Characterization of human alveolar osteoblasts in two- dimensional and three-dimensional cultures

Ph.DDOCTOR OF PHILOSOPH

Shared Low-Speed Autonomous Vehicle System for Suburban Residential Areas

In the context of global suburbanization and population aging, a low-speed, automated vehicle (LSAV) system provides essential mobility services in suburban residential areas. Although extensive studies on shared autonomous vehicle (SAV) services have been conducted, quantitative investigations on the operation of suburban LSAV systems are limited. Based on a demonstration pilot project of an autonomous vehicle called “Slocal Automated Driving”, we investigated the performance of an SAV system considering several scenarios in Kozoji Newtown, a suburban commuter town in Japan. The agent-based simulation results revealed that 40 LSAVs can satisfy the demands of 2263 daily trips with an average wait time of 15 min. However, in the case of a high-speed scenario, the same fleet size improved the level of service (LOS) by reducing the average wait time to two and a half minutes and halving the in-vehicle time. By contrast, the wait time in terms of the average and 95th percentile of the no-sharing ride scenario drastically deteriorated to an unacceptable level. Based on the fluctuations of hourly share rates, wait times, and the number of vacant vehicles, we determined that preparing for the potential fleet insufficiency periods from 7:00–13:00 and 15:00–18:00 can improve the LOS

Engineering tubular bone constructs

Cell-sheet techniques have been proven effective in various soft tissue engineering applications. In this experiment, we investigated the feasibility of bone tissue engineering using a hybrid of mesenchymal stem cell (MSC) sheets and PLGA meshes. Porcine MSCs were cultured to a thin layer of cell sheets via osteogenic induction. Tube-like long bones were constructed by wrapping the cell sheet on to PLGA meshes resulting in constructs which could be cultured in spinner flasks, prior to implantation in nude rats. Our results showed that the sheets were composed of viable cells and dense matrix with a thickness of about 80–120 mm, mineral deposition was also observed in the sheet. In vitro cultures demonstrated calcified cartilage-like tissue formation and most PLGA meshes were absorbed during the 8-week culture period. In vivo experiments revealed that dense mineralized tissue was formed in subcutaneous sites and the 8- week plants shared similar micro-CT characteristics with native bone. The neo tissue demonstrated histological markers for both bone and cartilage, indicating that the bone formation pathway in constructs was akin to endochondral ossification, with the residues of PLGA having an effect on the neo tissue organization and formation. These results indicate that cell-sheet approaches in combination with custom-shaped scaffolds have potential in producing bone tissue

A System of Shared Autonomous Vehicles Combined with Park-And-Ride in Residential Areas

As suburbanization and unprecedented population aging are converging, enhanced personal mobility for suburban residents is required. In this study, a collaborative scheme involving park-and-ride services associated with public transport and a shared autonomous vehicle system are proposed. Two residential areas in the Nagoya metropolitan region, Japan, are considered: a residential area at the outer edge of a subway line and a commuter town with a nearby railway station. Three user groups are assumed: park-and-ride commuters who park shared autonomous vehicles at the station and take the train to their workplaces; inbound commuters who disembark from trains at the station and use the vehicles to reach their workplaces within the target area; and elderly and disabled residents, who use shared autonomous vehicles for trips within the target area. The system performance is investigated through agent-based simulation. The results suggest that, in the edge case, approximately 400 shared autonomous vehicles can facilitate more than 10,000 trips at an appropriate level of service. For the commuter town, fewer than 400 vehicles can provide rapid responses with a wait time of approximately 5 min for more than 5000 trips per day. Thus, the proposed system can feasibly provide a quick response service

Composite electrospun scaffolds for engineering tubular bone grafts

In this study, poly (e-caprolactone) [PCL] and its collagen composite blend (PCL=Col) were fabricated to scaffolds using electrospinning method. Incorporated collagen was present on the surface of the fibers, and it modulated the attachment and proliferation of pig bone marrow mesenchymal cells (pBMMCs). Osteogenic differentiation markers were more pronounced when these cells were cultured on PCL=Col fibrous meshes, as determined by immunohistochemistry for collagen type I, osteopontin, and osteocalcin. Matrix mineralization was observed only on osteogenically induced PCL=Col constructs. Long bone analogs were created by wrapping osteogenic cell sheets around the PCL=Col meshes to form hollow cylindrical cell-scaffold constructs. Culturing these constructs under dynamic conditions enhanced bone-like tissue formation and mechanical strength.We conclude that electrospun PCL=Col mesh is a promising material for bone engineering applications. Its combination with osteogenic cell sheets offers a novel and promising strategy for engineering of tubular bone analogs

Osteogenic and adipogenic induction potential of human periodontal cells

BACKGROUND: Human periodontium contains different cell types that have various potential roles in hard and soft tissue regeneration. However, there is limited knowledge about how these diverse cell populations contribute to the regenerative process. In this study, we investigated the surface marker difference between different periodontal cells (alveolar osteoblasts [AOs], periodontal ligament fibroblasts [PDLFs], and gingival fibroblasts [GFs]) and their differentiation potential toward osteogenic and adipogenic phenotypes. METHODS: Periodontal cells (AOs, PDLFs, and GFs) from 14 subjects were isolated. The surface antigen expression pattern of cells was analyzed by cell flow cytometry, and the molecular and histologic characterizations under osteogenic and adipogenic inductions were monitored by reverse transcription-polymerase chain reaction, Western blot, and immunocytohistology. RESULTS: The cell phenotypes of AOs were verified by the high expressions of CD29 and CD49a, whereas PDLFs showed distinctively low levels of CD63 and CD73. Under adipogenic induction, limited AOs formed cube-shaped adipose-like cells, whereas PDLFs formed spindle-shaped adipose-like cells. All three cell types expressed baseline osteo-related genes. AOs demonstrated the highest osteogenic ability followed by PDLFs and GFs. CONCLUSIONS: Cells in alveolar bone and periodontal ligament contain osteogenic and adipogenic progenitors. These observations indicate a possible application for periodontium cells in hard or soft tissue regeneration