A Time-Lapse and Quantitative Modelling Analysis of Neural Stem Cell Motion in the Absence of Directional Cues and in Electric Fields

Article (PDF Available)inJournal of Neuroscience Research 88(15):3267-74 · November 2010with36 Reads
DOI: 10.1002/jnr.22502 · Source: PubMed
Neural stem cell (NSC) migration is an important component of their developmental function and therapeutic potential. Understanding their mode of migration and their response to guidance cues can contribute to improved therapies for CNS repair, in which appropriate homing to sites of injury is essential. Using time-lapse imaging, we have analyzed the NSC mode of migration in vitro, both in the absence of directional cues and in the presence of applied electric fields (EFs), previously shown to constitute a strong directional signal for these cells. Without EFs, NSCs displayed an amoeboid motion, characterized by small lamellipodial-like protrusions with changing orientations, leading to highly tortuous migration. In EFs, tortuosity diminished as electrotaxis toward the cathode occurred. EFs suppressed the formation of protrusions oriented toward the anode, suggesting that restriction of protrusions with opposing orientation could underlie the change from tortuous motion to directed migration. Treatment with LY294002, a phosphatidylinositol-3-OH kinase (Pi3K) inhibitor, reduced the cathodal bias of protrusions in EFs and the frequency of changes in direction. We generated a model of NSC migration with only two key parameters, which could accurately reproduce experimental migration patterns, and we used it to show that both effects of LY294002 contribute to impair electrotaxis, although decreased protrusion bias is the most important. Our results show that control of protrusion orientation by EFs is an important component of the electrotactic response. A simple modelling approach might be useful in understanding how diverse pharmacological treatments or genetic deletions affect different kinds of directional cell migration.
    • "ODE-and PDE-based models have been developed to simulate molecular motors [9], [10] or cilia motion[11]. There are cellular automata-based models of neural stem cell migration [12], cellular Potts models [13] or complex finiteelement methods [14] to study chemotaxis. The Cell Migration Consortium (http://www.cellmigration.org/) "
    [Show abstract] [Hide abstract] ABSTRACT: In this paper, we present a novel framework for the modeling of cell-migration, and more specifically the migration of human keratinocytes. The model decouples the embodiment of an artificial cell into two elements. A cell-body is implemented by two sets of springs forming a membrane and a supporting cortical-cytoskeleton, which allows for cell-body rigidity and flexibility. The leading-edge, a structure spreading around the cell-body, is simulated with a stochastic cellular-automata. It defines the migratory forces that pull the cell-body according to its local spread around the cell. The overall movement of the leading-edge depends on stochastic interaction with the environment and guides the whole cell movement through spatiotemporal integration of local forces. We demonstrate that our cell migration model allows for spontaneous symmetry-breaking and directed cell movement and has in-built obstacle-avoidance, closely mimicking the migration of living cells. The model is extended to simulate chemotactic behavior, the artificial cell can sense and move along a gradient with its trajectory depending on the cell shape, stiffness and leading-edge dynamics. In summary, we have developed a novel cell migration model with emergent properties, wherein local forces create an integrated cell movement. The presented interplay of the distributed physical and an informational embodiment is not limited in reach to the example of cell migration, but can of interest for design of perception-action loops and sensor evolution in general.
    Full-text · Conference Paper · Apr 2013
    • "It is important to note that while migratory behaviors of HB1.F3 cells appear to be cell-intrinsic, they are also quite plastic. Comparing 2-and 3-dimensional culture conditions, the differences between movements with a pattern of extension followed by soma translocation extension of HB1.F3 cells in the 3-dimensional Puramatrix environment described here and the predominately amoeboid movements exhibited by these same cells in 2- dimensional culture [16] (see [28,36] for other examples) point to considerable sensitivity of these NSCs to variations in surrounding environmental cues. This flexibility in choice of migratory mechanisms could be reflected in the two distinct phases of HB1.F3 NSC movements observed here: locomotion in Puramatrix and encirclement of target cells. "
    [Show abstract] [Hide abstract] ABSTRACT: Pathotropic neural stem and/or progenitor cells (NSCs) can potentially deliver therapeutic agents to otherwise inaccessible cancers. In glioma, NSCs are found in close contact with tumor cells, raising the possibility that specificity of NSC contact with glioma targets originates in the tumor cells themselves. Alternatively, target preferences may originate, at least in part, in the tumor microenvironment. To better understand mechanisms underlying NSC interactions with glioma cells, we examined NSC-target cell contacts in a highly simplified 3-dimensional peptide hydrogel (Puramatrix) in which cell behaviors can be studied in the relative absence of external cues. HB1.F3 is an immortalized clonal human NSC line extensively characterized in preclinical investigations. To study contact formation between HB1.F3 NSCs and glioma cells, we first examined co-cultures of eGFP-expressing HB1.F3 (HB1.F3.eGFP) NSCs and dsRed-expressing U251 glioma (U251.dsRed) cells. Using confocal microscopy, HB1.F3.eGFP cells were observed contacting or encircling U251.dsRed glioma cells, but never the reverse. Next, examining specificity of these contacts, no significant quantitative differences in either percentages of HB1.F3 NSCs contacting targets, or in the extent of target cell encirclement, were observed when HB1.F3.eGFP cells were presented with various potential target cells (human glioma and breast cancer cell lines, patient-derived brain tumor lines, non-tumor fibroblasts, primary mouse and human astroglial cells, and primary adult and newborn human dermal fibroblasts) except that interactions between HB1.F3 cells did not progress beyond establishing contacts. Finally cytoskeletal mechanisms employed by HB1.F3.eGFP cells varied with the substrate. When migrating in Puramatrix, HB1.F3 NSCs exhibited intermittent process extension followed by soma translocation, while during encirclement their movements were more amoeboid. We conclude that formation of contacts and subsequent encirclement of target cells by HB1.F3 NSCs is an intrinsic property of these NSCs, and that preferential contact formation with tumor cells in vivo must therefore be highly dependent on microenvironmental cues.
    Full-text · Article · Dec 2012
    • "DPSC and DFSC motion was tortuous, probably due to the frequent reversals in directions caused by successive protrusions with opposing orientations. Reduction of direction reversals makes cell movement less tortuous and cells adopt an oriented trajectory towards a chemical or electric signal (Aman and Piotrowski, 2010; Arocena et al., 2010; Zhao et al., 2011a). Indeed, the co-culture of DPSC and DFSC stimulated their migration abilities, particularly when these two stem cell populations were seeded in equal cell numbers. "
    [Show abstract] [Hide abstract] ABSTRACT: Stem cell migration is a critical step during the repair of damaged tissues. In order to achieve appropriate cell-based therapies for tooth and periodontal ligament repair it is necessary first to understand the dynamics of tissue-specific stem cell populations such as dental pulp stem cells (DPSC) and dental follicle stem cells (DFSC). Using time-lapse imaging, we analysed migratory and proliferative capabilities of these two human stem cell lines in vitro. When cultured alone, both DPSC and DFSC exhibited low and irregular migration profiles. In co-cultures, DFSC, but not DPSC, spectacularly increased their migration activity and velocity. DFSC rapidly surrounded the DPSC, thus resembling the in vivo developmental process, where follicle cells encircle both dental epithelium and pulp. Cell morphology was dependent on the culture conditions (mono-culture or co-culture) and changed over time. Regulatory genes involved in dental cell migration and differentiation such as TWIST1, MSX1, RUNX2, SFRP1 and ADAM28, were also evaluated in co-cultures. MSX1 up-regulation indicates that DPSC and DFSC retain their odontogenic potential. However, DPSC lose their capacity to differentiate into odontoblasts in the presence of DFSC, as suggested by RUNX2 up-regulation and TWIST1 down-regulation. In contrast, the unchanged levels of SFRP1 expression suggest that DFSC retain their potential to form periodontal tissues even in the presence of DPSC. These findings demonstrate that stem cells behave differently according to their environment, retain their genetic memory, and compete with each other to acquire the appropriate territory. Understanding the mechanisms involved in stem cell migration may lead to new therapeutic approaches for tooth repair.
    Full-text · Article · Jul 2012
Show more