NanoBioreactors recreate the microenvironments of normal tissue, non-adherent cells, tumor-infected tissue and wounded tissue in vitro. These microfabricated bioreactors provide independent control of chemokine and growth factor gradients, shear forces, cellular perfusion and the permeability of physical barriers to cellular migration. This fine control allows detailed optical and electrochemical observations of normal, immune and cancerous cells during activation, division, cell migration, intravasation, extravasation and angiogenesis.