Self-renewal Ability Of Stem Cells Research Articles

Organ Regeneration Through Stem Cells and Tissue Engineering.

Loss of organ and tissue due to injuries or diseases led to the development of regenerative therapies to decrease reliance on organ transplantations. It deals with employing the self-renewal ability of stem cells to differentiate into numerous lineages to assist in providing effective treatment for a range of various injuries and diseases. Regenerative engineering of organs or tissues represents an ever-expanding field that is aimed at developing biological replacements for dysfunctional organs or injured tissues. The critical issue, however, with the engineering of organs outside the human body is the insufficient availability of human cells, the absence of a suitable matrix with the same architecture and composition as the target tissue, and the maintenance of organ viability in the absence of the blood supply. The issue regarding the maintenance of the engineered organ viability can be solved using bioreactors consisting of mediums with defined chemical composition, i.e., nutrients, cofactors, and growth factors that can successively sustain the target cell's viability. Engineered extracellular matrices and stem cells toregenerate organs outside the human body are also being used. Clinically, various adult stem cell therapies are readily under practice. This review will focus on the regeneration of organs through various types of stem cells and tissue engineering techniques.

Targeting the stem cell niche: role of collagen XVII in skin aging and wound repair.

The skin epidermis and appendages undergo ongoing renewal throughout life. Stem cells residing in the epidermis and hair follicles are pivotal for sustaining skin homeostasis. The self-renewal ability of stem cells significantly decreases during skin aging but actively increases during wound repair. Residential stem cells reside in niches that provide spatially distinct microenvironments for stem cell maintenance and function. Cell-extracellular matrix (ECM) adhesion is essential for the establishment of niche architecture. Collagen XVII (COL17), as a transmembrane protein constituting hemidesmosomes (HDs), mediates the interactions of stem cells with surrounding cells and the matrix to regulate skin homeostasis, aging and wound repair. This review focuses on the pivotal role of the niche component COL17 in stem cell maintenance and its function in regulation of skin aging and wound repair.

Inflammatory Regulation by TNF-α-Activated Adipose-Derived Stem Cells in the Human Bladder Cancer Microenvironment.

Mesenchymal stem cells (MSCs), such as adipose-derived stem cells (ADSCs), have the most impressive ability to reduce inflammation through paracrine growth factors and cytokines that participate in inflammation. Tumor necrosis factor (TNF)-α bioactivity is a prerequisite in several inflammatory and autoimmune disease models. This study investigated the effects of TNF-α stimulate on ADSCs in the tumor microenvironment. The RNAseq analysis and cytokines assay demonstrated that TNF-α stimulated ADSCs proliferation and pro-inflammatory genes that correlated to leukocytes differentiation were upregulated. We found that upregulation of TLR2 or PTGS2 toward to IRF7 gene-associated with immunomodulatory and antitumor pathway under TNF-α treatment. In TNF-α-treated ADSCs cultured with the bladder cancer (BC) cell medium, the results showed that apoptosis ratio and OCT-4 and TLR2 genes which maintained the self-renewal ability of stem cells were decreased. Furthermore, the cell survival regulation genes including TRAF1, NF-kB, and IRF7 were upregulated in TNF-α-treated ADSCs. Additionally, these genes have not been upregulated in BC cell medium. A parallel study showed that tumor progressing genes were downregulated in TNF-α-treated ADSCs. Hence, the study suggests that TNF-α enhances the immunomodulatory potential of ADSCs during tumorigenesis and provides insight into highly efficacious MSC-based therapeutic options for BC.

Functionally enhanced placenta-derived mesenchymal stem cells inhibit adipogenesis in orbital fibroblasts with Graves\u2019 ophthalmopathy

BackgroundPlacenta-derived mesenchymal stem cells (PD-MSCs) have unique immunomodulatory properties. Phosphatase of regenerating liver-1 (PRL-1) regulates the self-renewal ability of stem cells and promotes proliferation. Graves’ ophthalmopathy (GO) is an autoimmune inflammatory disease of the orbit and is characterized by increased orbital levels of adipose tissue. Here, we evaluated the therapeutic mechanism for regulation of adipogenesis by PRL-1-overexpressing PD-MSCs (PD-MSCsPRL-1, PRL-1+) in orbital fibroblast (OF) with GO patients.MethodsPD-MSCs isolated from human placenta were transfected with the PRL-1 gene using nonviral transfection method. Primary OFs were isolated from orbital adipose tissue specimens from GO patients. After maturation as adipogenic differentiation, normal and GO-derived OFs were cocultured with naïve and PD-MSCsPRL-1. We analyzed the protein levels of adipogenesis markers and their signaling pathways in OFs from GO patients.ResultsThe characteristics of PD-MSCsPRL-1 were similar to those of naïve cells. OFs from GO patients induced adipocyte differentiation and had significantly decreased a lipid accumulation after coculture with PD-MSCsPRL-1 compared to naïve cells. The mRNA and protein expression of adipogenic markers was decreased in PD-MSCsPRL-1. Insulin-like growth factor-binding proteins (IGFBPs) secreting PD-MSCsPRL-1 downregulated the phosphorylated PI3K/AKT/mTOR expression in OFs from GO patients. Interestingly, IGFBP2, − 4, − 6, and − 7 expression in PD-MSCsPRL-1, which was mediated by integrin alpha 4 (ITGA4) and beta 7 (ITGB7), was higher than that in naïve cells and upregulated phosphorylated FAK downstream factor.ConclusionIn summary, IGFBPs secreting PD-MSCPRL-1 inhibit adipogenesis in OFs from GO patients by upregulating phosphorylated FAK and downregulating PI3K/AKT/mTOR signaling pathway. The functional enhancement of PD-MSCs by nonviral gene modification provides a novel therapeutic strategy for the treatment of degenerative diseases.

MicroRNA‐377 acts as a suppressor in esophageal squamous cell carcinoma through CBX3‐dependent P53/P21 pathway

Stem cells play pivotal roles in esophageal squamous cell carcinoma (ESCC) recurrence and metastasis. The self-renewal ability of stem cells was associated with specific microRNAs (miRs). Herein, we identified the effects of miR-377 on ESCC stem cell activities. First, the expression of miR-377 in ESCC and adjacent normal tissues was determined. The relationship between miR-377 and chromobox protein homolog 3 (CBX3) was assessed by a dual-luciferase reporter gene assay. miR-377 was overexpressed or inhibited in ESCC stem cells to explore its role in ESCC. To further investigate the mechanism of miR-377 in ESCC, cells were introduced with short hairpin RNA against CBX3 or pifithrin-α (inhibitor of P53 pathway). Besides, the expression of P21, P53, CD133, CD13, Nanog, sex determining region Y-Box 2 (Sox2), and octamer-binding transcription factor 4 (Oct4), cell sphere formation, colony formation, and proliferation were evaluated respectively. Finally, limiting dilution assay in vivo and tumor xenograft in nude mice were conducted to confirm the roles of miR-377 in vivo. miR-377 was poorly expressed in ESCC. Overexpression of miR-377 could suppress the stem-like trait of ESCC as well as the tumor growth in vivo. miR-377 targeted CBX3 to activate the P53/P21 pathway. Besides, the expression of stem-like markers including CD133, CD13, Oct4, Sox2, and Nanog was decreased, and the abilities of cell sphere formation, colony formation, proliferation, and tumorigenicity were significantly reduced by overexpressing miR-377 or silencing CBX3. The results were reversed after inactivating the P53/P21 pathway. In summary, upregulation of miR-377 inhibits the self-renewal of ESCC stem cells by inhibiting CBX3 expression and promoting activation of the P53/P21 pathway.

Abstract 3125: SOX2 controls the tumor initiation and development and acts as a prognostic predictor of oral squamous cell carcinoma

Abstract Background: Sex determining region Y-BOX2 (SOX2), a regulator of the self-renewal ability of stem cells, plays a compelling role in initiation and development of cancer. However, little is known about the role and network controlling of SOX2 in oral squamous cell carcinoma (OSCC) development. Method: In this study, we conducted a retrospective cohort of 229 OSCC patients from two independent Chinese centers from May 2003 to August 2012. SOX2 expression in these samples was determined by immunostaining. Univariate and multivariate analyses were performed. Then we generated SOX2-creERT2 mice that expressing an inducible Cre recombinase under the control of a minimal promoter of SOX2, along with a tdTomato reporter. These mice were exposed to low dose 4NQO in the drinking water either for 8, 12 or 16 weeks. We further investigate the network controlling of SOX2 by ChIP assay. Then we detected the expression of SOX2 in response to AFF4 knockdown and overexpression by western blot, respectively. Furthermore, we used wound-healing, transwell, sphere formation and limiting dilution assay to confirm whether SOX2 expression was regulated by AFF4. Results: In the multiple cohorts, high SOX2 protein expression was negatively correlated with the overall survival for OSCC patients. Impressively, we found chemotherapy only improved outcomes of patients with low SOX2 expression, but very limited effects to high SOX2 expression patients. Meanwhile low SOX2 expression patients had significantly better survival with rather than without chemotherapies. Lineage tracing study in vivo suggested that SOX2 positive cells play an important role in the carcinogenesis of OSCC as epithelial stem cells. Increasing SOX2 positive cells and their daughter cells was a major trigger in the initiation of OSCC. Mechanistically, we found SOX2 was regulated by AFF4, the core component of Super elongation complex (SEC) to promote the proliferation, migration and invasion of OSCC cells. SOX2 expression changed in parallel with AFF4 expression in response to depletion and overexpression of AFF4, respectively. More importantly, the inhibited proliferation, migration, invasion and ALDH activity induced by knockdown of AFF4 in OSCC cells were rescued by overexpression of SOX2. Conclusion: Collectively, our findings indicate SOX2 acts as a prognostic predictor and controls the tumor initiation and development in oral squamous cell carcinoma. SOX2 may serve as a potential target of therapies for patients with OSCC. Note: This abstract was not presented at the meeting. Citation Format: ZIHAO WEI, FENGYING YIN, PENG DENG, XUEFENG ZHANG, JING DENG, JING LI, LIANG XIE, QIANMING CHEN. SOX2 controls the tumor initiation and development and acts as a prognostic predictor of oral squamous cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3125.

CD133 promotes the self-renewal capacity of thyroid cancer stem cells through activation of glutamate aspartate transporter SLC1A3 expression

CD133+ cancer stem cells are responsible for thyroid cancer initiation. The regulatory pathways essential for sustaining the self-renewal of thyroid cancer stem cells remain largely unknown. Glutamate signaling regulates the self-renewal ability of stem cells. In the present study, we found that the level of glutamate was higher in CD133+ thyroid cancer cells than in CD133- thyroid cancer cells. The transcriptional level of glutamate aspartate transporter SLC1A3 was high in CD133+ thyroid cancer cells. Activation of NF-κB signaling by CD133 was responsible for SLC1A3 high transcription level in CD133+ thyroid cancer cells. Knock down of SLC1A3 significantly reduced the level of glutamate and inhibited the self-renewal activity and tumorigenicity of CD133+ thyroid cancer cells. Overexpression of SLC1A3 rescued the negative effect of CD133 knockdown on the self-renewal capability of CD133+ thyroid cancer cells. Taken together, CD133 promotes the self-renewal capacity of CD133+ thyroid cancer cells at least partly through activation of SLC1A3 expression.

Biophysical factors in the regulation of asymmetric division of stem cells.

Stem cells are a promising cell source for regenerative medicine due to their characteristics of self-renewal and differentiation. The intricate balance between these two cell fates is maintained by precisely controlled symmetric and asymmetric cell divisions. Asymmetric division has a fundamental importance in maintaining tissue homeostasis and in the development of multi-cellular organisms. For example, during development, asymmetric cell divisions are responsible for the formation of the body axis. Mechanistically, mitotic spindle dynamics determine the assembly and separation of chromosomes and regulate the orientation of cell division. Interestingly, symmetric and asymmetric cell division is not mutually exclusive and a range of factors are involved in such cell-fate decisions, the measurement of which can provide efficient and reliable information on the regenerative potential of a cell. The balance between self-renewal and differentiation in stem cells is controlled by various biophysical and biochemical cues. Although the role of biochemical factors in asymmetric stem cell division has been widely studied, the effect of biophysical cues in stem-cell self-renewal is not comprehensively understood. Herein, we review the biological relevance of stem-cell asymmetric division to regenerative medicine and discuss the influences of various intrinsic and extrinsic biophysical cues in stem-cell self-renewal. This review particularly aims to inform the clinical translation of efforts to control the self-renewal ability of stem cells through the tuning of various biophysical cues.

Abstract 3059: SOX2 is a novel biomarker for poor long-term outcomes in oral cancer

Abstract Purpose: Sex determining region Y-BOX2 (SOX2), a key regulator of the self-renewal ability of stem cells, plays a role in the initiation and development of head and neck squamous cell carcinoma (HNSCC). However, the association between SOX2 expression and the outcomes of patients with oral squamous cell carcinoma (OSCC) has not been investigated. Thus, in this study, we investigated the possibility of predicting the survival outcomes of patients with OSCC by evaluating SOX2 expression. Experiment design: First, we analyzed SOX2 expression in patients with OSCC in The Cancer Genome Atlas (TCGA) dataset by a bioinformatics approach. In addition, samples of 219 patients with OSCC from two independent Chinese centers were collected. The median follow-up time and 95% confidence interval (CI) for the cohorts were 36 (25.06, 46.93) months and SOX2 expression in these samples was determined by immunostaining using tissue microarray. The Kaplan-Meier analysis, log-rank test, and Cox proportional hazards regression model were used to determine univariate and multivariate analyses, and hazard ratios for overall survival (OS), respectively. Results: In TCGA database, amplification of SOX2 was negatively correlated with the OS rate for patients who survived more than 300 days after the first diagnosis. Moreover, 39.7% of the samples from the cohorts showed high SOX2 expression. We found a significant difference in the survival rate between patients with high and low SOX2 expression ranging from 13 to 126 months. Conclusion: High SOX2 expression can predict poor long-term, but not short-term, survival outcomes in patients with OSCC. Our findings not only indicated that SOX2 may be a novel biomarker for the long-term prognosis of OSCC but also strongly supported the cancer stem cell theory that dysregulation of the self-renewal ability of stem cells may contribute to the development of OSCC. Citation Format: Xuefeng Zhang, Hao Xu, Chongkui Sun, Xinhua Liang, Peng Deng, Xin Zeng, Qianming Chen. SOX2 is a novel biomarker for poor long-term outcomes in oral cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3059.

Long-Term InVitro Expansion of Salivary Gland Stem Cells Driven by Wnt Signals.

SummaryAdult stem cells are the ultimate source for replenishment of salivary gland (SG) tissue. Self-renewal ability of stem cells is dependent on extrinsic niche signals that have not been unraveled for the SG. The ductal compartment in SG has been identified as the location harboring stem cells. Here, we report that rare SG ductal EpCAM+ cells express nuclear β-catenin, indicating active Wnt signaling. In cell culture experiments, EpCAMhigh cells respond potently to Wnt signals stimulating self-renewal and long-term expansion of SG organoids, containing all differentiated SG cell types. Conversely, Wnt inhibition ablated long-term organoid cultures. Finally, transplantation of cells pre-treated with Wnt agonists into submandibular glands of irradiated mice successfully and robustly restored saliva secretion and increased the number of functional acini in vivo. Collectively, these results identify Wnt signaling as a key driver of adult SG stem cells, allowing extensive in vitro expansion and enabling restoration of SG function upon transplantation.

Regulation of Mitochondrial Morphology Is Important for Leukemia Stem Cell Function

Studies from normal cell biology have demonstrated that mitochondria can switch between fission-active and fusion-active states to dramatically change their morphology during important developmental events such as lineage differentiation and cell division. Further, very recent research has revealed intriguing interactions between mitochondrial morphology regulation and oncogenic signals in cancer. To date however, whether mitochondrial morphology regulation plays a role in cancer stem cell function remains largely unknown.We report, in acute myelogenous leukemia (AML), leukemia stem cells (LSCs), characterized by a low level of reactive oxygen species (ROS), have hyper-active mitochondrial fission regulators as evidenced by higher levels of mitochondrial fission 1 (FIS1) and activating phosphorylation of dynamin-related protein 1 (DRP1), compared to non-LSCs. To directly compare the mitochondrial morphology in LSCs versus non-LSCs, we imaged mitochondrial morphology using transmission electron microscopy. Quantification of the imaging results showed that the LSCs contain an increased number of smaller and globular-shaped mitochondria (see Figure), indicating that they reside in a fission-active state relative to non-LSCs. Inhibition of mitochondrial fission through genetic knock-down of FIS1 (FIS1-KD) induces mitochondrial fusion and dramatically diminishes both colony-forming ability and serial engraftment potential of primary AML cells, suggesting a fission-active state of mitochondrial morphology is critical for LSC function.To dissect the mechanism by which FIS1 regulates primitive leukemia cells, we performed detailed analysis of molecular events following FIS1-KD. We found that AML cells lacking the function of FIS1 up-regulated the expression of mitochondrial oxidative phosphorylation (OXPHOS) proteins, suggesting an increased OXPHOS activity. We then observed through metabolomic studies that knock-down of FIS1 altered the level of metabolites involved in glycolysis and the citric acid cycle (TCA), suggesting that the FIS1-KD-induced change in OXPHOS activity affected other aspects of global cellular energy metabolism as well. Among the metabolic changes seen was an increase in Acetyl-CoA, which plays an important role in epigenetic regulation by serving as the substrate for histone acetylation. Consistently, we observed an increase in H3K27-acetylation in AML cells following FIS-KD, and our transcriptomic analysis using RNA-seq showed that AML cells lacking FIS1 function exhibited global up-regulation of a hematopoietic lineage differentiation gene signature including CD11B, CD14, CD36, and CD68, indicating an induction of differentiation. In addition to affecting energy metabolism and epigenetic landscape, FIS1-KD also increased cellular ROS level in AML cells. This may happen as a consequence of induced OXPHOS activity, since ROS is a major byproduct of oxygen metabolism in OXPHOS machineries.Taken together, our functional studies raise the hypothesis that mitochondrial morphology critically regulates LSC function. Our subsequent molecular studies begin to reveal two major potential mechanisms by which mitochondrial morphology regulators can affect LSC potential. First, FIS1-regulated mitochondrial morphology may sequentially affect mitochondrial OXPHOS activity, global energy metabolism, homeostasis of metabolites such as Acetyl-CoA that can link metabolism to epigenetics, and regulation of the epigenome that is required for sustaining LSCs. Second, FIS1 can also affect cellular ROS, a critical determinant of self-renewal ability of stem cells, to effect LSC function. Overall, our current study elucidates a previously unknown link between the regulation of mitochondrial morphology and LSC function, targeting of which represents a novel therapeutic means to eradicate LSCs. [Display omitted] DisclosuresPollyea:Ariad: Consultancy; GlycoMimetics: Other: Member of data safety monitoring board; Agios: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Consultancy; Karyopharm: Consultancy.

Comparison of gene expression of SOX2 and OCT4 in normal tissue, polyps, and colon adenocarcinoma using immunohistochemical staining

Background:Cancer stem cells have been isolated and characterized in all common cancers. SOX2 and OCT4 are important genes to enhance the self-renewal ability as activate stem cells and inhibit the genes that start differentiation and thus maintain the self-renewal ability of stem cells. Also, the aim of this study is “Comparison of gene expression of SOX2 and OCT4 in normal tissue, polyps, and colon adenocarcinoma using immunohistochemical staining.”Materials and Methods:This cross-sectional study conducted on 20 patients so that for each patient, a sample of healthy tissue, dysplastic polyp tissue, and colon adenocarcinoma were provided as microscopic sections and staining on each tissue was performed through immunohistochemistry method by markers OCT4 and SOX2. The collected data were interred into SPSS version 18.0, (SPSS Inc., Chicago, IL, USA) software and the level of significance were considered as <0.05.Results:The study sample consisted of 20 patients including 11 men (55%) and 9 women (45%) with a mean age of 55.6 ± 9.88 years. There was no association between Oct4 and colorectal cancer (CRC) patients (P > 0.05), but there was a significant correlation between Sox2 expression and CRC (P < 0.05). Patients in many aspects such as race, type of polyp, presence of lymph node, grade and intensity of Sox2 in different types of patients’ tissues (P < 0.05).Conclusion:Regarding our findings, the expression of Sox2 would be a liable marker for evaluating of cancer progression and could be a treatment target of CRC cells.

Biomaterial Strategies for Stem Cell Maintenance DuringIn VitroExpansion

Stem cells, having the potential for self-renewal and multilineage differentiation, are the building blocks for tissue/organ regeneration. Stem cells can be isolated from various sources but are, in general, available in too small numbers to be used directly for clinical purpose without intermediate expansion procedures in vitro. Although this in vitro expansion of undifferentiated stem cells is necessary, stem cells typically diminish their ability to self-renew and proliferate during passaging. Consequently, maintaining the stemness of stem cells has been recognized as a major challenge in stem cell-based research. This review focuses on the latest developments in maintaining the self-renewal ability of stem cells during in vitro expansion by biomaterial strategies. Further, this review highlights what should be the focus for future studies using stem cells for regenerative applications.