Since cells are very sensitive to geometrical and chemical constrains from their microenvironment, controlling cell adhesion to polymer substrates is one of key issue in tissue engineering. Meanwhile, micrometer-scale patterns are commonly used to guide the cell attachment and growth. There are many sophisticated methods available for generating patterned surfaces typically applied only to the planar substrates. To provide a more biomimetic environment for cell culture than 2D surface , patterned 3-dimensional (3D) scaffolds with native tissue morphology are desirable. However, the ability to structure the microporous material to predetermined geometries as well as to guide cell adhesion to non-planar surface still remains a technical challenge.
To overcome these limitations we developed strategies, which combine chemical patterning with microstructuring in one process and allowed the production of 3D porous scaffolds with chemical guidance cues. To structure microporous polymer materials to predetermined geometries we used microthermoforming process . This process is highly efficient and works for most thermoplastics polymers, including permeable polycarbonate membranes as well as biodegradable materials like microporous polylactid acide. Additionaly, to spatially control cellular micro-organization, local modification of the surface of polymer foils during the microthermoforming process was applied. For this purpose we used an elastomeric PDMS stamps developed with standard microstructuring technologies. Stamps with different structures were covered with appropriate macromolecules and used to transfer these molecules onto a selected area of polymer surface during the microthermoforming process. In this case the silicone tools acted as a combined micro patterning and thermoforming tool. Using this process biomolecules suitable for the applied cell type were coated on the surface of microstructured polymers .
Cell culture results revealed that the scaffolds have promising capability to manipulate cellular organizations. EA.hy926 and L929 cell lines cultivated on thermoformed surfaces showed guided adhesion and growth. Cell attachment and spreading were predominantly limited to the microthermoformed structures, in which 3D cell organization was observed.