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In Search of In Vivo MSC

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889452354 Year: Pages: 102 DOI: 10.3389/978-2-88945-235-4 Language: English
Publisher: Frontiers Media SA
Subject: Science (General) --- Biology
Added to DOAB on : 2017-10-13 14:57:01
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Stem cells and progenitor cells in ischemic stroke - fashion or future?

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889197248 Year: Pages: 156 DOI: 10.3389/978-2-88919-724-8 Language: English
Publisher: Frontiers Media SA
Subject: Neurology --- Science (General)
Added to DOAB on : 2016-04-07 11:22:02
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Abstract

Stroke remains one of the most devastating diseases in industrialized countries. Recanalization of the occluded arterial vessel using thrombolysis is the only causal therapy available. However, thrombolysis is limited due to severe side effects and a limited time window. As such, only a minority of patients receives this kind of therapy, showing a need for new and innovative treatment strategies. Although neuroprotective drugs have been shown to be beneficial in a variety of experimental stroke models, they ultimately failed in clinical trials. Consequently, recent scientific focus has been put on modulation of post-ischemic neuroregeneration, either via stimulation of endogenous neurogenesis or via application of exogenous stem cells or progenitor cells. Neurogenesis persists within the adult brain of both rodents and primates. As such, neural progenitor cells (NPCs) are found within distinct niches like the subventricular zone (SVZ) of the lateral ventricles and the subgranular zone of the dentate gyrus. Cerebral ischemia stimulates these astrocyte-like progenitor cells, upon which NPCs proliferate and migrate towards the site of lesion. There, NPCs partly differentiate into mature neurons, without significantly being integrated into the residing neural network. Rather, the majority of new-born cells dies within the first weeks post-stroke, leaving post-ischemic neurogenesis a phenomenon of unknown biological significance. Since NPCs do not replace lost brain tissue, beneficial effects observed in some studies after either stimulated or protected neurogenesis are generally contributed to indirect effects of these new-born cells. The precise identification of appropriated cellular mediators, however, is still elusive. How do these mediators work? Are they soluble factors or maybe even vesicular structures emanating from NPCs? What are the cues that guide NPCs towards the ischemic lesion site? How can post-ischemic neurogenesis be stimulated? How can the poor survival of NPCs be increased? In order to support post-ischemic neurogenesis, a variety of research groups have focused on application of exogenous stem/progenitor cells from various tissue sources. Among these, cultivated NPCs from the SVZ and mesenchymal stem cells (MSCs) from the bone marrow are frequently administered after induction of stroke. Although neuroprotection after delivery of stem/progenitor cells has been shown in various experimental stroke models, transplanted cells are usually not integrated in the neural network. Again, the vast amount of grafted cells dies or does not reach its target despite profound neuroprotection, also suggesting indirect paracrine effects as the cause of neuroprotection. Yet, the factors being responsible for these observations are under debate and still have to be addressed. Is there any “optimal” cell type for transplantation? How can the resistance of grafted cells against a non-favorable extracellular milieu be increased? What are the molecules that are vital for interaction between grafted cells and endogenous NPCs? The present research topic seeks to answer - at least in part - some of the aforementioned questions. Although the research topic predominantly focuses on experimental studies (and reviews alike), a current outlook towards clinical relevance is given as well.

Stem Cell and Biologic Scaffold Engineering

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ISBN: 9783039214976 / 9783039214983 Year: Pages: 110 DOI: 10.3390/books978-3-03921-498-3 Language: eng
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Science (General) --- Biology
Added to DOAB on : 2019-12-09 11:49:15
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Tissue engineering and regenerative medicine is a rapidly evolving research field which effectively combines stem cells and biologic scaffolds in order to replace damaged tissues. Biologic scaffolds can be produced through the removal of resident cellular populations using several tissue engineering approaches, such as the decellularization method. Indeed, the decellularization method aims to develop a cell-free biologic scaffold while keeping the extracellular matrix (ECM) intact. Furthermore, biologic scaffolds have been investigated for their in vitro potential for whole organ development. Currently, clinical products composed of decellularized matrices, such as pericardium, urinary bladder, small intestine, heart valves, nerve conduits, trachea, and vessels, are being evaluated for use in human clinical trials. Tissue engineering strategies require the interaction of biologic scaffolds with cellular populations. Among them, stem cells are characterized by unlimited cell division, self-renewal, and differentiation potential, distinguishing themselves as a frontline source for the repopulation of decellularized matrices and scaffolds. Under this scheme, stem cells can be isolated from patients, expanded under good manufacturing practices (GMPs), used for the repopulation of biologic scaffolds and, finally, returned to the patient. The interaction between scaffolds and stem cells is thought to be crucial for their infiltration, adhesion, and differentiation into specific cell types. In addition, biomedical devices such as bioreactors contribute to the uniform repopulation of scaffolds. Until now, remarkable efforts have been made by the scientific society in order to establish the proper repopulation conditions of decellularized matrices and scaffolds. However, parameters such as stem cell number, in vitro cultivation conditions, and specific growth media composition need further evaluation. The ultimate goal is the development of “artificial” tissues similar to native ones, which is achieved by properly combining stem cells and biologic scaffolds and thus bringing them one step closer to personalized medicine. The original research articles and comprehensive reviews in this Special Issue deal with the use of stem cells and biologic scaffolds that utilize state-of-the-art tissue engineering and regenerative medicine approaches.

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