Stem cells: units of development, units of regeneration, and units in evolution

Synergistic effect and molecular mechanism of nicotinamide and UM171 in ex vivo expansion of long-term hematopoietic stem cells

Introduction

Several approaches to expand human hematopoietic stem cells (HSCs) have been reported, but the ability of these methods to expand long-term hematopoietic stem cells (LT-HSCs) remains to be improved, which limits the application of HSCs-based therapies.

Methods

CD34+ cells were purified from umbilical cord blood using MacsCD34 beads, and then cultured for 12 d in a serum-free medium. Flow cytometry was used to detect phenotype, cell cycle distribution, and apoptosis of the cultured cells. Colony-forming cell (CFC) assays can evaluate multi-lineage differentiation potential of HSCs. Real-time polymerase chain reaction was employed to detect the expression of genes related to self-renewal programs and antioxidant activity. DCFH-DA probes were used to evaluate intracellular production of reactive oxygen species (ROS). Determination of the effect of different culture conditions on the balance of cytokine by cytometric bead array.

Results

Here, we show a combination, Nicotinamide (NAM) combined with pyrimidoindole derivative UM171, can massively expand LT-HSCs ex vivo, and the expanded cells maintained the capability of self-renewal and multilineage differentiation. Additionally, our data indicated that UM171 promoted self-renewal of HSCs by inducing HSCs entry into the cell cycle and activating Notch and Wnt pathways, but the infinite occurrence of this process may lead to mitochondrial metabolism disorder and differentiation of HSCs. NAM kept HSCs in their primitive and dormant states by reducing intracellular ROS levels and upregulating the expression of stemness related genes, so we believed that NAM can act as a brake to control the above process.

Conclusions

The discovery of the synergistic effect of NAM and UM171 for expanding LT-HSCs provides a new strategy in solving the clinical issue of limited numbers of HSCs.

Improvement of motor function in mice after implantation of mononuclear stem cells from human umbilical cord and placenta blood after 3 and 6 weeks of experimental spinal cord injury

STUDY DESIGN

Experimental study utilizing with a standardized model (MASCIS Impactor) of Spinal Cord Injury (SCI) in Balb C mouse model with implantation of mononuclear stem cells derived from the human umbilical cord and placenta blood in the early chronic phase of SCI.

OBJECTIVES

The aim of this study was to evaluate the nerve regeneration and motor functional recovery in Balb C mice with surgically induced paraplegia in response to the use of mononuclear stem cells, in early chronic phase (> 2 weeks and < 6 months), because there is yet potential of neuronal and functional recovery as the neuronal scar is not still completely established.

METHODS

Forty-eight mice were randomly assigned to 6 groups of 8 animals. Group 1 received the stem cells 3 weeks after the trauma, and Group 2 received them six weeks later. In Group 3, saline solution was injected at the site of the lesion 3 weeks after the trauma, and in Group 4, 6 weeks later. Group 5 underwent only spinal cord injury and Group 6 underwent laminectomy only. The scales used for motor assessment were BMS and MFS for 12 weeks.

RESULTS

The intervention groups showed statistically significant motor improvement. In the histopathological analysis, the intervention groups had a lower degree of injury (p < 0.05). Regarding axonal budding, the intervention groups showed increasing in axonal budding in the caudal portion (p < 0.05).

CONCLUSIONS

The use of stem cells in mice in the chronic phase after 3 and 6 weeks of SCI brings functional and histopathological benefits to them.

Unraveling the interplay between inflammation and stem cell mobilization or homing: Implications for tissue repair and therapeutics

Inflammation and stem cell mobilization or homing play pivotal roles in tissue repair and regeneration. This review explores their intricate interplay, elucidating their collaborative role in maintaining tissue homeostasis and responding to injury or disease. While examining the fundamentals of stem cells, we detail the mechanisms underlying inflammation, including immune cell recruitment and inflammatory mediator release, highlighting their self-renewal and differentiation capabilities. Central to our exploration is the modulation of hematopoietic stem cell behavior by inflammatory cues, driving their mobilization from the bone marrow niche into circulation. Key cytokines, chemokines, growth factors, and autophagy, an intracellular catabolic mechanism involved in this process, are discussed alongside their clinical relevance. Furthermore, mesenchymal stem cell homing in response to inflammation contributes to tissue repair processes. In addition, we discuss stem cell resilience in the face of inflammatory challenges. Moreover, we examine the reciprocal influence of stem cells on the inflammatory milieu, shaping immune responses and tissue repair. We underscore the potential of targeting inflammation-induced stem cell mobilization for regenerative therapies through extensive literature analysis and clinical insights. By unraveling the complex interplay between inflammation and stem cells, this review advances our understanding of tissue repair mechanisms and offers promising avenues for clinical translation in regenerative medicine.

Satellite glial cell manipulation prior to axotomy enhances developing dorsal root ganglion central branch regrowth into the spinal cord

The central and peripheral nervous systems (CNS and PNS, respectively) exhibit remarkable diversity in the capacity to regenerate following neuronal injury with PNS injuries being much more likely to regenerate than those that occur in the CNS. Glial responses to damage greatly influence the likelihood of regeneration by either promoting or inhibiting axonal regrowth over time. However, despite our understanding of how some glial lineages participate in nerve degeneration and regeneration, less is known about the contributions of peripheral satellite glial cells (SGC) to regeneration failure following central axon branch injury of dorsal root ganglia (DRG) sensory neurons. Here, using in vivo, time-lapse imaging in larval zebrafish coupled with laser axotomy, we investigate the role of SGCs in axonal regeneration. In our studies we show that SGCs respond to injury by relocating their nuclei to the injury site during the same period that DRG neurons produce new central branch neurites. Laser ablation of SGCs prior to axon injury results in more neurite growth attempts and ultimately a higher rate of successful central axon regrowth, implicating SGCs as inhibitors of regeneration. We also demonstrate that this SGC response is mediated in part by ErbB signaling, as chemical inhibition of this receptor results in reduced SGC motility and enhanced central axon regrowth. These findings provide new insights into SGC-neuron interactions under injury conditions and how these interactions influence nervous system repair.

Targeted therapy of cancer stem cells: inhibition of mTOR in pre-clinical and clinical research

Cancer stem cells (CSCs) are a type of stem cell that possesses not only the intrinsic abilities of stem cells but also the properties of cancer cells. Therefore, CSCs are known to have self-renewal and outstanding proliferation capacity, along with the potential to differentiate into specific types of tumor cells. Cancers typically originate from CSCs, making them a significant target for tumor treatment. Among the related cascades of the CSCs, mammalian target of rapamycin (mTOR) pathway is regarded as one of the most important signaling pathways because of its association with significant upstream signaling: phosphatidylinositol 3‑kinase/protein kinase B (PI3K/AKT) pathway and mitogen‑activated protein kinase (MAPK) cascade, which influence various activities of stem cells, including CSCs. Recent studies have shown that the mTOR pathway not only affects generation of CSCs but also the maintenance of their pluripotency. Furthermore, the maintenance of pluripotency or differentiation into specific types of cancer cells depends on the regulation of the mTOR signal in CSCs. Consequently, the clinical potential and importance of mTOR in effective cancer therapy are increasing. In this review, we demonstrate the association between the mTOR pathway and cancer, including CSCs. Additionally, we discuss a new concept for anti-cancer drug development aimed at overcoming existing drawbacks, such as drug resistance, by targeting CSCs through mTOR inhibition.

Application of Mesenchymal Stem Cells in Female Infertility Treatment: Protocols and Preliminary Results

Infertility is a global phenomenon that impacts people of both the male and the female sex; it is related to multiple factors affecting an individual's overall systemic health. Recently, investigators have been using mesenchymal stem cell (MSC) therapy for female-fertility-related disorders such as polycystic ovarian syndrome (PCOS), premature ovarian failure (POF), endometriosis, preeclampsia, and Asherman syndrome (AS). Studies have shown promising results, indicating that MSCs can enhance ovarian function and restore fertility for affected individuals. Due to their regenerative effects and their participation in several paracrine pathways, MSCs can improve the fertility outcome. However, their beneficial effects are dependent on the methodologies and materials used from isolation to reimplantation. In this review, we provide an overview of the protocols and methods used in applications of MSCs. Moreover, we summarize the findings of published preclinical studies on infertility treatments and discuss the multiple properties of these studies, depending on the isolation source of the MSCs used.

Profiling cell identity and tissue architecture with single-cell and spatial transcriptomics

Single-cell transcriptomics has broadened our understanding of cellular diversity and gene expression dynamics in healthy and diseased tissues. Recently, spatial transcriptomics has emerged as a tool to contextualize single cells in multicellular neighbourhoods and to identify spatially recurrent phenotypes, or ecotypes. These technologies have generated vast datasets with targeted-transcriptome and whole-transcriptome profiles of hundreds to millions of cells. Such data have provided new insights into developmental hierarchies, cellular plasticity and diverse tissue microenvironments, and spurred a burst of innovation in computational methods for single-cell analysis. In this Review, we discuss recent advancements, ongoing challenges and prospects in identifying and characterizing cell states and multicellular neighbourhoods. We discuss recent progress in sample processing, data integration, identification of subtle cell states, trajectory modelling, deconvolution and spatial analysis. Furthermore, we discuss the increasing application of deep learning, including foundation models, in analysing single-cell and spatial transcriptomics data. Finally, we discuss recent applications of these tools in the fields of stem cell biology, immunology, and tumour biology, and the future of single-cell and spatial transcriptomics in biological research and its translation to the clinic.

The hematopoietic stem cell expansion niche in fetal liver: Current state of the art and the way forward

Hematopoietic development goes through a number of embryonic sites that host hematopoietic progenitor and stem cells with function required at specific developmental stages. Among embryonic sites, the fetal liver (FL) hosts definitive hematopoietic stem cells (HSCs) capable of engrafting adult hematopoietic system and supports their rapid expansion. Hence, this site provides an excellent model to understand the cellular and molecular components of the machinery involved in HSC-proliferative events, leading to their overall expansion. It has been unequivocally established that extrinsic regulators orchestrate events that maintain HSC function. Although most studies on extrinsic regulation of HSC function are targeted at adult bone marrow (BM) hematopoiesis, little is known about how FL HSC function is regulated by their microniche. This review provides the current state of our understanding on molecular and cellular niche factors that support FL hematopoiesis.

Mechanotransduction in stem cells

Nowadays, it is an established concept that the capability to reach a specialised cell identity via differentiation, as in the case of multi- and pluripotent stem cells, is not only determined by biochemical factors, but that also physical aspects of the microenvironment play a key role; interpreted by the cell through a force-based signalling pathway called mechanotransduction. However, the intricate ties between the elements involved in mechanotransduction, such as the extracellular matrix, the glycocalyx, the cell membrane, Integrin adhesion complexes, Cadherin-mediated cell/cell adhesion, the cytoskeleton, and the nucleus, are still far from being understood in detail. Here we report what is currently known about these elements in general and their specific interplay in the context of multi- and pluripotent stem cells. We furthermore merge this overview to a more comprehensive picture, that aims to cover the whole mechanotransductive pathway from the cell/microenvironment interface to the regulation of the chromatin structure in the nucleus. Ultimately, with this review we outline the current picture of the interplay between mechanotransductive cues and epigenetic regulation and how these processes might contribute to stem cell dynamics and fate.

Enhanced Learning and Memory in Patients with CRB1 Retinopathy

Mutations in the CRB1 gene are associated with a diverse spectrum of retinopathies with phenotypic variability causing severe visual impairment. The CRB1 gene has a role in retinal development and is expressed in the cerebral cortex and hippocampus, but its role in cognition has not been described before. This study compares cognitive function in CRB1 retinopathy individuals with subjects with other retinopathies and the normal population.

METHODS

Neuropsychological tests of cognitive function were used to test individuals with CRB1 and non-CRB1 retinopathies and compare results with a standardised normative dataset.

RESULTS

CRB1 retinopathy subjects significantly outperformed those with non-CRB1 retinopathy in list learning tasks of immediate (p = 0.001) and delayed memory (p = 0.007), tests of semantic verbal fluency (p = 0.017), verbal IQ digit span subtest (p = 0.037), and estimation test of higher execution function (p = 0.020) but not in the remaining tests of cognitive function (p > 0.05). CRB1 retinopathy subjects scored significantly higher than the normal population in all areas of memory testing (p < 0.05) and overall verbal IQ tests (p = 0.0012). Non-CRB1 retinopathy subjects scored significantly higher than the normal population in story recall, verbal fluency, and overall verbal IQ tests (p = 0.0016).

CONCLUSIONS

Subjects with CRB1 retinopathy may have enhanced cognitive function in areas of memory and learning. Further work is required to understand the role of CRB1 in cognition.

Unlocking the Future of Periodontal Regeneration: An Interdisciplinary Approach to Tissue Engineering and Advanced Therapeutics

Periodontal defects present a significant challenge in dentistry, necessitating innovative solutions for comprehensive regeneration. Traditional restoration methods have inherent limitations in achieving complete and functional periodontal tissue reconstruction. Tissue engineering, a multidisciplinary approach integrating cells, biomaterials, and bioactive factors, holds tremendous promise in addressing this challenge. Central to tissue engineering strategies are scaffolds, pivotal in supporting cell behavior and orchestrating tissue regeneration. Natural and synthetic materials have been extensively explored, each offering unique advantages in terms of biocompatibility and tunable properties. The integration of growth factors and stem cells further amplifies the regenerative potential, contributing to enhanced tissue healing and functional restoration. Despite significant progress, challenges persist. Achieving the seamless integration of regenerated tissues, establishing proper vascularization, and developing biomimetic scaffolds that faithfully replicate the natural periodontal environment are ongoing research endeavors. Collaborative efforts across diverse scientific disciplines are essential to overcoming these hurdles. This comprehensive review underscores the critical need for continued research and development in tissue engineering strategies for periodontal regeneration. By addressing current challenges and fostering interdisciplinary collaborations, we can unlock the full regenerative potential, paving the way for transformative advancements in periodontal care. This research not only enhances our understanding of periodontal tissues but also offers innovative approaches that can revolutionize dental therapies, improving patient outcomes and reshaping the future of periodontal treatments.

Advances in hematopoietic stem cells ex vivo expansion associated with bone marrow niche

Hematopoietic stem cells (HSCs) are an ideal source for the treatment of many hematological diseases and malignancies, as well as diseases of other systems, because of their two important features, self-renewal and multipotential differentiation, which have the ability to rebuild the blood system and immune system of the body. However, so far, the insufficient number of available HSCs, whether from bone marrow (BM), mobilized peripheral blood or umbilical cord blood, is still the main restricting factor for the clinical application. Therefore, strategies to expand HSCs numbers and maintain HSCs functions through ex vivo culture are urgently required. In this review, we outline the basic biology characteristics of HSCs, and focus on the regulatory factors in BM niche affecting the functions of HSCs. Then, we introduce several representative strategies used for HSCs from these three sources ex vivo expansion associated with BM niche. These findings have deepened our understanding of the mechanisms by which HSCs balance self-renewal and differentiation and provided a theoretical basis for the efficient clinical HSCs expansion.

Autophagy prevents graft failure during murine graft-versus-host disease

ABSTRACT

Autophagy is an intracellular survival process that has established roles in the long-term survival and function of hematopoietic stem cells (HSC). We investigated the contribution of autophagy to HSC fitness during allogeneic transplantation and graft-versus-host disease (GVHD). We demonstrate in vitro that both tumor necrosis factor and IL-1β, major components of GVHD cytokine storm, synergistically promote autophagy in both HSC and their more mature hematopoietic progenitor cells (HPC). In vivo we demonstrate that autophagy is increased in donor HSC and HPC during GVHD. Competitive transplant experiments demonstrated that autophagy-deficient cells display reduced capacity to reconstitute the hematopoietic system compared to wild-type counterparts. In a major histocompatibility complex-mismatched model of GVHD and associated cytokine dysregulation, we demonstrate that autophagy-deficient HSC and progenitors fail to establish durable hematopoiesis, leading to primary graft failure and universal transplant related mortality. Using several different models, we confirm that autophagy activity is increased in early progenitor and HSC populations in the presence of T-cell-derived inflammatory cytokines and that these HSC populations require autophagy to survive. Thus, autophagy serves as a key survival mechanism in HSC and progenitor populations after allogeneic stem cell transplant and may represent a therapeutic target to prevent graft failure during GVHD.

Following the p63/Keratin5 basal cells in the sensory and non-sensory epithelia of the vomeronasal organ

The vomeronasal organ (VNO) is a part of the accessory olfactory system, which detects pheromones and chemical factors that trigger a spectrum of sexual and social behaviors. The vomeronasal epithelium (VNE) shares several features with the epithelium of the main olfactory epithelium (MOE). However, it is a distinct neuroepithelium populated by chemosensory neurons that differ from the olfactory sensory neurons in cellular structure, receptor expression, and connectivity. The vomeronasal organ of rodents comprises a sensory epithelium (SE) and a thin non-sensory epithelium (NSE) that morphologically resembles the respiratory epithelium. Sox2-positive cells have been previously identified as the stem cell population that gives rise to neuronal progenitors in MOE and VNE. In addition, the MOE also comprises p63 positive horizontal basal cells, a second pool of quiescent stem cells that become active in response to injury. Immunolabeling against the transcription factor p63, Keratin-5 (Krt5), Krt14, NrCAM, and Krt5Cre tracing experiments highlighted the existence of horizontal basal cells distributed along the basal lamina of SE of the VNO. Single cell sequencing and genetic lineage tracing suggest that the vomeronasal horizontal basal cells arise from basal progenitors at the boundary between the SE and NSE proximal to the marginal zones. Moreover, our experiments revealed that the NSE of rodents is, like the respiratory epithelium, a stratified epithelium where the p63/Krt5+ basal progenitor cells self-replicate and give rise to the apical columnar cells facing the lumen of the VNO.

Optimization of seeding density of OP9 cells to improve hematopoietic differentiation efficiency

BACKGROUND

OP9 mouse stromal cell line has been widely used to induce differentiation of human embryonic stem cells (hESCs) into hematopoietic stem/progenitor cells (HSPCs). However, the whole co-culture procedure usually needs 14-18 days, including preparing OP9 cells at least 4 days. Therefore, the inefficient differentiation system is not appreciated. We aimed to optimize the culture conditions to improve differentiation efficiency.

METHODS

In the experimental group, we set six different densities of OP9 cells and just cultured them for 24 h before co-culture, and in the control group, OP9 cells were cultured for 4 days to reach an overgrown state before co-culture. Then we compared the hematopoietic differentiation efficiency among them.

RESULTS

OP9 cells were randomly assigned into two groups. In the experimental group, six different plated numbers of OP9 cells were cultured for 1 day before co-culture with hESCs. In contrast, in the control group, OP9 cells were cultured for 4 days at a total number of 3.1 × 104 cells/cm2 in a 6-well plate to reach an overgrown state before co-culture. Hematopoietic differentiation was evaluated with CD34 immunostaining, and compared between these two groups. We could not influence the differentiation efficiency of OP9 cells with a total number of 10.4 × 104 cells/cm2 in a 6-well plate which was cultured just for 1 day, followed by co-culture with hESCs. It reached the same differentiation efficiency 5 days earlier than the control group.

CONCLUSION

The peak of CD34 + cells appeared 2 days earlier compared to the control group. A total number of 1.0 × 106 cells in a 6-well plate for OP9 cells was appropriate to have high differentiation efficiency.

Static magnetic fields in regenerative medicine

All organisms on Earth live in the weak but ubiquitous geomagnetic field. Human beings are also exposed to magnetic fields generated by multiple sources, ranging from permanent magnets to magnetic resonance imaging (MRI) in hospitals. It has been shown that different magnetic fields can generate various effects on different tissues and cells. Among them, stem cells appear to be one of the most sensitive cell types to magnetic fields, which are the fundamental units of regenerative therapies. In this review, we focus on the bioeffects of static magnetic fields (SMFs), which are related to regenerative medicine. Most reports in the literature focus on the influence of SMF on bone regeneration, wound healing, and stem cell production. Multiple aspects of the cellular events, including gene expression, cell signaling pathways, reactive oxygen species, inflammation, and cytoskeleton, have been shown to be affected by SMFs. Although no consensus yet, current evidence indicates that moderate and high SMFs could serve as a promising physical tool to promote bone regeneration, wound healing, neural differentiation, and dental regeneration. All in vivo studies of SMFs on bone regeneration and wound healing have shown beneficial effects, which unravel the great potential of SMFs in these aspects. More mechanistic studies, magnetic field parameter optimization, and clinical investigations on human bodies will be imperative for the successful clinical applications of SMFs in regenerative medicine.

Purging myeloma cell contaminants and simultaneous expansion of peripheral blood-mobilized stem cells

Human hematopoietic stem cells (HSCs) are widely used as a cellular source for hematopoietic stem cell transplantation (HSCT) in the clinical treatment of hematological malignancies. After transplantation therapy, delays in hematopoietic recovery due to insufficient donor-derived HSCs can lead to increased risks of life-threatening infections and bleeding. Our previous studies developed an efficient ex vivo expansion culture medium (3a medium) for umbilical cord blood-derived HSCs (CBSCs), offering a potential solution to this problem. Nevertheless, the broader applicability of our culture method to alternative cell sources and, of greater significance, its efficacy in eliminating potentially disease-associated contaminated tumor cells, especially in autologous transplantation, raise critical clinical questions. In this study, we modified the 3a medium by incorporating UM729 to replace UM171, adding FMS-like tyrosine kinase 3 (Flt3) ligand, and adjusting the concentrations of butyzamide, 740Y-P, polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer (PCL-PVAc-PEG, Soluplus) to create the modified-3a medium. This sophistication allowed the efficient expansion of not only CBSCs but also peripheral blood-mobilized HSCs (PBSCs). Additionally, we successfully removed contaminated myeloma cells by adding bortezomib and tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) at appropriate concentrations, although we maintained HSCs through the addition of lenalidomide. Our research findings present the potential for widespread clinical application of the modified-3a medium and suggest a safe ex vivo culture technique for expanding human HSCs within peripheral blood-derived donor grafts used for autologous HSCT.

Stress-protecting harbors for hematopoietic stem cells

Hematopoietic stem cells (HSCs) rely on specialized microenvironments known as niches to maintain their self-renewal and multilineage potential to generate diverse types of blood cells continuously. Over the last two decades, substantial advancements have been made in unraveling the niche cell components and HSC localizations under homeostatic and stressed circumstances. Advances in imaging, combined with the discovery of phenotypic surface markers combinations and single cell sequencing, have greatly facilitated the systematic examination of HSC localizations. This review aims to present a summary of HSC localizations, highlighting potential distinctions between phenotypically and functionally defined HSCs, and explore the functionality of niches in ensuring the integrity and long-term maintenance of HSCs.

Identifying optimal candidates for autologous peripheral blood stem cell therapy in patients with decompensated liver cirrhosis: a prognostic scoring system

BACKGROUND

Stem cell transplantation shows great potential to improve the long-term survival of cirrhosis patients. However, therapeutic effects may not be homogeneous across the whole study population. This study constructed an easy-to-use nomogram to improve prognostic prediction and aid in treatment decision making for cirrhotic patients.

METHODS

From August 2005 to April 2019, 315 patients with decompensated cirrhosis receiving autologous peripheral blood stem cell (PBSC) transplantation were enrolled in this study. They were randomly classified into training (2/3) and validation (1/3) groups. A predictive model was developed using Cox proportional hazard models and subsequently validated. The predictive performance of the model was evaluated and also compared with other prognostic models.

RESULTS

Age, creatinine, neutrophil-to-lymphocyte ratio, and Child-Turcotte-Pugh class were included in the nomogram as prognostic variables. The nomogram showed high discrimination power concerning the area under receiver operating characteristic curves (3/5-year AUC: 0.742/0.698) and good consistency suggested by calibration plots. Patients could be accurately stratified into poor- and good-outcome groups regarding liver-transplantation free survival after receiving PBSC therapy (P < 0.001). Compared with poor-outcome group, the liver function of patients listed for liver transplantation in the good-outcome group was significantly improved (P < 0.001). Besides, our nomogram achieved a higher C-index (0.685, 95% CI 0.633-0.738) and better clinical utility compared with other conventional prognostic models.

CONCLUSIONS

The proposed nomogram facilitated an accurate prognostic prediction for patients with decompensated cirrhosis receiving PBSC transplantation. Moreover, it also held the promise to stratify patients in clinical trials or practice to implement optimal treatment regimens for individuals.

Placental cell conditioned media modifies hematopoietic stem cell transcriptome invitro

INTRODUCTION

Hematopoietic stem cells are cells that differentiate into blood cell types. Although the placenta secretes hormones, proteins and other factors important for maternal/fetal health, cross-talk between placental and hematopoietic stem cells is poorly understood. Moreover, toxicant impacts on placental-hematopoietic stem cell communication is understudied. The goals of this study were to determine if factors secreted from placental cells alter transcriptomic responses in hematopoietic stem cells and if monoethylhexyl phthalate (MEHP), the bioactive metabolite of the pollutant diethylhexyl phthalate, modifies these effects.

METHODS

We used K-562 and BeWo cells as in vitro models of hematopoietic stem cells and placental syncytiotrophoblasts, respectively. We treated K-562 cells with medium conditioned by incubation with BeWo cells, medium conditioned with BeWo cells treated with 10 μM MEHP for 24 h, or controls treated with unconditioned medium. We extracted K-562 cell RNA, performed RNA sequencing, then conducted differential gene expression and pathway analysis.

RESULTS

Relative to controls, K-562 cells treated with BeWo cell conditioned medium differentially expressed 173 genes (FDR<0.05 and fold-change>2.0), including 2.4-fold upregulatation of tropomyosin 4 (TPM4, a cytoskeletal regulator involved in processes such as cell morphology and migration) and 3.3-fold upregulatation of sphingosine-1-phosphate receptor 3 (S1PR3, a mediator of myeloid cell differentiation and inflammatory responses). Upregulated genes were enriched for pathways including stem cell maintenance, cell proliferation and immune processes. Downregulated genes were enriched for terms involved in protein translation and transcriptional regulation. MEHP treatment differentially expressed eight genes (FDR<0.05), including genes involved in lipid metabolism (e.g., Perilipin 2, fold-change: 1.4; Carnitine Palmitoyltransferase 1A, fold-change: 1.4).

DISCUSSION

K-562 cells, a model of hematopoietic stem cells, are responsive to media conditioned by placental cells, potentially impacting pathways like stem cell maintenance.

Impact of the overexpression of the tyrosine kinase receptor RET in the hematopoietic potential of induced pluripotent stem cells (iPSCs)

INTRODUCTION

Previous studies have suggested that the tyrosine kinase receptor RET plays a significant role in the hematopoietic potential in mice and could also be used to expand cord-blood derived hematopoietic stem cells (HSCs). The role of RET in human iPSC-derived hematopoiesis has not been tested so far.

METHODS

To test the implication of RET on the hematopoietic potential of iPSCs, we activated its pathway with the lentiviral overexpression of RETWT or RETC634Y mutation in normal iPSCs. An iPSC derived from a patient harboring the RETC634Y mutation (iRETC634Y) and its CRISPR-corrected isogenic control iPSC (iRETCTRL) were also used. The hematopoietic potential was tested using 2D cultures and evaluated regarding the phenotype and the clonogenic potential of generated cells.

RESULTS

Hematopoietic differentiation from iPSCs with RET overexpression (WT or C634Y) led to a significant reduction in the number and in the clonogenic potential of primitive hematopoietic cells (CD34+/CD38-/CD49f+) as compared to control iPSCs. Similarly, the hematopoietic potential of iRETC634Y was reduced as compared to iRETCTRL. Transcriptomic analyses revealed a specific activated expression profile for iRETC634Y compared to its control with evidence of overexpression of genes which are part of the MAPK network with negative hematopoietic regulator activities.

CONCLUSION

RET activation in iPSCs is associated with an inhibitory activity in iPSC-derived hematopoiesis, potentially related to MAPK activation.

Late fetal hematopoietic failure results from ZBTB11 deficiency despite abundant HSC specification

Hematopoiesis produces diverse blood cell lineages to meet the basal needs and sudden demands of injury or infection. A rapid response to such challenges requires the expansion of specific lineages and a prompt return to balanced steady-state levels, necessitating tightly coordinated regulation. Previously we identified a requirement for the zinc finger and broad complex, tramtrak, bric-a-brac domain-containing 11 (ZBTB11) transcription factor in definitive hematopoiesis using a forward genetic screen for zebrafish myeloid mutants. To understand its relevance to mammalian systems, we extended these studies to mice. When Zbtb11 was deleted in the hematopoietic compartment, embryos died at embryonic day (E) 18.5 with hematopoietic failure. Zbtb11 hematopoietic knockout (Zbtb11hKO) hematopoietic stem cells (HSCs) were overabundantly specified from E14.5 to E17.5 compared with those in controls. Overspecification was accompanied by loss of stemness, inability to differentiate into committed progenitors and mature lineages in the fetal liver, failure to seed fetal bone marrow, and total hematopoietic failure. The Zbtb11hKO HSCs did not proliferate in vitro and were constrained in cell cycle progression, demonstrating the cell-intrinsic role of Zbtb11 in proliferation and cell cycle regulation in mammalian HSCs. Single-cell RNA sequencing analysis identified that Zbtb11-deficient HSCs were underrepresented in an erythroid-primed subpopulation and showed downregulation of oxidative phosphorylation pathways and dysregulation of genes associated with the hematopoietic niche. We identified a cell-intrinsic requirement for Zbtb11-mediated gene regulatory networks in sustaining a pool of maturation-capable HSCs and progenitor cells.

Use of mesenchymal stem cells to enhance or restore fertility potential: a systematic review of available experimental strategies

STUDY QUESTION

To what extent does regenerative medicine with stem cell therapy help to address infertility issues for future clinical application?

SUMMARY ANSWER

Regenerative medicine using different stem cell sources is yielding promising results in terms of protecting the ovarian reserve from damage and senescence, and improving fertility potential in various preclinical settings.

WHAT IS KNOWN ALREADY

Regenerative medicine using stem cell therapy is emerging as a potential strategy to address a number of issues in the field of human reproduction. Indeed, different types of adult and fetal mesenchymal stem cells (MSCs) have been tested with promising results, owing to their ability to differentiate into different tissue lineages, move toward specific injured sites (homing), and generate a secretome with wound-healing, proangiogenic, and antioxidant capacities.

STUDY DESIGN SIZE DURATION

Guided by the checklist for preferred reporting items for systematic reviews and meta-analyses, we retrieved relevant studies from PubMed, Medline, and Embase databases until June 2023 using the following keywords: 'mesenchymal stem cells' AND 'ovarian follicles' OR 'ovarian tissue culture' OR 'ovarian follicle culture' OR 'cumulus oocyte complex'. Only peer-reviewed published articles written in English were included.

PARTICIPANTS/MATERIALS SETTING METHODS

The primary outcome for the experimental strategies was evaluation of the ovarian reserve, with a focus on follicle survival, number, and growth. Secondary outcomes involved analyses of other parameters associated with the follicle pool, such as hormones and growth factors, ovarian tissue viability markers including oxidative stress levels, oocyte growth and maturation rates, and of course pregnancy outcomes.

MAIN RESULTS AND THE ROLE OF CHANCE

Preclinical studies exploring MSCs from different animal origins and tissue sources in specific conditions were selected (n = 112), including: in vitro culture of granulosa cells, ovarian tissue and isolated ovarian follicles; ovarian tissue transplantation; and systemic or intraovarian injection after gonadotoxic or age-related follicle pool decline. Protecting the ovarian reserve from aging and gonadotoxic damage has been widely tested in vitro and in vivo using murine models and is now yielding initial data in the first ever case series of patients with premature ovarian insufficiency. Use of MSCs as feeder cells in ovarian tissue culture was found to improve follicle outcomes and oocyte competence, bringing us one step closer to future clinical application. MSCs also have proved effective at boosting revascularization in the transplantation site when grafting ovarian tissue in experimental animal models.

LIMITATIONS REASONS FOR CAUTION

While preclinical results look promising in terms of protecting the ovarian reserve in different experimental models (especially those in vitro using various mammal experimental models and in vivo using murine models), there is still a lot of work to do before this approach can be considered safe and successfully implemented in a clinical setting.

WIDER IMPLICATIONS OF THE FINDINGS

All gathered data on the one hand show that regenerative medicine techniques are quickly gaining ground among innovative techniques being developed for future clinical application in the field of reproductive medicine. After proving MSC effectiveness in preclinical settings, there is still a lot of work to do before MSCs can be safely and effectively used in different clinical applications.

STUDY FUNDING/COMPETING INTERESTS

This study was supported by grants from the Fonds National de la Recherche Scientifique de Belgique (FNRS-PDR T.0077.14, FNRS-CDR J.0063.20, and grant 5/4/150/5 awarded to Marie-Madeleine Dolmans), Fonds Spéciaux de Recherche, and the Fondation St Luc. None of the authors have any competing interest to disclose.

REGISTRATION NUMBER

N/A.

HDAC6 deacetylates IDH1 to promote the homeostasis of hematopoietic stem and progenitor cells

Hematopoietic stem and progenitor cells (HSPCs) are cells mainly present in the bone marrow and capable of forming mature blood cells. However, the epigenetic mechanisms governing the homeostasis of HSPCs remain elusive. Here, we demonstrate an important role for histone deacetylase 6 (HDAC6) in regulating this process. Our data show that the percentage of HSPCs in Hdac6 knockout mice is lower than in wild-type mice due to decreased HSPC proliferation. HDAC6 interacts with isocitrate dehydrogenase 1 (IDH1) and deacetylates IDH1 at lysine 233. The deacetylation of IDH1 inhibits its catalytic activity and thereby decreases the 5-hydroxymethylcytosine level of ten-eleven translocation 2 (TET2) target genes, changing gene expression patterns to promote the proliferation of HSPCs. These findings uncover a role for HDAC6 and IDH1 in regulating the homeostasis of HSPCs and may have implications for the treatment of hematological diseases.

A new era of stem cell and developmental biology: from blastoids to synthetic embryos and beyond

Recent discoveries in stem cell and developmental biology have introduced a new era marked by the generation of in vitro models that recapitulate early mammalian development, providing unprecedented opportunities for extensive research in embryogenesis. Here, we present an overview of current techniques that model early mammalian embryogenesis, specifically noting models created from stem cells derived from two significant species: Homo sapiens, for its high relevance, and Mus musculus, a historically common and technically advanced model organism. We aim to provide a holistic understanding of these in vitro models by tracing the historical background of the progress made in stem cell biology and discussing the fundamental underlying principles. At each developmental stage, we present corresponding in vitro models that recapitulate the in vivo embryo and further discuss how these models may be used to model diseases. Through a discussion of these models as well as their potential applications and future challenges, we hope to demonstrate how these innovative advances in stem cell research may be further developed to actualize a model to be used in clinical practice.

DNA methylation cooperates with H3K9me2 at HCN4 promoter to regulate the differentiation of bone marrow mesenchymal stem cells into pacemaker-like cells

Sick sinus syndrome (SSS) is a a life-threatening disease, and biological pacemakers derived from bone marrow mesenchymal stem cells (BMSCs) have practical clinical applications. Previous studies demonstrated that epigenetics plays an important role in the differentiation of BMSCs into pacemaker-like cells. However, the underlying mechanisms remain unclear. In the present study, we investigated the role of DNA methylation and histone methylation in pacemaker cells formation and found that changes in DNA and H3K9 methylation occur in the promoter region of the pacemaker cell-specific gene HCN4. In addition, the combined addition of methylation inhibitors was able to improve the efficiency of transduction of Tbx18 in inducing the differentiation of BMSCs into pacemaker-like cells. In vitro experiments have shown that inhibition of DNA methylation and H3K9 methylation can enhance the activity of the HCN4 promoter activity, and both can affect the binding of the transcription factor NKx2.5to the HCN4 promoter region. Further research on the interaction mechanism between DNA methylation and H3K9me2 in the HCN4 promoter region revealed that the two may be coupled, and that the methylesterase G9a and DNMT1 may directly interact to bind as a complex that affects DNA methylation and H3K9me2 regulation of HCN4 transcription. In conclusion, our studies suggest that the mutual coupling of DNA and H3K9 methylation plays a critical role in regulating the differentiation of BMSCs into pacemaker-like cells from the perspective of interactions between epigenetic modifications, and combined methylation is a promising strategy to optimise pacemaker-like cells for in vitro applications.

Advances in the study of exosomes derived from mesenchymal stem cells and cardiac cells for the treatment of myocardial infarction

Acute myocardial infarction has long been the leading cause of death in coronary heart disease, which is characterized by irreversible cardiomyocyte death and restricted blood supply. Conventional reperfusion therapy can further aggravate myocardial injury. Stem cell therapy, especially with mesenchymal stem cells (MSCs), has emerged as a promising approach to promote cardiac repair and improve cardiac function. MSCs may induce these effects by secreting exosomes containing therapeutically active RNA, proteins and lipids. Notably, normal cardiac function depends on intracardiac paracrine signaling via exosomes, and exosomes secreted by cardiac cells can partially reflect changes in the heart during disease, so analyzing these vesicles may provide valuable insights into the pathology of myocardial infarction as well as guide the development of new treatments. The present review examines how exosomes produced by MSCs and cardiac cells may influence injury after myocardial infarction and serve as therapies against such injury. Video Abstract.

Bovine milk-derived cells express transcriptome markers of pluripotency and secrete bioactive factors with regenerative and antimicrobial activity

The bovine mammary stem/progenitor cell secretome stimulates regeneration in vitro and contains proteins associated with antimicrobial defense. This has led to the exploration of the secretome as a biologic treatment for mastitis, a costly inflammation of the udder commonly caused by bacteria. This study reports on a population of bovine mammary stem/progenitor cells isolated non-invasively from milk (MiDCs). MiDCs were characterized by immunophenotyping, mammosphere formation assays, and single cell RNA sequencing. They displayed epithelial morphology, exhibited markers of mammary stem/progenitor cells, and formed mammospheres, like mammary gland tissue-isolated stem/progenitor cells. Single cell RNA sequencing revealed two sub-populations of MiDCs: epithelial cells and macrophages. Functionally, the MiDC secretome increased fibroblast migration, promoted angiogenesis of endothelial cells, and inhibited the growth of mastitis-associated bacteria, including antibiotic-resistant strains, in vitro. These qualities of MiDCs render them a source of stem cells and stem cell products that may be used to treat diseases affecting the dairy industry, including mastitis.

The Implications of Cannabinoid-Induced Metabolic Dysregulation for Cellular Differentiation and Growth

The endocannabinoid system (ECS) governs and coordinates several physiological processes through an integrated signaling network, which is responsible for inducing appropriate intracellular metabolic signaling cascades in response to (endo)cannabinoid stimulation. This intricate cellular system ensures the proper functioning of the immune, reproductive, and nervous systems and is involved in the regulation of appetite, memory, metabolism, and development. Cannabinoid receptors have been observed on both cellular and mitochondrial membranes in several tissues and are stimulated by various classes of cannabinoids, rendering the ECS highly versatile. In the context of growth and development, emerging evidence suggests a crucial role for the ECS in cellular growth and differentiation. Indeed, cannabinoids have the potential to disrupt key energy-sensing metabolic signaling pathways requiring mitochondrial-ER crosstalk, whose functioning is essential for successful cellular growth and differentiation. This review aims to explore the extent of cannabinoid-induced cellular dysregulation and its implications for cellular differentiation.

Inflammatory auxo-action in the stem cell division theory of cancer

Acute inflammation is a beneficial response to the changes caused by pathogens or injuries that can eliminate the source of damage and restore homeostasis in damaged tissues. However, chronic inflammation causes malignant transformation and carcinogenic effects of cells through continuous exposure to pro-inflammatory cytokines and activation of inflammatory signaling pathways. According to the theory of stem cell division, the essential properties of stem cells, including long life span and self-renewal, make them vulnerable to accumulating genetic changes that can lead to cancer. Inflammation drives quiescent stem cells to enter the cell cycle and perform tissue repair functions. However, as cancer likely originates from DNA mutations that accumulate over time via normal stem cell division, inflammation may promote cancer development, even before the stem cells become cancerous. Numerous studies have reported that the mechanisms of inflammation in cancer formation and metastasis are diverse and complex; however, few studies have reviewed how inflammation affects cancer formation from the stem cell source. Based on the stem cell division theory of cancer, this review summarizes how inflammation affects normal stem cells, cancer stem cells, and cancer cells. We conclude that chronic inflammation leads to persistent stem cells activation, which can accumulate DNA damage and ultimately promote cancer. Additionally, inflammation not only facilitates the progression of stem cells into cancer cells, but also plays a positive role in cancer metastasis.

Multipotent fetal stem cells in reproductive biology research

Due to the limited accessibility of the in vivo situation, the scarcity of the human tissue, legal constraints, and ethical considerations, the underlying molecular mechanisms of disorders, such as preeclampsia, the pathological consequences of fetomaternal microchimerism, or infertility, are still not fully understood. And although substantial progress has already been made, the therapeutic strategies for reproductive system diseases are still facing limitations. In the recent years, it became more and more evident that stem cells are powerful tools for basic research in human reproduction and stem cell-based approaches moved into the center of endeavors to establish new clinical concepts. Multipotent fetal stem cells derived from the amniotic fluid, amniotic membrane, chorion leave, Wharton´s jelly, or placenta came to the fore because they are easy to acquire, are not associated with ethical concerns or covered by strict legal restrictions, and can be banked for autologous utilization later in life. Compared to adult stem cells, they exhibit a significantly higher differentiation potential and are much easier to propagate in vitro. Compared to pluripotent stem cells, they harbor less mutations, are not tumorigenic, and exhibit low immunogenicity. Studies on multipotent fetal stem cells can be invaluable to gain knowledge on the development of dysfunctional fetal cell types, to characterize the fetal stem cells migrating into the body of a pregnant woman in the context of fetomaternal microchimerism, and to obtain a more comprehensive picture of germ cell development in the course of in vitro differentiation experiments. The in vivo transplantation of fetal stem cells or their paracrine factors can mediate therapeutic effects in preeclampsia and can restore reproductive organ functions. Together with the use of fetal stem cell-derived gametes, such strategies could once help individuals, who do not develop functional gametes, to conceive genetically related children. Although there is still a long way to go, these developments regarding the usage of multipotent fetal stem cells in the clinic should continuously be accompanied by a wide and detailed ethical discussion.

Regulation of hematopoietic stem cells differentiation, self-renewal, and quiescence through the mTOR signaling pathway

Hematopoietic stem cells (HSCs) are important for the hematopoietic system because they can self-renew to increase their number and differentiate into all the blood cells. At a steady state, most of the HSCs remain in quiescence to preserve their capacities and protect themselves from damage and exhaustive stress. However, when there are some emergencies, HSCs are activated to start their self-renewal and differentiation. The mTOR signaling pathway has been shown as an important signaling pathway that can regulate the differentiation, self-renewal, and quiescence of HSCs, and many types of molecules can regulate HSCs' these three potentials by influencing the mTOR signaling pathway. Here we review how mTOR signaling pathway regulates HSCs three potentials, and introduce some molecules that can work as the regulator of HSCs' these potentials through the mTOR signaling. Finally, we outline the clinical significance of studying the regulation of HSCs three potentials through the mTOR signaling pathway and make some predictions.

Differentiation Kinetics of Hematopoietic Stem and Progenitor Cells In Vivo Are Not Affected by β-Glucan Treatment in Trained Immunity

Agonists of trained immunity induce epigenetic changes in hematopoietic stem and progenitor cells (HSPCs) to generate long-lasting immune protection. Although trained HSPCs generate myeloid cells with increased responsiveness to secondary challenges, whether their differentiation kinetics is affected by prior exposure to inducers of trained immunity remains elusive. Here, we used lineage tracing to examine the cell fates of endothelial protein C receptor-positive hematopoietic stem cells (EPCR⁺ HSCs) and fms-like tyrosine kinase 3-positive multipotent progenitor cells (Flt3⁺ MPPs) in β-glucan-induced trained immunity. We found that although β-glucan triggered the expected expansion of myeloid progenitors, the differentiation behaviors of EPCR⁺ HSCs and Flt3⁺ MPPs in multiple cycles of hematopoietic regeneration were hardly affected. Thus, our results rule out changed kinetics in cell differentiation by EPCR⁺ HSC and Flt3⁺ MPP as the cause of enhanced myelopoiesis upon secondary immune challenges.

Cell population dynamics in the course of adult hippocampal neurogenesis: Remaining unknowns

Neural stem cells (NSCs) generate new neurons throughout life in the mammalian hippocampus. The distinct developmental steps in the course of adult neurogenesis, including NSC activation, expansion, and neuronal integration, are increasingly well characterized down to the molecular level. However, substantial gaps remain in our knowledge about regulators and mechanisms involved in this biological process. This review highlights three long-standing unknowns. First, we discuss potency and identity of NSCs and the quest for a unifying model of short- and long-term self-renewal dynamics. Next, we examine cell death, specifically focusing on the early demise of newborn cells. Then, we outline the current knowledge on cell integration dynamics, discussing which (if any) neurons are replaced by newly added neurons in the hippocampal circuits. For each of these unknowns, we summarize the trajectory of studies leading to the current state of knowledge. Finally, we offer suggestions on how to fill the remaining gaps by taking advantage of novel technology to reveal currently hidden secrets in the course of adult hippocampal neurogenesis.

Placental Cell Conditioned Media Modifies Hematopoietic Stem Cell Transcriptome In Vitro

Background

Hematopoietic stem cells are cells that differentiate into all blood cell types. Although the placenta secretes hormones, proteins and other factors important for maternal and fetal health, cross-talk between placental cells and hematopoietic stem cells is poorly understood. Moreover, toxicant impacts on placental-hematopoietic stem cell communication is understudied. The goals of this study were to determine if factors secreted from placental cells alter transcriptomic responses in hematopoietic stem cells and if monoethylhexyl phthalate (MEHP), the bioactive metabolite of the pollutant diethylhexyl phthalate, modifies these effects.

Methods

We used K-562 and BeWo cells as in vitro models of hematopoietic stem cells and placental syncytiotrophoblasts, respectively. We treated K-562 cells with medium conditioned by incubation with BeWo cells, medium conditioned with BeWo cells treated with 10 μM MEHP for 24 hours, or controls treated with unconditioned medium. We extracted K-562 cell RNA, performed RNA sequencing, then conducted differential gene expression and pathway analysis by treatment group.

Results

Relative to controls, K-562 cells treated with BeWo cell conditioned medium differentially expressed 173 genes (FDR<0.05 and fold-change>2.0), including 2.4 fold upregulatation of TPM4 and 3.3 fold upregulatation of S1PR3. Upregulated genes were enriched for pathways including stem cell maintenance, cell proliferation and immune processes. Downregulated genes were enriched for terms involved in protein translation and transcriptional regulation. MEHP treatment differentially expressed eight genes (FDR<0.05), including genes involved in lipid metabolism (PLIN2, fold-change: 1.4; CPT1A, fold-change: 1.4).

Conclusion

K-562 cells, a model of hematopoietic stem cells, are responsive to media conditioned by placental cells, potentially impacting pathways like stem cell maintenance and proliferation.

A Simplified and Effective Approach for the Isolation of Small Pluripotent Stem Cells Derived from Human Peripheral Blood

Pluripotent stem cells are key players in regenerative medicine. Embryonic pluripotent stem cells, despite their significant advantages, are associated with limitations such as their inadequate availability and the ethical dilemmas in their isolation and clinical use. The discovery of very small embryonic-like (VSEL) stem cells addressed the aforementioned limitations, but their isolation technique remains a challenge due to their small cell size and their efficiency in isolation. Here, we report a simplified and effective approach for the isolation of small pluripotent stem cells derived from human peripheral blood. Our approach results in a high yield of small blood stem cell (SBSC) population, which expresses pluripotent embryonic markers (e.g., Nanog, SSEA-3) and the Yamanaka factors. Further, a fraction of SBSCs also co-express hematopoietic markers (e.g., CD45 and CD90) and/or mesenchymal markers (e.g., CD29, CD105 and PTH1R), suggesting a mixed stem cell population. Finally, quantitative proteomic profiling reveals that SBSCs contain various stem cell markers (CD9, ITGA6, MAPK1, MTHFD1, STAT3, HSPB1, HSPA4), and Transcription reg complex factors (e.g., STAT5B, PDLIM1, ANXA2, ATF6, CAMK1). In conclusion, we present a novel, simplified and effective isolating process that yields an abundant population of small-sized cells with characteristics of pluripotency from human peripheral blood.

Chemically defined cytokine-free expansion of human haematopoietic stem cells

Haematopoietic stem cells (HSCs) are a rare cell type that reconstitute the entire blood and immune systems after transplantation and can be used as a curative cell therapy for a variety of haematological diseases1,2. However, the low number of HSCs in the body makes both biological analyses and clinical application difficult, and the limited extent to which human HSCs can be expanded ex vivo remains a substantial barrier to the wider and safer therapeutic use of HSC transplantation3. Although various reagents have been tested in attempts to stimulate the expansion of human HSCs, cytokines have long been thought to be essential for supporting HSCs ex vivo4. Here we report the establishment of a culture system that allows the long-term ex vivo expansion of human HSCs, achieved through the complete replacement of exogenous cytokines and albumin with chemical agonists and a caprolactam-based polymer. A phosphoinositide 3-kinase activator, in combination with a thrombopoietin-receptor agonist and the pyrimidoindole derivative UM171, were sufficient to stimulate the expansion of umbilical cord blood HSCs that are capable of serial engraftment in xenotransplantation assays. Ex vivo HSC expansion was further supported by split-clone transplantation assays and single-cell RNA-sequencing analysis. Our chemically defined expansion culture system will help to advance clinical HSC therapies.

MicroRNA Profiles in Intestinal Epithelial Cells in a Mouse Model of Sepsis

Sepsis is a systemic inflammatory disorder that leads to the dysfunction of multiple organs. In the intestine, the deregulation of the epithelial barrier contributes to the development of sepsis by triggering continuous exposure to harmful factors. However, sepsis-induced epigenetic changes in gene-regulation networks within intestinal epithelial cells (IECs) remain unexplored. In this study, we analyzed the expression profile of microRNAs (miRNAs) in IECs isolated from a mouse model of sepsis generated via cecal slurry injection. Among 239 miRNAs, 14 miRNAs were upregulated, and 9 miRNAs were downregulated in the IECs by sepsis. Upregulated miRNAs in IECs from septic mice, particularly miR-149-5p, miR-466q, miR-495, and miR-511-3p, were seen to exhibit complex and global effects on gene regulation networks. Interestingly, miR-511-3p has emerged as a diagnostic marker in this sepsis model due to its increase in blood in addition to IECs. As expected, mRNAs in the IECs were remarkably altered by sepsis; specifically, 2248 mRNAs were decreased, while 612 mRNAs were increased. This quantitative bias may be possibly derived, at least partly, from the direct effects of the sepsis-increased miRNAs on the comprehensive expression of mRNAs. Thus, current in silico data indicate that there are dynamic regulatory responses of miRNAs to sepsis in IECs. In addition, the miRNAs that were increased with sepsis had enriched downstream pathways including Wnt signaling, which is associated with wound healing, and FGF/FGFR signaling, which has been linked to chronic inflammation and fibrosis. These modifications in miRNA networks in IECs may lead to both pro- and anti-inflammatory effects in sepsis. The four miRNAs discovered above were shown to putatively target LOX, PTCH1, COL22A1, FOXO1, or HMGA2, via in silico analysis, which were associated with Wnt or inflammatory pathways and selected for further study. The expressions of these target genes were downregulated in sepsis IECs, possibly through posttranscriptional modifications of these miRNAs. Taken together, our study suggests that IECs display a distinctive miRNA profile which is capable of comprehensively and functionally reshaping the IEC-specific mRNA landscape in a sepsis model.

A clinical feasible stem cell encapsulation ensures an improved wound healing

Cell encapsulation has proven to be promising in stem cell therapy. However, there are issues needed to be addressed, including unsatisfied yield, unmet clinically friendly formulation, and unacceptable viability of stem cells after cryopreservation and thawing. We developed a novel biosynsphere technology to encapsulate stem cells in clinically-ready biomaterials with controlled microsphere size. We demonstrated that biosynspheres ensure the bioviability and functionality of adipose-derived stromal cells (ADSCs) encapsulated, as delineated by a series of testing procedures. We further demonstrated that biosynspheres protect ADSCs from the hardness of clinically handling such as cryopreservation, thawing, high-speed centrifugation and syringe/nozzle injection. In a swine full skin defect model, we showed that biosynspheres were integrated to the destined tissues and promoted the repair of injured tissues with an accelerating healing process, less scar tissue formation and normalized deposition of collagen type I and type III, the ratio similar to that found in normal skin. These findings underscore the potential of biosynsphere as an improved biofabrication technology for tissue regeneration in clinical setting.

Aging of hair follicle stem cells and their niches

Hair follicles in the skin undergo cyclic rounds of regeneration, degeneration, and rest throughout life. Stem cells residing in hair follicles play a pivotal role in maintaining tissue homeostasis and hair growth cycles. Research on hair follicle aging and age-related hair loss has demonstrated that a decline in hair follicle stem cell (HFSC) activity with aging can decrease the regeneration capacity of hair follicles. This review summarizes our understanding of how age-associated HFSC intrinsic and extrinsic mechanisms can induce HFSC aging and hair loss. In addition, we discuss approaches developed to attenuate ageassociated changes in HFSCs and their niches, thereby promoting hair regrowth. [BMB Reports 2023; 56(1): 2-9].

Hydrogel-based microenvironment engineering of haematopoietic stem cells

Haematopoietic Stem cells (HSCs) have the potential for self-renewal and multilineage differentiation, and their behaviours are finely tuned by the microenvironment. HSC transplantation (HSCT) is widely used in the treatment of haematologic malignancies while limited by the quantity of available HSCs. With the development of tissue engineering, hydrogels have been deployed to mimic the HSC microenvironment in vitro. Engineered hydrogels influence HSC behaviour by regulating mechanical strength, extracellular matrix microstructure, cellular ligands and cytokines, cell-cell interaction, and oxygen concentration, which ultimately facilitate the acquisition of sufficient HSCs. Here, we review recent advances in the application of hydrogel-based microenvironment engineering of HSCs, and provide future perspectives on challenges in basic research and clinical practice.

The Role of SOX Transcription Factors in Ageing and Age-Related Diseases

The quest for eternal youth and immortality is as old as humankind. Ageing is an inevitable physiological process accompanied by many functional declines that are driving factors for age-related diseases. Stem cell exhaustion is one of the major hallmarks of ageing. The SOX transcription factors play well-known roles in self-renewal and differentiation of both embryonic and adult stem cells. As a consequence of ageing, the repertoire of adult stem cells present in various organs steadily declines, and their dysfunction/death could lead to reduced regenerative potential and development of age-related diseases. Thus, restoring the function of aged stem cells, inducing their regenerative potential, and slowing down the ageing process are critical for improving the health span and, consequently, the lifespan of humans. Reprograming factors, including SOX family members, emerge as crucial players in rejuvenation. This review focuses on the roles of SOX transcription factors in stem cell exhaustion and age-related diseases, including neurodegenerative diseases, visual deterioration, chronic obstructive pulmonary disease, osteoporosis, and age-related cancers. A better understanding of the molecular mechanisms of ageing and the roles of SOX transcription factors in this process could open new avenues for developing novel strategies that will delay ageing and prevent age-related diseases.

Aging of hair follicle stem cells and their niches

Hair follicles in the skin undergo cyclic rounds of regeneration, degeneration, and rest throughout life. Stem cells residing in hair follicles play a pivotal role in maintaining tissue homeostasis and hair growth cycles. Research on hair follicle aging and age-related hair loss has demonstrated that a decline in hair follicle stem cell (HFSC) activity with aging can decrease the regeneration capacity of hair follicles. This review summarizes our understanding of how age-associated HFSC intrinsic and extrinsic mechanisms can induce HFSC aging and hair loss. In addition, we discuss approaches developed to attenuate ageassociated changes in HFSCs and their niches, thereby promoting hair regrowth. [BMB Reports 2023; 56(1): 2-9].

Effects of non-steroidal anti-inflammatory drug (ibuprofen) in low and high dose on stemness and biological characteristics of human dental pulp-derived mesenchymal stem cells

PURPOSE

The effect of ibuprofen, an NSAID, on biological characteristics such as proliferation, viability, DNA damage and cell cycle in dental pulp derived stem cells (DPSCs) can be important for regenerative medicine. Our aim is to investigate how low and high doses of ibuprofen affect stem cell characteristics in DPSCs.

MATERIALS AND METHODS

DPSCs were isolated from human teeth and characterized by flow cytometry and differentiation tests. Low dose (0.1 mmol/L) and high dose (3 mmol/L) ibuprofen were administered to DPSCs. Surface markers between groups were analyzed by immunofluorescence staining. Membrane depolarization, DNA damage, viability and cell cycle analysis were performed between groups using biological activity test kits. Cellular proliferation was measured by the MTT and cell count kit. Statistical analyzes were performed using GraphPad Prism software.

RESULTS

High dose ibuprofen significantly increased CD44 and CD73 expression in DPSCs. High-dose ibuprofen significantly reduced mitochondrial membrane depolarization in DPSCs. It was determined that DNA damage in DPSCs decreased significantly with high dose ibuprofen. Parallel to this, cell viability increased significantly in the ibuprofen applied groups. High-dose ibuprofen was found to increase mitotic activity in DPSCs. Proliferation in DPSCs increased in parallel with the increase in mitosis stage because of high-dose ibuprofen administration compared to the control and low-dose ibuprofen groups. Our proliferation findings appeared to support cell cycle analyses.

CONCLUSION

High dose ibuprofen improved the immunophenotypes and biological activities of DPSCs. The combination of ibuprofen in the use of DPSCs in regenerative medicine can make stem cell therapy more effective.

Amniotic Fluid Stem Cells: What They Are and What They Can Become

In the last two decades, fetal amniotic fluid stem cells progressively attracted attention in the context of both basic research and the development of innovative therapeutic concepts. They exhibit broadly multipotent plasticity with the ability to differentiate into cells of all three embryonic germ layers and low immunogenicity. They are convenient to maintain, highly proliferative, genomically stable, non-tumorigenic, perfectly amenable to genetic modifications, and do not raise ethical concerns. However, it is important to note that among the various fetal amniotic fluid cells, only c-Kit+ amniotic fluid stem cells represent a distinct entity showing the full spectrum of these features. Since amniotic fluid additionally contains numerous terminally differentiated cells and progenitor cells with more limited differentiation potentials, it is of highest relevance to always precisely describe the isolation procedure and characteristics of the used amniotic fluid-derived cell type. It is of obvious interest for scientists, clinicians, and patients alike to be able to rely on up-todate and concisely separated pictures of the utilities as well as the limitations of terminally differentiated amniotic fluid cells, amniotic fluid-derived progenitor cells, and c-Kit+ amniotic fluid stem cells, to drive these distinct cellular models towards as many individual clinical applications as possible.

Future stem cell analysis: progress and challenges towards state-of-the art approaches in automated cells analysis

Background and Aims

A microscopic image has been used in cell analysis for cell type identification and classification, cell counting and cell size measurement. Most previous research works are tedious, including detailed understanding and time-consuming. The scientists and researchers are seeking modern and automatic cell analysis approaches in line with the current in-demand technology.

Objectives

This article provides a brief overview of a general cell and specific stem cell analysis approaches from the history of cell discovery up to the state-of-the-art approaches.

Methodology

A content description of the literature study has been surveyed from specific manuscript databases using three review methods: manuscript identification, screening, and inclusion. This review methodology is based on Prism guidelines in searching for originality and novelty in studies concerning cell analysis.

Results

By analysing generic cell and specific stem cell analysis approaches, current technology offers tremendous potential in assisting medical experts in performing cell analysis using a method that is less laborious, cost-effective, and reduces error rates.

Conclusion

This review uncovers potential research gaps concerning generic cell and specific stem cell analysis. Thus, it could be a reference for developing automated cells analysis approaches using current technology such as artificial intelligence and deep learning.

Prolyl-hydroxylase inhibitor-induced regeneration of alveolar bone and soft tissue in a mouse model of periodontitis through metabolic reprogramming

Bone injuries and fractures reliably heal through a process of regeneration with restoration to original structure and function when the gap between adjacent sides of a fracture site is small. However, when there is significant volumetric loss of bone, bone regeneration usually does not occur. In the present studies, we explore a particular case of volumetric bone loss in a mouse model of human periodontal disease (PD) in which alveolar bone surrounding teeth is permanently lost and not replaced. This model employs the placement a ligature around the upper second molar for 10 days leading to inflammation and bone breakdown and faithfully replicates the bacterially-induced inflammatory etiology of human PD to induce bone degeneration. After ligature removal, mice are treated with a timed-release formulation of a small molecule inhibitor of prolylhydroxylases (PHDi; 1,4-DPCA) previously shown to induce epimorphic regeneration of soft tissue in non-regenerating mice. This PHDi induces high expression of HIF-1α and is able to shift the metabolic state from OXPHOS to aerobic glycolysis, an energetic state used by stem cells and embryonic tissue. This regenerative response was completely blocked by siHIF1a. In these studies, we show that timed-release 1,4-DPCA rapidly and completely restores PD-affected bone and soft tissue with normal anatomic fidelity and with increased stem cell markers due to site-specific stem cell migration and/or de-differentiation of local tissue, periodontal ligament (PDL) cell proliferation, and increased vascularization. In-vitro studies using gingival tissue show that 1,4-DPCA indeed induces de-differentiation and the expression of stem cell markers but does not exclude the role of migrating stem cells. Evidence of metabolic reprogramming is seen by the expression of not only HIF-1a, its gene targets, and resultant de-differentiation markers, but also the metabolic genes Glut-1, Gapdh, Pdk1, Pgk1 and Ldh-a in jaw periodontal tissue.

Stemness Activity Underlying Whole Brain Regeneration in a Basal Chordate

Understanding how neurons regenerate following injury remains a central challenge in regenerative medicine. Adult mammals have a very limited ability to regenerate new neurons in the central nervous system (CNS). In contrast, the basal chordate Polycarpa mytiligera can regenerate its entire CNS within seven days of complete removal. Transcriptome sequencing, cellular labeling, and proliferation in vivo essays revealed that CNS regeneration is mediated by a newly formed neural progeny and the activation of neurodevelopmental pathways that are associated with enhanced stem-cell activity. Analyzing the expression of 239 activated pathways enabled a quantitative understanding of gene-set enrichment patterns at key regeneration stages. The molecular and cellular mechanisms controlling the regenerative ability that this study reveals can be used to develop innovative approaches to enhancing neurogenesis in closely-related chordate species, including humans.

MSCs vs. iPSCs: Potential in therapeutic applications

Over the past 2 decades, mesenchymal stem cells (MSCs) have attracted a lot of interest as a unique therapeutic approach for a variety of diseases. MSCs are capable of self-renewal and multilineage differentiation capacity, immunomodulatory, and anti-inflammatory properties allowing it to play a role in regenerative medicine. Furthermore, MSCs are low in tumorigenicity and immune privileged, which permits the use of allogeneic MSCs for therapies that eliminate the need to collect MSCs directly from patients. Induced pluripotent stem cells (iPSCs) can be generated from adult cells through gene reprogramming with ectopic expression of specific pluripotency factors. Advancement in iPS technology avoids the destruction of embryos to make pluripotent cells, making it free of ethical concerns. iPSCs can self-renew and develop into a plethora of specialized cells making it a useful resource for regenerative medicine as they may be created from any human source. MSCs have also been used to treat individuals infected with the SARS-CoV-2 virus. MSCs have undergone more clinical trials than iPSCs due to high tumorigenicity, which can trigger oncogenic transformation. In this review, we discussed the overview of mesenchymal stem cells and induced pluripotent stem cells. We briefly present therapeutic approaches and COVID-19-related diseases using MSCs and iPSCs.