Metabolic regulation of functional decline during in vitro expansion of human mesenchymal stem cells

Human mesenchymal stem cells (hMSCs) isolated from various adult tissues are primary candidates in cell therapy and being tested in clinical trials for a wide range of diseases. The pro-regenerative and therapeutic properties of hMSCs are largely attributed to their trophic effects that coordinately modulate the progression of inflammation and enhance the endogenous tissue repair by host progenitor cells. However, immediately after isolation and upon culture expansion, hMSCs lose their in vivo quiescent state and start to accumulate genetic and phenotypic changes that significantly alter their phenotypic properties with reduced clonogenic population and therapeutic potential [1]. The culture-induced changes lead to both cellular senescence and metabolic alteration, resulting in reduced therapeutic outcome in various disease models. Since clinical application requires defined cellular properties and large-scale production of hMSCs, preserving cellular homeostasis during hMSCs in vitro expansion is a major barrier for hMSCs-based therapy and production. Once viewed as a mere consequence of the state of a cell, metabolism is now known to play active roles in regulating cellular events that govern stem cell phenotype and age-related functional properties during in vitro culture. Replicative passaging of hMSCs leads to cellular senescence following with insufficient energy production, decline of stemness and functional properties. Here, we report that energy metabolism in regulating hMSC aging-related properties due to in vitro replicative culture expansion in 2D planner or spinner flask bioreactor. hMSCs under in vitro culture up to 15 passages exhibited higher senescence with significant morphological alteration. 13C-glucose-based GC-MS metabolomics analysis suggested that metabolically heterogeneity at low passage hMSCs population while metabolic shift from glycolysis towards OXPHOS at high passage hMSCs. Rapid production of energy required for maintaining cellular properties of hMSCs alters mitochondrial function and leads to breakdown of cellular homeostasis with metabolic and redox imbalance. The alteration of metabolic profile and disruption of cellular homeostasis results in the replicative senescence and decline of therapeutic potentials of hMSCs. Understanding of hMSCs aging during in vitro culture expansion provides the insight of metabolic regulation for stem cell fate and engineering aspects for preserving and rejuvenating hMSCs functions via 3D culture or restore of metabolic balance [2]. Please click Additional Files below to see the full abstract

Metabolism Regulation Of Phenotypic And Therapeutic Properties Of Human Mesenchymal Stem Cells

Introduction Human mesenchymal stem cells (hMSCs) isolated from various adult tissues are primary candidates in cell therapy and tissue regeneration. The pro-regenerative properties of hMSCs are largely attributed to their trophic effects by the release of factors that coordinately modulate the progression of inflammation and enhance the endogenous tissue repair by host progenitor cells. However, immediately after isolation and upon culture expansion, hMSCs acquire and accumulate genetic and phenotypic changes that significantly alter their phenotypic properties with reduced clonogenic and therapeutic potential. The culture-induced changes are not only correlated with reduced clonogenicity and proliferation but also with reduced therapeutic outcome in various disease models. Thus, preserving hMSC therapeutic potency following in vitro expansion is an important goal in hMSC application. Once viewed as a mere consequence of the state of a cell, metabolism is now known to play active roles in regulating cellular events that govern stem cell phenotype and functional properties. Our long term objective is to understand the role of energy metabolism in regulating hMSC cell fate with ultimate goals of developing metabolic strategies to augment hMSCs therapeutic properties. Results Our recent studies show that hMSCs have heterogeneity at the level of primary energy metabolism [1] and possess metabolic plasticity to reconfigure their metabolic network in their reacquisition of stem cell primitive properties and immune-modulatory property [2]. First, 13C-glucose-based metabolomics analysis suggested that hMSC are metabolically heterogeneous and that clonogenic subpopulation of hMSCs enriched in low density culture (100 cells/cm2) possesses a metabolic phenotype that differs from that of hMSCs in high-density (3,000 cells/cm2) in their levels of glycolysis metabolism and pentose phosphate pathway (PPP). Metabolic inhibition studies revealed that glycolysis and PPP play active roles in maintaining hMSCs clonogenicity by regulating ATP generation, maintaining cellular redox state, and scavenging exogenous reactive oxygen species [1]. Second, we showed that hMSCs possess metabolic plasticity and effectively reconfigure their metabolism during 3D aggregation culture, and that this metabolic reconfiguration plays a central role in their reacquisition of primitive phenotypic properties [2]. Specifically, aggregate formation of hMSCs remodeled their mitochondrial network with reduced mitochondrial membrane potential, resulting in metabolic reconfiguration with reduced mitochondrial citric acid cycle (TCA cycle) activity, increased aerobic glycolysis, and anaplerotic flux. The effects of metabolic reconfiguration on stem cell gene expression and secretory function was recapitulated in the gain- and loss-of-function experiments using small molecule metabolic modulators, confirming its functional role in regulating hMSC properties. Finally, we showed that hMSC immuno-activation in response to interferon-γ (IFN-γ) treatment is associated with metabolic reconfiguration towards increased aerobic glycolysis, characterized by increased glucose consumption and upregulation of glycolysis-related genes and enzymes. We further demonstrated that both glucose deprivation and glycolysis inhibition were sufficient to abolish the secretion of indoleamine 2,3-dioxygenase (IDO) a critical anti-inflammatory cytokine secreted by hMSCs, suggesting the central role of aerobic glycolysis in regulating hMSC immunomodulatory properties. Conclusions Together, the results revealed the mechanistic connection between metabolic regulation and hMSC therapeutic phenotype, and demonstrated the regulation of metabolism as a strategy in potentiating hMSCs properties for cell therapy. In the presentation, the implication of these findings in hMSC bioprocessing and therapeutic application will be discussed. References [1]. Liu, Y., N. Munoz, B.A. Bunnell, T.M. Logan, and T. Ma, Density-Dependent Metabolic Heterogeneity in Human Mesenchymal Stem Cells. Stem Cells, 2015. 33(11): p. 3368-81. [2]. Liu, Y., N. Munoz, A.C. Tsai, B.A. Bunnell, T.M. Logan, and T. Ma, Metabolic Reconfiguration Supports Reacquisition of Primitive Phenotype in Human Mesenchymal Stem Cell Aggregates. Stem Cells, 2016. August 2016, (Accepted

The Functionality Discussion with LTE Simulator for Emergency Disaster-Resilient Network Systems

The emergency communication system is a critical factor of any disaster rescue operation. Emergency communication based on an LTE system provides an evolution path toward broadband capabilities for existing and new public safety networks. The development of an LTE communication simulator is aimed at improving the performance of radio access. However, backhaul network such as base station and satellite-based relay would cause limited communication resources to hamper the rescue operation process. In this paper, we discuss the problems of disaster relief communication systems and investigate the requirements in the disaster scenario. Based on the previous LTE simulator comparison and the requirement of emergency communication, five functionalities are discussed that include disaster-oriented network management, mobility/user management, radio resource management, disaster-oriented flow management, and modeling framework. These five functionalities can help to evaluate overall resource management after disaster relief. The paper also conducted an offloading simulation to evaluate the radio resource usage for emergent disaster-resilient LTE network systems

Heterotypic cell-cell interaction of human stem cells for neural differentiation of hybrid spheroids

Organoids, the condensed 3-D tissues emerged at the early stage of organogenesis, are a promising approach to regenerate functional and vascularized organ mimics [1]. While incorporation of heterotypic cell types such as human mesenchymal stem cells (hMSCs) and human induced pluripotent stem cells (hiPSCs) derived neural progenitors aid neural organ development, the interactions of secreted factors during neurogenesis have not been well understood. The objective of this study is to investigate the impact of the composition and structure of 3-D hybrid spheroids of hiPSCs and hMSCs on dorsal cortical differentiation and the secretion of extracellular matrices and trophic factors in vitro. The hybrid spheroids were formed at different hiPSC:hMSC ratios (100:0, 75:25, 50:50, 25:75, 0:100) using direct mixing or pre-hiPSC aggregation method, which generated dynamic spheroid structure. The cellular organization, proliferation, neural marker expression, the secretion of extracellular matrix proteins and the cytokines were characterized. The incorporation of MSCs upregulated Nestin and β-tubulin III expression (the dorsal cortical identity was shown by Pax6 and TBR1 expression), matrix remodeling proteins and the secretion of transforming growth factor-β1 and prostaglandin E2. This study indicates that the appropriate composition and structure of hiPSC-MSC spheroids promote neural differentiation and trophic factor and matrix secretion due to the heterotypic cell-cell interactions. Please click Additional Files below to see the full abstract

A scalable xeno-free microcarrier suspension bioreactor system for regenerative medicine biomanufacturing of hMSCs

An economical biomanufacturing paradigm for human mesenchymal stem/stromal cells (hMSCs) is in critical need, as indicated by over 800 clinical trials investigating the use of hMSCs for regenerative medicine. To meet the demand for clinical manufacturing, a scalable process and production technology platform that can generate billions to trillions of cells per manufacturing lot is needed. Suspension bioreactors show great promise in reaching commercially-viable working volumes, however, scalability of cell production remains an issue. Overcoming this challenge is necessary to drive widespread adoption of this culture system for hMSCs. We have taken the Quality by Design (QbD) approach to develop a scalable xeno-free (XF) hMSC bioreactor process that maintains the final cell population doubling level (PDL) within the recommended range of 16-20 to ensure product quality. Our strategic XF bioprocess was designed using high volume XF cell banks, an optimized XF fed-batch media system, and XF microcarriers, all combined in a scalable bioreactor system to meet our design criteria and streamlined production at different culture scales. Please click Additional Files below to see the full abstract

Asset prices regime-switching and the role of inflation targeting monetary policy

This paper provides the empirical framework to assess whether UK monetary policy shocks induce both the UK housing market and the UK stock market to remain at a high-volatility (risk) environment. The Markov regime switching modelling approach is employed in order to identify two distinct environments for each market; namely, a high-risk environment and a low-risk environment, while a probit model is employed in order to test whether monetary policy shocks provide this predictive information regarding the current state of both markets under consideration. Our findings indicate that monetary policy shocks do indeed have predictive power on the stock market. In addition, in both asset markets there is a key role for inflation. Results are important especially within the framework of the inflation targeting monetary policy regime

Longitudinal seroepidemiologic study of the 2009 pandemic influenza A (H1N1) infection among health care workers in a children's hospital

<p>Abstract</p> <p>Background</p> <p>To probe seroepidemiology of the 2009 pandemic influenza A (H1N1) among health care workers (HCWs) in a children's hospital.</p> <p>Methods</p> <p>From August 2009 to March 2010, serum samples were drawn from 150 HCWs in a children's hospital in Taipei before the 2009 influenza A (H1N1) pandemic, before H1N1 vaccination, and after the pandemic. HCWs who had come into direct contact with 2009 influenza A (H1N1) patients or their clinical respiratory samples during their daily work were designated as a high-risk group. Antibody levels were determined by hemagglutination inhibition (HAI) assay. A four-fold or greater increase in HAI titers between any successive paired sera was defined as seroconversion, and factors associated with seroconversion were analyzed.</p> <p>Results</p> <p>Among the 150 HCWs, 18 (12.0%) showed either virological or serological evidence of 2009 pandemic influenza A (H1N1) infection. Of the 90 unvaccinated HCWs, baseline and post-pandemic seroprotective rates were 5.6% and 20.0%. Seroconversion rates among unvaccinated HCWs were 14.4% (13/90), 22.5% (9/40), and 8.0% (4/50) for total, high-risk group, and low-risk group, respectively. Multivariate analysis revealed being in the high-risk group is an independent risk factor associated with seroconversion.</p> <p>Conclusion</p> <p>The infection rate of 2009 pandemic influenza A (H1N1) in HCWs was moderate and not higher than that for the general population. The majority of unvaccinated HCWs remained susceptible. Direct contact of influenza patients and their respiratory samples increased the risk of infection.</p

The interplay of competition and cooperation

Research streams on competition and cooperation are central to the field of strategic management but have evolved independently. The emerging literature on coopetition has brought attention to the phenomenon of simultaneous competition and cooperation, yet the interplay between the two has remained under-researched. We offer a roadmap for studying this interplay, which identifies some of its antecedents and consequences, highlights debates concerning the nature of competition and cooperation and the association between the two, and directs attention to the tension between competition and cooperation and the alternative approaches for managing this tension. We discuss the broader implications of the interplay, note some intriguing open questions, offer directions for future research, and present an organizing framework for the interplay of competition and cooperation