Efficient and Scalable Expansion of Human Pluripotent Stem Cells Under Clinically Compliant Settings: A View in 2013

Human pluripotent stem cells (hPSCs) hold great promise for revolutionizing regenerative medicine for their potential applications in disease modeling, drug discovery, and cellular therapy. Many their applications require robust and scalable expansion of hPSCs, even under settings compliant to good clinical practices. Rapid evolution of media and substrates provided safer and more defined culture conditions for long-term expansion of undifferentiated hPSCs in either adhesion or suspension. With well-designed automatic systems or fully controlled bioreactors, production of a clinically relevant quantity of hPSCs could be achieved in the near future. The goal is to find a scalable, xeno-free, chemically defined, and economic culture system for clinical-grade expansion of hPSCs that complies the requirements of current Good Manufacturing Practices (cGMP). This review provides an updated overview of the current development and challenges on the way to accomplish this goal, including discussions on basic principles for bioprocess design, serum-free media, extracellular matric or synthesized substrate, microcarrier- or cell aggregate-based suspension culture, and scalability and practicality of equipment

Study on equilibrium strategies for transboundary pollution under competitive conditions

Competitive relationships among players plays an increasing role on transboundary pollution management. In this paper, a transboundary pollution game between two competitive regions as a player is constructed to explore the equilibrium strategies of output and pollution abatement efforts. The dynamic of the pollution stocks for regions are modeled separately in terms of a differential equation. Subsequently, the corresponding equilibrium strategies and value functions are derived in two regimes: Nash non-cooperative and Stackelberg leader–follower games. And the expectation and variances of pollution stocks are calculated over time. Our results are summarized as follows. First, an increase in the proportion of transboundary pollution increases the output of pollution upstream region, decreases the output of pollution downstream region, and ultimately raises the aggregate pollution stock of both regions. Second, regional competitive preference can enhance the local abatement effort and reduce the aggregate pollution stock. Finally, the total social welfare and environmental quality are higher in the Nash non-cooperative game, but pollution downstream region seek to be a leader in the Stackelberg game