Cardiac Progenitor Cells and the Interplay with Their Microenvironment

The microenvironment plays a crucial role in the behavior of stem and progenitor cells. In the heart, cardiac progenitor cells (CPCs) reside in specific niches, characterized by key components that are altered in response to a myocardial infarction. To date, there is a lack of knowledge on these niches and on the CPC interplay with the niche components. Insight into these complex interactions and into the influence of microenvironmental factors on CPCs can be used to promote the regenerative potential of these cells. In this review, we discuss cardiac resident progenitor cells and their regenerative potential and provide an overview of the interactions of CPCs with the key elements of their niche. We focus on the interaction between CPCs and supporting cells, extracellular matrix, mechanical stimuli, and soluble factors. Finally, we describe novel approaches to modulate the CPC niche that can represent the next step in recreating an optimal CPC microenvironment and thereby improve their regeneration capacity

Cardiac Progenitor Cells and the Interplay with Their Microenvironment

The microenvironment plays a crucial role in the behavior of stem and progenitor cells. In the heart, cardiac progenitor cells (CPCs) reside in specific niches, characterized by key components that are altered in response to a myocardial infarction. To date, there is a lack of knowledge on these niches and on the CPC interplay with the niche components. Insight into these complex interactions and into the influence of microenvironmental factors on CPCs can be used to promote the regenerative potential of these cells. In this review, we discuss cardiac resident progenitor cells and their regenerative potential and provide an overview of the interactions of CPCs with the key elements of their niche. We focus on the interaction between CPCs and supporting cells, extracellular matrix, mechanical stimuli, and soluble factors. Finally, we describe novel approaches to modulate the CPC niche that can represent the next step in recreating an optimal CPC microenvironment and thereby improve their regeneration capacity

A study of the equitransference level of concentrated aqueous rubidium bromide, rubidium iodide and ammonium iodide and their characterization as ultra-concentrated salt bridges for the minimization of liquid junction potentials

Ion and solvent transference nos. for aq. RbBr, RbI and NH4I solns. were detd. at molalities up to 5.5, 6.5 and 7.5 mol/kg, resp., from emf. measurements on appropriate transference cells. For the minimization of liq. junction potentials, all the 3 salts above are better salt bridges than the popular satd.-KCl, both because they are more nearly equitransferent (over the whole molality range) and because they can reach satn. molalities (7.01, 7.38 and 12.69 mol/kg, resp., at 25\ub0) much higher than that of KCl (4.804 mol/kg). Therefore, concd. RbBr, RbI and NH4I solns. can be recommended as advantageous salt bridges for replacement of KCl

Cardiomyocyte progenitor cell mechanoresponse unrevealed: strain avoidance and mechanosome development.

For emerging cardiac regeneration strategies, it is essential to know if and how cardiac stem cells sense and respond to the mechanical stimuli provided by their environment in the beating heart. Here, we study the response to cyclic strain of undifferentiated and predifferentiated human cardiomyocyte progenitor cells (CMPCs), as well as the formation and activation of the cellular structures involved in mechanosensing, that we termed 'mechanosome'. Once verified that the applied uniaxial cyclic strain (10%, 0.5 Hz) did not alter the cardiac lineage commitment and differentiation state of CMPCs, the cellular mechanoresponse to the applied strain was quantified by cellular orientation. While undifferentiated cells maintained their original (random) orientation, upon early cardiomyogenic differentiation (predifferentiated) CMPCs exhibited a distinct strain avoidance response after 48 h of cyclic straining. Interestingly, the mechanosome development and the activation of the mechanotransduction pathways also occurred with early cardiac differentiation of the CMPCs, regardless of the substrate or the applied cyclic strain. These results indicate that the mechanoresponse of CMPCs depends on the presence of a developed mechanosome, which only develops during early cardiomyogenic differentiation Our findings provide the first understanding of mechanotransduction in human CMPCs and as such can contribute to the improvement of cardiac regeneration strategies