Browsing by Subject "EMBRYONIC STEM-CELLS"

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Now showing items 1-9 of 9
  • Clark, Christine; Palta, Priit; Joyce, Christopher J.; Scott, Carol; Grundberg, Elin; Deloukas, Panos; Palotie, Aarno; Coffey, Alison J. (2012)
  • Narva, Elisa; Stubb, Aki; Guzman, Camilo; Blomqvist, Matias; Balboa, Diego; Lerche, Martina; Saari, Markku; Otonkoski, Timo; Ivaska, Johanna (2017)
    Cell-type-specific functions and identity are tightly regulated by interactions between the cell cytoskeleton and the extracellular matrix (ECM). Human pluripotent stem cells (hPSCs) have ultimate differentiation capacity and exceptionally low-strength ECM contact, yet the organization and function of adhesion sites and associated actin cytoskeleton remain poorly defined. We imaged hPSCs at the cell-ECM interface with total internal reflection fluorescence microscopy and discovered that adhesions at the colony edge were exceptionally large and connected by thick ventral stress fibers. The actin fence encircling the colony was found to exert extensive Rho-ROCK-myosin-dependent mechanical stress to enforce colony morphology, compaction, and pluripotency and to define mitotic spindle orientation. Remarkably, differentiation altered adhesion organization and signaling characterized by a switch from ventral to dorsal stress fibers, reduced mechanical stress, and increased integrin activity and cell-ECM adhesion strength. Thus, pluripotency appears to be linked to unique colony organization and adhesion structure.
  • Punovuori, Anna Karolina; Malaguti, Mattias; Lowell, Sally (2021)
    During early neural development, changes in signalling inform the expression of transcription factors that in turn instruct changes in cell identity. At the same time, switches in adhesion molecule expression result in cellular rearrangements that define the morphology of the emerging neural tube. It is becoming increasingly clear that these two processes influence each other; adhesion molecules do not simply operate downstream of or in parallel with changes in cell identity but rather actively feed into cell fate decisions. Why are differentiation and adhesion so tightly linked? It is now over 60 years since Conrad Waddington noted the remarkable "Constancy of the Wild Type" (Waddington in Nature 183: 1654-1655, 1959) yet we still do not fully understand the mechanisms that make development so reproducible. Conversely, we do not understand why directed differentiation of cells in a dish is sometimes unpredictable and difficult to control. It has long been suggested that cells make decisions as 'local cooperatives' rather than as individuals (Gurdon in Nature 336: 772-774, 1988; Lander in Cell 144: 955-969, 2011). Given that the cadherin family of adhesion molecules can simultaneously influence morphogenesis and signalling, it is tempting to speculate that they may help coordinate cell fate decisions between neighbouring cells in the embryo to ensure fidelity of patterning, and that the uncoupling of these processes in a culture dish might underlie some of the problems with controlling cell fate decisions ex-vivo. Here we review the expression and function of cadherins during early neural development and discuss how and why they might modulate signalling and differentiation as neural tissues are formed.
  • Bogacheva, Mariia S.; Khan, Sofia; Kanninen, Liisa K.; Yliperttula, Marjo; Leung, Alan W.; Lou, Yan-Ru (2018)
    Definitive endoderm (DE) is the first stage of human pluripotent stem cell (hPSC) differentiation into hepatocyte-like cells. Developing human liver cell models for pharmaceutical applications is highly demanding. Due to the vast number of existing protocols to generate DE cells from hPSCs, we aimed to compare the specificity and efficiency of selected published differentiation conditions. We differentiated two hPSC lines (induced PSC and embryonic stem cell) to DE cells on Matrigel matrix using growth factors (Activin A and Wnt-3a) and small molecules (sodium butyrate and IDE 1) in different combinations. By studying dynamic changes during 6 days in cell morphology and the expression of markers for pluripotency, DE, and other germ layer lineages, we found that Activin A is essential for DE differentiation, while Wnt-3a and sodium butyrate are dispensable. Although sodium butyrate exerted rapid DE differentiation kinetics, it caused massive cell death and could not generate sufficient cells for further differentiation and applications. We further discover that IDE 1 could not induce DE as reported previously. Hereby, we compared different conditions for DE induction and found an effective six day-protocol to obtain DE cells for the further differentiation and applications.
  • Ahlgren, Johanna; Voikar, Vootele (2019)
    Low replicability of animal experiments is perceived as a major hurdle in the field of biomedicine. Attempts to enhance the replicability and to reduce the variability in basic research has led to the recommendation to use isogenic mice. The C57BL/6 strain has evolved as a gold standard strain for this purpose. However, C57BL/6 mice are maintained as substrains by multiple vendors. Evidence exists that the subtle differences between these mouse lines have not been systematically investigated and are often ignored. In the present study, we characterized the female mice of two closely related substrains (C57BL/6J and C57BL/6N) from three vendors in Europe (Charles River Laboratories, Envigo, Janvier Labs) in a battery of behavioral tests. Our data show and confirm substantial behavioral differences between the C57BL/6J and C57BL/6N mice. Importantly, the substrain differences were largely affected by the origin of the animals, as a significant effect of vendor or interaction between the substrain and vendor occurred in all tests. This work highlights the importance of adhering to precise international nomenclature in all publications reporting animal experiments. Moreover, the generalization of research findings from a single mouse substrain can be seriously limited due to genetic drift and environmental variables occurring at different vendors. However, heterogenization of samples, by including animals of different substrains, can enhance generalizability. These issues need to be seriously addressed to improve reproducibility, replicability, and the translational potential of the mouse models.
  • Karvonen, Eira; Krohn, Kai J. E.; Ranki, Annamari; Hau, Annika (2022)
    APECED (Autoimmune-Polyendocrinopathy-Candidiasis-Ectodermal-Dystrophy) is a severe and incurable multiorgan autoimmune disease caused by mutations in the AIRE (autoimmune regulator) gene. Without functional AIRE, the development of central and peripheral immune tolerance is severely impaired allowing the accumulation of autoreactive immune cells in the periphery. This leads to multiple endocrine and non-endocrine autoimmune disorders and mucocutaneous candidiasis in APECED patients. Recent studies have suggested that AIRE also has novel functions in stem cells and contributes to the regulatory network of pluripotency. In preparation of therapeutic gene correction, we generated and assessed patient blood cell-derived iPSCs, potentially suitable for cell therapy in APECED. Here, we describe APECED-patient derived iPSCs's properties, expression of AIRE as well as classical stem cell markers by qPCR and immunocytochemistry. We further generated self-aggregated EBs of the iPSCs. We show that APECED patient-derived iPSCs and EBs do not have any major proliferative or apoptotic defects and that they express all the classical pluripotency markers similarly to healthy person iPSCs. The results suggest that the common AIRE R257X truncation mutation does not affect stem cell properties and that APECED iPSCs can be propagated in vitro and used for subsequent gene-correction. This first study on APECED patient-derived iPSCs validates their pluripotency and confirms their ability for differentiation and potential therapeutic use.
  • Välimäki, Mika J.; Ruskoaho, Heikki J. (2020)
    Various strategies have been applied to replace the loss of cardiomyocytes in order to restore reduced cardiac function and prevent the progression of heart disease. Intensive research efforts in the field of cellular reprogramming and cell transplantation may eventually lead to efficient in vivo applications for the treatment of cardiac injuries, representing a novel treatment strategy for regenerative medicine. Modulation of cardiac transcription factor (TF) networks by chemical entities represents another viable option for therapeutic interventions. Comprehensive screening projects have revealed a number of molecular entities acting on molecular pathways highly critical for cellular lineage commitment and differentiation, including compounds targeting Wnt- and transforming growth factor beta (TGF beta)-signaling. Furthermore, previous studies have demonstrated that GATA4 and NKX2-5 are essential TFs in gene regulation of cardiac development and hypertrophy. For example, both of these TFs are required to fully activate mechanical stretch-responsive genes such as atrial natriuretic peptide and brain natriuretic peptide (BNP). We have previously reported that the compound 3i-1000 efficiently inhibited the synergy of the GATA4-NKX2-5 interaction. Cellular effects of 3i-1000 have been further characterized in a number of confirmatory in vitro bioassays, including rat cardiac myocytes and animal models of ischemic injury and angiotensin II-induced pressure overload, suggesting the potential for small molecule-induced cardioprotection.
  • Emani, Maheswara Reddy; Narva, Elisa; Stubb, Aki; Chakroborty, Deepankar; Viitala, Miro; Rokka, Anne; Rahkonen, Nelly; Moulder, Robert; Denessiouk, Konstantin; Trokovic, Ras; Lund, Riikka; Elo, Laura L.; Lahesmaa, Riitta (2015)
  • Nilsson, Ingrid; Bahram, Fuad; Li, Xiujuan; Gualandi, Laura; Koch, Sina; Jarvius, Malin; Soderberg, Ola; Anisimov, Andrei; Kholova, Ivana; Pytowski, Bronislaw; Baldwin, Megan; Yla-Herttuala, Seppo; Alitalo, Kari; Kreuger, Johan (2010)