System for creating an oxygen gradient across a cell culture insert barrier

A cell culture device 10 suitable for co-culturing cells, particularly for co-culturing aerobic and anaerobic cells comprising upper and lower well plate elements 1, 2, said elements together defining a culture well 9, wherein the device further comprises a cell culture insert 5 having apical 3 and basal 4 surfaces, said insert located within the culture well and separating said culture well into first and second apical and basal volumes; wherein at least a portion 11 of said insert is gas permeable, to permit gas to exchange across the apical and basal surfaces between the apical and basal volumes; and wherein said upper and lower well plate elements each further comprise at least one opening extending between the interior and exterior of each respective element, to permit movement of gas between the interior and exterior of each respective element. Also claimed is a method of culturing cells using such a cell culture device comprising adding cells to the device and introducing a low oxygen gas through at least one opening of at least one well plate element, so that one volume has a low oxygen atmosphere compared to the other volume.