Differences between human and mouse embryonic stem cells

Ultrasound-triggered three dimensional hyaluronic acid hydrogel promotes in vitro and in vivo reprogramming into induced pluripotent stem cells

Cellular reprogramming technologies have been developed with different physicochemical factors to improve the reprogramming efficiencies of induced pluripotent stem cells (iPSCs). Ultrasound is a clinically applied noncontact biophysical factor known for regulating various cellular behaviors but remains uninvestigated for cellular reprogramming. Here, we present a new reprogramming strategy using low-intensity ultrasound (LIUS) to improve cellular reprogramming of iPSCs in vitro and in vivo. Under 3D microenvironment conditions, increased LIUS stimulation shows enhanced cellular reprogramming of the iPSCs. The cellular reprogramming process facilitated by LIUS is accompanied by increased mesenchymal to epithelial transition and histone modification. LIUS stimulation transiently modulates the cytoskeletal rearrangement, along with increased membrane fluidity and mobility to increase HA/CD44 interactions. Furthermore, LIUS stimulation with HA hydrogel can be utilized in application of both human cells and in vivo environment, for enhanced reprogrammed cells into iPSCs. Thus, LIUS stimulation with a combinatorial 3D microenvironment system can improve cellular reprogramming in vitro and in vivo environments, which can be applied in various biomedical fields.

Stem cell therapies: a new era in the treatment of multiple sclerosis

Multiple Sclerosis (MS) is an immune-mediated condition that persistently harms the central nervous system. While existing treatments can slow its course, a cure remains elusive. Stem cell therapy has gained attention as a promising approach, offering new perspectives with its regenerative and immunomodulatory properties. This article reviews the application of stem cells in MS, encompassing various stem cell types, therapeutic potential mechanisms, preclinical explorations, clinical research advancements, safety profiles of clinical applications, as well as limitations and challenges, aiming to provide new insights into the treatment research for MS.

Characterization of the Nucleus Pulposus Progenitor Cells via Spatial Transcriptomics

Loss of refreshment in nucleus pulposus (NP) cellularity leads to intervertebral disc (IVD) degeneration. Nevertheless, the cellular sequence of NP cell differentiation remains unclear, although an increasing body of literature has identified markers of NP progenitor cells (NPPCs). Notably, due to their fragility, the physical enrichment of NP-derived cells has limited conventional transcriptomic approaches in multiple studies. To overcome this limitation, a spatially resolved transcriptional atlas of the mouse IVD is generated via the 10x Genomics Visium platform dividing NP spots into two clusters. Based on this, most reported NPPC-markers, including Cathepsin K (Ctsk), are rare and predominantly located within the NP-outer subset. Cell lineage tracing further evidence that a small number of Ctsk-expressing cells generate the entire adult NP tissue. In contrast, Tie2, which has long suggested labeling NPPCs, is actually neither expressed in NP subsets nor labels NPPCs and their descendants in mouse models; consistent with this, an in situ sequencing (ISS) analysis validated the absence of Tie2 in NP tissue. Similarly, no Tie2-cre-mediated labeling of NPPCs is observed in an IVD degenerative mouse model. Altogether, in this study, the first spatial transcriptomic map of the IVD is established, thereby providing a public resource for bone biology.

Stem cell-based therapies for heart failure management: a narrative review of current evidence and future perspectives

Heart failure (HF) is a prevalent and debilitating global cardiovascular condition affecting around 64 million individuals, placing significant strain on healthcare systems and diminishing patients' quality of life. The escalating prevalence of HF underscores the urgent need for innovative therapeutic approaches that target the root causes and aim to restore normal cardiac function. Stem cell-based therapies have emerged as promising candidates, representing a fundamental departure from conventional treatments focused primarily on symptom management. This review explores the evolving landscape of stem cell-based therapies for HF management. It delves into the mechanisms of action, clinical evidence from both positive and negative outcomes, ethical considerations, and regulatory challenges. Key findings include the potential for improved cardiac function, enhanced quality of life, and long-term benefits associated with stem cell therapies. However, adverse events and patient vulnerabilities necessitate stringent safety assessments. Future directions in stem cell-based HF therapies include enhancing efficacy and safety through optimized stem cell types, delivery techniques, dosing strategies, and long-term safety assessments. Personalized medicine, combining therapies, addressing ethical and regulatory challenges, and expanding access while reducing costs are crucial aspects of the evolving landscape.

Dynamic Roles of Signaling Pathways in Maintaining Pluripotency of Mouse and Human Embryonic Stem Cells

Culturing of mouse and human embryonic stem cells (ESCs) in vitro was a major breakthrough in the field of stem cell biology. These models gained popularity very soon mainly due to their pluripotency. Evidently, the ESCs of mouse and human origin share typical phenotypic responses due to their pluripotent nature, such as self-renewal capacity and potency. The conserved network of core transcription factors regulates these responses. However, significantly different signaling pathways and upstream transcriptional networks regulate expression and activity of these core pluripotency factors in ESCs of both the species. In fact, ample evidence shows that a pathway, which maintains pluripotency in mouse ESCs, promotes differentiation in human ESCs. In this review, we discuss the role of canonical signaling pathways implicated in regulation of pluripotency and differentiation particularly in mouse and human ESCs. We believe that understanding these distinct and at times-opposite mechanisms-is critical for the progress in the field of stem cell biology and regenerative medicine.

Learning Towards Maturation of Defined Feeder-free Pluripotency Culture Systems: Lessons from Conventional Feeder-based Systems

Pluripotent stem cells (PSCs) are widely recognized as one of the most promising types of stem cells for applications in regenerative medicine, tissue engineering, disease modeling, and drug screening. This is due to their unique ability to differentiate into cells from all three germ layers and their capacity for indefinite self-renewal. Initially, PSCs were cultured using animal feeder cells, but these systems presented several limitations, particularly in terms of Good Manufacturing Practices (GMP) regulations. As a result, feeder-free systems were introduced as a safer alternative. However, the precise mechanisms by which feeder cells support pluripotency are not fully understood. More importantly, it has been observed that some aspects of the need for feeder cells like the optimal density and cell type can vary depending on conditions such as the developmental stage of the PSCs, phases of the culture protocol, the method used in culture for induction of pluripotency, and intrinsic variability of PSCs. Thus, gaining a better understanding of the divergent roles and necessity of feeder cells in various conditions would lead to the development of condition-specific defined feeder-free systems that resolve the failure of current feeder-free systems in some conditions. Therefore, this review aims to explore considerable feeder-related issues that can lead to the development of condition-specific feeder-free systems.

Modulation of mitochondrial activity by sugarcane (Saccharum officinarum L.) top extract and its bioactive polyphenols: a comprehensive transcriptomics analysis in C2C12 myotubes and HepG2 hepatocytes

Age-related mitochondrial dysfunction leads to defects in cellular energy metabolism and oxidative stress defense systems, which can contribute to tissue damage and disease development. Among the key regulators responsible for mitochondrial quality control, peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) is an important target for mitochondrial dysfunction. We have previously reported that bioactive polyphenols extracted from sugarcane top (ST) ethanol extract (STEE) could activate neuronal energy metabolism and increase astrocyte PGC-1α transcript levels. However, their potential impact on the mitochondria activity in muscle and liver cells has not yet been investigated. To address this gap, our current study examined the effects of STEE and its polyphenols on cultured myotubes and hepatocytes in vitro. Rhodamine 123 assay revealed that the treatment with STEE and its polyphenols resulted in an increase in mitochondrial membrane potential in C2C12 myotubes. Furthermore, a comprehensive examination of gene expression patterns through transcriptome-wide microarray analysis indicated that STEE altered gene expressions related to mitochondrial functions, fatty acid metabolism, inflammatory cytokines, mitogen-activated protein kinase (MAPK) signaling, and cAMP signaling in both C2C12 myotubes and HepG2 hepatocytes. Additionally, protein-protein interaction analysis identified the PGC-1α interactive-transcription factors-targeted regulatory network of the genes regulated by STEE, and the quantitative polymerase chain reaction results confirmed that STEE and its polyphenols upregulated the transcript levels of PGC-1α in both C2C12 and HepG2 cells. These findings collectively suggest the potential beneficial effects of STEE on muscle and liver tissues and offer novel insights into the potential nutraceutical applications of this material.

Microarray Analysis for Transcriptomic Profiling of Myocardium in Patients with Fatal Myocardial Infarction

Transcriptomic evidence from human myocardium in myocardial infarction (MI) is still not sufficient. Thus, there is a need for studies on human cardiac samples in relation to the clinical data of patients. The purpose of our pilot study was to investigate the transcriptomic profile of myocardium in the infarct zone, in comparison to the remote myocardium, in patients with fatal MI, via microarray analysis. This study included four patients with fatal MI type 1. We selected histologically verified samples from within the infarct area (n = 4) and remote myocardium (n = 4). The whole transcriptome was evaluated using microarray analysis. Differentially expressed genes (DEGs) clustered in the infarct area and in the remote myocardium allowed their differentiation. We identified a total of 1785 DEGs (8.32%) in the infarct area, including 1692 up-regulated (94.79%) and 93 down-regulated (5.21%) genes. The top 10 up-regulated genes were TRAIL, SUCLA2, NAE1, PDCL3, OSBPL5, FCGR2C, SELE, CEP63, ST3GAL3 and C4orf3. In the infarct area, we found up-regulation of seventeen apoptosis-related genes, eleven necroptosis-related, and six necrosis-related genes. Transcriptome profiling of the myocardium in patients with MI remains a relevant area of research for the formation of new scientific hypotheses and a potential way to increase the translational significance of studies into myocardial infarction.

Engineered hematopoietic and immune cells derived from human pluripotent stem cells

For the past decade, significant advances have been achieved in human hematopoietic stem cell (HSC) transplantation for treating various blood diseases and cancers. However, challenges remain with the quality control, amount, and cost of HSCs and HSC-derived immune cells. The advent of human pluripotent stem cells (hPSCs) may transform HSC transplantation and cancer immunotherapy by providing a cost-effective and scalable cell source for fundamental studies and translational applications. In this review, we discuss the current developments in the field of stem cell engineering for hematopoietic stem and progenitor cell (HSPC) differentiation and further differentiation of HSPCs into functional immune cells. The key advances in stem cell engineering include the generation of HSPCs from hPSCs, genetic modification of hPSCs, and hPSC-derived HSPCs for improved function, further differentiation of HPSCs into functional immune cells, and applications of cell culture platforms for hematopoietic cell manufacturing. Current challenges impeding the translation of hPSC-HSPCs and immune cells as well as further directions to address these challenges are also discussed.

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.

Functional Cardiovascular Characterization of the Common Marmoset (Callithrix jacchus)

Appropriate cardiovascular animal models are urgently needed to investigate genetic, molecular, and therapeutic approaches, yet the translation of results from the currently used species is difficult due to their genetic distance as well as their anatomical or physiological differences. Animal species that are closer to the human situation might help to bridge this translational gap. The common marmoset (Callithrix jacchus) is an interesting candidate to investigate certain heart diseases and cardiovascular comorbidities, yet a basic functional characterization of its hemodynamic system is still missing. Therefore, cardiac functional analyses were performed by utilizing the invasive intracardiac pressure-volume loops (PV loop) system in seven animals, magnetic resonance imaging (MRI) in six animals, and echocardiography in five young adult male common marmosets. For a direct comparison between the three methods, only data from animals for which all three datasets could be acquired were selected. All three modalities were suitable for characterizing cardiac function, though with some systemic variations. In addition, vena cava occlusions were performed to investigate the load-independent parameters collected with the PV loop system, which allowed for a deeper analysis of the cardiac function and for a more sensitive detection of the alterations in a disease state, such as heart failure or certain cardiovascular comorbidities.

A canine model of chronic ischemic heart failure

Preclinical large animal models of chronic heart failure (HF) are crucial to both understanding pathological remodeling and translating fundamental discoveries into novel therapeutics for HF. Canine models of ischemic cardiomyopathy are historically limited by either high early mortality or failure to develop chronic heart failure. Twenty-nine healthy adult dogs (30 ± 4 kg, 15/29 male) underwent thoracotomy followed by one of three types of left anterior descending (LAD) coronary artery ligation procedures: group 1 (n = 4) (simple LAD: proximal and distal LAD ligation); group 2 (n = 14) (simple LAD plus lateral wall including ligation of the distal first diagonal and proximal first obtuse marginal); and group 3 (n = 11) (total LAD devascularization or TLD: simple LAD plus ligation of proximal LAD branches to both the right and left ventricles). Dogs were followed until chronic severe HF developed defined as left ventricular ejection fraction (LVEF) < 40% and NH2-terminal-prohormone B-type natriuretic peptide (NT-proBNP) > 900 pmol/L. Overall early survival (48-h postligation) in 29 dogs was 83% and the survival rate at postligation 5 wk was 69%. Groups 1 and 2 had 100% and 71% early survival, respectively, yet only a 50% success rate of developing chronic HF. Group 3 had excellent survival at postligation 48 h (91%) and a 100% success in the development of chronic ischemic HF. The TLD approach, which limits full LAD and collateral flow to its perfusion bed, provides excellent early survival and reliable development of chronic ischemic HF in canine hearts.NEW & NOTEWORTHY The novel total left anterior descending devascularization (TLD) approach in a canine ischemic heart failure model limits collateral flow in the ischemic zone and provides excellent early survival and repeatable development of chronic ischemic heart failure in the canine heart. This work provides a consistent large animal model for investigating heart failure mechanisms and testing novel therapeutics.

Molecular Mechanisms Underlying Pluripotency and Self-Renewal of Embryonic Stem Cells

Embryonic stem cells (ESCs) are derived from the inner cell mass (ICM) of the blastocyst. ESCs have two distinctive properties: ability to proliferate indefinitely, a feature referred as "self-renewal", and to differentiate into different cell types, a peculiar characteristic known as "pluripotency". Self-renewal and pluripotency of ESCs are finely orchestrated by precise external and internal networks including epigenetic modifications, transcription factors, signaling pathways, and histone modifications. In this systematic review, we examine the main molecular mechanisms that sustain self-renewal and pluripotency in both murine and human ESCs. Moreover, we discuss the latest literature on human naïve pluripotency.

Regulation of Embryonic Stem Cell Self-Renewal

Embryonic stem cells (ESCs) are a type of cells capable of self-renewal and multi-directional differentiation. The self-renewal of ESCs is regulated by factors including signaling pathway proteins, transcription factors, epigenetic regulators, cytokines, and small molecular compounds. Similarly, non-coding RNAs, small RNAs, and microRNAs (miRNAs) also play an important role in the process. Functionally, the core transcription factors interact with helper transcription factors to activate the expression of genes that contribute to maintaining pluripotency, while suppressing the expression of differentiation-related genes. Additionally, cytokines such as leukemia suppressor factor (LIF) stimulate downstream signaling pathways and promote self-renewal of ESCs. Particularly, LIF binds to its receptor (LIFR/gp130) to trigger the downstream Jak-Stat3 signaling pathway. BMP4 activates the downstream pathway and acts in combination with Jak-Stat3 to promote pluripotency of ESCs in the absence of serum. In addition, activation of the Wnt-FDZ signaling pathway has been observed to facilitate the self-renewal of ESCs. Small molecule modulator proteins of the pathway mentioned above are widely used in in vitro culture of stem cells. Multiple epigenetic regulators are involved in the maintenance of ESCs self-renewal, making the epigenetic status of ESCs a crucial factor in this process. Similarly, non-coding RNAs and cellular energetics have been described to promote the maintenance of the ESC's self-renewal. These factors regulate the self-renewal and differentiation of ESCs by forming signaling networks. This review focused on the role of major transcription factors, signaling pathways, small molecular compounds, epigenetic regulators, non-coding RNAs, and cellular energetics in ESC's self-renewal.

Dichotomous role of Shp2 for naïve and primed pluripotency maintenance in embryonic stem cells

Background

The requirement of the Mek1 inhibitor (iMek1) during naïve pluripotency maintenance results from the activation of the Mek1-Erk1/2 (Mek/Erk) signaling pathway upon leukemia inhibitory factor (LIF) stimulation.

Methods

Through a meta-analysis of previous genome-wide screening for negative regulators of naïve pluripotency, Ptpn11 (encoding the Shp2 protein, which serves both as a tyrosine phosphatase and putative adapter), was predicted as one of the key factors for the negative modulation of naïve pluripotency through LIF-dependent Jak/Stat3 signaling. Using an isogenic pair of naïve and primed mouse embryonic stem cells (mESCs), we demonstrated the differential role of Shp2 in naïve and primed pluripotency.

Results

Loss of Shp2 increased naïve pluripotency by promoting Jak/Stat3 signaling and disturbed in vivo differentiation potential. In sharp contrast, Shp2 depletion significantly impeded the self-renewal of ESCs under primed culture conditions, which was concurrent with a reduction in Mek/Erk signaling. Similarly, upon treatment with an allosteric Shp2 inhibitor (iShp2), the cells sustained Stat3 phosphorylation and decoupled Mek/Erk signaling, thus iShp2 can replace the use of iMek1 for maintenance of naïve ESCs.

Conclusions

Taken together, our findings highlight the differential roles of Shp2 in naïve and primed pluripotency and propose the usage of iShp2 instead of iMek1 for the efficient maintenance and establishment of naïve pluripotency.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-02976-z.

Soft substrate maintains stemness and pluripotent stem cell-like phenotype of human embryonic stem cells under defined culture conditions

Human embryonic stem cells (hESCs) are derived from the inner cell mass (ICM) of the pre-implantation blastocyst. Prior to embryo implantation, the ICM cells are surrounded by trophoblasts which have mechanical stiffness ranging from Pascal (Pa) to kilopascal (kPa). However, under in vitro conditions these cells are cultured on stiff tissue culture treated plastic plates (TCP) which have stiffness of approximately 1 gigapascal (GPa). This obvious dichotomy motivated us to investigate the fate of hESCs cultured on softer substrate, and to probe if the hESCs undergo differentiation or they retain pluripotency on soft substrates. We investigated the expression of pluripotency markers, and lineage-specific markers; we particularly looked at the expression of transcriptional coactivator YAP (Yes-associated protein), an important mediator of extracellular matrix (ECM) mechanical cues and a known downstream transducer of Hippo pathway. Downregulation of YAP has been correlated to the loss of multipotency of human mesenchymal stem cells (hMSCs) and pluripotency in mouse ESCs (mESCs); but we report that hESCs maintain their stemness on soft substrate of varying stiffness. Our findings revealed that on soft substrate hESCs express pluripotency markers and does not undergo substrate-mediated differentiation. Interestingly we show that hESCs maintained basal level of YAP expression for cell survival and proliferation, but YAP expression does not correlate directly with pluripotency in hESCs. To summarize, our results show that hESCs retain their stemness on soft substrate despite downregulation of YAP.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10616-022-00537-z.

An Improved Monkey Model of Myocardial Ischemic Infarction for Cardiovascular Drug Development

Non-human primate monkey model of myocardial ischemic infarction is precious for translational medicine research. Ligation of the left anterior descending (LAD) artery is a common procedure to induce myocardial ischemic infarction. However, the consistency of the myocardial infarction thus generated remains problematic. The present study was undertaken to critically evaluate the monkey model of myocardial ischemic infarction to develop a procedure for a consistent cross-study comparison. Forty male Rhesus monkeys were divided into 4 groups and subjected to LAD artery ligation at different levels along the artery. In addition, the major diagonal branch was selectively ligated parallel to the ligation site of the LAD artery according to the diagonal branch distribution. Analyses of MRI, echocardiography, cardiac hemodynamics, electrocardiography, histopathology, and cardiac injury biomarkers were undertaken to characterize the monkeys with myocardial infarction. Ligation at 40% of the total length of the artery, measured from the apex end, produced variable infarct areas with inconsistent functional alterations. Ligation at 60% or above coupled with selective ligation of diagonal branches produced a consistent myocardial infarction with uniform dysfunction. However, ligation at 70% caused a lethal threat. After a thorough analysis, it is concluded that ligation at 60% of the total length coupled with selective ligation of diagonal branches, enables standardization of the location of occlusion and the subsequent ischemic area, as well as avoids the influence of the diagonal branches, are ideal to produce a consistent monkey model of myocardial ischemic infarction.

Large and Small Animal Models of Heart Failure With Reduced Ejection Fraction

Heart failure (HF) describes a heterogenous complex spectrum of pathological conditions that results in structural and functional remodeling leading to subsequent impairment of cardiac function, including either systolic dysfunction, diastolic dysfunction, or both. Several factors chronically lead to HF, including cardiac volume and pressure overload that may result from hypertension, valvular lesions, acute, or chronic ischemic injuries. Major forms of HF include hypertrophic, dilated, and restrictive cardiomyopathy. The severity of cardiomyopathy can be impacted by other comorbidities such as diabetes or obesity and external stress factors. Age is another major contributor, and the number of patients with HF is rising worldwide in part due to an increase in the aged population. HF can occur with reduced ejection fraction (HF with reduced ejection fraction), that is, the overall cardiac function is compromised, and typically the left ventricular ejection fraction is lower than 40%. In some cases of HF, the ejection fraction is preserved (HF with preserved ejection fraction). Animal models play a critical role in facilitating the understanding of molecular mechanisms of how hearts fail. This review aims to summarize and describe the strengths, limitations, and outcomes of both small and large animal models of HF with reduced ejection fraction that are currently used in basic and translational research. The driving defect is a failure of the heart to adequately supply the tissues with blood due to impaired filling or pumping. An accurate model of HF with reduced ejection fraction would encompass the symptoms (fatigue, dyspnea, exercise intolerance, and edema) along with the pathology (collagen fibrosis, ventricular hypertrophy) and ultimately exhibit a decrease in cardiac output. Although countless experimental studies have been published, no model completely recapitulates the full human disease. Therefore, it is critical to evaluate the strength and weakness of each animal model to allow better selection of what animal models to use to address the scientific question proposed.

Feeding role of mouse embryonic fibroblast cells is influenced by genetic background, cell passage and day of isolation

Mouse embryonic fibroblast (MEF) cells are commonly used as feeder cells to maintain the pluripotent state of stem cells. MEFs produce growth factors and provide adhesion molecules and extracellular matrix (ECM) compounds for cellular binding. In the present study, we compared the expression levels of Fgf2, Bmp4, ActivinA, Lif and Tgfb1 genes at the mRNA level and the level of Fgf2 protein secretion and Lif cytokine secretion at passages one, three and five of MEFs isolated from 13.5-day-old and 15.5-day-old embryos of NMRI and C57BL/6 mice using real-time PCR and enzyme-linked immunosorbent assay. We observed differences in the expression levels of the studied genes and secretion of the two growth factors in the three passages of MEFs isolated from 13.5-day-old and 15.5-day-old embryos, respectively. These differences were also observed between the NMRI and C57BL/6 strains. The results of this study suggested that researchers should use mice embryos that have different genetic backgrounds and ages, in addition to different MEF passages, when producing MEFs based on the application and type of their study.

Free-breathing gradient recalled echo-based CMR in a swine heart failure model

In swine models, there are well-established protocols for creating a closed-chest myocardial infarction (MI) as well as protocols for characterization of cardiac function with cardiac magnetic resonance (CMR). This methods manuscript outlines a novel technique in CMR data acquisition utilizing smart-signal gradient recalled echo (GRE)-based array sequences in a free-breathing swine heart failure model allowing for both high spatial and temporal resolution imaging. Nine male Yucatan mini swine weighing 48.7 ± 1.6 kg at 58.2 ± 3.1 weeks old underwent the outlined imaging protocol before and 1-month after undergoing closed chest left anterior descending coronary artery (LAD) occlusion/reperfusion. The left ventricular ejection fraction (LVEF) at baseline was 59.3 ± 2.4% and decreased to 48.1 ± 3.7% 1-month post MI (P = 0.029). The average end-diastolic volume (EDV) at baseline was 55.2 ± 1.7 ml and increased to 74.2 ± 4.2 ml at 1-month post MI (P = 0.001). The resulting images from this novel technique and post-imaging analysis are presented and discussed. In a Yucatan swine model of heart failure via closed chest left anterior descending coronary artery (LAD) occlusion/reperfusion, we found that CMR with GRE-based array sequences produced clinical-grade images with high spatial and temporal resolution in the free-breathing setting.

A practical guide to setting up pig models for cardiovascular catheterization, electrophysiological assessment and heart disease research

Over the past years, the use of large animals has become increasingly interesting in translational research, to bridge the gap between basic research in rodents and targeted therapies in humans. Pigs are highly valued in cardiovascular research because of their anatomical, hemodynamic and electrophysiological features, which closely resemble those of humans. For studying these aspects in swine, cardiac catheterization techniques are essential procedures. Although cardiac catheterization seems to be comparatively easy in pigs as human equipment can be used to perform the procedure, there are some pitfalls. Here we provide a detailed protocol to guide the reader through different aspects of cardiac catheterization in pigs. We suggest an approach for safe intubation and extubation, provide tips for perioperative and postoperative management of the animals and guide the reader through different experimental steps, including sheath insertion. We also describe the procedures for basic electrophysiological assessment of conduction properties and atrial fibrillation induction, hemodynamic assessment via pressure-volume loops, right heart and left heart catheterization and the development of a myocardial infarction model by balloon occlusion. This protocol was developed in Landrace pigs and can be adapted to other pig breeds or other large animal species. This protocol requires approximately six and a half working hours in total and should be performed by researchers with previous experience in large animal experimentation and in the presence of a veterinarian.

Nucleus-cytoskeleton communication impacts on OCT4-chromatin interactions in embryonic stem cells

BACKGROUND

The cytoskeleton is a key component of the system responsible for transmitting mechanical cues from the cellular environment to the nucleus, where they trigger downstream responses. This communication is particularly relevant in embryonic stem (ES) cells since forces can regulate cell fate and guide developmental processes. However, little is known regarding cytoskeleton organization in ES cells, and thus, relevant aspects of nuclear-cytoskeletal interactions remain elusive.

RESULTS

We explored the three-dimensional distribution of the cytoskeleton in live ES cells and show that these filaments affect the shape of the nucleus. Next, we evaluated if cytoskeletal components indirectly modulate the binding of the pluripotency transcription factor OCT4 to chromatin targets. We show that actin depolymerization triggers OCT4 binding to chromatin sites whereas vimentin disruption produces the opposite effect. In contrast to actin, vimentin contributes to the preservation of OCT4-chromatin interactions and, consequently, may have a pro-stemness role.

CONCLUSIONS

Our results suggest roles of components of the cytoskeleton in shaping the nucleus of ES cells, influencing the interactions of the transcription factor OCT4 with the chromatin and potentially affecting pluripotency and cell fate.

MUC1-C Contributes to the Maintenance of Human Embryonic Stem Cells and Promotes Somatic Cell Reprogramming

Mucin 1 (MUC1) is a transmembrane glycoprotein overexpressed in several cancer cells in which it regulates cell surface properties, tumor invasion, and cell death. Recently, we reported that MUC1-C, the C-terminal subunit of MUC1, is involved in the growth of mouse embryonic stem (ES) cells. However, the functional significance of MUC1-C in human ES cells remains unclear. In this study, we investigated the expression and function of MUC1-C in human ES cells. Based on reverse transcription-polymerase chain reaction, western blotting, and confocal microscopy following immunostaining, undifferentiated human ES cells expressed MUC1-C and the expression level decreased during differentiation. Inhibition of MUC1-C, by the peptide inhibitor GO201 that targets the cytoplasmic domain of MUC1-C (MUC1-CD), reduced cell proliferation and OCT4 protein expression, and promoted cell death. Moreover, the inhibition of MUC1-C increased the intracellular reactive oxygen species (ROS) levels and downregulated expression of glycolysis-related enzymes. These findings indicate that expression and function of MUC1-C are required for stem cell properties involved in cell proliferation, maintenance of pluripotency and optimal ROS levels, and a high glycolytic flux in human ES cells. In addition, forced overexpression of MUC1-CD increased the efficiency of reprogramming from fibroblast cells to induced pluripotent stem cells, suggesting that MUC1-C expression can contribute to the reprogramming process.

The Presence or Absence of Alkaline Phosphatase Activity to Discriminate Pluripotency Characteristics in Porcine Epiblast Stem Cell-Like Cells

Porcine embryonic stem cells (pESCs) would provide potentials for agricultural- and biotechnological-related applications. However, authentic pESCs have not been established yet because standards for porcine stem cell-specific markers and culture conditions are not clear. Therefore, the present study reports attempts to derive pluripotent epiblast stem cells either from in vitro or in vivo derived porcine embryos. Nine epiblast cell lines (seven lines from Berkshire and two lines from Duroc) could only be isolated from day 9- to 9.5-old in vivo derived early conceptuses. Pluripotency features were analyzed in relation to the presence or absence of alkaline phosphatase (AP) activity. Interestingly, the mRNA expression of several marker genes for pluripotency or epiblast was different between putative epiblast stem cells of the two groups [AP-positive (+) pEpiSC-like cell 2 line and AP-negative (-) pEpiSC-like cell 8 line]. For example, expressions of OCT-3/4, NANOG, SOX2, c-MYC, FGF2, and NODAL in AP-negative (-) porcine epiblast stem cell (pEpiSC)-like cells were higher than those in AP-positive (+) pEpiSC-like cells. Expression of surface markers differed between the two groups to some extent. SSEA-1 was strongly expressed only in AP-negative (-) pEpiSC-like cells, whereas AP-positive (+) pEpiSC-like cells did not express. In addition, we report to have some differences in the in vitro differentiation capacity between AP-positive (+) and AP-negative (-) epiblast cell lines. Primary embryonic germ layer markers (cardiac actin, nestin, and GATA 6) and primordial germ cell markers (Dazl and Vasa) were strongly expressed in embryoid bodies (EBs) aggregated from AP-negative (-) pEpiSC-like cells, whereas EBs aggregated from AP-positive (+) pEpiSCs did not show expression of primary embryonic germ layers and primordial germ cell markers except GATA 6. These results indicate that pEpiSC-like cells display different pluripotency characteristics in relation to AP activity.

Small Molecules that Promote Self-Renewal of Stem Cells and Somatic Cell Reprogramming

The ground state of embryonic stem cells (ESCs) is closely related to the development of regenerative medicine. Particularly, long-term culture of ESCs in vitro, maintenance of their undifferentiated state, self-renewal and multi-directional differentiation ability is the premise of ESCs mechanism and application research. Induced pluripotent stem cells (iPSC) reprogrammed from mouse embryonic fibroblasts (MEF) cells into cells with most of the ESC characteristics show promise towards solving ethical problems currently facing stem cell research. However, integration into chromosomal DNA through viral-mediated genes may activate proto oncogenes and lead to risk of cancer of iPSC. At the same time, iPS induction efficiency needs to be further improved to reduce the use of transcription factors. In this review, we discuss small molecules that promote self-renewal and reprogramming, including growth factor receptor inhibitors, GSK-3β and histone deacetylase inhibitors, metabolic regulators, pathway modulators as well as EMT/MET regulation inhibitors to enhance maintenance of ESCs and enable reprogramming. Additionally, we summarize the mechanism of action of small molecules on ESC self-renewal and iPSC reprogramming. Finally, we will report on the progress in identification of novel and potentially effective agents as well as selected strategies that show promise in regenerative medicine. On this basis, development of more small molecule combinations and efficient induction of chemically induced pluripotent stem cell (CiPSC) is vital for stem cell therapy. This will significantly improve research in pathogenesis, individualized drug screening, stem cell transplantation, tissue engineering and many other aspects.

Regulation of endothelial cell differentiation in embryonic vascular development and its therapeutic potential in cardiovascular diseases

During vertebrate development, the cardiovascular system begins operating earlier than any other organ in the embryo. Endothelial cell (EC) forms the inner lining of blood vessels, and its extensive proliferation and migration are requisite for vasculogenesis and angiogenesis. Many aspects of cellular biology are involved in vasculogenesis and angiogenesis, including the tip versus stalk cell specification. Recently, epigenetics has attracted growing attention in regulating embryonic vascular development and controlling EC differentiation. Some proteins that regulate chromatin structure have been shown to be directly implicated in human cardiovascular diseases. Additionally, the roles of important EC signaling such as vascular endothelial growth factor and its receptors, angiopoietin-1 and tyrosine kinase containing immunoglobulin and epidermal growth factor homology domain-2, and transforming growth factor-β in EC differentiation during embryonic vasculature development are briefly discussed in this review. Recently, the transplantation of human induced pluripotent stem cell (iPSC)-ECs are promising approaches for the treatment of ischemic cardiovascular disease including myocardial infarction. Patient-specific iPSC-derived EC is a potential new target to study differences in gene expression or response to drugs. However, clinical application of the iPSC-ECs in regenerative medicine is often limited by the challenges of maintaining cell viability and function. Therefore, novel insights into the molecular mechanisms underlying EC differentiation might provide a better understanding of embryonic vascular development and bring out more effective EC-based therapeutic strategies for cardiovascular diseases.

Cell Surface Glycoprotein CD24 Marks Bone Marrow-Derived Human Mesenchymal Stem/Stromal Cells with Reduced Proliferative and Differentiation Capacity In Vitro

Bone marrow-derived mesenchymal stem/stromal cells (BMSCs) are fundamental to bone regenerative therapies, tissue engineering, and postmenopausal osteoporosis. Donor variation among patients, cell heterogeneity, and unpredictable capacity for differentiation reduce effectiveness of BMSCs for regenerative cell therapies. The cell surface glycoprotein CD24 exhibits the most prominent differential expression during osteogenic versus adipogenic differentiation of human BMSCs. Therefore, CD24 may represent a selective biomarker for subpopulations of BMSCs with increased osteoblastic potential. In undifferentiated human BMSCs, CD24 cell surface expression is variable among donors (range: 2%-10%) and increased by two to fourfold upon osteogenic differentiation. Strikingly, FACS sorted CD24^pos cells exhibit delayed mineralization and reduced capacity for adipocyte differentiation. RNAseq analysis of CD24^pos and CD24^neg BMSCs identified a limited number of genes with increased expression in CD24^pos cells that are associated with cell adhesion, motility, and extracellular matrix. Downregulated genes are associated with cell cycle regulation, and biological assays revealed that CD24^pos cells have reduced proliferation. Hence, expression of the cell surface glycoprotein CD24 identifies a subpopulation of human BMSCs with reduced capacity for proliferation and extracellular matrix mineralization. Functional specialization among BMSCs populations may support their regenerative potential and therapeutic success by accommodating cell activities that promote skeletal tissue formation, homeostasis, and repair.

In Vitro Methods to Model Cardiac Mechanobiology in Health and Disease

In vitro cardiac modeling has taken great strides in the past decade. While most cell and engineered tissue models have focused on cell and tissue contractile function as readouts, mechanobiological cues from the cell environment that affect this function, such as matrix stiffness or organization, are less well explored. In this study, we review two-dimensional (2D) and three-dimensional (3D) models of cardiac function that allow for systematic manipulation or precise control of mechanobiological cues under simulated (patho)physiological conditions while acquiring multiple readouts of cell and tissue function. We summarize the cell types used in these models and highlight the importance of linking 2D and 3D models to address the multiscale organization and mechanical behavior. Finally, we provide directions on how to advance in vitro modeling for cardiac mechanobiology using next generation hydrogels that mimic mechanical and structural environmental features at different length scales and diseased cell types, along with the development of new tissue fabrication and readout techniques. Impact statement Understanding the impact of mechanobiology in cardiac (patho)physiology is essential for developing effective tissue regeneration and drug discovery strategies and requires detailed cause-effect studies. The development of three-dimensional in vitro models allows for such studies with high experimental control, while integrating knowledge from complementary cell culture models and in vivo studies for this purpose. Complemented by the use of human-induced pluripotent stem cells, with or without predisposed genetic diseases, these in vitro models will offer promising outlooks to delineate the impact of mechanobiological cues on human cardiac (patho)physiology in a dish.

[The influence of harvesting and processing on the regenerative potential in fat grafting]

The autologous lipotransfer represents an established method in the field of Plastic Surgery. As a reliable and safe method for breast reconstruction and breast augmentation it offers an alternative to established methods such as implants and flap surgery.Survival rate of adipose derived stromal cells limits success or failure of fat grafting. Slight changes in the fat grafting process can lead to huge changes in ADSC-survival rate.This review wants to optimize the fat-grafting process to ensure best outcomes.

Stabilization of heterochromatin by CLOCK promotes stem cell rejuvenation and cartilage regeneration

Accumulating evidence indicates an association between the circadian clock and the aging process. However, it remains elusive whether the deregulation of circadian clock proteins underlies stem cell aging and whether they are targetable for the alleviation of aging-associated syndromes. Here, we identified a transcription factor-independent role of CLOCK, a core component of the molecular circadian clock machinery, in counteracting human mesenchymal stem cell (hMSC) decay. CLOCK expression was decreased during hMSC aging. In addition, CLOCK deficiency accelerated hMSC senescence, whereas the overexpression of CLOCK, even as a transcriptionally inactive form, rejuvenated physiologically and pathologically aged hMSCs. Mechanistic studies revealed that CLOCK formed complexes with nuclear lamina proteins and KAP1, thus maintaining heterochromatin architecture and stabilizing repetitive genomic sequences. Finally, gene therapy with lentiviral vectors encoding CLOCK promoted cartilage regeneration and attenuated age-related articular degeneration in mice. These findings demonstrate a noncanonical role of CLOCK in stabilizing heterochromatin, promoting tissue regeneration, and mitigating aging-associated chronic diseases.

The Secret Life of lncRNAs: Conserved, yet Not Conserved

Guo and colleagues discover a new layer of complexity to the lncRNA evolution where positionally conserved lncRNAs in human ESCs are broadly spliced and exported to the cytoplasm contrary to their mouse counterpart that are predominantly unspliced and nuclear retained. Distinct processing leads to species-specific lncRNA function in pluripotency maintenance.

Differentiation Induction of Human Stem Cells for Corneal Epithelial Regeneration

Deficiency of corneal epithelium causes vision impairment or blindness in severe cases. Transplantation of corneal epithelial cells is an effective treatment but the availability of the tissue source for those cells is inadequate. Stem cells can be induced to differentiate to corneal epithelial cells and used in the treatment. Multipotent stem cells (mesenchymal stem cells) and pluripotent stem cells (embryonic stem cells and induced pluripotent stem cells) are promising cells to address the problem. Various protocols have been developed to induce differentiation of the stem cells into corneal epithelial cells. The feasibility and efficacy of both human stem cells and animal stem cells have been investigated for corneal epithelium regeneration. However, some physiological aspects of animal stem cells are different from those of human stem cells, the protocols suited for animal stem cells might not be suitable for human stem cells. Therefore, in this review, only the investigations of corneal epithelial differentiation of human stem cells are taken into account. The available protocols for inducing the differentiation of human stem cells into corneal epithelial cells are gathered and compared. Also, the pathways involving in the differentiation are provided to elucidate the relevant mechanisms.

Cardiac and lung endothelial cells in response to fluid shear stress on physiological matrix stiffness and composition

OBJECTIVE

Preconditioning of endothelial cells from different vascular beds has potential value for re-endothelialization and implantation of engineered tissues. Understanding how substrate stiffness and composition affects tissue-specific cell response to shear stress will aid in successful endothelialization of engineered tissues. We developed a platform to test biomechanical and biochemical stimuli.

METHODS

A novel polydimethylsiloxane-based parallel plate flow chamber enabled application of laminar fluid shear stress of 2 dynes/cm² for 12 hours to microvascular cardiac and lung endothelial cells cultured on cardiac and lung-derived extracellular matrix. Optical imaging of cells was used to quantify cell changes in cell alignment. Analysis of integrin expression was performed using flow cytometry.

RESULTS

Application of fluid shear stress caused the greatest cell alignment in cardiac endothelial cells seeded on polystyrene and lung endothelial cells on polydimethylsiloxane. This resulted in elongation of the lung endothelial cells. α_v and β₃ integrin expression decreased after application of shear stress in both cell types.

CONCLUSION

Substrate stiffness plays an important role in regulating tissue-specific endothelial response to shear stress, which may be due to differences in their native microenvironments. Furthermore, cardiac and lung endothelial cell response to shear stress was significantly regulated by the type of coating used.

New Insights and Current Approaches in Cardiac Hypertrophy Cell Culture, Tissue Engineering Models, and Novel Pathways Involving Non-Coding RNA

Cardiac hypertrophy is an ongoing clinical challenge, as risk factors such as obesity, smoking and increasing age become more widespread, which lead to an increasing prevalence of developing hypertrophy. Pathological hypertrophy is a maladaptive response to stress conditions, such as pressure overload, and involve a number of changes in cellular mechanisms, gene expression and pathway regulations. Although several important pathways involved in the remodeling and hypertrophy process have been identified, further research is needed to achieve a better understanding and explore new and better treatment options. More recently discovered pathways showed the involvement of several non-coding RNAs, including micro RNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs), which either promote or inhibit the remodeling process and pose a possible target for novel therapy approaches. In vitro modeling serves as a vital tool for this further pathway analysis and treatment testing and has vastly improved over the recent years, providing a less costly and labor-intensive alternative to in vivo animal models.

Mesenchymal Stem Cells in Cardiac Repair: Effects on Myocytes, Vasculature, and Fibroblasts

PURPOSE

Cardiac pathologies remain a dominant cause of morbidity and mortality within the community. The drive to develop therapies capable of repairing damaged heart tissue to achieve clinically significant restoration of function has motivated the pursuit of novel approaches such as cell therapy. To this end, evidence of therapeutic benefits achieved by using mesenchymal stem cells (MSCs) has captured considerable interest despite a relative lack of information regarding the mechanisms involved. This narrative review synthesizes and interprets the current literature describing mechanisms by which MSCs can elicit cardiac repair, thereby directing attention to avenues of further inquiry.

METHODS

OVID versions of MEDLINE and EMBASE were searched for studies describing the role of MSCs in mammalian cardiac repair. Additional studies were sourced from the reference lists of relevant articles and other personal files.

FINDINGS

MSCs elicit cardiac repair in a range of in vitro systems and animal models of diseases such as myocardial infarction and heart failure. Important mechanisms include the preservation of myocardial contractility, the promotion of angiogenesis, and the modulation of fibrosis. Exposing in vitro MSCs to a microenvironment reflective of that encountered in the injured heart seems to potentiate these therapeutic mechanisms.

IMPLICATIONS

Promising results in animal studies warrant continuation of clinical MSC cardiac therapy studies. Paracrine functions of MSCs seem to be the dominant mechanism of cardiac repair over direct cellular effects. Although integral, the MSC secretome remains poorly defined. In addition, most of the mechanistic data within the literature have been derived from animal MSC research, necessitating more human MSC-based work.

Expression of Calcification and Extracellular Matrix Genes in the Cardiovascular System of the Healthy Domestic Sheep (Ovis aries)

The maintenance of a healthy cardiovascular system requires expression of genes that contribute to essential biological activities and repression of those that are associated with functions likely to be detrimental to cardiovascular homeostasis. Vascular calcification is a major disruption to cardiovascular homeostasis, where tissues of the cardiovascular system undergo ectopic calcification and consequent dysfunction, but little is known about the expression of calcification genes in the healthy cardiovascular system. Large animal models are of increasing importance in cardiovascular disease research as they demonstrate more similar cardiovascular features (in terms of anatomy, physiology and size) to humans than do rodent species. We used RNA sequencing results from the sheep, which has been utilized extensively to examine calcification of prosthetic cardiac valves, to explore the transcriptome of the heart and cardiac valves in this large animal, in particular looking at expression of calcification and extracellular matrix genes. We then examined genes implicated in the process of vascular calcification in a wide array of cardiovascular tissues and across multiple developmental stages, using RT-qPCR. Our results demonstrate that there is a balance between genes that promote and those that suppress mineralization during development and across cardiovascular tissues. We show extensive expression of genes encoding proteins involved in formation and maintenance of the extracellular matrix in cardiovascular tissues, and high expression of hematopoietic genes in the cardiac valves. Our analysis will support future research into the functions of implicated genes in the development of valve calcification, and increase the utility of the sheep as a large animal model for understanding ectopic calcification in cardiovascular disease. This study provides a foundation to explore the transcriptome of the developing cardiovascular system and is a valuable resource for the fields of mammalian genomics and cardiovascular research.

Cis and trans effects differentially contribute to the evolution of promoters and enhancers

BACKGROUND

Gene expression differences between species are driven by both cis and trans effects. Whereas cis effects are caused by genetic variants located on the same DNA molecule as the target gene, trans effects are due to genetic variants that affect diffusible elements. Previous studies have mostly assessed the impact of cis and trans effects at the gene level. However, how cis and trans effects differentially impact regulatory elements such as enhancers and promoters remains poorly understood. Here, we use massively parallel reporter assays to directly measure the transcriptional outputs of thousands of individual regulatory elements in embryonic stem cells and measure cis and trans effects between human and mouse.

RESULTS

Our approach reveals that cis effects are widespread across transcribed regulatory elements, and the strongest cis effects are associated with the disruption of motifs recognized by strong transcriptional activators. Conversely, we find that trans effects are rare but stronger in enhancers than promoters and are associated with a subset of transcription factors that are differentially expressed between human and mouse. While we find that cis-trans compensation is common within promoters, we do not see evidence of widespread cis-trans compensation at enhancers. Cis-trans compensation is inversely correlated with enhancer redundancy, suggesting that such compensation may often occur across multiple enhancers.

CONCLUSIONS

Our results highlight differences in the mode of evolution between promoters and enhancers in complex mammalian genomes and indicate that studying the evolution of individual regulatory elements is pivotal to understand the tempo and mode of gene expression evolution.

Robust Fabrication of Composite 3D Scaffolds with Tissue-Specific Bioactivity: A Proof-of-Concept Study

The basic requirement of any engineered scaffold is to mimic the native tissue extracellular matrix (ECM). Despite substantial strides in understanding the ECM, scaffold fabrication processes of sufficient product robustness and bioactivity require further investigation, owing to the complexity of the natural ECM. A promising bioacive platform for cardiac tissue engineering is that of decellularized porcine cardiac ECM (pcECM, used here as a soft tissue representative model). However, this platform's complexity and batch-to-batch variability serve as processing limitations in attaining a robust and tunable cardiac tissue-specific bioactive scaffold. To address these issues, we fabricated 3D composite scaffolds (3DCSs) that demonstrate comparable physical and biochemical properties to the natural pcECM using wet electrospinning and functionalization with a pcECM hydrogel. The fabricated 3DCSs are non-immunogenic in vitro and support human mesenchymal stem cells' proliferation. Most importantly, the 3DCSs demonstrate tissue-specific bioactivity in inducing spontaneous cardiac lineage differentiation in human induced pluripotent stem cells (hiPSC) and further support the viability, functionality, and maturation of hiPSC-derived cardiomyocytes. Overall, this work illustrates the technology to fabricate robust yet tunable 3D scaffolds of tissue-specific bioactivity (with a proof of concept provided for cardiac tissues) as a platform for basic materials science studies and possible future R&D application in regenerative medicine.

Links between Nutrition, Infectious Diseases, and Microbiota: Emerging Technologies and Opportunities for Human-Focused Research

The interaction between nutrition and human infectious diseases has always been recognized. With the emergence of molecular tools and post-genomics, high-resolution sequencing technologies, the gut microbiota has been emerging as a key moderator in the complex interplay between nutrients, human body, and infections. Much of the host-microbial and nutrition research is currently based on animals or simplistic in vitro models. Although traditional in vivo and in vitro models have helped to develop mechanistic hypotheses and assess the causality of the host-microbiota interactions, they often fail to faithfully recapitulate the complexity of the human nutrient-microbiome axis in gastrointestinal homeostasis and infections. Over the last decade, remarkable progress in tissue engineering, stem cell biology, microfluidics, sequencing technologies, and computing power has taken place, which has produced a new generation of human-focused, relevant, and predictive tools. These tools, which include patient-derived organoids, organs-on-a-chip, computational analyses, and models, together with multi-omics readouts, represent novel and exciting equipment to advance the research into microbiota, infectious diseases, and nutrition from a human-biology-based perspective. After considering some limitations of the conventional in vivo and in vitro approaches, in this review, we present the main novel available and emerging tools that are suitable for designing human-oriented research.

Identification of human temporomandibular joint fibrocartilage stem cells with distinct chondrogenic capacity

OBJECTIVE

This study was aimed to identify the residence of human fibrocartilage stem cells (hFCSCs), characterize their stem cell properties and investigate the functional mechanisms which regulate fibrocartilage stem cells (FCSCs) toward chondrogenic differentiation during cartilage homeostasis and repairing.

METHODS

Cytological characteristics of hFCSCs and human orofacial mesenchymal stem cells (hOFMSCs) were analyzed. Chondrogenic potential of hFCSCs was compared with hOFMSCs both in vitro and in vivo. Regulatory role of SOX9 during FCSCs chondrogenesis was studied by shRNA interference in vitro, and by GFP⁺ FCSCs treatment in rat condylar cartilage defect model. SOX9 expression was also examined in temporomandibular joint osteoarthritis (TMJOA) patients' cartilage surface.

RESULTS

hFCSCs exhibited typical mesenchymal stem cell characteristics, with significantly stronger chondrogenic capability compared to hOFMSCs. Moreover, hFCSCs showed remarkably increased expression of SOX9. During cartilage pellet culture, there was stronger SOX9 expression in hFCSCs than hOFMSCs. SOX9 shRNA interference downregulated chondrogenic capability of hFCSCs in vitro, as well as disrupting migration and chondrogenic differentiation of GFP⁺ FCSCs toward mature chondrocytes in rat condylar cartilage defect. Of note, SOX9 expression was also found suppressed in the condylar superficial zone of TMJOA patients.

CONCLUSION

We found the existence of FCSCs in human TMJ cartilage, and characterized their distinct stem cell features. SOX9 is essential for hFCSCs chondrogenic differentiation, and a comprehensive understanding of the regulatory role of SOX9 in hFCSCs would be important for exploring potential intervention strategy of condylar cartilage degradation during TMJ disorders.

An engineered three-dimensional stem cell niche in the inner ear by applying a nanofibrillar cellulose hydrogel with a sustained-release neurotrophic factor delivery system

Although the application of human embryonic stem cells (hESCs) in stem cell-replacement therapy remains promising, its potential is hindered by a low cell survival rate in post-transplantation within the inner ear. Here, we aim to enhance the in vitro and in vivo survival rate and neuronal differentiation of otic neuronal progenitors (ONPs) by generating an artificial stem cell niche consisting of three-dimensional (3D) hESC-derived ONP spheroids with a nanofibrillar cellulose hydrogel and a sustained-release brain-derivative neurotrophic factor delivery system. Our results demonstrated that the transplanted hESC-derived ONP spheroids survived and neuronally differentiated into otic neuronal lineages in vitro and in vivo and also extended neurites toward the bony wall of the cochlea 90 days after the transplantation without the use of immunosuppressant medication. Our data in vitro and in vivo presented here provide sufficient evidence that we have established a robust, reproducible protocol for in vivo transplantation of hESC-derived ONPs to the inner ear. Using our protocol to create an artificial stem cell niche in the inner ear, it is now possible to work on integrating transplanted hESC-derived ONPs further and also to work toward achieving functional auditory neurons generated from hESCs. Our findings suggest that the provision of an artificial stem cell niche can be a future approach to stem cell-replacement therapy for inner-ear regeneration. STATEMENT OF SIGNIFICANCE: Inner ear regeneration utilizing human embryonic stem cell-derived otic neuronal progenitors (hESC-derived ONPs) has remarkable potential for treating sensorineural hearing loss. However, the local environment of the inner ear requires a suitable stem cell niche to allow hESC-derived ONP engraftment as well as neuronal differentiation. To overcome this obstacle, we utilized three-dimensional spheroid formation (direct contact), nanofibrillar cellulose hydrogel (extracellular matrix), and a neurotrophic factor delivery system to artificially create a stem cell niche in vitro and in vivo. Our in vitro and in vivo data presented here provide sufficient evidence that we have established a robust, reproducible protocol for in vivo transplantation of hESC-derived ONPs to the inner ear.

SOX2, OCT4 and NANOG: The core embryonic stem cell pluripotency regulators in oral carcinogenesis

Embryonic stem cells provide their major contribution to embryogenesis through formation of germ layers as they have pluripotency potential and capacity for self-renewal. Retention of pluripotency of these stem cells depends on expression/level of transcription factors, i.e., SOX2, OCT4 and NANOG. During organogenesis, the altered expression of the molecules also influences these stem cells to lose their pluripotency and turn toward the lineage selection. As the differentiation progresses, the maintenance of the somatic cells including the oral squamous cells also depends on differential expression of the transcription factors to some extent. Recently, many experimental and observational studies documented the significant contribution in carcinogenesis of various human cancers. In this review, we have attempted to summarize the evidences indicating about the putative role of these master pluripotency regulators in various phases of oral carcinogenesis i.e. initiation , progression and prognosis of oral squamous cell carcinoma.

Decoding pluripotency: Genetic screens to interrogate the acquisition, maintenance, and exit of pluripotency

Pluripotent stem cells have the ability to unlimitedly self-renew and differentiate to any somatic cell lineage. A number of systems biology approaches have been used to define this pluripotent state. Complementary to systems level characterization, genetic screens offer a unique avenue to functionally interrogate the pluripotent state and identify the key players in pluripotency acquisition and maintenance, exit of pluripotency, and lineage differentiation. Here we review how genetic screens have helped us decode pluripotency regulation. We will summarize results from RNA interference (RNAi) based screens, discuss recent advances in CRISPR/Cas-based genetic perturbation methods, and how these advances have made it possible to more comprehensively interrogate pluripotency and differentiation through genetic screens. Such investigations will not only provide a better understanding of this unique developmental state, but may enhance our ability to use pluripotent stem cells as an experimental model to study human development and disease progression. Functional interrogation of pluripotency also provides a valuable roadmap for utilizing genetic perturbation to gain systems level understanding of additional cellular states, from later stages of development to pathological disease states. This article is categorized under: Developmental Biology > Stem Cell Biology and Regeneration Developmental Biology > Developmental Processes in Health and Disease Biological Mechanisms > Cell Fates.

Modification of stem cell states by alcohol and acetaldehyde

Ethanol (EtOH) is a recreationally ingested compound that is both teratogenic and carcinogenic in humans. Because of its abundant consumption worldwide and the vital role of stem cells in the formation of birth defects and cancers, delineating the effects of EtOH on stem cell function is currently an active and urgent pursuit of scientific investigation to explicate some of the mechanisms contributing to EtOH toxicity. Stem cells represent a primordial, undifferentiated phase of development; thus encroachment on normal physiologic processes of differentiation into terminal lineages by EtOH can greatly alter the function of progenitors and terminally differentiated cells, leading to pathological consequences that manifest as fetal alcohol spectrum disorders and cancers. In this review we explore the disruptive role of EtOH in differentiation of stem cells. Our primary objective is to elucidate the mechanisms by which EtOH alters differentiation-related gene expression and lineage specifications, thus modifying stem cells to promote pathological outcomes. We additionally review the effects of a reactive metabolite of EtOH, acetaldehyde (AcH), in causing both differentiation defects in stem cells as well as genomic damage that incites cellular aging and carcinogenesis.

Quantification of the morphological characteristics of hESC colonies

The maintenance of the undifferentiated state in human embryonic stem cells (hESCs) is critical for further application in regenerative medicine, drug testing and studies of fundamental biology. Currently, the selection of the best quality cells and colonies for propagation is typically performed by eye, in terms of the displayed morphological features, such as prominent/abundant nucleoli and a colony with a tightly packed appearance and a well-defined edge. Using image analysis and computational tools, we precisely quantify these properties using phase-contrast images of hESC colonies of different sizes (0.1–1.1 \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${{\bf{\text{mm}}}}^{{\bf{2}}}$$\end{document}mm2) during days 2, 3 and 4 after plating. Our analyses reveal noticeable differences in their structure influenced directly by the colony area \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\boldsymbol{A}}$$\end{document}A. Large colonies (A > 0.6 mm²) have cells with smaller nuclei and a short intercellular distance when compared with small colonies (A < 0.2 mm²). The gaps between the cells, which are present in small and medium sized colonies with A ≤ 0.6 mm², disappear in large colonies (A > 0.6 mm²) due to the proliferation of the cells in the bulk. This increases the colony density and the number of nearest neighbours. We also detect the self-organisation of cells in the colonies where newly divided (smallest) cells cluster together in patches, separated from larger cells at the final stages of the cell cycle. This might influence directly cell-to-cell interactions and the community effects within the colonies since the segregation induced by size differences allows the interchange of neighbours as the cells proliferate and the colony grows. Our findings are relevant to efforts to determine the quality of hESC colonies and establish colony characteristics database.

Biological process activity transformation of single cell gene expression for cross-species alignment

The maintenance and transition of cellular states are controlled by biological processes. Here we present a gene set-based transformation of single cell RNA-Seq data into biological process activities that provides a robust description of cellular states. Moreover, as these activities represent species-independent descriptors, they facilitate the alignment of single cell states across different organisms.

Single cell RNA-Seq data can report on cellular types and states, but low signal-to noise and sparse data can make interpretation of cellular state difficult. Here the authors propose a transformation strategy to map RNA-Seq data to biological process activities that are species-agnostic and allow for comparison across species.