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

Perspective on Epitaxial NiCo2O4 Film as an Emergent Spintronic Material: Magnetism and Transport Properties

The ferrimagnetic inverse spinel NiCo2O4 has attracted extensive research interests for its versatile electrochemical properties, robust magnetic order, high conductivity, and fast spin dynamics, as well as its highly tunable nature due to the closely coupled charge, spin, orbital, lattice, and defect effects. Single-crystalline epitaxial thin films of NiCo2O4 present a model system for elucidating the intrinsic physical properties and strong tunability, which are not viable in bulk single crystals. In this perspective, we discuss the recent advances in epitaxial NiCo2O4 thin films, focusing on understanding its unusual magnetic and transport properties in light of crystal structure and electronic structure. The perpendicular magnetic anisotropy in compressively strained NiCo2O4 films is explained by considering the strong spin-lattice coupling, particularly on Co ions. The prominent effect of growth conditions reveals the complex interplay between the crystal structure, cation stoichiometry, valence state, and site occupancy. NiCo2O4 thin films also exhibit various magnetotransport anomalies, including linear magnetoresistance and sign change in anomalous Hall effect, which illustrate the competing effects of band intrinsic Berry phase and impurity scattering. The fundamental understanding of these phenomena will facilitate the functional design of NiCo2O4 thin films for nanoscale spintronic applications

Effect of correlated oxide electrodes on disorder pinning and thermal roughening of ferroelectric domain walls in epitaxial PbZr\u3csub\u3e0.2\u3c/sub\u3eTi\u3csub\u3e0.8\u3c/sub\u3eO\u3csub\u3e3\u3c/sub\u3e thin films

We report the competing effects of disorder pinning and thermal roughening on ferroelectric domain walls as a function of temperature in epitaxial PbZr0.2Ti0.8O3 thin films deposited on (001) SrTiO3 substrates buffered by three types of correlated oxide electrodes, La0.67Sr0.33MnO3, LaNiO3, and SrIrO3. Piezoresponse force microscopy studies show that the 50-nm PbZr0.2Ti0.8O3 films are uniformly polarized in the as-grown states, with the patterned domain structures persisting above 700 °C. For all three types of films, the domain wall roughness is dominated by two-dimensional (2D) random bond disorder at room temperature, and transitions to 1D thermal roughening upon heating. The roughness exponent ζ increases progressively from 0.3 to 0.5 within a temperature window that depends on the bottom conducting oxide type, from which we extracted the distribution of disorder pinning energy. We discuss the possible origins of the disorder pinning and the effect of the correlated oxide electrodes on the energy landscape of DW motion

Numerical analysis of pipe jacking in deep soft soil based on the construction of urban underground sewage pipeline

Pipe jacking construction in complex soil layers and soil conditions remains to be a tough issue, because various factors are supposed to be considered and the jacking parameters needs optimization. The purpose of this paper is to analyze the impact of pipe jacking on surface settlement, soil deformation and pipe-soil interaction in a numerical model of pipe jacking through deep soft soil, which is a simulated construction of urban underground sewage pipeline. The results show that the pipe jacking construction adopted in the deep soft soil layer has little effect on the surrounding soil layers. And the maximum ground settlement is only about 8 mm. The impact of pipe jacking construction in deep soft soil layer on ground settlement is about 6 times the diameter of the jacking pipe along the pipe axis. Finally, the input force needs to be selected according to the condition of the soil layer to ensure the safety of the pipe jacking construction

Numerical assessment of the reduction of specific absorption rate by adding high dielectric materials for fetus MRI at 3 T

The specific absorption rate (SAR) is an important issue to be considered in fetus MRI at 3 T due to the high radiofrequency energy deposited inside the body of pregnant woman. The high dielectric material (HDM) has shown its potential for enhancing B field and reducing SAR in MRI. The aim of this study is to assess the feasibility of SAR reduction by adding an HDM to the fetus MRI. The feasibility of SAR reduction is numerically assessed in this study, using a birdcage coil in transmission loaded with an electromagnetic pregnant woman model in the SEMCAD-EM solver. The HDMs with different geometric arrangements and dielectric constants are manually optimized. The B1+ ${B-1}^ +$ homogeneity is also considered while calculating the optimized fetus 10 g local SAR among different strategies in the application of HDM. The optimum maximum fetus 10 g local SAR was obtained as 2.25 W/kg, by using two conformal pads placed left and right with the dielectric constant to be 400, reduced by 24.75% compared to that without the HDM. It indicated that the SAR can be significantly reduced with strategic placement of the HDM and the use of HDM may provide a simple, effective and low-cost method for reducing the SAR for the fetus MRI at 3 T

Numerical analysis of pipe jacking in deep soft soil based on the construction of urban underground sewage pipeline

Pipe jacking construction in complex soil layers and soil conditions remains to be a tough issue, because various factors are supposed to be considered and the jacking parameters needs optimization. The purpose of this paper is to analyze the impact of pipe jacking on surface settlement, soil deformation and pipe-soil interaction in a numerical model of pipe jacking through deep soft soil, which is a simulated construction of urban underground sewage pipeline. The results show that the pipe jacking construction adopted in the deep soft soil layer has little effect on the surrounding soil layers. And the maximum ground settlement is only about 8 mm. The impact of pipe jacking construction in deep soft soil layer on ground settlement is about 6 times the diameter of the jacking pipe along the pipe axis. Finally, the input force needs to be selected according to the condition of the soil layer to ensure the safety of the pipe jacking construction

Calculating the Mean Amplitude of Glycemic Excursions from Continuous Glucose Data Using an Open-Code Programmable Algorithm Based on the Integer Nonlinear Method

The mean amplitude of glycemic excursions (MAGE) is an essential index for glycemic variability assessment, which is treated as a key reference for blood glucose controlling at clinic. However, the traditional “ruler and pencil” manual method for the calculation of MAGE is time-consuming and prone to error due to the huge data size, making the development of robust computer-aided program an urgent requirement. Although several software products are available instead of manual calculation, poor agreement among them is reported. Therefore, more studies are required in this field. In this paper, we developed a mathematical algorithm based on integer nonlinear programming. Following the proposed mathematical method, an open-code computer program named MAGECAA v1.0 was developed and validated. The results of the statistical analysis indicated that the developed program was robust compared to the manual method. The agreement among the developed program and currently available popular software is satisfied, indicating that the worry about the disagreement among different software products is not necessary. The open-code programmable algorithm is an extra resource for those peers who are interested in the related study on methodology in the future

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