Hydrogels are networks of hydrophilic polymers which can retain large amounts of water. Poly(2-hydroxyethyl methacrylate) [poly(HEMA)] is a synthetic hydrogel well known for various biomedical applications due to excellent biocompatibility, high retention of water, and high mechanical and chemical stability, but, has limited applications in tissue engineering because of low cell-adhesion properties. Patterning surfaces of hydrogels with microscale features changes the surface properties and enables the regulation of functions of cultured cells. However, generating patterns of intricate microstructures onto the hydrogel surfaces remains challenging. In this work, arrays of micropillars were successfully patterned onto a hydrogel based on 2-hydroxyethyl methacrylate by using soft lithography technique. The self-delamination of the hydrogel induced by swelling in solvents such as phosphate buffered saline, deionized water, 60% ethanol, and absolute ethanol facilitated the reproducible replication of the pattern. The swelling, mechanical properties, and structural parameters of the hydrogel were studied in detail. The biological properties of the hydrogel were evaluated using HeLa cells and human mesenchymal stem cells. It was revealed that the attachment of cells on the intrinsically non-adhesive hydrogel was enhanced by the micropillars. As well, the stem cells tend to form aggregates on the hydrogel and the size and number of cell aggregates can be tuned by changing the height of the micropillars. The fabricated material was not cytotoxic and did not inhibit the chondrogenic and adipogenic differentiation of stem cells at the composition used in synthesis
