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The coculture of osteogenic and angiogenic cells and the resulting paracrine signaling via soluble factors are supposed to be crucial for successfully engineering vascularized bone tissue equivalents. In this study, a coculture system combining primary human adiposederived stem cells (hASCs) and primary human dermal microvascular endothelial cells (HDMECs) within two types of hydrogels based on methacryloyl‐modified gelatin (GM) as three‐dimensional scaffolds was examined for its support of tissue specific cell functions. HDMECs, together with hASCs as supporting cells, were encapsulated in soft GM gels and were indirectly cocultured with hASCs encapsulated in stiffer GM hydrogels additionally containing methacrylate‐modified hyaluronic acid and hydroxyapatite particles. After 14 days, the hASC in the stiffer gels (constituting the “bone gels”) expressed matrix proteins like collagen type I and fibronectin, as well as bone‐specific proteins osteopontin and alkaline phosphatase. After 14 days of coculture with HDMEC‐laden hydrogels, the viscoelastic properties of the bone gels were significantly higher compared with the gels in monoculture. Within the soft vascularization gels, the formed capillary‐like networks were significantly longer after 14 days of coculture than the structures in the control gels. In addition, the stability as well as the complexity of the vascular networks was significantly increased by coculture. We discussed and concluded that osteogenic and angiogenic signals from the culture media as well as from cocultured cell types, and tissue‐specific hydrogel composition all contribute to stimulate the interplay between osteogenesis and angiogenesis in vitro and are a basis for engineering vascularized bone.
Small Island Developing States (SIDS) face tension between economic growth and environmental impact. Tourism fuels growth, but the resulting solid waste and other pollutants threaten the SIDS’ natural beauty, quality of life for residents, attractiveness to tourists, and economic success. We assess the tension between tourism-driven economic growth and environmental degradation from a limits-to-growth perspective, developing a generic system dynamics model of the problem using 38 years of data from the Maldives to estimate parameters and Monte-Carlo methods to assess the sensitivity of results to uncertainty. We contrast development paths for the next three decades under three sets of policies focusing on promoting growth, managing tourism demand–supply balance, and improving waste management. Findings are counterintuitive; policies focused on better waste management alone are self defeating, because they increase tourism, growth and waste generation, undermining attractiveness and growth later. Policies that limit tourism demand improve economic and environmental health.
Relocation of production to countries with low labour costs has induced increased labour market flexibility, which has been praised as a silver bullet for economic growth and low unemployment. Within a unionised oligopoly framework, in which a multinational firm has the option to relocate its production to a foreign country, we analyse the welfare implications of both centralised and flexible wage-setting regimes. For very low foreign wages, wage flexibility leads to higher welfare than a rigid centralised regime. In contrast, for ‘intermediate’ wage levels in the foreign country, an industry-wide uniform wage leads to higher social welfare than flexible wages.