern in progenitor cells to be indistinguishable from that in stem cells, which can be recapitulated using a Polα inhibitor in a concentration-dependent manner. Furthermore, stem cell-derived chromatin fibers display a higher degree of old histone recycling by the leading strand compared to progenitor cell-derived chromatin fibers. However, upon reducing Polα levels in progenitor cells, the chromatin fibers now display asymmetric old histone recycling just like GSC-derived fibers. The old versus new histone asymmetry is comparable between stem cells and progenitor cells at both S-phase and M-phase. Together, these results indicate that developmentally programmed expression of key DNA replication components is important to shape stem cell chromatin. Furthermore, manipulating one crucial DNA replication component can induce replication-coupled histone dynamics in non-stem cells in a manner similar to that in stem cells.

A MTA2-SATB2 chromatin complex restrains colonic plasticity toward small intestine by retaining HNF4A at colonic chromatin

Plasticity among cell lineages is a fundamental, but poorly understood, property of regenerative tissues. In the gut tube, the small intestine absorbs nutrients, whereas the colon absorbs electrolytes. In a striking display of inherent plasticity, adult colonic mucosa lacking the chromatin factor SATB2 is converted to small intestine. Using proteomics and CRISPR-Cas9 screening, we identify MTA2 as a crucial component of the molecular machinery that, together with SATB2, restrains colonic plasticity. MTA2 loss in the adult mouse colon activated lipid absorptive genes and functional lipid uptake. Mechanistically, MTA2 co-occupies DNA with HNF4A, an activating pan-intestinal transcription factor (TF), on colonic chromatin. MTA2 loss leads to HNF4A release from colonic chromatin, and accumulation on small intestinal chromatin. SATB2 similarly restrains colonic plasticity through an HNF4A-dependent mechanism. Our study provides a generalizable model of lineage plasticity in which broadly-expressed TFs are retained on tissue-specific enhancers to maintain cell identity and prevent activation of alternative lineages, and their release unleashes plasticity.

Mechanical guidance to self-organization and pattern formation of stem cells

The self-organization of stem cells (SCs) constitutes the fundamental basis of the development of biological organs and structures. SC-driven patterns are essential for tissue engineering, yet unguided SCs tend to form chaotic patterns, impeding progress in biomedical engineering. Here, we show that simple geometric constraints can be used as an effective mechanical modulation approach that promotes the development of controlled self-organization and pattern formation of SCs. Using the applied SC guidance with geometric constraints, we experimentally uncover a remarkable deviation in cell aggregate orientation from a random direction to a specific orientation. Subsequently, we propose a dynamic mechanical framework, including cells, the extracellular matrix (ECM), and the culture environment, to characterize the specific orientation deflection of guided cell aggregates relative to initial geometric constraints, which agrees well with experimental observation. Based on this framework, we further devise various theoretical strategies to realize complex biological patterns, such as radial and concentric structures. Our study highlights the key role of mechanical factors and geometric constraints in governing SCs' self-organization. These findings yield critical insights into the regulation of SC-driven pattern formation and hold great promise for advancements in tissue engineering and bioactive material design for regenerative application.

Intraepithelial lymphocytes promote intestinal regeneration through CD160/HVEM signaling

Chemotherapy and radiotherapy frequently lead to intestinal damage. The mechanisms governing the repair or regeneration of intestinal damage are still not fully elucidated. Intraepithelial lymphocytes (IELs) are the primary immune cells residing in the intestinal epithelial layer. However, whether IELs are involved in intestinal epithelial injury repair remains unclear. Here, we found that IELs rapidly infiltrated the intestinal crypt region and are crucial for the recovery of the intestinal epithelium post-chemotherapy. Interestingly, IELs predominantly promoted intestinal regeneration by modulating the proliferation of transit-amplifying (TA) cells. Mechanistically, the expression of CD160 on IELs allows for interaction with herpes virus entry mediator (HVEM) on the intestinal epithelium, thereby activating downstream nuclear factor kappa (NF-κB) signaling and further promoting intestinal regeneration. Deficiency in either CD160 or HVEM resulted in reduced proliferation of intestinal progenitor cells, impaired intestinal damage repair, and increased mortality following chemotherapy. Remarkably, the adoptive transfer of CD160-sufficient IELs rescued the Rag1 deficient mice from chemotherapy-induced intestinal inflammation. Overall, our study underscores the critical role of IELs in intestinal regeneration and highlights the potential applications of targeting the CD160-HVEM axis for managing intestinal adverse events post-chemotherapy and radiotherapy.

Functional consequences of somatic polyploidy in development

Polyploid cells contain multiple genome copies and arise in many animal tissues as a regulated part of development. However, polyploid cells can also arise due to cell division failure, DNA damage or tissue damage. Although polyploidization is crucial for the integrity and function of many tissues, the cellular and tissue-wide consequences of polyploidy can be very diverse. Nonetheless, many polyploid cell types and tissues share a remarkable similarity in function, providing important information about the possible contribution of polyploidy to cell and tissue function. Here, we review studies on polyploid cells in development, underlining parallel functions between different polyploid cell types, as well as differences between developmentally-programmed and stress-induced polyploidy.

The emerging role of the gut microbiome in cancer cell plasticity and therapeutic resistance

Resistance to therapeutic agents is one of the major challenges in cancer therapy. Generally, the focus is given to the genetic driver, especially the genetic mutation behind the therapeutic resistance. However, non-mutational mechanisms, such as epigenetic modifications, and TME alteration, which is mainly driven by cancer cell plasticity, are also involved in therapeutic resistance. The concept of plasticity mainly relies on the conversion of non-cancer stem cells (CSCs) to CSCs or epithelial-to-mesenchymal transition via different mechanisms and various signaling pathways. Cancer plasticity plays a crucial role in therapeutic resistance as cancer cells are able to escape from therapeutics by shifting the phenotype and thereby enhancing tumor progression. New evidence suggests that gut microbiota can change cancer cell characteristics by impacting the mechanisms involved in cancer plasticity. Interestingly, gut microbiota can also influence the therapeutic efficacy of anticancer drugs by modulating the mechanisms involved in cancer cell plasticity. The gut microbiota has been shown to reduce the toxicity of certain clinical drugs. Here, we have documented the critical role of the gut microbiota on the therapeutic efficacy of existing anticancer drugs by altering the cancer plasticity. Hence, the extended knowledge of the emerging role of gut microbiota in cancer cell plasticity can help to develop gut microbiota-based novel therapeutics to overcome the resistance or reduce the toxicity of existing drugs. Furthermore, to improve the effectiveness of therapy, it is necessary to conduct more clinical and preclinical research to fully comprehend the mechanisms of gut microbiota.

Lipid metabolism and its implications in tumor cell plasticity and drug resistance: what we learned thus far?

Metabolic reprogramming, a hallmark of cancer, allows cancer cells to adapt to their specific energy needs. The Warburg effect benefits cancer cells in both hypoxic and normoxic conditions and is a well-studied reprogramming of metabolism in cancer. Interestingly, the alteration of other metabolic pathways, especially lipid metabolism has also grabbed the attention of scientists worldwide. Lipids, primarily consisting of fatty acids, phospholipids and cholesterol, play essential roles as structural component of cell membrane, signalling molecule and energy reserves. This reprogramming primarily involves aberrations in the uptake, synthesis and breakdown of lipids, thereby contributing to the survival, proliferation, invasion, migration and metastasis of cancer cells. The development of resistance to the existing treatment modalities poses a major challenge in the field of cancer therapy. Also, the plasticity of tumor cells was reported to be a contributing factor for the development of resistance. A number of studies implicated that dysregulated lipid metabolism contributes to tumor cell plasticity and associated drug resistance. Therefore, it is important to understand the intricate reprogramming of lipid metabolism in cancer cells. In this review, we mainly focused on the implication of disturbed lipid metabolic events on inducing tumor cell plasticity-mediated drug resistance. In addition, we also discussed the concept of lipid peroxidation and its crucial role in phenotypic switching and resistance to ferroptosis in cancer cells. Elucidating the relationship between lipid metabolism, tumor cell plasticity and emergence of resistance will open new opportunities to develop innovative strategies and combinatorial approaches for the treatment of cancer.

A synthetic differentiation circuit in Escherichia coli for suppressing mutant takeover

Differentiation is crucial for multicellularity. However, it is inherently susceptible to mutant cells that fail to differentiate. These mutants outcompete normal cells by excessive self-renewal. It remains unclear what mechanisms can resist such mutant expansion. Here, we demonstrate a solution by engineering a synthetic differentiation circuit in Escherichia coli that selects against these mutants via a biphasic fitness strategy. The circuit provides tunable production of synthetic analogs of stem, progenitor, and differentiated cells. It resists mutations by coupling differentiation to the production of an essential enzyme, thereby disadvantaging non-differentiating mutants. The circuit selected for and maintained a positive differentiation rate in long-term evolution. Surprisingly, this rate remained constant across vast changes in growth conditions. We found that transit-amplifying cells (fast-growing progenitors) underlie this environmental robustness. Our results provide insight into the stability of differentiation and demonstrate a powerful method for engineering evolutionarily stable multicellular consortia.

The interaction between ageing and Alzheimer's disease: insights from the hallmarks of ageing

Ageing is a crucial risk factor for Alzheimer's disease (AD) and is characterised by systemic changes in both intracellular and extracellular microenvironments that affect the entire body instead of a single organ. Understanding the specific mechanisms underlying the role of ageing in disease development can facilitate the treatment of ageing-related diseases, such as AD. Signs of brain ageing have been observed in both AD patients and animal models. Alleviating the pathological changes caused by brain ageing can dramatically ameliorate the amyloid beta- and tau-induced neuropathological and memory impairments, indicating that ageing plays a crucial role in the pathophysiological process of AD. In this review, we summarize the impact of several age-related factors on AD and propose that preventing pathological changes caused by brain ageing is a promising strategy for improving cognitive health.

A computational model of stem cells' internal mechanism to recapitulate spatial patterning and maintain the self-organized pattern in the homeostasis state

The complex functioning of multi-cellular tissue development relies on proper cell production rates to replace dead or differentiated specialized cells. Stem cells are critical for tissue development and maintenance, as they produce specialized cells to meet the tissues' demands. In this study, we propose a computational model to investigate the stem cell's mechanism, which generates the appropriate proportion of specialized cells, and distributes them to their correct position to form and maintain the organized structure in the population through intercellular reactions. Our computational model focuses on early development, where the populations overall behavior is determined by stem cells and signaling molecules. The model does not include complicated factors such as movement of specialized cells or outside signaling sources. The results indicate that in our model, the stem cells can organize the population into a desired spatial pattern, which demonstrates their ability to self-organize as long as the corresponding leading signal is present. We also investigate the impact of stochasticity, which provides desired non-genetic diversity; however, it can also break the proper boundaries of the desired spatial pattern. We further examine the role of the death rate in maintaining the system's steady state. Overall, our study sheds light on the strategies employed by stem cells to organize specialized cells and maintain proper functionality. Our findings provide insight into the complex mechanisms involved in tissue development and maintenance, which could lead to new approaches in regenerative medicine and tissue engineering.

Reversibly immortalization establishes a hair follicle stem cell line with hair follicle reconstruction ability

Hair follicle stem cells (HFSCs) play critical roles in the periodic regeneration of hair follicles. HFSCs are also a good model for stem cell biology research. However, no stable mouse HFSC cell line has been reported, which restricts the research and application of HFSCs. We isolated HFSCs from mouse hair follicles and immortalized them by inducing a reversible SV40 large T antigen. Through monoclonal screening, we identified a reversibly immortalized cell line, immortalized HFSC (iHFSC2). RNA sequencing, fluorescence-activated cell sorting, western blotting and immunofluorescence experiments revealed that the expression patterns of iHFSC2 and HFSC were similar at the protein and mRNA levels. After that, iHFSC2s were passaged and morphologically monitored for up to 40 times to detect their long-term culture potential. The long-term cultured iHFSC2 could regenerate hair follicles with complete hair follicle structure and HFSCs in the bulge area. This work successfully established an HFSC cell line with the ability of hair follicle reconstruction.

A closer look into the cellular and molecular biology of myoepithelial cells across various exocrine glands

Myoepithelial cells (MECs) are a unique subset of epithelial cells that possess several smooth muscle cell characteristics, such as a high number of actin-myosin filaments and the ability to contract. These cells are primarily located around the secretory cells of exocrine glands, including the salivary, mammary, lacrimal, and sweat glands. Their primary functions involve the construction of the basement membrane and help with secretion of gland products through contraction. So far, no comparative analysis of MECs in different exocrine glands had ever evaluated their differences. In this review, we took advantage of the various publicly available scRNAseq data from mouse exocrine glands to identify their shared and unique characteristics. The aim of this review is to compare the role of MECs in maintaining healthy glandular function, their involvement in disease states, and their regenerative capacity, with a particular emphasis on the latest research findings in these areas.

Skin innate immune response against fungal infections and the potential role of trained immunity

Fungal skin infections are distributed worldwide and can be associated with economic and social traits. The immune response related to skin cells is complex and its understanding is essential to the comprehension of each cell's role and the discovery of treatment alternatives. The first studies of trained immunity (TI) described the ability of monocytes, macrophages and natural killer (NK) cells to develop a memory-like response. However, the duration of TI does not reflect the shorter lifespan of these cells. These conclusions supported later studies showing that TI can be observed in stem and haematopoietic cells and, more recently, also in non-immune skin cells such as fibroblasts, highlighting the importance of resident cells in response to skin disorders. Besides, the participation of less studied proinflammatory cytokines in the skin immune response, such as IL-36γ, shed light into a new possibility of inflammatory pathway blockade by drugs. In this review, we will discuss the skin immune response associated with fungal infections, the role of TI in skin and clinical evidence supporting opportunities and challenges of TI and other inflammatory responses in the pathogenesis of fungal skin infections.

Decoding aging-dependent regenerative decline across tissues at single-cell resolution

Regeneration across tissues and organs exhibits significant variation throughout the body and undergoes a progressive decline with age. To decode the relationships between aging and regenerative capacity, we conducted a comprehensive single-cell transcriptome analysis of regeneration in eight tissues from young and aged mice. We employed diverse analytical models to study tissue regeneration and unveiled the intricate cellular and molecular mechanisms underlying the attenuated regenerative processes observed in aged tissues. Specifically, we identified compromised stem cell mobility and inadequate angiogenesis as prominent contributors to this age-associated decline in regenerative capacity. Moreover, we discovered a unique subset of Arg1+ macrophages that were activated in young tissues but suppressed in aged regenerating tissues, suggesting their important role in age-related immune response disparities during regeneration. This study provides a comprehensive single-cell resource for identifying potential targets for interventions aimed at enhancing regenerative outcomes in the aging population.

BMP signaling in cancer stemness and differentiation

The BMP (Bone morphogenetic protein) signaling pathway plays a central role in metazoan biology, intricately shaping embryonic development, maintaining tissue homeostasis, and influencing disease progression. In the context of cancer, BMP signaling exhibits context-dependent dynamics, spanning from tumor suppression to promotion. Cancer stem cells (CSCs), a modest subset of neoplastic cells with stem-like attributes, exert substantial influence by steering tumor growth, orchestrating therapy resistance, and contributing to relapse. A comprehensive grasp of the intricate interplay between CSCs and their microenvironment is pivotal for effective therapeutic strategies. Among the web of signaling pathways orchestrating cellular dynamics within CSCs, BMP signaling emerges as a vital conductor, overseeing CSC self-renewal, differentiation dynamics, and the intricate symphony within the tumor microenvironment. Moreover, BMP signaling's influence in cancer extends beyond CSCs, intricately regulating cellular migration, invasion, and metastasis. This multifaceted role underscores the imperative of comprehending BMP signaling's contributions to cancer, serving as the foundation for crafting precise therapies to navigate multifaceted challenges posed not only by CSCs but also by various dimensions of cancer progression. This article succinctly encapsulates the diverse roles of the BMP signaling pathway across different cancers, spanning glioblastoma multiforme (GBM), diffuse intrinsic pontine glioma (DIPG), colorectal cancer, acute myeloid leukemia (AML), lung cancer, prostate cancer, and osteosarcoma. It underscores the necessity of unraveling underlying mechanisms and molecular interactions. By delving into the intricate tapestry of BMP signaling's engagement in cancers, researchers pave the way for meticulously tailored therapies, adroitly leveraging its dualistic aspects-whether as a suppressor or promoter-to effectively counter the relentless march of tumor progression.

Regeneration and anti-inflammatory effects of stem cells and their extracellular vesicles in gynecological diseases

There are many gynecological diseases, among which breast cancer (BC), cervical cancer (CC), endometriosis (EMs), and polycystic ovary syndrome (PCOS) are common and difficult to cure. Stem cells (SCs) are a focus of regenerative medicine. They are commonly used to treat organ damage and difficult diseases because of their potential for self-renewal and multidirectional differentiation. SCs are also commonly used for difficult-to-treat gynecological diseases because of their strong directional differentiation ability with unlimited possibilities, their tendency to adhere to the diseased tissue site, and their use as carriers for drug delivery. SCs can produce exosomes in a paracrine manner. Exosomes can be produced in large quantities and have the advantage of easy storage. Their safety and efficacy are superior to those of SCs, which have considerable potential in gynecological treatment, such as inhibiting endometrial senescence, promoting vascular reconstruction, and improving anti-inflammatory and immune functions. In this paper, we review the mechanisms of the regenerative and anti-inflammatory capacity of SCs and exosomes in incurable gynecological diseases and the current progress in their application in genetic engineering to provide a foundation for further research.