MMP modulated differentiation of mouse embryonic stem cells on engineered cell derived matrices.

Stem cell differentiation is dictated by the dynamic crosstalk between cells and their underlying extracellular matrix. While the importance of matrix degradation mediated by enzymes such as matrix metalloproteinases (MMPs) in the context of cancer invasion is well established, the role of MMPs in stem cell differentiation remains relatively unexplored. Here we address this question by assaying MMP expression and activity during differentiation of mouse embryonic stem cells (mESCs) on mouse embryonic fibroblast (MEF) derived matrices (MEFDMs) of varying stiffness and composition. We show that mESC differentiation into different germ layers is associated with expression of several MMPs including MMP-11, 2, 17, 25 and 9, with MMP-9 detected in cell secreted media. Different extents of softening of the different MEFDMs led to altered integrin expression, activated distinct mechanotransduction and metabolic pathways, and induced expression of germ layer-specific markers. Inhibition of MMP proteolytic activity by the broad spectrum MMP inhibitor GM6001 led to alterations in germ layer commitment of the differentiating mESCs. Together, our results illustrate the effect of MMPs in regulating mESC differentiation on engineered cell derived matrices and establish MEFDMs as suitable substrates for understanding molecular mechanisms regulating stem cell development and for regenerative medicine applications.

Geographical Appraisal of COVID-19 in West Bengal, India.

Study shows that COVID-19 cases, deaths and recoveries vary in macro level. Geographical phenomena may act as potential controlling factor. The present paper investigates spatial pattern of COVID-19 cases and deaths in West Bengal (WB), India and assumes Kolkata is the source region of this disease in WB. Thematic maps on COVID related issues are prepared with the help of QGIS 3.10 software. As on 15th January 2021, WB has 564032 number of COVID-19 cases which is 0.618% to the total population of the state. However, the COVID-19 case for India is 0.843% and for world is 1.341% to its total population. Lorenz Curve shows skewed distribution of the COVID-19 cases in WB. 17 (90%) districts hold 84.11% of the total population and carry 56.30% of the total COVID-19 cases. However, the remaining two districts-Kolkata and North 24 Parganas-hold remaining 43.70% COVID-19 cases. Correlation coefficient with COVID-19 cases and Population Density, Urban Population and Concrete Roof of their house are significant at 1% level of significance.

Initial Priming on Soft Substrates Enhances Subsequent Topography-Induced Neuronal Differentiation in ESCs but Not in MSCs.

Differentiation of stem cells into neurogenic lineage is of great interest for treatment of neurodegenerative diseases. While the role of chemical cues in regulating stem cell fate is well appreciated, the identification of physical cues has revolutionized the field of tissue engineering leading to development of scaffolds encoding one or more physical cues for inducing stem cell differentiation. In this study, using human mesenchymal stem cells (hMSCs) and mouse embryonic stem cells (mESCs), we have tested if stiffness and topography can be collectively tuned for inducing neuronal differentiation by culturing these cells on polyacrylamide hydrogels of varying stiffness (5, 10, and 20 kPa) containing rectangular grooves (10, 15, and 25 µm in width). While hMSCs maximally elongate and express neuronal markers on soft 5 kPa gels containing 10/15 µm grooves, single mESCs are unable to sense topographical features when cultured directly on grooved gels. However, this inability to sense topography is rescued by priming mESCs initially on soft 1 kPa flat gels and then replating these cells onto the grooved gels. Compared to direct culture on the grooved gels, this sequential adaptation increases both viability as well as neuronal differentiation. However, this two-step process does not enhance neuronal marker expression in hMSCs. In addition to highlighting important differences between hMSCs and mESCs in their responsiveness to physical cues, our study suggests that conditioning on soft substrates is essential for inducing topography-mediated neuronal differentiation in mESCs.