Models of cell migration Sample Clauses

Models of cell migration. The extracellular environment is a crucial influencing factor leading to differential results depending on whether cell migration is considered in 2D and 3D in vitro studies, or intravital in vivo studies thus making the study of cell migration challenging and complex (Xxxxx and Xxxxxxxxx, 2015). Nonetheless, studies in 2D cell migration have provided much of our understanding regarding cell motility while the main mechanisms have also been confirmed in 3D; for example forward cell extension is defined by the same molecular and structural characteristics both in 2D and 3D (Xxxxxx and Xxxxxx, 2012). Cells migrate either individually or collectively (figure 1.2); individual cell migration has been studied extensively but interestingly the significance of collective cell migration has been highlighted at the invasive front of breast tumours in organoid systems where invading leader cells were reported to express E-cadherin and other basal epithelial markers (Xxxxxx et al., 2013). Additionally, intravital imaging of MDA-MB-231 and low passage primary breast cancer cells revealed that these cells migrated as multi-cellular streams and that this particular mode of invasion was associated with increased intravasation and circulating tumour cells in the blood vessels of a mouse model (Xxxxxxxxx et al., 2013). Multi- cellular streaming is an intermediate mode of migration which involves cells migrating in a single line while forming short-lived cell junctions (figure 1.2), (Xxxxxx et al., 2012). Cell migration is also classified according to the shape of migrating cells as well as their engagement with the extracellular matrix (Xxxxxx and Xxxx, 2010). Mesenchymal migration is adopted by cells extending a pseudopod that gradually lead to lamellipodia dynamics and an elongated morphology (figure 1.2). The protrusion then engages with the extracellular matrix forming strong focal adhesions that create high traction forces pulling on the surrounding matrix (Xxxxxx, 2004). Large focal adhesions have a slower turnover rate and are thus associated with slower cell speed (Xxxxxx, 2004). Localised pericellular proteolysis mediated by MT1-MMP behind the leading protrusion realigns the extracellular matrix and reduces cell stress during forward moving as it creates paths of least resistance (Xxxxxx and Xxxx, 2009). Focalised matrix degradation together with cell body contraction mediates the forward pulling of the cell body and finally cell tail retraction ultimately achievin...