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  • pterostilbene Introduction The stem cells extracted from the

    2018-11-08

    Introduction The stem cells extracted from the inner cell mass of an embryo are pluripotent, i.e. they have unique ability of long-term self-renewal and the potential to develop into all specialized cell types (Evans and Kaufman, 1981; Martin, 1981). However, embryonic stem cells with different origins have different characteristics. Mouse and human embryonic stem cells (mESCs and hESCs, respectively) are distinguished for example, by their morphology, marker gene expression, and culture requirements (Xue et al., 2011). Also, different pluripotent states of embryonic cells have been identified in both species at different stages of pre- and postimplantation embryos. Epiblast stem cells (EpiSC) (Brons et al., 2007) from mouse postimplantation embryo are considered pluripotent, however, but exhibit limited differentiation potential and the characteristics more resemble hESCs than mESCs (Nichols and Smith, 2009; Tesar et al., 2007). It has been proposed that mESCs represent the naïve, ground state pluripotency, whereas EpiSCs and hESCs are primed pluripotent cells. Recent studies have also succeeded in establishing naïve human stem cell cultures that differ from hESCs and have mESC characteristics (Chan et al., 2013; Gafni et al., 2013; Hanna et al., 2010; Takashima et al., 2014; Theunissen et al., 2014; Ware et al., 2014), but more closely resemble human preimplantation pterostilbene (Huang et al., 2014). Micro RNAs (miRNA) are small non-coding RNA molecules acting primarily in translational repression. Interestingly, different pluripotent states can be discriminated by their miRNA profiles (Jouneau et al., 2012; Neveu et al., 2010). The family of Let-7 miRNAs is highly expressed in somatic cells, and repression of Let-7 is thought to be important in establishing the pluripotent state (Melton et al., 2010; Viswanathan and Daley, 2010). Let-7 together with Lin28 has been reported to form a bistable switch in mice and nematodes. This double negative feedback loop is thought to stabilize and determine different cellular fates, Lin28 in establishing the undifferentiated and Let-7 the differentiated cell state (Shyh-Chang and Daley, 2013; Viswanathan and Daley, 2010). Human LIN28 protein has two paralogs, LIN28A (also LIN28) and LIN28B, and both have been shown to have a role in pluripotency and cell reprogramming (Qiu et al., 2010; Yu et al., 2007; Zhang et al., 2016). LIN28 proteins have also been shown to be important in cancers and to inhibit Let-7 biogenesis. However, there is increasing evidence that LIN28 proteins have also Let-7 independent functions (Mayr and Heinemann, 2013; Shyh-Chang and Daley, 2013).
    Materials and methods
    Results and discussion
    Funding The work was supported by Turku Doctoral Programme of Biomedical Sciences, The Finnish Cancer Organization, The Hospital District of Southwest Finland, Finnish Cultural Foundation, Emil Aaltonen Foundation, Ida Montin Foundation, Waldemar von Frenckell Foundation, Finnish-Norwegian medical Foundation, the Sigrid Jusélius Foundation and Paulo Foundation, and the Academy of Finland Centre of Excellence in Molecular Systems Immunology and Physiology Research, 2012–2017 and the pterostilbene Academy of Finland (grants 123322, 116713, and 250114).
    Author contributions
    Acknowledgements
    Introduction The increasing demand for alternatives to bone grafting as a method of treating critical bone defects has led to a growing interest in cell based regenerative therapies and selection of appropriate cell sources for bone tissue engineering is a key research area. Recently, cells derived from human dental pulp (DPCs) have been characterised as an accessible source of multipotent stem cells which can be differentiated to a matrix mineralised phenotype. In vivo transplant studies with DPCs indicate a tissue formation whose phenotype most resembles dentin in structure although the processes of dentinogenesis and osteogenesis share regulatory mechanisms and gene expression profiles (Gronthos et al., 2002). Subsequently stem cells have been isolated from other tissue niches within the oral cavity including periodontal ligament (PDLSCs) (Seo et al., 2004), apical papilla (SCAP) (Sonoyama et al., 2006), dental follicle (DFSCs) (Morsczeck et al., 2005), and exfoliated deciduous teeth (SHED) (Gronthos et al., 2000a). As dental tissues develop from oral ectoderm and neural crest derived mesenchyme, they contain pluripotent stem cell populations which display a developmental potential similar to embryonic stem cells (ESCs) and are able to differentiate into several different lineages (Le Douarin & Dupin, 2003; Le Douarin et al., 2004). Typically undifferentiated cells display a fibroblast-like morphology with associated high efficiency for adherent colony formation and high proliferative potential (Kerkis & Caplan, 2011). All of these factors suggest that adult dental tissues may provide a source of material (often discarded in the clinic) to provide multipotent cells for subsequent tissue engineering studies.