Microdevice platform recapitulating hypoxic tissue microenvironments

Abstract

Hypoxia plays a central role in cancer progression and resistance to therapy. A microdevice platform is engineered to recapitulate the intratumor oxygen gradients that drive the heterogeneous hypoxic landscapes in solid tumors. The microdevice design features a “tumor section”-like culture by incorporating a cell layer between two diffusion barriers, where an oxygen gradient is established by cellular metabolism and physical constraints. The oxygen gradient is confirmed by numerical simulation and imaging-based oxygen sensor measurement. Spatially-resolved hypoxic signaling in cancer cells is also demonstrated through immunostaining, gene expression assay, and hypoxia-targeted drug treatment. The microdevice platform can accurately generate and control oxygen gradients, eliminates complex microfluidic handling, allows for incorporation of additional tumor components, and is compatible with high-content imaging and high-throughput applications. It is well suited for understanding hypoxia-mediated mechanisms in cancer disease and other biological tissues and processes, and discovery of new therapeutics.

What is claimed is: 
     
         1 . A method for inducing an oxygen concentration gradient, the method comprising:
 providing a first component that is a diffusion barrier, the first component including a central pillar having a first space-defining surface;   providing a second component having a second space-defining surface, the first component being positioned proximate to the second component such that the first space-defining surface and the second space-defining surface define a confined space;   providing an aqueous solution having dissolved oxygen that fills the confined space; and   placing a layer of living cells over the second space-defining surface, wherein the first space-defining surface and the second space-defining surface are sufficiently close that passive oxygen diffusion in the confined space is insufficient to replenish oxygen consumed by cells thereby establishing an oxygen gradient in the confined space.   
     
     
         2 . The method of  claim 1  wherein the central pillar is an oxygen barrier. 
     
     
         3 . The method of  claim 1  wherein the first space-defining surface and the second space-defining surface are separated by a gap distance from about 30 μm to about 1000 μm. 
     
     
         4 . The method of  claim 1  wherein the first space-defining surface and the second space-defining surface are separated by a gap distance from about 50 μm to about 500 μm. 
     
     
         5 . The method of  claim 1  wherein the first space-defining surface and the second space-defining surface are substantially flat in the vicinity of the confined space. 
     
     
         6 . The method of  claim 1  wherein the first space-defining surface is curved or cone-shaped. 
     
     
         7 . The method of  claim 1  wherein the confined space is open along a periphery. 
     
     
         8 . The method of  claim 1  wherein the first space-defining surface is circular. 
     
     
         9 . The method of  claim 1  further comprising an extracellular component associated with the layer of living cells, the extracellular component having tunable mechanical properties and/or biochemical properties. 
     
     
         10 . The method of  claim 1  wherein the layer of living cells includes cells selected from the group consisting of cancer cells, stem cells, cardiomyocytes, neurons, hepatocytes, pancreatic cells, fibroblasts, immune cells, epithelial cells, endothelial cells, and combinations thereof. 
     
     
         11 . The method of  claim 1  wherein the first component includes a cap structure that includes the central pillar 
     
     
         12 . The method of  claim 1  wherein the first component further includes three spatial reference pillars that are longer than the central pillar thereby defining a gap distance between the layer of living cells and the central pillar. 
     
     
         13 . The method of  claim 12  wherein the second component includes a base structure and a glass plate held by the base structure, the plurality of living cells being disposed over the glass plate. 
     
     
         14 . A device for inducing an oxygen concentration gradient, the device comprising:
 a first component that is a diffusion barrier, the first component including a central pillar having a first space-defining surface;   a second component having a second space-defining surface, the first component being positioned proximate to the second component such that the first space-defining surface and the second space-defining surface define a confined space;   a layer of living cells disposed over the second space-defining surface; and   an aqueous solution having dissolved oxygen therein that fills the confined space, wherein the first space-defining surface and the second space-defining surface are sufficiently close that passive oxygen diffusion in the confined space is insufficient to replenish oxygen consumed by cells thereby establishing an oxygen gradient in the confined space.   
     
     
         15 . The device of  claim 14  wherein the central pillar is an oxygen barrier. 
     
     
         16 . The device of  claim 14  wherein the first space-defining surface and the second space-defining surface are separated by a gap distance from about 30 μm to about 1000 μm. 
     
     
         17 . The device of  claim 14  wherein the first component includes a cap structure that includes the central pillar 
     
     
         18 . The device of  claim 14  wherein the first component further includes three spatial reference pillars that are longer than the central pillar thereby defining a gap distance between the layer of living cells and the central pillar. 
     
     
         19 . The device of  claim 14  wherein the confined space is open along a periphery. 
     
     
         20 . The device of  claim 14  wherein the first space-defining surface is circular.