Effects of mechanical stimulation in osteogenic differentiation of bone marrow-derived mesenchymal stem cells on aligned nanofibrous scaffolds

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.