Fig. 4 Microfluidic model of immune and tumor cell trafficking between the microvasculature and tissues.

. ( a ) A microfluidic device comprising a central tissue-containing channel, flanked by two channels for flow of culture medium, is inoculated with a mixture of fibrin containing endothelial and stromal cells. Over the initial few days, cells undergo morphogenesis to form perfusable microvascular networks which are stable for weeks in culture as shown in ( b ) for a day 23 culture (actin stain). ( c ) Immune cells (green) can be perfused through the microvasculature (red) to model peripheral cell recruitment. ( d ) The dynamic cell-level phenomena in the devices can be imagined by confocal or two-photon microscopy to observe phenomena such as neutrophil–tumor cell interactions in the extravasation of tumor cells through the vascular wall into tissue. (Images from Zhang et al, ¹¹⁰ permission is in progress.)