Ryota Toyohara

According to medical statistics, sacroiliac joints (SIJs) appear to be the source of low back pain in 15 - 30% of cases. The SIJs are located at the junction between the sacrum and the ilium, supported by strong ligaments and with low mobility. Due to unexpected external force or repeated impact, pain may arise from the SIJ region (SIJ dysfunction). The treatment to cure SIJ dysfunction includes nonsurgical approaches as well as surgery with implants (SIJ fixation). Previous studies have assessed the consequences of SIJ fixation, but no simulation study so far has been performed during walking. The SIJ is burdened with variant loads during walking. In this given study, walking conditions were replicated in a finite element model of the pelvis combined with 3D walking analysis data. The simulation mimicked two types of unilateral SIJ fixation: anterior fixation with a plate implant and screws (model A) and posterior fixation with a rod, a cage and screws (model P). Equivalent stress of the SIJ and the loading of the SIJ ligaments decreased in the fixed models. In these fixed pelves, the slight motion on the SIJ decreased. The reduction rates on equivalent stress, ligament loads and equivalent stress were low during the swing phase. In addition, the efficiency of fixations was mostly same on anterior and posterior fixations. It can be concluded that the stronger fixation reduces the loading but also may have a greater impairment effects on walking.

Cell migration plays a crucial role in the physiological and pathological phenomena in our body such as morphogenesis, wound healing, immune response, and cancer metastasis. Cell migration can be regulated by chemical cues, although negative side effects on cell behavior may potentially be induced due to chemical treatments. Mechanical cues are also known to regulate cell migration behavior, however, how cell migration responds to mechanical cues is still under investigation. Therefore, in this study, we developed a confined PDMS-based microchannel with three different widths of 25 μm, 50 μm and 75 μm to study the effect of the width of the microchannel device on cell migration behavior. After the fabrication of the microchannel device, MDCK cells are introduced in the microchannel device for cell culture experiments. When the cells reached the confluent state, the cell migration behavior is observed using time lapse microcopy for 12 h. As a result, the velocity of cells increased with increasing the width of the microchannel from 9.7 μm/h with 25 μm in width to 26.6 μm/h with 75 μm in width. The morphology of the cells and nuclei were not elongated in the middle regions of the microchannels and the cells were oriented parallel to the long axes of the microchannels near the walls. The information on the cell response inside a confined microchannel device can be useful in developing strategies for tissue engineering and cancer metastasis therapies.