Regulation of Stem Cell Fate by ROS-mediated Alteration of Metabolism

Ryu, Jung Min,Lee, Hyun Jik,Jung, Young Hyun,Lee, Ki Hoon,Kim, Dah Ihm,Kim, Jeong Yeon,Ko, So Hee,Choi, Gee Euhn,Chai, Ing Ing,Song, Eun Ju,Oh, Ji Young,Lee, Sei-Jung,Han, Ho Jae Korean Society for Stem Cell Research 2015 International journal of stem cells Vol.8 No.1

<P>Stem cells have attracted much attention due to their distinct features that support infinite self-renewal and differentiation into the cellular derivatives of three lineages. Recent studies have suggested that many stem cells both embryonic and adult stem cells reside in a specialized niche defined by hypoxic condition. In this respect, distinguishing functional differences arising from the oxygen concentration is important in understanding the nature of stem cells and in controlling stem cell fate for therapeutic purposes. ROS act as cellular signaling molecules involved in the propagation of signaling and the translation of environmental cues into cellular responses to maintain cellular homeostasis, which is mediated by the coordination of various cellular processes, and to adapt cellular activity to available bioenergetic sources. Thus, in this review, we describe the physiological role of ROS in stem cell fate and its effect on the metabolic regulation of stem cells.</P>

Cell Sources, Liver Support Systems and Liver Tissue Engineering: Alternatives to Liver Transplantation

Lee, Soo Young,Kim, Han Joon,Choi, Dongho Korean Society for Stem Cell Research 2015 International journal of stem cells Vol.8 No.1

<P>The liver is the largest organ in the body; it has a complex architecture, wide range of functions and unique regenerative capacity. The growing incidence of liver diseases worldwide requires increased numbers of liver transplant and leads to an ongoing shortage of donor livers. To meet the huge demand, various alternative approaches are being investigated including, hepatic cell transplantation, artificial devices and bioprinting of the organ itself. Adult hepatocytes are the preferred cell sources, but they have limited availability, are difficult to isolate, propagate poor and undergo rapid functional deterioration in vitro. There have been efforts to overcome these drawbacks; by improving culture condition for hepatocytes, providing adequate extracellular matrix, co-culturing with extra-parenchymal cells and identifying other cell sources. Differentiation of human stem cells to hepatocytes has become a major interest in the field of stem cell research and has progressed greatly. At the same time, use of decellularized organ matrices and 3 D printing are emerging cutting-edge technologies for tissue engineering, opening up new paths for liver regenerative medicine. This review provides a compact summary of the issues, and the locations of liver support systems and tissue engineering, with an emphasis on reproducible and useful sources of hepatocytes including various candidates formed by differentiation from stem cells.</P>

The Molecular Nature of Very Small Embryonic-Like Stem Cells in Adult Tissues

Kim, YongHwan,Jeong, Jaeho,Kang, Hyunsook,Lim, Jisun,Heo, Jinbeom,Ratajczak, Janina,Ratajczak, Mariusz Z.,Shin, Dong-Myung Korean Society for Stem Cell Research 2014 International journal of stem cells Vol.7 No.2

<P>Pluripotent stem cells (PSCs) have been considered as the most important cells in regenerative medicine as they are able to differentiate into all types of cells in the human body. PSCs have been established from several sources of embryo tissue or by reprogramming of terminally differentiated adult tissue by transduction of so-called Yamanaka factors (<I>Oct4</I>, <I>Sox2</I>, <I>Klf4</I>, and <I>cMyc</I>). Interestingly, accumulating evidence has demonstrated the residence of PSCs in adult tissue and with the ability to differentiate into multiple types of tissue-committed stem cells (TCSCs). We also recently demonstrated that a population of pluripotent Oct4<SUP>+</SUP> SSEA-1<SUP>+</SUP>Sca-1<SUP>+</SUP>Lin<SUP>−</SUP>CD45<SUP>−</SUP> very small embryonic-like stem cells (VSELs) resides in the adult murine bone marrow (BM) and in other murine tissue. These very small (∼3–6 <I>μ</I>m) cells express pluripotent markers such as Oct4, Nanog, and SSEA-1. VSELs could be specified into several tissue-residing TCSCs in response to tissue/organ injury, and thus suggesting that these cells have a physiological role in the rejuvenation of a pool of TCSCs under steady-state conditions. In this review article, we discuss the molecular nature of the rare population of VSELs which have a crucial role in regulating the pluripotency, proliferation, differentiation, and aging of these cells.</P>

In vivo Evaluation of Human Embryonic Stem Cells Isolated by 57-C11 Monoclonal Antibody

Kim, Won-Tae,Lee, Hyun Min,Kim, Min Kyu,Choi, Hong Seo,Ryu, Chun Jeih Korean Society for Stem Cell Research 2016 International journal of stem cells Vol.9 No.2

<P><B>Background</B></P><P>The normal cells derived from human embryonic stem cells (hESCs) are regarded as substitutes for damaged or dysfunctional adult cells. However, tumorigenicity of hESCs remains a major challenge in clinical application of hESC-derived cell transplantation. Previously, we generated monoclonal antibody (MAb) 57-C11 specific to the surface molecule on undifferentiated hESCs. The aim of this study is to prove whether 57-C11-positive hESCs are pluripotent and tumorigenic in immunodeficient mice.</P><P><B>Methods</B></P><P>Undifferentiated hESCs were mixed with retinoic acid (RA)-differentiated hESCs at different ratios prior to 57-C11-mediated separation. To isolate 57-C11-positive hESCs from the mixture, biotinylated 57-C11 and streptavidin-coated magnetic beads were added to the mixture. Unbound 57-C11-negative hESCs were first isolated after applying magnet to the cell mixture, and 57-C11-bound hESCs were then released from the magnetic beads. In order to measure the efficiency of separation, 57-C11-positive or -negative hESCs were counted after isolation. To evaluate the efficiency of teratoma formation <I>in vivo</I>, 57-C11-positive or negative cells were further injected into left and right, respectively, testes of nonobese diabetic/severe combined immunodeficiency (NOD/SCID) mice.</P><P><B>Results</B></P><P>Approximately 77~100% of undifferentiated hESCs were isolated after applying 57-C11-coated magnetic beads to the mixed cell populations. Importantly, teratomas were not observed in NOD/SCID mice after the injection of isolated 57-C11-negative hESCs, whereas teratomas were observed with 57-C11-positive hESCs.</P><P><B>Conclusion</B></P><P>57-C11-positive hESCs are pluripotent and tumorigenic. The combination of 57-C11 and magnetic beads will be useful to eliminate remaining undifferentiated hESCs for the safe cell transplantation.</P>

The Bromodomain Inhibitor JQ1 Enhances the Responses to All- <i>trans</i> Retinoic Acid in HL-60 and MV4-11 Leukemia Cells

Kang, Changhee,Kim, C-Yoon,Kim, Hyuk Soon,Park, Se-Pill,Chung, Hyung-Min Korean Society for Stem Cell Research 2018 International journal of stem cells Vol.11 No.1

<P>All-<I>trans</I> retinoic acid (ATRA) is a highly effective treatment for acute promyelocytic leukemia (APL), a cytogenetically distinct subtype of acute myeloid leukemia (AML). However, ATRA-based treatment is not effective in other subtypes of AML. In non-APL AML, ATRA signaling pathway is impaired or downmodulated, and consequently fails to respond to pharmacological doses of ATRA. Therefore, complementary treatment strategies are needed to improve ATRA responsiveness in non-APL AML. In this study, we investigated the combined effect of ATRA and bromodomain inhibitor JQ1, proven to have potent anti-cancer activity mainly through inhibition of c-Myc. We showed that the combination of ATRA with JQ1 synergistically inhibited proliferation of AML cells. The synergistic growth inhibition was resulted from differentiation or apoptosis depending on the kind of AML cells. Concomitantly, the combined treatment of ATRA and JQ1 caused greater depletion of c-Myc and hTERT expression than each agent alone in AML cells. Taken together, these findings support the rationale for the use of the combination of ATRA and JQ1 as a therapeutic strategy for the treatment of AML.</P>

Regeneration of Bovine Mammary Gland in Immunodeficient Mice by Transplantation of Bovine Mammary Epithelial Cells Mixed with Matrigel

Park, Hyun Jung,Lee, Won Young,Jeong, Ha Yeon,Song, Hyuk Korean Society for Stem Cell Research 2016 International journal of stem cells Vol.9 No.2

<P><B>Background and Objectives</B></P><P>With the global demand for dairy protein for consumption growing annually, there has been increasing activity in the research field of dairy protein synthesis and production. From a manipulation perspective, it is more difficult to use live cattle for laboratory studies on the production of milk as well as of dairy protein such as casein, as compared with using laboratory animals like rodents. Therefore, we aimed to develop a mouse model of bovine mammary alveolar ducts for laboratory-scale studies. We studied the formation of the bovine mammary gland ductal structure by transplanting the MAC-T bovine alveolar cell line into mice.</P><P><B>Methods and Results</B></P><P>MAC-T cells (1×10<SUP>7</SUP>) were suspended in Matrigel and injected into the dorsal tissue of 8-week-old male BALB/C nude mice. Histological analysis of tissue dissected from the MAC-T cell-transplanted mice after 6 weeks showed the typical morphology of the tubuloalveolar female gland, as well as glands made up of branching ducts that were surrounded by smooth muscle with small alveoli budding off the ducts. In addition, the epithelial markers CK14 and CK18 were expressed within the duct-like structure. Prolactin was detected in the duct interior in these CK14+ and CK18+ cells but not in the non-transplanted MAC-T cells.</P><P><B>Conclusions</B></P><P>These results showed that duct-like tissue had been successfully formed after 6 weeks of transplantation of the CK14+ and CK18+ MAC-T cells into mice dorsal tissue. This mouse model will be a useful tool for further research on the bovine mammary gland.</P>

FGF8 is Essential for Functionality of Induced Neural Precursor Cell-derived Dopaminergic Neurons

Lim, Mi-Sun,Lee, Soo Young,Park, Chang-Hwan Korean Society for Stem Cell Research 2015 International journal of stem cells Vol.8 No.2

<P>Induced neural precursor cells (iNPCs) are one source of transplantable dopaminergic neurons used in cell therapy for Parkinson’s disease. In the present study, we demonstrate that iNPCs can be generated by transducing Brn2, Ascl1, Myt1L and Bcl-xL in a culture supplemented with several mitogens and subsequently can be differentiated to dopaminergic neurons (DA). However, studies have shown that iDA and/or iNPC-derived DA neurons using various conversion protocols have low efficiency. Here, we show that early exposure of FGF8 to fibroblasts efficiently improves differentiation of DA neurons. So our study demonstrates that FGF8 is a critical factor for generation of iNPC-derived DA neurons.</P>

The Pharmacological Inhibition of ERK5 Enhances Apoptosis in Acute Myeloid Leukemia Cells

Kang, Changhee,Kim, Jong Soo,Kim, C-Yoon,Kim, Eun-Young,Chung, Hyung-Min Korean Society for Stem Cell Research 2018 International journal of stem cells Vol.11 No.2

<P>Acute myeloid leukemia (AML) is a fatal hematological malignancy which is resistant to a variety of chemotherapy drugs. Extracellular signal-regulated kinase 5 (ERK5) plays a novel role in chemoresistance in some cancer cells and this pathway is a central mediator of cell survival and apoptotic regulation. The aim of this study was to investigate the effect of ERK5 inhibitor, XMD8-92, on proliferation and apoptosis in AML cell lines. Findings showed that XMD8-92 inhibited the activation of ERK5 by G-CSF and decreased the expression of c-Myc and Cyclin D1. The treatment of XMD8-92 reduced the phosphorylation of ERK5 leading to a distinct inhibition of cell proliferation and increased apoptosis in Kasumi-1 and HL-60 cells. Taken together, our study suggests that the inhibition of ERK5 by XMD8-92 can trigger apoptosis and inhibit proliferation in AMLs. Therefore, the inhibition of ERK5 may be an effective adjuvant in AML chemotherapy.</P>

Improved Transfection Efficiency and Metabolic Activity in Human Embryonic Stem Cell Using Non-Enzymatic Method

Kim, C-Yoon,Hwang, In-Kyu,Kang, Changhee,Chung, Eun-Bin,Jung, Cho-Rok,Oh, Hanseul,Jeong, Young-Hoon,Moon, Sung-Hwan,Kim, Jong Soo,Hong, Ki-Sung,Park, Jae-Hak,Chung, Hyung-Min Korean Society for Stem Cell Research 2018 International journal of stem cells Vol.11 No.2

<P>Human embryonic stem cells (hESCs) are pluripotent cells widely used in conventional and regenerative medicine due to their ability to self-renew, proliferate and differentiate. Recently, genetic modification of stem cells using genome editing is the most advanced technique for treating hereditary diseases. Nevertheless, the low transfection efficiency of hESCs using enzymatic methods is still limited in <I>in vitro</I> preclinical research. To overcome these limitations, we have developed transfection methods using non-enzymatic treatments on hESCs. In this study, hESCs were transfected following enzymatic (TrypLE and trypsin) and non-enzymatic treatment ethylenediaminetetraacetic acid (EDTA) to increase transfection efficiency. Flow cytometric analysis using an enhanced green fluorescent protein vector showed a significantly increased transfection efficiency of EDTA method compared to standard enzyme method. In addition, the EDTA approach maintained stable cell viability and recovery rate of hESCs after transfection. Also, metabolic activity by using Extracellular Flux Analyzer revealed that EDTA method maintained as similar levels of cell functionality as normal group comparing with enzymatic groups. These results suggest that transfection using EDTA is a more efficient and safe substitute for transfection than the use of standard enzymatic methods.</P>

MiR-9 Controls Chemotactic Activity of Cord Blood CD34+ Cells by Repressing CXCR4 Expression

Ha, Tae Won,Kang, Hyun Soo,Kim, Tae-Hee,Kwon, Ji Hyun,Kim, Hyun Kyu,Ryu, Aeli,Jeon, Hyeji,Han, Jaeseok,Broxmeyer, Hal E.,Hwang, Yongsung,Lee, Yun Kyung,Lee, Man Ryul Korean Society for Stem Cell Research 2018 International journal of stem cells Vol.11 No.2

<P>Improved approaches for promoting umbilical cord blood (CB) hematopoietic stem cell (HSC) homing are clinically important to enhance engraftment of CB-HSCs. Clinical transplantation of CB-HSCs is used to treat a wide range of disorders. However, an improved understanding of HSC chemotaxis is needed for facilitation of the engraftment process. We found that ectopic overexpression of miR-9 and antisense-miR-9 respectively down- and up-regulated C-X-C chemokine receptor type 4 (CXCR4) expression in CB-CD34<SUP>+</SUP> cells as well as in 293T and TF-1 cell lines. Since CXCR4 is a specific receptor for the stromal cell derived factor-1 (SDF-1) chemotactic factor, we investigated whether sense miR-9 and antisense miR-9 influenced CXCR4-mediated chemotactic mobility of primary CB CD34<SUP>+</SUP> cells and TF-1 cells. Ectopic overexpression of sense miR-9 and antisense miR-9 respectively down- and up-regulated SDF-1-mediated chemotactic cell mobility. To our knowledge, this study is the first to report that miR-9 may play a role in regulating CXCR4 expression and SDF-1-mediated chemotactic activity of CB CD34<SUP>+</SUP> cells.</P>