Epigenetic signatures associated with different levels of differentiation potential in human stem cells

Stem Cell-Derived Exosomal MicroRNAs as Novel Potential Approach for Multiple Sclerosis Treatment

Multiple Sclerosis (MS) is an autoimmune disease of the central nervous system (CNS) characterized by inflammation and demyelination of CNS neurons. Up to now, there are many therapeutic strategies for MS but they are only being able to reduce progression of diseases and have not got any effect on repair and remyelination. Stem cell therapy is an appropriate method for regeneration but has limitations and problems. So recently, researches were used of exosomes that facilitate intercellular communication and transfer cell-to-cell biological information. MicroRNAs (miRNAs) are a class of short non-coding RNAs that we can used to their dysregulation in order to diseases diagnosis. The miRNAs of microvesicles obtained stem cells may change the fate of transplanted cells based on received signals of injured regions. The miRNAs existing in MSCs may be displayed the cell type and their biological activities. Current studies show also that the miRNAs create communication between stem cells and tissue-injured cells. In the present review, firstly we discuss the role of miRNAs dysregulation in MS patients and miRNAs expression by stem cells. Finally, in this study was confirmed the relationship of microRNAs involved in MS and miRNAs expressed by stem cells and interaction between them in order to find appropriate treatment methods in future for limit to disability progression.

MicroRNA-93-5p regulates odontogenic differentiation and dentin formation via KDM6B

BACKGROUND

Epigenetic factors influence the odontogenic differentiation of dental pulp stem cells and play indispensable roles during tooth development. Some microRNAs can epigenetically regulate other epigenetic factors like DNA methyltransferases and histone modification enzymes, functioning as epigenetic-microRNAs. In our previous study, microarray analysis suggested microRNA-93-5p (miR-93-5p) was differentially expressed during the bell stage in human tooth germ. Prediction tools indicated that miR-93-5p may target lysine-specific demethylase 6B (KDM6B). Therefore, we explored the role of miR-93-5p as an epi-miRNA in tooth development and further investigated the underlying mechanisms of miR-93-5p in regulating odontogenic differentiation and dentin formation.

METHODS

The expression pattern of miR-93-5p and KDM6B of dental pulp stem cells (DPSCs) was examined during tooth development and odontogenic differentiation. Dual luciferase reporter and ChIP-qPCR assay were used to validate the target and downstream regulatory genes of miR-93-5p in human DPSCs (hDPSCs). Histological analyses and qPCR assays were conducted for investigating the effects of miR-93-5p mimic and inhibitor on odontogenic differentiation of hDPSCs. A pulpotomy rat model was further established, microCT and histological analyses were performed to explore the effects of KDM6B-overexpression and miR-93-5p inhibition on the formation of tertiary dentin.

RESULTS

The expression level of miR-93-5p decreased as odontoblast differentiated, in parallel with elevated expression of histone demethylase KDM6B. In hDPSCs, miR-93-5p overexpression inhibited the odontogenic differentiation and vice versa. MiR-93-5p targeted 3' untranslated region (UTR) of KDM6B, thereby inhibiting its protein translation. Furthermore, KDM6B bound the promoter region of BMP2 to demethylate H3K27me3 marks and thus upregulated BMP2 transcription. In the rat pulpotomy model, KDM6B-overexpression or miR-93-5p inhibition suppressed H3K27me3 level in DPSCs and consequently promoted the formation of tertiary dentin.

CONCLUSIONS

MiR-93-5p targets epigenetic regulator KDM6B and regulates H3K27me3 marks on BMP2 promoters, thus modulating the odontogenic differentiation of DPSCs and dentin formation.

Wharton's jelly mesenchymal stem cells: a concise review of their secretome and prospective clinical applications

Accumulating evidence indicates that most primary Wharton's jelly mesenchymal stem cells (WJ-MSCs) therapeutic potential is due to their paracrine activity, i.e., their ability to modulate their microenvironment by releasing bioactive molecules and factors collectively known as secretome. These bioactive molecules and factors can either be released directly into the surrounding microenvironment or can be embedded within the membrane-bound extracellular bioactive nano-sized (usually 30-150 nm) messenger particles or vesicles of endosomal origin with specific route of biogenesis, known as exosomes or carried by relatively larger particles (100 nm-1 μm) formed by outward blebbing of plasma membrane called microvesicles (MVs); exosomes and MVs are collectively known as extracellular vesicles (EVs). The bioactive molecules and factors found in secretome are of various types, including cytokines, chemokines, cytoskeletal proteins, integrins, growth factors, angiogenic mediators, hormones, metabolites, and regulatory nucleic acid molecules. As expected, the secretome performs different biological functions, such as immunomodulation, tissue replenishment, cellular homeostasis, besides possessing anti-inflammatory and anti-fibrotic effects. This review highlights the current advances in research on the WJ-MSCs' secretome and its prospective clinical applications.

ALS is imprinted in the chromatin accessibility of blood cells

Amyotrophic Lateral Sclerosis (ALS) is a complex and incurable neurodegenerative disorder in which genetic and epigenetic factors contribute to the pathogenesis of all forms of ALS. The interplay of genetic predisposition and environmental footprints generates epigenetic signatures in the cells of affected tissues, which then alter transcriptional programs. Epigenetic modifications that arise from genetic predisposition and systemic environmental footprints should in theory be detectable not only in affected CNS tissue but also in the periphery. Here, we identify an ALS-associated epigenetic signature ('epiChromALS') by chromatin accessibility analysis of blood cells of ALS patients. In contrast to the blood transcriptome signature, epiChromALS includes also genes that are not expressed in blood cells; it is enriched in CNS neuronal pathways and it is present in the ALS motor cortex. By combining simultaneous ATAC-seq and RNA-seq with single-cell sequencing in PBMCs and motor cortex from ALS patients, we demonstrate that epigenetic changes associated with the neurodegenerative disease can be found in the periphery, thus strongly suggesting a mechanistic link between the epigenetic regulation and disease pathogenesis.

Circulating Histones to Detect and Monitor the Progression of Cancer

Liquid biopsies have emerged as a minimally invasive cancer detection and monitoring method, which could identify cancer-related alterations in nucleosome or histone levels and modifications in blood, saliva, and urine. Histones, the core component of the nucleosome, are essential for chromatin compaction and gene expression modulation. Increasing evidence suggests that circulating histones and histone complexes, originating from cell death or immune cell activation, could act as promising biomarkers for cancer detection and management. In this review, we provide an overview of circulating histones as a powerful liquid biopsy approach and methods for their detection. We highlight current knowledge on circulating histones in hematologic malignancies and solid cancer, with a focus on their role in cancer dissemination, monitoring, and tumorigenesis. Last, we describe recently developed strategies to identify cancer tissue-of-origin in blood plasma based on nucleosome positioning, inferred from nucleosomal DNA fragmentation footprint, which is independent of the genetic landscape.

Methionine affects the expression of pluripotency genes and protein levels associated with methionine metabolism in adult, fetal, and cancer stem cells

Intracellular and extracellular regulatory factors promote the potency and self-renewal property of stem cells. Methionine is fundamental for protein synthesis and regulation of methylation reactions. Specifically, methionine metabolism in embryonic and fetal development processes regulates gene expression profile/epigenetic identity of stem cells to achieve pluripotency and cellular functions. We aimed to reveal the differences in methionine metabolism of bone marrow (BM)-mesenchymal stem cells (MSCs), umbilical cord blood (UCB)-MSCs, and cancer stem cells (CSCs), which reflect different metabolic profiles and developmental stages of stem cells. UCB-MSC, BM-MSCs, and breast CSCs were treated with different doses (0, 10, 25, 50, and 100 µM) of l-methionine. Cell surface marker and cell cycle assessment were performed by flow cytometry. Changes in gene expressions (OCT3/4, NANOG, DMNT1, DNMT3A, and DNMT3B, MAT2A, and MAT2B) with methionine supplementation were examined by quantitative real-time polymerase chain reaction and the changes in histone methylation (H3K4me3, H3K27me3) levels were demonstrated by western blot analysis. S-adenosylmethionine//S-adenosylhomocysteine (SAM/SAH) levels were evaluated by enzyme-linked immunosorbent assay. Cells that were exposed to different concentrations of l-methionine, were mostly arrested in the G0/G1 phase for each stem cell group. It was evaluated that BM-MSCs increased all gene expressions in the culture medium-containing 100 µM methionine, in addition to SAM/SAH levels. On the other hand, UCB-MSCs were found to increase OCT3/4, NANOG, and DNMT1 gene expressions and decrease MAT2A and MAT2B expressions in the culture medium containing 10 µM methionine. Moreover, an increase was observed in the He3K4me3 methylation profile. In addition, OCT3/4, NANOG, DNMT1, and MAT2B gene expressions in CSCs increased starting from the addition of 25 µM methionine. An increase was determined in H3K4me3 protein expression at 50 and 100 µM methionine-supplemented culture condition. This study demonstrates that methionine plays a critical role in metabolism and epigenetic regulation in different stem cell groups.

Effect of initial seeding density on cell behavior-driven epigenetic memory and preferential lineage differentiation of human iPSCs

Understanding the cellular behavioral mechanisms underlying memory formation and maintenance in human induced pluripotent stem cell (hiPSC) culture provides key strategies for achieving stability and robustness of cell differentiation. Here, we show that changes in cell behavior-driven epigenetic memory of hiPSC cultures alter their pluripotent state and subsequent differentiation. Interestingly, pluripotency-associated genes were activated during the entire cell growth phases along with increased active modifications and decreased repressive modifications. This memory effect can last several days in the long-term stationary phase and was sustained in the aspect of cell behavioral changes after subculture. Further, changes in growth-related cell behavior were found to induce nucleoskeletal reorganization and active versus repressive modifications, thereby enabling hiPSCs to change their differentiation potential. Overall, we discuss the cell behavior-driven epigenetic memory induced by the culture environment, and the effect of previous memory on cell lineage specification in the process of hiPSC differentiation.

Illuminating the Regenerative Properties of Stem Cells In Vivo with Bioluminescence Imaging

Preclinical animal studies are essential to the development of safe and effective stem cell therapies. Bioluminescence imaging (BLI) is a powerful tool in animal studies that enables the real-time longitudinal monitoring of stem cells in vivo to elucidate their regenerative properties. This review describes the application of BLI in preclinical stem cell research to address critical challenges in producing successful stem cell therapeutics. These challenges include stem cell survival, proliferation, homing, stress response, and differentiation. The applications presented here utilize bioluminescence to investigate a variety of stem and progenitor cells in several different in vivo models of disease and implantation. An overview of luciferase reporters is provided, along with the advantages and disadvantages of BLI. Additionally, BLI is compared to other preclinical imaging modalities and potential future applications of this technology are discussed in emerging areas of stem cell research.

Large intestine embryogenesis: Molecular pathways and related disorders (Review)

The large intestine, part of the gastrointestinal tract (GI), is composed of all three germ layers, namely the endoderm, the mesoderm and the ectoderm, forming the epithelium, the smooth muscle layers and the enteric nervous system, respectively. Since gastrulation, these layers develop simultaneously during embryogenesis, signaling to each other continuously until adult age. Two invaginations, the anterior intestinal portal (AIP) and the caudal/posterior intestinal portal (CIP), elongate and fuse, creating the primitive gut tube, which is then patterned along the antero‑posterior (AP) axis and the radial (RAD) axis in the context of left‑right (LR) asymmetry. These events lead to the formation of three distinct regions, the foregut, midgut and hindgut. All the above‑mentioned phenomena are under strict control from various molecular pathways, which are critical for the normal intestinal development and function. Specifically, the intestinal epithelium constitutes a constantly developing tissue, deriving from the progenitor stem cells at the bottom of the intestinal crypt. Epithelial differentiation strongly depends on the crosstalk with the adjacent mesoderm. Major molecular pathways that are implicated in the embryogenesis of the large intestine include the canonical and non‑canonical wingless‑related integration site (Wnt), bone morphogenetic protein (BMP), Notch and hedgehog systems. The aberrant regulation of these pathways inevitably leads to several intestinal malformation syndromes, such as atresia, stenosis, or agangliosis. Novel theories, involving the regulation and homeostasis of intestinal stem cells, suggest an embryological basis for the pathogenesis of colorectal cancer (CRC). Thus, the present review article summarizes the diverse roles of these molecular factors in intestinal embryogenesis and related disorders.

Oriented immobilization of basic fibroblast growth factor: Bioengineered surface design for the expansion of human mesenchymal stromal cells

E. coli expressed recombinant basic fibroblast growth factor (bFGF) with histidine-tag (bFGF-His) was immobilized onto the surface of a glass plate modified with a Ni(II)-chelated alkanethiol monolayer. The immobilization is expected to take place through the coordination between Ni(II) and His-tag. The bFGF-immobilized surface was exposed to citrate buffer solution to refold in situ the surface-immobilized bFGF. The secondary structure of immobilized bFGF-His was analyzed by solid-phase circular dichroism (CD) spectroscopy. Immortalized human mesenchymal stromal cells (hMSCs) were cultured on the bFGF-His-immobilized surface to examine their proliferation. CD spectroscopy revealed that the immobilized bFGF initially exhibited secondary structure rich in α-helix and that the spectrum was gradually transformed to exhibit the formation of β-strands upon exposure to citrate buffer solution, approaching to the spectrum of native bFGF. The rate of hMSC proliferation was 1.2-fold higher on the bFGF-immobilized surface treated with in situ citrate buffer, compared to the polystyrene surface. The immobilized bFGF-His treated in situ with citrate buffer solution seemed to be biologically active because its secondary structure approached its native state. This was well demonstrated by the cell culture experiments. From these results we conclude that immobilization of bFGF on the culture substrate serves to enhance proliferation of hMSCs.

MiR-615 Regulates NSC Differentiation In Vitro and Contributes to Spinal Cord Injury Repair by Targeting LINGO-1

LINGO-1(LRR and Ig domain-containing NOGO receptor interacting protein 1) is a viable target for spinal cord injury (SCI) repair due to its potent negative regulation in neuron survival and axonal regeneration. Although promising, the intracellular mechanism underlying LINGO-1 regulation is unclear. Here, we identified miR-615 as a potential microRNA (miRNA) that directly targets LINGO-1 by binding its 3'-untranslated region (3'-UTR) and caused the translation inhibition of LINGO-1. MiR-615 negatively regulated LINGO-1 during neural stem cell (NSC) differentiation and facilitated its neuronal differentiation in vitro. Interestingly, compared to the control, neurons differentiated from miR-615-treated NSCs were immature with short processes. Further results showed LINGO-1/epidermal growth factor receptor (EGFR) signaling may be involved in this process, as blockade of EGFR using specific antagonist resulted in mature neurons with long processes. Furthermore, intrathecal administration of miR-615 agomir in SCI rats effectively knocked down LINGO-1, increased neuronal survival, enhanced axonal extension and myelination, and improved recovery of hindlimbs motor functions. This work thus uncovers miR-615 as an effective miRNA that regulates LINGO-1 in NSC and SCI animals, and suggests miR-615 as a potential therapeutic target for traumatic central nervous system (CNS) injury.

Adipose stem cells from patients with Crohn's disease show a distinctive DNA methylation pattern

Background

Crohn’s disease (CD) is characterized by persistent inflammation and ulceration of the small or large bowel, and expansion of mesenteric adipose tissue, termed creeping fat (CF). We previously demonstrated that human adipose-derived stem cells (hASCs) from CF of patients with CD exhibit dysfunctional phenotypes, including a pro-inflammatory profile, high phagocytic capacity, and weak immunosuppressive properties. Importantly, these phenotypes persist in patients in remission and are found in all adipose depots explored including subcutaneous fat. We hypothesized that changes in hASCs are a consequence of epigenetic modifications.

Methods

We applied epigenome-wide profiling with a methylation array (Illumina EPIC/850k array) and gene expression analysis to explore the impact of CD on the methylation signature of hASCs isolated from the subcutaneous fat of patients with CD and healthy controls (n = 7 and 5, respectively; cohort I). Differentially methylated positions (p value cutoff < 1 × 10⁻⁴ and ten or more DMPs per gene) and regions (inclusion threshold 0.2, p value cutoff < 1 × 10⁻² and more than 2 DMRs per gene) were identified using dmpfinder and Bumphunter (minfi), respectively. Changes in the expression of differentially methylated genes in hASCs were validated in a second cohort (n = 10/10 inactive and active CD and 10 controls; including patients from cohort I) and also in peripheral blood mononuclear cells (PBMCs) of patients with active/inactive CD and of healthy controls (cohort III; n = 30 independent subjects).

Results

We found a distinct DNA methylation landscape in hASCs from patients with CD, leading to changes in the expression of differentially methylated genes involved in immune response, metabolic, cell differentiation, and development processes. Notably, the expression of several of these genes in hASCs and PBMCs such as tumor necrosis factor alpha (TNFA) and PR domain zinc finger protein 16 (PRDM16) were not restored to normal (healthy) levels after disease remission.

Conclusions

hASCs of patients with CD exhibit a unique DNA methylation and gene expression profile, but the expression of several genes are only partially restored in patients with inactive CD, both in hASCs and PBMCs. Understanding how CD shapes the functionality of hASCs is critical for investigating the complex pathophysiology of this disease, as well as for the success of cell-based therapies.

Graphical abstract

Human adipose-stem cells isolated from subcutaneous fat of patients with Crohn’s disease exhibit an altered DNA methylation pattern and gene expression profile compared with those isolated from healthy individuals, with immune system, cell differentiation, metabolic and development processes identified as the main pathways affected. Interestingly, the gene expression of several genes involved in these pathways is only partially restored to control levels in patients with inactive Crohn’s disease, both in human adipose-stem cells and peripheral blood mononuclear cells. Understanding how Crohn’s disease shapes the functionality of human adipose-stem cells is critical for investigating the complex pathophysiology of this disease, as well as for the success of cell-based therapies.

Deciphering Master Gene Regulators and Associated Networks of Human Mesenchymal Stromal Cells

Mesenchymal Stromal Cells (MSC) are multipotent cells characterized by self-renewal, multilineage differentiation, and immunomodulatory properties. To obtain a gene regulatory profile of human MSCs, we generated a compendium of more than two hundred cell samples with genome-wide expression data, including a homogeneous set of 93 samples of five related primary cell types: bone marrow mesenchymal stem cells (BM-MSC), hematopoietic stem cells (HSC), lymphocytes (LYM), fibroblasts (FIB), and osteoblasts (OSTB). All these samples were integrated to generate a regulatory gene network using the algorithm ARACNe (Algorithm for the Reconstruction of Accurate Cellular Networks; based on mutual information), that finds regulons (groups of target genes regulated by transcription factors) and regulators (i.e., transcription factors, TFs). Furtherly, the algorithm VIPER (Algorithm for Virtual Inference of Protein-activity by Enriched Regulon analysis) was used to inference protein activity and to identify the most significant TF regulators, which control the expression profile of the studied cells. Applying these algorithms, a footprint of candidate master regulators of BM-MSCs was defined, including the genes EPAS1, NFE2L1, SNAI2, STAB2, TEAD1, and TULP3, that presented consistent upregulation and hypomethylation in BM-MSCs. These TFs regulate the activation of the genes in the bone marrow MSC lineage and are involved in development, morphogenesis, cell differentiation, regulation of cell adhesion, and cell structure.

Promoter methylation and expression pattern of DLX3, ATF4, and FRA1 genes during osteoblastic differentiation of adipose-derived mesenchymal stem cells

Introduction: Nowadays, mesenchymal stem cells are touted as suitable cell supply for the restoration of injured bone tissue. The existence of osteogenic differentiation makes these cells capable of replenishing damaged cells in the least possible time. It has been shown that epigenetic modifications, especially DNA methylation, contribute to the regulation of various transcription factors during phenotype acquisition. Hence, we concentrated on the correlation between the promoter methylation and the expression of genes DLX3, ATF4 , and FRA1 during osteoblastic differentiation of adipose-derived mesenchymal stem cells in vitro after 21 days.

Methods: Adipose-derived mesenchymal stem cells were cultured in osteogenesis differentiation medium supplemented with 0.1 µM dexamethasone, 10 mM β-glycerol phosphate, and 50 µM ascorbate-2-phosphate for 21 days. RNA and DNA extraction was done on days 0, 7, 14, and 21. Promoter methylation and expression levels of genes DLX3 , ATF4 , and FRA1 were analyzed by methylation-specific quantitative PCR and real-time PCR assays, respectively.

Results: We found an upward expression trend with the increasing time for genes DLX3, ATF4, and FRA1 in stem cells committed to osteoblast-like lineage compared to the control group (P <0.05). On the contrary, methylation-specific quantitative PCR displayed decreased methylation rates of DLX3 and ATF4 genes, but not FRA1 , over time compared to the non-treated control cells (P <0.05). Bright-field images exhibited red-colored calcified deposits around Alizarin Red S-stained cells after 21 days compared to the control group. Statistical analysis showed a strong correlation between the transcription of genes DLX3 and ATF4 and methylation rate (P <0.05).

Conclusion: In particular, osteoblastic differentiation of adipose-derived mesenchymal stem cells enhances DLX3 and ATF4 transcriptions by reducing methylation rate for 21 days.

Developmental Impairments in a Rat Model of Methyl Donor Deficiency: Effects of a Late Maternal Supplementation with Folic Acid

Vitamins B9 (folate) and B12 act as methyl donors in the one-carbon metabolism which influences epigenetic mechanisms. We previously showed that an embryofetal deficiency of vitamins B9 and B12 in the rat increased brain expression of let-7a and miR-34a microRNAs involved in the developmental control of gene expression. This was reversed by the maternal supply with folic acid (3 mg/kg/day) during the last third of gestation, resulting in a significant reduction of associated birth defects. Since the postnatal brain is subject to intensive developmental processes, we tested whether further folate supplementation during lactation could bring additional benefits. Vitamin deficiency resulted in weaned pups (21 days) in growth retardation, delayed ossification, brain atrophy and cognitive deficits, along with unchanged brain level of let-7a and decreased expression of miR-34a and miR-23a. Whereas maternal folic acid supplementation helped restore the levels of affected microRNAs, it led to a reduction of structural and functional defects taking place during the perinatal/postnatal periods, such as learning/memory capacities. Our data suggest that a gestational B-vitamin deficiency could affect the temporal control of the microRNA regulation required for normal development. Moreover, they also point out that the continuation of folate supplementation after birth may help to ameliorate neurological symptoms commonly associated with developmental deficiencies in folate and B12.

The spleen may be an important target of stem cell therapy for stroke

Stroke is the most common cerebrovascular disease, the second leading cause of death behind heart disease and is a major cause of long-term disability worldwide. Currently, systemic immunomodulatory therapy based on intravenous cells is attracting attention. The immune response to acute stroke is a major factor in cerebral ischaemia (CI) pathobiology and outcomes. Over the past decade, the significant contribution of the spleen to ischaemic stroke has gained considerable attention in stroke research. The changes in the spleen after stroke are mainly reflected in morphology, immune cells and cytokines, and these changes are closely related to the stroke outcomes. Autonomic nervous system (ANS) activation, release of central nervous system (CNS) antigens and chemokine/chemokine receptor interactions have been documented to be essential for efficient brain-spleen cross-talk after stroke. In various experimental models, human umbilical cord blood cells (hUCBs), haematopoietic stem cells (HSCs), bone marrow stem cells (BMSCs), human amnion epithelial cells (hAECs), neural stem cells (NSCs) and multipotent adult progenitor cells (MAPCs) have been shown to reduce the neurological damage caused by stroke. The different effects of these cell types on the interleukin (IL)-10, interferon (IFN), and cholinergic anti-inflammatory pathways in the spleen after stroke may promote the development of new cell therapy targets and strategies. The spleen will become a potential target of various stem cell therapies for stroke represented by MAPC treatment.

Pancreatic endocrine-like cells differentiated from human umbilical cords Wharton's jelly mesenchymal stem cells using small molecules

Following success of pancreatic islet transplantation in the treatment of Type I diabetes mellitus, there is a growing interest in using cell-based treatment approaches. However, severe shortage of donor islets-pancreas impeded the growth, and made researchers to search for an alternative treatment approaches. In this context, recently, stem cell-based therapy has gained more attention. The current study demonstrated that epigenetic modification improves the in vitro differentiation of Wharton's jelly mesenchymal stem cells (WJMSCs) into pancreatic endocrine-like cells. Here we used two histone deacetylase (HDAC) inhibitors namely trichostatin A (TSA) and TMP269. TSA inhibits both class I and II HDACs whereas TMP269 inhibits only class IIa HDACs. WJMSCs were differentiated using a multistep protocol in a serum-free condition with or without TSA pretreatment. A marginal improvement in differentiation was observed after TSA pretreatment though it was not significant. However, exposing endocrine precursor-like cells derived from WJMSCs to TMP269 alone has significantly improved the differentiation toward insulin-producing cells. Further, increase in the expression of paired box 4 (PAX4), insulin, somatostatin, glucose transporter 2 (GLUT2), MAF bZIP transcription factor A (MAFA), pancreatic duodenal homeobox 1 (PDX-1), and NKX6.1 was observed both at messenger RNA and protein levels. Nevertheless, TMP269-treated cells secreted higher insulin upon glucose challenge, and demonstrated increased dithizone staining. These findings suggest that TMP269 may improve the in vitro differentiation of WJMSCs into insulin-producing cells.

Stem Cell Therapy in Cerebrovascular Disease

PURPOSE OF REVIEW

The purpose of this article is to provide a review of state-of-the-art cellular therapy in cerebrovascular diseases by discussing published and ongoing clinical trials.

RECENT FINDINGS

In spite of the challenge in translating the success of cellular therapy in acute strokes from preclinical models to clinical trials, early phase clinical trial have recently shown promise in overcoming these challenges. Various stem cell types and doses are being studied, different routes of administration are under investigation, as well as defining the optimal time window to intervene. In addition, experimental methods to enhance cellular therapy, such as ischemic preconditioning, are evolving. After the failure of neuroprotectants in cerebrovascular diseases, researchers have been keen to provide a way of replacement of damaged brain tissue and to promote recovery in order to achieve better outcomes. The field has progressed from intravenous delivery in the 24- to 36-h time window to later intracerebral administration in chronic stroke in clinical trials. New optimism in acute stroke care fostered by the success of mechanical thrombectomy will hopefully extend into cell therapy to promote recovery.

Clinical Cellular Therapeutics Accelerate Clot Formation

Clinical cellular therapeutics (CCTs) have shown preliminary efficacy in reducing inflammation after trauma, preserving cardiac function after myocardial infarction, and improving functional recovery after stroke. However, most clinically available cell lines express tissue factor (TF) which stimulates coagulation. We sought to define the degree of procoagulant activity of CCTs as related to TF expression. CCT samples from bone marrow, adipose, amniotic fluid, umbilical cord, multi-potent adult progenitor cell donors, and bone marrow mononuclear cells were tested. TF expression and phenotype were quantified using flow cytometry. Procoagulant activity of the CCTs was measured in vitro with thromboelastography and calibrated thrombogram. Fluorescence-activated cell sorting (FACS) separated samples into high- and low-TF expressing populations to isolate the contribution of TF to coagulation. A TF neutralizing antibody was incubated with samples to demonstrate loss of procoagulant function. All CCTs tested expressed procoagulant activity that correlated with expression of tissue factor. Time to clot and thrombin formation decreased with increasing TF expression. High-TF expressing cells decreased clotting time more than low-TF expressing cells when isolated from a single donor using FACS. A TF neutralizing antibody restored clotting time to control values in some, but not all, CCT samples. CCTs demonstrate wide variability in procoagulant activity related to TF expression. Time to clot and thrombin formation decreases as TF load increases and this procoagulant effect is neutralized by a TF blocking antibody. Clinical trials using CCTs are in progress and TF expression may emerge as a safety release criterion. Stem Cells Translational Medicine 2018;7:731-739.

Dual ECM Biomimetic Scaffolds for Dental Pulp Regenerative Applications

Dental pulp is a highly vascularized and innervated tissue that provides sensitivity and vitality to the tooth. Chronic caries results in an infected pulp tissue prone to necrosis. Existing clinical treatments replace the living pulp tissue with a non-responsive resin filling resulting in loss of tooth vitality. Tissue engineering approaches to dental pulp tissue regeneration have been investigated to preserve tooth vitality and function. However, a critical criterion is the choice of growth factors that may promote mesenchymal stem cell differentiation and more importantly, vascularization. But, the problems associated with growth factor dosage, delivery, safety, immunological and ectopic complications affect their translatory potential severely. The purpose of this study is to develop, characterize and evaluate a biomimetic native extracellular matrix (ECM) derived dual ECM scaffold that consists of a pulp-specific ECM to promote MSC attachment, proliferation and differentiation and an endothelial ECM to promote migration of host endothelial cells and eventual vascularization in vivo. Our results show that the dual ECM scaffolds possess similar properties as a pulp-ECM scaffold to promote MSC attachment and odontogenic differentiation in vitro. Additionally, when implanted subcutaneously in a tooth root slice model in vivo, the dual ECM scaffolds promoted robust odontogenic differentiation of both dental pulp and bone marrow derived MSCs and also extensive vascularization when compared to respective controls. These scaffolds are mass producible for clinical use and hence have the potential to replace root canal therapy as a treatment for chronic dental caries.

Therapeutic time window of multipotent adult progenitor therapy after traumatic brain injury

BACKGROUND

Traumatic brain injury (TBI) is a major cause of death and disability. TBI results in a prolonged secondary central neuro-inflammatory response. Previously, we have demonstrated that multiple doses (2 and 24 h after TBI) of multipotent adult progenitor cells (MAPC) delivered intravenously preserve the blood-brain barrier (BBB), improve spatial learning, and decrease activated microglia/macrophages in the dentate gyrus of the hippocampus. In order to determine if there is an optimum treatment window to preserve the BBB, improve cognitive behavior, and attenuate the activated microglia/macrophages, we administered MAPC at various clinically relevant intervals.

METHODS

We administered two injections intravenously of MAPC treatment at hours 2 and 24 (2/24), 6 and 24 (6/24), 12 and 36 (12/36), or 36 and 72 (36/72) post cortical contusion injury (CCI) at a concentration of 10 million/kg. For BBB experiments, animals that received MAPC at 2/24, 6/24, and 12/36 were euthanized 72 h post injury. The 36/72 treated group was harvested at 96 h post injury.

RESULTS

Administration of MAPC resulted in a significant decrease in BBB permeability when administered at 2/24 h after TBI only. For behavior experiments, animals were harvested post behavior paradigm. There was a significant improvement in spatial learning (120 days post injury) when compared to cortical contusion injury (CCI) in groups when MAPC was administered at or before 24 h. In addition, there was a significant decrease in activated microglia/macrophages in the dentate gyrus of hippocampus of the treated group (2/24) only when compared to CCI.

CONCLUSIONS

Intravenous injections of MAPC at or before 24 h after CCI resulted in improvement of the BBB, improved cognitive behavior, and attenuated activated microglia/macrophages in the dentate gyrus.

Cancer Is to Embryology as Mutation Is to Genetics: Hypothesis of the Cancer as Embryological Phenomenon

Despite numerous advances in cell biology, genetics, and developmental biology, cancer origin has been attributed to genetic mechanisms primarily involving mutations. Embryologists have expressed timidly cancer embryological origin with little success in leveraging the discussion that cancer could involve a set of conventional cellular processes used to build the embryo during morphogenesis. Thus, this "cancer process" allows the harmonious and coherent construction of the embryo structural base, and its implementation as the embryonic process involves joint regulation of differentiation, proliferation, cell invasion, and migration, enabling the human being recreation of every generation. On the other hand, "cancer disease" is the representation of an abnormal state of the cell that might happen in the stem cells of an adult person, in which the mechanism for joint gene regulating of differentiation, proliferation, cell invasion, and migration could be reactivated in an entirely inappropriate context.

Enhancement of individual differences in proliferation and differentiation potentials of aged human adipose-derived stem cells

Background

Adipose-derived stem cells (ASCs) are a robust, multipotent cell source. They are easily obtained and hold promise in many regenerative applications. It is generally considered that the function of somatic stem cells declines with age. Although several studies have examined the effects of donor age on proliferation potential and pluripotency of ASCs, the results of these studies were not consistent.

Objective

This study tested whether the donor age affects the yield of ASCs from adipose tissue, as well as the proliferation and differentiation potentials of ASCs.

Methods

This study used ASCs obtained from adipose tissues of 260 donors (ages 5–97 years). ASCs were examined for individual differences in proliferation, and adipogenic, osteogenic and chondrogenic differentiation potentials in vitro. Characteristics of ASCs from each donor were evaluated by the principal component analysis (PCA) using their potential parameters.

Results

Analyses on ASCs demonstrated that adipogenic potentials declined with age, but proliferation, osteogenic and chondrogenic potentials were not correlated with age. Interestingly, in all ASC potentials, including adipogenesis, individual differences were observed. Principal component analysis (PCA) revealed that individual differences became evident in the elderly, and those variations were more prominent in females than in males.

Conclusions

This study demonstrated age-related changes in the potentials of ASCs and revealed that the individual differences of ASCs become significant in people over 60 years of age (for females over 60, and for males over 80). We believe that it is important to carefully observe ASC potentials in order to achieve effective regenerative medicine treatments using ASCs.

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ASCs can be isolated from subjects in all ages.

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Adipogenic potential of ASCs declines with age.

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Chondrogenic and osteogenic potentials of ASCs are not affected by age.

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Proliferation and differentiation potentials of ASCs are individually different.

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Individual difference of ASC potentials becomes significant over 60 years of age.

Thymidine phosphorylase exerts complex effects on bone resorption and formation in myeloma

Myelomatous bone disease is characterized by the development of lytic bone lesions and a concomitant reduction in bone formation, leading to chronic bone pain and fractures. To understand the underlying mechanism, we investigated the contribution of myeloma-expressed thymidine phosphorylase (TP) to bone lesions. In osteoblast progenitors, TP up-regulated the methylation of RUNX2 and osterix, leading to decreased bone formation. In osteoclast progenitors, TP up-regulated the methylation of IRF8 and thereby enhanced expression of NFATc1 (nuclear factor of activated T cells, cytoplasmic 1 protein), leading to increased bone resorption. TP reversibly catalyzes thymidine into thymine and 2-deoxy-d-ribose (2DDR). Myeloma-secreted 2DDR bound to integrin αVβ3/α5β1 in the progenitors, activated PI3K (phosphoinositide 3-kinase)/Akt signaling, and increased DNMT3A (DNA methyltransferase 3A) expression, resulting in hypermethylation of RUNX2, osterix, and IRF8 This study elucidates an important mechanism for myeloma-induced bone lesions, suggesting that targeting TP may be a viable approach to healing resorbed bone in patients. Because TP overexpression is common in bone-metastatic tumors, our findings could have additional mechanistic implications.

Late Maternal Folate Supplementation Rescues from Methyl Donor Deficiency-Associated Brain Defects by Restoring Let-7 and miR-34 Pathways

The micronutrients folate and vitamin B12 are essential for the proper development of the central nervous system, and their deficiency during pregnancy has been associated with a wide range of disorders. They act as methyl donors in the one-carbon metabolism which critically influences epigenetic mechanisms. In order to depict further underlying mechanisms, we investigated the role of let-7 and miR-34, two microRNAs regulated by methylation, on a rat model of maternal deficiency. In several countries, public health policies recommend periconceptional supplementation with folic acid. However, the question about the duration and periodicity of supplementation remains. We therefore tested maternal supply (3 mg/kg/day) during the last third of gestation from embryonic days (E) 13 to 20. Methyl donor deficiency-related developmental disorders at E20, including cerebellar and interhemispheric suture defects and atrophy of selective cerebral layers, were associated with increased brain expression (by 2.5-fold) of let-7a and miR-34a, with subsequent downregulation of their regulatory targets such as Trim71 and Notch signaling partners, respectively. These processes could be reversed by siRNA strategy in differentiating neuroprogenitors lacking folate, with improvement of their morphological characteristics. While folic acid supplementation helped restoring the levels of let-7a and miR-34a and their downstream targets, it led to a reduction of structural and functional defects taking place during the perinatal period. Our data outline the potential role of let-7 and miR-34 and their related signaling pathways in the developmental defects following gestational methyl donor deficiency and support the likely usefulness of late folate supplementation in at risk women.

Using miRNA-mRNA Interaction Analysis to Link Biologically Relevant miRNAs to Stem Cell Identity Testing for Next-Generation Culturing Development

Therapeutic benefit of stem cells has been demonstrated in multiple disease models and clinical trials. Robust quality assurance is imperative to make advancements in culturing procedures to enable large-scale cell manufacturing without hampering therapeutic potency. MicroRNAs (miRNAs or miRs) are shown to be master regulators of biological processes and are potentially ideal quality markers. We determined miRNA markers differentially expressed under nonclinical multipotent adult progenitor cell (MAPC) and mesenchymal stem cell (MSC) culturing conditions that regulate important stem cell features, such as proliferation and differentiation. These bone marrow-derived stem cell types were selected because they both exert therapeutic functions, but have different proliferative and regenerative capacities. To determine cell-specific marker miRNAs and assess their effects on stem cell qualities, a miRNA and mRNA profiling was performed on MAPCs and MSCs isolated from three shared donors. We applied an Ingenuity Pathway Analysis-based strategy that combined an integrated RNA profile analysis and a biological function analysis to determine the effects of miRNA-mRNA interactions on phenotype. This resulted in the identification of important miRNA markers linked to cell-cycle regulation and development, the most distinctive being MAPC marker miR-204-5p and MSC marker miR-335-5p, for which we provide in vitro validation of its function in differentiation and cell cycle regulation, respectively. Importantly, marker expression is maintained under xeno-free conditions and during bioreactor isolation and expansion of MAPC cultures. In conclusion, the identified biologically relevant miRNA markers can be used to monitor stem cell stability when implementing variations in culturing procedures.

SIGNIFICANCE

Human adult marrow stromal stem cells have shown great potential in addressing unmet health care needs. Quality assurance is imperative to make advancements in large-scale manufacturing procedures. MicroRNAs are master regulators of biological processes and potentially ideal quality markers. MicroRNA and mRNA profiling data of two human adult stem cell types were correlated to biological functions in silico. Doing this provided evidence that differentially expressed microRNAs are involved in regulating specific stem cell features. Furthermore, expression of a selected microRNA panel was maintained in next-generation culturing platforms, demonstrating the robustness of microRNA profiling in stem cell comparability testing.

Epigenetic Mechanisms Regulating Mesenchymal Stem Cell Differentiation

Human Mesenchymal Stem Cells (hMSCs) have emerged in the last few years as one of the most promising therapeutic cell sources and, in particular, as an important tool for regenerative medicine of skeletal tissues. Although they present a more restricted potency than Embryonic Stem (ES) cells, the use of hMCS in regenerative medicine avoids many of the drawbacks characteristic of ES cells or induced pluripotent stem cells. The challenge in using these cells lies into developing precise protocols for directing cellular differentiation to generate a specific cell lineage. In order to achieve this goal, it is of the upmost importance to be able to control de process of fate decision and lineage commitment. This process requires the coordinate regulation of different molecular layers at transcriptional, posttranscriptional and translational levels. At the transcriptional level, switching on and off different sets of genes is achieved not only through transcriptional regulators, but also through their interplay with epigenetic modifiers. It is now well known that epigenetic changes take place in an orderly way through development and are critical in the determination of lineage-specific differentiation. More importantly, alteration of these epigenetic changes would, in many cases, lead to disease generation and even tumour formation. Therefore, it is crucial to elucidate how epigenetic factors, through their interplay with transcriptional regulators, control lineage commitment in hMSCs.

Chromosome intermingling-the physical basis of chromosome organization in differentiated cells

Chromosome territories (CTs) in higher eukaryotes occupy tissue-specific non-random three-dimensional positions in the interphase nucleus. To understand the mechanisms underlying CT organization, we mapped CT position and transcriptional changes in undifferentiated embryonic stem (ES) cells, during early onset of mouse ES cell differentiation and in terminally differentiated NIH3T3 cells. We found chromosome intermingling volume to be a reliable CT surface property, which can be used to define CT organization. Our results show a correlation between the transcriptional activity of chromosomes and heterologous chromosome intermingling volumes during differentiation. Furthermore, these regions were enriched in active RNA polymerase and other histone modifications in the differentiated states. These findings suggest a correlation between the evolution of transcription program in modifying CT architecture in undifferentiated stem cells. This leads to the formation of functional CT surfaces, which then interact to define the three-dimensional CT organization during differentiation.

The role of Ca(2+) signaling on the self-renewal and neural differentiation of embryonic stem cells (ESCs)

Embryonic stem cells (ESCs) are promising resources for both scientific research and clinical regenerative medicine. With regards to the latter, ESCs are especially useful for treating several neurodegenerative disorders. Two significant characteristics of ESCs, which make them so valuable, are their capacity for self-renewal and their pluripotency, both of which are regulated by the integration of various signaling pathways. Intracellular Ca(2+) signaling is involved in several of these pathways. It is known to be precisely controlled by different Ca(2+) channels and pumps, which play an important role in a variety of cellular activities, including proliferation, differentiation and apoptosis. Here, we provide a review of the recent work conducted to investigate the function of Ca(2+) signaling in the self-renewal and the neural differentiation of ESCs. Specifically, we describe the role of intracellular Ca(2+) mobilization mediated by RyRs (ryanodine receptors); by cADPR (cyclic adenosine 5'-diphosphate ribose) and CD38 (cluster of differentiation 38/cADPR hydrolase); and by NAADP (nicotinic acid adenine dinucleotide phosphate) and TPC2 (two pore channel 2). We also discuss the Ca(2+) influx mediated by SOCs (store-operated Ca(2+) channels), TRPCs (transient receptor potential cation channels) and LTCC (L-type Ca(2+) channels) in the pluripotent ESCs as well as in neural differentiation of ESCs. Moreover, we describe the integration of Ca(2+) signaling in the other signaling pathways that are known to regulate the fate of ESCs.

Impact of tissue-specific stem cells on lineage-specific differentiation: a focus on the musculoskeletal system

Tissue-specific stem cells are found throughout the body and, with proper intervention and environmental cues, these stem cells exercise their capabilities for differentiation into several lineages to form cartilage, bone, muscle, and adipose tissue in vitro and in vivo. Interestingly, it has been widely demonstrated that they do not differentiate with the same efficacy during lineage-specific differentiation studies, as the tissue-specific stem cells are generally more effective when differentiating toward the tissues from which they were derived. This review focuses on four mesodermal lineages for tissue-specific stem cell differentiation: adipogenesis, chondrogenesis, myogenesis, and osteogenesis. It is intended to give insight into current multilineage differentiation and comparative research, highlight and contrast known trends regarding differentiation, and introduce supporting evidence which demonstrates particular tissue-specific stem cells' superiority in lineage-specific differentiation, along with their resident tissue origins and natural roles. In addition, some epigenetic and transcriptomic differences between stem cells which may explain the observed trends are discussed.

Transforming Growth Factor-β-Induced KDM4B Promotes Chondrogenic Differentiation of Human Mesenchymal Stem Cells

The high prevalence of cartilage diseases and limited treatment options create a significant biomedical burden. Due to the inability of cartilage to regenerate itself, introducing chondrocyte progenitor cells to the affected site is of significant interest in cartilage regenerative therapies. Tissue engineering approaches using human mesenchymal stem cells (MSCs) are promising due to their chondrogenic potential, but a comprehensive understanding of the mechanisms governing the fate of MSCs is required for precise therapeutic applications in cartilage regeneration. TGF-β is known to induce chondrogenesis by activating SMAD signaling pathway and upregulating chondrogenic genes such as SOX9; however, the epigenetic regulation of TGF-β-mediated chondrogenesis is not understood. In this report, we found that TGF-β dramatically induced the expression of KDM4B in MSCs. When KDM4B was overexpressed, chondrogenic differentiation was significantly enhanced while KDM4B depletion by shRNA led to a significant reduction in chondrogenic potential. Mechanistically, upon TGF-β stimulation, KDM4B was recruited to the SOX9 promoter, removed the silencing H3K9me3 marks, and activated the transcription of SOX9. Furthermore, KDM4B depletion reduced the occupancy of SMAD3 in the SOX9 promoter, suggesting that KDM4B is required for SMAD-dependent coactivation of SOX9. Our results demonstrate the critical role of KDM4B in the epigenetic regulation of TGF-β-mediated chondrogenic differentiation of MSCs. Since histone demethylases are chemically modifiable, KDM4B may be a novel therapeutic target in cartilage regenerative therapy.

Adenosine Signaling Mediates Osteogenic Differentiation of Human Embryonic Stem Cells on Mineralized Matrices

Human embryonic stem cells (hESCs) are attractive cell sources for tissue engineering and regenerative medicine due to their self-renewal and differentiation ability. Design of biomaterials with an intrinsic ability that promotes hESC differentiation to the targeted cell type boasts significant advantages for tissue regeneration. We have previously developed biomineralized calcium phosphate (CaP) matrices that inherently direct osteogenic differentiation of hESCs without the need of osteogenic-inducing chemicals or growth factors. Here, we show that CaP matrix-driven osteogenic differentiation of hESCs occurs through A2b adenosine receptor (A2bR). The inhibition of the receptor with an A2bR-specific antagonist attenuated mineralized matrix-mediated osteogenic differentiation of hESCs. In addition, when cultured on matrices in an environment deficient of CaP minerals, exogenous adenosine promoted osteogenic differentiation of hESCs, but was attenuated by the inhibition of A2bR. Such synthetic matrices that intrinsically support osteogenic commitment of hESCs are not only beneficial for bone tissue engineering but can also be used as a platform to study the effect of the physical and chemical cues to the extracellular milieu on stem cell commitment. Insights into the cell signaling during matrix-induced differentiation of stem cells will also help define the key processes and enable discovery of new targets that promote differentiation of pluripotent stem cells for bone tissue engineering.

Epigenetic regulation of human adipose-derived stem cells differentiation

Adult stem cells have more restricted differentiation potential than embryonic stem cells (ESCs), but upon appropriate stimulation can differentiate into cells of different germ layers. Epigenetic factors, including DNA modifications, take a significant part in regulation of pluripotency and differentiation of ESCs. Less is known about the epigenetic regulation of these processes in adult stem cells. Gene expression profile and location of DNA modifications in adipose-derived stem cells (ADSCs) and their osteogenically differentiated lineages were analyzed using Agilent microarrays. Methylation-specific PCR and restriction-based quantitative PCR were applied for 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC) detection in selected loci. The level of DNA modifications in the POU5F1 locus was quantified with deep sequencing. Expression levels of selected genes were assayed by real-time PCR. ADSCs differentiation into osteogenic lineages involved marked changes in both 5mC and 5hmC profiles, but 5hmC changes were more abundant. 5mC losses and 5hmC gains were the main events observed during ADSCs differentiation, and were accompanied by increased expression of TET1 (P = 0.009). In ADSCs, POU5F1 was better expressed than NANOG or SOX2 (P ≤ 0.001). Both 5mC and 5hmC marks were present in the POU5F1 locus, but only hydroxymethylation of specific cytosine showed significant effect on the gene expression. In summary, the data of our study suggest significant involvement of changes in 5hmC profile during the differentiation of human adult stem cells.

Toying with fate: Redirecting the differentiation of adrenocortical progenitor cells into gonadal-like tissue

Cell fate decisions are integral to zonation and remodeling of the adrenal cortex. Animal models exhibiting ectopic differentiation of gonadal-like cells in the adrenal cortex can shed light on the molecular mechanisms regulating steroidogenic cell fate. In one such model, prepubertal gonadectomy (GDX) of mice triggers the formation of adrenocortical neoplasms that resemble luteinized ovarian stroma. Transcriptomic analysis and genome-wide DNA methylation mapping have identified genetic and epigenetic markers of GDX-induced adrenocortical neoplasia. Members of the GATA transcription factor family have emerged as key regulators of cell fate in this model. Expression of Gata4 is pivotal for the accumulation of gonadal-like cells in the adrenal glands of gonadectomized mice, whereas expression of Gata6 limits the spontaneous and GDX-induced differentiation of gonadal-like cells in the adrenal cortex. Additionally, Gata6 is essential for proper development of the adrenal X-zone, a layer analogous to the fetal zone of the human adrenal cortex. The relevance of these observations to developmental signaling pathways in the adrenal cortex, to other animal models of altered adrenocortical cell fate, and to human diseases is discussed.

Biomimetic extracellular matrix mediated somatic stem cell differentiation: applications in dental pulp tissue regeneration

Dental caries is one of the most widely prevalent infectious diseases in the world. It affects more than half of the world's population. The current treatment for necrotic dental pulp tissue arising from dental caries is root canal therapy. This treatment results in loss of tooth sensitivity and vitality making it prone for secondary infections. Over the past decade, several tissue-engineering approaches have attempted regeneration of the dental pulp tissue. Although several studies have highlighted the potential of dental stem cells, none have transitioned into a clinical setting owing to limited availability of dental stem cells and the need for growth factor delivery systems. Our strategy is to utilize the intact ECM of pulp cells to drive lineage specific differentiation of bone marrow derived mesenchymal stem cells. From a clinical perspective, pulp ECM scaffolds can be generated using cell lines and patient specific somatic stem cells can be used for regeneration. Our published results have shown the feasibility of using pulp ECM scaffolds for odontogenic differentiation of non-dental mesenchymal cells. This focused review discusses the issues surrounding dental pulp tissue regeneration and the potential of our strategy to overcome these issues.

Different Methylation Patterns of RUNX2, OSX, DLX5 and BSP in Osteoblastic Differentiation of Mesenchymal Stem Cells

Objective

Runt-related transcription factor 2 (RUNX2) and osterix (OSX) as two specific osteoblast transcription factors and distal-less homeobox 5 (DLX5) as a non-specific one are of paramount importance in regulating osteoblast related genes including osteocalcin, bone sialoprotein (BSP), osteopontin and collagen type Iα1. The present study sets out to investigate whether epigenetic regulation of these genes is important in osteoblastic differentiation of mesenchymal stem cells (MSCs).

Materials and Methods

In this experimental study, MSCs were differentiated to osteoblasts under the influence of the osteogenic differentiation medium. DNA and RNA were extracted at days 0, 7, 14 and 21 from MSCs differentiating to osteoblasts. Promoter regions of RUNX2, OSX, DLX5 and BSP were analyzed by methylation-specific PCR (MSP). Gene expression was analyzed during osteoblastic differentiation by quantitative real-time polymerase chain reaction (PCR).

Results

MSP analysis revealed that promoter methylation status did not change in RUNX2, DLX5 and BSP during MSC osteoblastic differentiation. In contrast, OSX promoter showed a dynamic change in methylation pattern. Moreover, RUNX2, OSX, DLX5 and BSP promoter regions showed three different methylation patterns during MSC differentiation. Gene expression analyses confirmed these results.

Conclusion

The results show that in differentiation of MSCs to osteoblasts, epigenetic regulation of OSX may play a leading role.

Novel markers of gonadectomy-induced adrenocortical neoplasia in the mouse and ferret

Gonadectomy (GDX) induces sex steroid-producing adrenocortical tumors in certain mouse strains and in the domestic ferret. Transcriptome analysis and DNA methylation mapping were used to identify novel genetic and epigenetic markers of GDX-induced adrenocortical neoplasia in female DBA/2J mice. Markers were validated using a combination of laser capture microdissection, quantitative RT-PCR, in situ hybridization, and immunohistochemistry. Microarray expression profiling of whole adrenal mRNA from ovariectomized vs. intact mice demonstrated selective upregulation of gonadal-like genes including Spinlw1 and Insl3 in GDX-induced adrenocortical tumors of the mouse. A complementary candidate gene approach identified Foxl2 as another gonadal-like marker expressed in GDX-induced neoplasms of the mouse and ferret. That both "male-specific" (Spinlw1) and "female-specific" (Foxl2) markers were identified is noteworthy and implies that the neoplasms exhibit mixed characteristics of male and female gonadal somatic cells. Genome-wide methylation analysis showed that two genes with hypomethylated promoters, Igfbp6 and Foxs1, are upregulated in GDX-induced adrenocortical neoplasms. These new genetic and epigenetic markers may prove useful for studies of steroidogenic cell development and for diagnostic testing.

Transcriptional coexpression network reveals the involvement of varying stem cell features with different dysregulations in different gastric cancer subtypes

Despite the advancements in the cancer therapeutics, gastric cancer ranks as the second most common cancers with high global mortality rate. Integrative functional genomic investigation is a powerful approach to understand the major dysregulations and to identify the potential targets toward the development of targeted therapeutics for various cancers. Intestinal and diffuse type gastric tumors remain the major subtypes and the molecular determinants and drivers of these distinct subtypes remain unidentified. In this investigation, by exploring the network of gene coexpression association in gastric tumors, mRNA expressions of 20,318 genes across 200 gastric tumors were categorized into 21 modules. The genes and the hub genes of the modules show gastric cancer subtype specific expression. The expression patterns of the modules were correlated with intestinal and diffuse subtypes as well as with the differentiation status of gastric tumors. Among these, G1 module has been identified as a major driving force of diffuse type gastric tumors with the features of (i) enriched mesenchymal, mesenchymal stem cell like, and mesenchymal derived multiple lineages, (ii) elevated OCT1 mediated transcription, (iii) involvement of Notch activation, and (iv) reduced polycomb mediated epigenetic repression. G13 module has been identified as key factor in intestinal type gastric tumors and found to have the characteristic features of (i) involvement of embryonic stem cell like properties, (ii) Wnt, MYC and E2F mediated transcription programs, and (iii) involvement of polycomb mediated repression. Thus the differential transcription programs, differential epigenetic regulation and varying stem cell features involved in two major subtypes of gastric cancer were delineated by exploring the gene coexpression network. The identified subtype specific dysregulations could be optimally employed in developing subtype specific therapeutic targeting strategies for gastric cancer.

Identification of proteins related to epigenetic regulation in the malignant transformation of aberrant karyotypic human embryonic stem cells by quantitative proteomics

Previous reports have demonstrated that human embryonic stem cells (hESCs) tend to develop genomic alterations and progress to a malignant state during long-term in vitro culture. This raises concerns of the clinical safety in using cultured hESCs. However, transformed hESCs might serve as an excellent model to determine the process of embryonic stem cell transition. In this study, ITRAQ-based tandem mass spectrometry was used to quantify normal and aberrant karyotypic hESCs proteins from simple to more complex karyotypic abnormalities. We identified and quantified 2583 proteins, and found that the expression levels of 316 proteins that represented at least 23 functional molecular groups were significantly different in both normal and abnormal hESCs. Dysregulated protein expression in epigenetic regulation was further verified in six pairs of hESC lines in early and late passage. In summary, this study is the first large-scale quantitative proteomic analysis of the malignant transformation of aberrant karyotypic hESCs. The data generated should serve as a useful reference of stem cell-derived tumor progression. Increased expression of both HDAC2 and CTNNB1 are detected as early as the pre-neoplastic stage, and might serve as prognostic markers in the malignant transformation of hESCs.

Pluripotent reprogramming and lineage reprogramming: promises and challenges in cardiovascular regeneration

Cardiovascular disease is a leading cause of death in industrialized countries. Scientists are trying to generate cardiomyocytes in vitro and in vivo to repair damaged heart tissue. Pluripotent reprogramming brings an alternative source of embryonic-like stem cells, and the possibility of regenerating mammalian tissues by first reverting somatic cells to induced pluripotent stem cells, followed by redifferentiating these cells into cardiomyocytes. More recently, lineage reprogramming of fibroblasts directly into functional cardiomyocytes has been reported. The procedure does not involve reverting cells back to a pluripotent stage, and, thus, would presumably reduce tumorigenic potential. Interestingly, lineage reprogramming could be used for in situ conversion of cell fate. Moreover, zebrafish-like regenerative mechanism in mammalian heart tissue, which was observed in mice within the first week of postpartum, should be further addressed. Here, we review the landmark progresses of the two major reprogramming strategies, compare their pros and cons in cardiovascular regeneration, and forecast the future directions of cardiac repair.

Impact of epigenetic dietary compounds on transgenerational prevention of human diseases

The etiology of most human diseases involves complicated interactions of multiple environmental factors with individual genetic background which is initially generated early in human life, for example, during the processes of embryogenesis and fetal development in utero. Early embryogenesis includes a series of programming processes involving extremely accurate time-controlled gene activation/silencing expressions, and epigenetic control is believed to play a key role in regulating early embryonic development. Certain dietary components with properties in influencing epigenetic processes are believed to have preventive effects on many human diseases such as cancer. Evidence shows that in utero exposure to certain epigenetic diets may lead to reprogramming of primary epigenetic profiles such as DNA methylation and histone modifications on the key coding genes of the fetal genome, leading to different susceptibility to diseases later in life. In this review, we assess the current advances in dietary epigenetic intervention on transgenerational human disease control. Enhanced understanding of the important role of early life epigenetics control may lead to cost-effective translational chemopreventive potential by appropriate administration of prenatal and/or postnatal dietary supplements leading to early disease prevention.

Intracerebroventricular transplantation of human bone marrow-derived multipotent progenitor cells in an immunodeficient mouse model of mucopolysaccharidosis type I (MPS-I)

Mucopolysaccharidosis type I (MPS-I; Hurler syndrome) is an inborn error of metabolism caused by lack of the functional lysosomal glycosaminoglycan (GAG)-degrading enzyme α-L-iduronidase (IDUA). Without treatment, the resulting GAG accumulation causes multisystem dysfunction and death within the first decade. Current treatments include allogeneic hematopoietic stem cell transplantation (HSCT) and enzyme replacement therapy. HSCT ameliorates clinical features and extends life but is not available to all patients, and inadequately corrects the most devastating features of the disease including mental retardation and skeletal deformities. Recent developments suggest that stem cells can be used to deliver needed enzymes to the central nervous system. To test this concept, we transplanted bone marrow-derived normal adult human MultiStem® cells into the cerebral lateral ventricles of immunodeficient MPS-I neonatal mice. Transplanted cells and human-specific DNA were detected in the hippocampal formation, striatum, and other areas of the central nervous system. Brain tissue assays revealed significant long-term decrease in GAG levels in the hippocampus and striatum. Sensorimotor testing 6 months after transplantation demonstrated significantly improved rotarod performance of transplanted mice in comparison to nontransplanted and sham-transplanted control animals. These results suggest that a single injection of MultiStem cells into the cerebral ventricles of neonatal MPS-I mice induces sustained reduction in GAG accumulation within the brain, and modest long-term improvement in sensorimotor function.

Culture of human bone marrow-derived mesenchymal stem cells on of poly(L-lactic acid) scaffolds: potential application for the tissue engineering of cartilage

PURPOSE

Due to the attractive properties of poly(L-lactic acid) (PLLA) for tissue engineering, the aim was to determine the growth and differentiation capacity of mesenchymal stromal cells (MSCs) in PLLA scaffolds and their potential use in the treatment of cartilage diseases.

METHODS

MSCs were cultured in PLLA films and thin porous membranes to study adherence and proliferation. Permeability and porosity were determined for the different scaffolds employed. The optimal conditions for cell seeding were first determined, as well as cell density and distribution inside the PLLA. Scaffolds were then maintained in expansion or chondrogenic differentiation media for 21 days. Apoptosis, proliferation and chondrogenic differentiation was assessed after 21 days in culture by immunohistochemistry. Mechanical characteristics of scaffolds were determined before and after cell seeding.

RESULTS

MSCs uniformly adhered to PLLA films as well as to porous membranes. Proliferation was detected only in monolayers of pure PLLA, but was no longer detected after 10 days. Mechanical characterization of PLLA scaffolds showed differences in the apparent compression elastic modulus for the two sizes used. After determining high efficiencies of seeding, the production of extracellular matrix (ECM) was determined and contained aggrecan and collagens type I and X. ECM produced by the cells induced a twofold increase in the apparent elastic modulus of the composite.

CONCLUSIONS

Biocompatible PLLA scaffolds have been developed that can be efficiently loaded with MSCs. The scaffold supports chondrogenic differentiation and ECM deposition that improves the mechanics of the scaffold. Although this improvement does not met the expectations of a hyaline-like cartilage ECM, in part due to the lack of a mechanical stimulation, their potential use in the treatment of cartilage pathologies encourages to improve the mechanical component.

Lessons learned about human stem cell responses to ionizing radiation exposures: a long road still ahead of us

Human stem cells (hSC) possess several distinct characteristics that set them apart from other cell types. First, hSC are self-renewing, capable of undergoing both asymmetric and symmetric cell divisions. Second, these cells can be coaxed to differentiate into various specialized cell types and, as such, hold great promise for regenerative medicine. Recent progresses in hSC biology fostered the characterization of the responses of hSC to genotoxic stresses, including ionizing radiation (IR). Here, we examine how different types of hSC respond to IR, with a special emphasis on their radiosensitivity, cell cycle, signaling networks, DNA damage response (DDR) and DNA repair. We show that human embryonic stem cells (hESCs) possess unique characteristics in how they react to IR that clearly distinguish these cells from all adult hSC studied thus far. On the other hand, a manifestation of radiation injuries/toxicity in human bodies may depend to a large extent on hSC populating corresponding tissues, such as human mesenchymal stem cells (hMSC), human hematopoietic stem cells (hHSC), neural hSC, intestine hSC, etc. We discuss here that hSC responses to IR differ notably across many types of hSC which may represent the distinct roles these cells play in development, regeneration and/or maintenance of homeostasis.

Mesenchymal stem cells and their use in therapy: what has been achieved?

The considerable therapeutic potential of human multipotent mesenchymal stromal cells or mesenchymal stem cells (MSCs) has generated increasing interest in a wide variety of biomedical disciplines. Nevertheless, researchers report studies on MSCs using different methods of isolation and expansion, as well as different approaches to characterize them; therefore, it is increasingly difficult to compare and contrast study outcomes. To begin to address this issue, the Mesenchymal and Tissue Stem Cell Committee of the International Society for Cellular Therapy proposed minimal criteria to define human MSCs. First, MSCs must be plastic-adherent when maintained in standard culture conditions (α minimal essential medium plus 20% fetal bovine serum). Second, MSCs must express CD105, CD73 and CD90, and MSCs must lack expression of CD45, CD34, CD14 or CD11b, CD79α or CD19 and HLA-DR surface molecules. Third, MSCs must differentiate into osteoblasts, adipocytes and chondroblasts in vitro. MSCs are isolated from many adult tissues, in particular from bone marrow and adipose tissue. Along with their capacity to differentiate and transdifferentiate into cells of different lineages, these cells have also generated great interest for their ability to display immunomodulatory capacities. Indeed, a major breakthrough was the finding that MSCs are able to induce peripheral tolerance, suggesting that they may be used as therapeutic tools in immune-mediated disorders. Although no significant adverse events have been reported in clinical trials to date, all interventional therapies have some inherent risks. Potential risks for undesirable events, such as tumor development, that might occur while using these stem cells for therapy must be taken into account and contrasted against the potential benefits to patients.

Stimulation of angiogenesis, neurogenesis and regeneration by side population cells from dental pulp

Mesenchymal stem cells (MSCs) have been used for cell therapy in various experimental disease models. However, the regenerative potential of MSCs from different tissue sources and the influence of the tissue niche have not been investigated. In this study, we compared the regenerative potential of dental pulp, bone marrow and adipose tissue-derived CD31(-) side population (SP) cells isolated from an individual porcine source. Pulp CD31(-) SP cells expressed the highest levels of angiogenic/neurotrophic factors and had the highest migration activity. Conditioned medium from pulp CD31(-) SP cells produced potent anti-apoptotic activity and neurite outgrowth, compared to those from bone marrow and adipose CD31(-) SP cells. Transplantation of pulp CD31(-) SP cells in a mouse hindlimb ischemia model produced higher blood flow and capillary density than transplantation of bone marrow and adipose CD31(-) SP cells. Motor function recovery and infarct size reduction were greater with pulp CD31(-) SP cells. Pulp CD31(-) SP cells induced maximal angiogenesis, neurogenesis and pulp regeneration in ectopic transplantation models compared to other tissue sources. These results demonstrate that pulp stem cells have higher angiogenic, neurogenic and regenerative potential and may therefore be superior to bone marrow and adipose stem cells for cell therapy.

Gap junctional coupling with cardiomyocytes is necessary but not sufficient for cardiomyogenic differentiation of cocultured human mesenchymal stem cells

Gap junctional coupling is important for functional integration of transplanted cells with host myocardium. However, the role of gap junctions in cardiomyogenic differentiation of transplanted cells has not been directly investigated. The objective of this work is to study the role of connexin43 (Cx43) in cardiomyogenic differentiation of human mesenchymal stem cells (hMSCs). Knockdown of Cx43 gene expression (Cx43↓) was established in naturally Cx43-rich fetal amniotic membrane (AM) hMSCs, while Cx43 was overexpressed (Cx43↑) in inherently Cx43-poor adult adipose tissue (AT) hMSCs. The hMSCs were exposed to cardiomyogenic stimuli by coincubation with neonatal rat ventricular cardiomyocytes (nrCMCs) for 10 days. Differentiation was assessed by immunostaining and whole-cell current clamping. To establish whether the effects of Cx43 knockdown could be rescued, Cx45 was overexpressed in Cx43↓ fetal AM hMSCs. Ten days after coincubation, not a single Cx43↓ fetal AM hMSC, control adult AT MSC, or Cx43↑ adult AT mesenchymal stem cell (MSC) expressed α-actinin, while control fetal AM hMSCs did (2.2% ± 0.4%, n = 5,000). Moreover, functional cardiomyogenic differentiation, based on action potential recordings, occurred only in control fetal AM hMSCs. Of interest, Cx45 overexpression in Cx43↓ fetal AM hMSCs restored their ability to undergo cardiomyogenesis (1.6% ± 0.4%, n = 2,500) in coculture with nrCMCs. Gap junctional coupling is required for differentiation of fetal AM hMSCs into functional CMCs after coincubation with nrCMCs. Heterocellular gap junctional coupling thus plays an important role in the transfer of cardiomyogenic signals from nrCMCs to fetal hMSCs but is not sufficient to induce cardiomyogenic differentiation in adult AT hMSCs.