Mechanical stimulation is one of the factors that regulating bone regeneration and healing. In this study, the biological responses of bone marrow derived mesenchymal stem cells (MSCs) to mechanical stimuli on aligned nanofibers and cast films were investigated. The uniaxial cyclic strain (1% strain and 1 Hz) was applied continuously to the cell substrates and osteoblastic activities were assessed at weeks 1, 2, and 4. The MSCs morphology on the aligned nanofibers was more elongated and spindle-like than MSCs on the cast films. Strain stimulation significantly attenuated the proliferation at week one but was significantly enhanced at week 4 for both types of substrates. Only the MSCs on strained nanofibers had greater alkaline phosphatase (ALP) levels at week one, while the ALP hindered the MSCs on both substrates at week 4. Strain application played a greater influence on osteocalcin expression for the cast films than the nanofibers at week 4. Clearly, the cellular response to strain induction was highly dependent on the surface-cell adhesion, which itself was greatly influenced by the surface texture of the substrate.

The development of techniques for immobilizing biomolecules on solid surfaces has attracted wide attention because of the broad potential applications of biofunctionalized surfaces in stem cell biology, tissue engineering, biosensor technology, and high-throughput screening for drug discovery.In particular, protein micropatterns on surfaces provide unprecedented spatial resolution to control cell shape and direct cell behavior. Combining with optical methods and functional assays, micropatterning techniques are one of the key tools for investigating cell molecular and mechanical mechanisms in basic cell behaviors, such as cell adhesion, cell migration, cell division and differentiation.In this work, we use a photolithographic approach to create cell adhesive micropatterns. We have designed different geometries to control and study cell adhesion. A pre-designed mask is fabricated for the photolithographic process. The designed features are transferred to a glass substrate by UV exposure of a protein solution containing a photoinitiator through the mask.Typically, patterns of fibronectin are produced in a non-adhesive background of poly-L-lysine grafted poly (ethylene glycol). Cells seeded on these substrates, can specifically adhere and spread on the adhesive protein micropatterns and display unique shapes according to the contour and size of the pattern.