The pressure differential across blood vessel walls drives flow of plasma across the wall into the interstitium where it supplies cells with nutrients and removes cellular waste.  This interstitial flow is typically collected in lymphatic vessels and recycled to the blood circulation system.  When endothelial layers are weakened at sites of vascular damage or disease (Figure 1 top) or become leaky as in cancer tumors (Figure 1 bottom), interstitial flow rates are increased.  While interstitial flow velocities are very low compared to blood flow velocities, they can impose significant fluid shear stresses on cells suspended in the interstitial matrix as was first shown by our group (Wang and Tarbell,1995).

 

Figure 1. Schematic diagrams showing interstitial flow across an artery wall exposing smooth muscle cells and fibroblasts to fluid shear stress (top), and across a tumor microvessel exposing tumor cells to fluid shear stress (bottom).

Figure 1. Schematic diagrams showing interstitial flow across an artery wall exposing smooth muscle cells and fibroblasts to fluid shear stress (top), and across a tumor microvessel exposing tumor cells to fluid shear stress (bottom).

                  CANCER CELLS                            SMOOTH MUSCLE CELLS