85 research outputs found
Unraveling the fate of grafted and endogenous stem cells in mouse models of multiple sclerosis
No full textSpatiotemporal evolution of early innate immune responses triggered by neural stem cell grafting
No full textINTRODUCTION: Transplantation of neural stem cells (NSCs) is increasingly suggested to become part of future therapeutic approaches to improve functional outcome of various central nervous system disorders. However, recently it has become clear that only a small fraction of grafted NSCs display long-term survival in the (injured) adult mouse brain. Given the clinical invasiveness of NSC grafting into brain tissue, profound characterisation and understanding of early post-transplantation events is imperative to claim safety and efficacy of cell-based interventions.
METHODS: Here, we applied in vivo bioluminescence imaging (BLI) and post-mortem quantitative histological analysis to determine the localisation and survival of grafted NSCs at early time points post-transplantation.
RESULTS: An initial dramatic cell loss (up to 80% of grafted cells) due to apoptosis could be observed within the first 24 hours post-implantation, coinciding with a highly hypoxic NSC graft environment. Subsequently, strong spatiotemporal microglial and astroglial cell responses were initiated, which stabilised by day 5 post-implantation and remained present during the whole observation period. Moreover, the increase in astrocyte density was associated with a high degree of astroglial scarring within and surrounding the graft site. During the two-week follow up in this study, the NSC graft site underwent extensive remodelling with NSC graft survival further declining to around 1% of the initial number of grafted cells.
CONCLUSIONS: The present study quantitatively describes the early post-transplantation events following NSC grafting in the adult mouse brain and warrants that such intervention is directly associated with a high degree of cell loss, subsequently followed by strong glial cell responses
Astrobiology and the Ultraviolet World
No full text© 2017 The Author(s). This is an open-access article distributed under the terms of a Creative Commons license (CC BY-NC-ND 3.0)
The Global Biosphere and Its Metaphysical Underpinnings: Ecumenical Alternatives in Animism and Astrobiology
No full textThe term biosphere designates the “zone of life” on Earth. Outside this sphere, everything becomes “alien.” In this view of things, which I take to be canonical in the modern West, terrestrial life and biosphere overlap more or less neatly. Yet this idea of an almost perfect convergence is not the only view possible. This study presents two anthro- pological cases which demonstrate, a contrario, that the modern tendency to envisage the biosphere as “our home environment” or as “our familiar world” is in many ways a his- torical accident. Other ecumenical possibilities (by which I refer to the ancient Greek notion of the “inhabited world,” the oikumene) are by no means unthinkable. Examining the ecumenical originality of two communities that at first sight seem unrelated – Chachi indigenous people in Ecuador and scientists involved in the search for extraterrestrial life – will allow us to cast new light on the metaphysical underpinnings of the modern biosphere concept.© 2021, The Author(s). The attached document (embargoed until 01/01/2022) is an author produced version of a paper published in SOCIOLOGUS uploaded in accordance with the publisher’s self-archiving policy. The final published version (version of record) is available online at the link. Some minor differences between this version and the final published version may remain. We suggest you refer to the final published version should you wish to cite from it. <br/
Distinct in vitro properties of embryonic and extraembryonic fibroblast-like cells are reflected in their in vivo behavior following grafting in the adult mouse brain
No full textAlthough intracerebral transplantation of various fibroblast(-like) cell populations has been shown feasible, little is known about the actual in vivo remodeling of these cellular grafts and their environment. In this study, we aimed to compare the in vitro and in vivo behavior of two phenotypically similar-but developmentally distinct-fibroblast-like cell populations, namely, mouse embryonic fibroblasts (mEFs) and mouse fetal membrane-derived stromal cells (mFMSCs). While both mEFs and mFMSCs are readily able to reduce TNF-α secretion by LPS/IFN-γ-activated BV-2 microglia, mFMSCs and mEFs display strikingly opposite behavior with regard to VEGF production under normal and inflammatory conditions. Whereas mFMSCs downregulate VEGF production upon coculture with LPS/IFN-γ-activated BV-2 microglia, mEFs upregulate VEGF production in the presence of LPS/IFN-γ-activated BV-2 microglia. Subsequently, in vivo grafting of mFMSCs and mEFs revealed no difference in microglial and astroglial responses toward the cellular grafts. However, mFMSC grafts displayed a lower degree of neoangiogenesis compared to mEF grafts, thereby potentially explaining the lower cell number able to survive in mFMSC grafts. In summary, our results suggest that physiological differences between fibroblast-like cell populations might lie at the basis of variations in histopathological and/or clinical outcome following cell grafting in mouse brain
Early inflammatory responses following cell grafting in the CNS trigger activation of the sub-ventricular zone: a proposed model of sequential cellular events.
No full textWhile multiple rodent pre-clinical studies, and to a lesser extent human clinical trials, claim the feasibility, safety and potential clinical benefit of cell grafting in the central nervous system (CNS), currently only little convincing knowledge exists regarding the actual fate of the grafted cells and their effect on the surrounding environment (or vice versa). Our preceding studies already indicated that only a minor fraction of the initially grafted cell population survives the grafting process, while the surviving cell population becomes invaded by highly activated microglia/macrophages and surrounded by reactive astrogliosis. In the current study, we further elaborate on early cellular and inflammatory events following syngeneic grafting of eGFP+ mouse embryonic fibroblasts (mEFs) in the CNS of immune-competent mice. Based on obtained quantitative histological data, we here propose a detailed mathematically-derived working model that sequentially comprises hypoxia-induced apoptosis of grafted mEFs, neutrophil invasion, neo-angiogenesis, microglia/macrophage recruitment, astrogliosis and eventually survival of a limited number of grafted mEFs. Simultaneously, we observed that the cellular events following mEF grafting activates the sub-ventricular zone neural stem and progenitor cell compartment. This proposed model therefore further contributes to our understanding of cell graft-induced cellular responses, and will eventually allow for successful manipulation of this intervention
Henri Pirenne’s 'Mahomet et Charlemagne' : de islam als breuklijn tussen Oudheid en Middeleeuwen
No full textHenri Pirenne (1862-1935) is without any doubt the most eminent Belgian historian. Much research has been carried out on his work and his actions, resulting in, among other things, a classic biography, several source editions and numerous detail studies, even more so since his influence on the development of historiography has recently been attached to the development of his scientific persona. After studying Humanity and Philosophy in Liège, where he promoted in 1883, he was appointed professor in medieval history at the University of Ghent in 1886. Until 1930 he lectured there on the growth of medieval cities, on medieval economy and more specifically on the influence of Islam in the fall of the Roman Empire - and of course also on Belgian history. Fascinated as he was by scientific disciplines such as sociology, economics and psychology, he was the first Belgian historian to expand the borders of his own discipline. His monumental work Histoire de Belgique en his thesis on the influence of islam on (Western) European history have earned him, up untill today, national and international reknown. This article wants to give insight in the development and experiences of that specific thesis, as written down in his Mahomet et Charlemagne, and identified with its author to that extent that it is simply referred to in literature as the Pirenne-thesis
Re-anchoring Rome’s protection in Constantinople : the pignora imperii in Late Antiquity and Byzantium
No full textThis paper uses the conceptual framework of “Anchoring Innovation”, which is being developed by OIKOS, the Dutch National Research School in Classical Studies, in order to assess matters of religious continuity and change in the late antique and Byzantine attitudes towards the pignora imperii, or talismans which vouched for the safety of the Roman Empire. Notable pignora are the Palladium, the ancilia, and the stone of Cybele. The paper focuses on two periods. In the first section, a close reading of a passage of Servius from the early fifth century AD discloses how the author re-anchored the pignora in the contemporary context of anxieties over the preservation of pagan heritage and the imminent shift of power and prestige from Rome to Constantinople. The second section focuses on the works of John Malalas and John of Lydia in order to trace the vicissitudes of the pignora in sixth century Constantinople. Servius’ pignora are re-anchored in the context of an Empire which saw itself increasingly as Christian and centred on Constantinople. Also new pignora, such as the Latin language and statues in Constantinople are being construed in the sixth century. The paper concludes with a short sketch of a field which merits further research; the continuity in religious attitudes towards pignora between late antiquity and the Byzantine period. It will be argued that icons of the Theotokos or Virgin Mary in Byzantium gradually usurp the role and function of the antique pignora. The paper has in two appendices 1) a list of testimonies to the Palladium, and 2) a list of transfers of Hero remains in antiquity
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