Simulated Microgravity Exerts an Age-Dependent Effect on the Differentiation of Cardiovascular Progenitors Isolated from the Human Heart

Abstract

Microgravity has a profound effect on cardiovascular function, however, little is known about the impact of microgravity on progenitors that reside within the heart. We investigated the effect of simulated microgravity exposure on progenitors isolated from the neonatal and adult human heart by quantifying changes in functional parameters, gene expression and protein levels after 6-7 days of 2D clinorotation. Utilization of neonatal and adult cardiovascular progenitors in ground-based studies has provided novel insight into how microgravity may affect cells differently depending on age.Simulated microgravity exposure did not impact AKT or ERK phosphorylation levels and did not influence cell migration, but elevated transcripts for paracrine factors were identified in neonatal and adult cardiovascular progenitors. Age-dependent responses surfaced when comparing the impact of microgravity on differentiation. Endothelial cell tube formation was unchanged or increased in progenitors from adults whereas neonatal cardiovascular progenitors showed a decline in tube formation (p<0.05). Von Willebrand Factor, an endothelial differentiation marker, and MLC2v and Troponin T, markers for cardiomyogenic differentiation, were elevated in expression in adult progenitors after simulated microgravity. DNA repair genes and telomerase reverse transcriptase which are highly expressed in early stem cells were increased in expression in neonatal but not adult cardiac progenitors after growth under simulated microgravity conditions. Neonatal cardiac progenitors demonstrated higher levels of MESP1, OCT4, and brachyury, markers for early stem cells. MicroRNA profiling was used to further investigate the impact of simulated microgravity on cardiovascular progenitors. Fifteen microRNAs were significantly altered in expression, including microRNAs-99a and 100 (which play a critical role in cell dedifferentiation). These microRNAs were unchanged in adult cardiac progenitors.The effect of exposure to simulated microgravity in cardiovascular progenitors is age-dependent. Adult cardiac progenitors showed elevated expression of markers for endothelial and cardiomyogenic differentiation whereas neonatal progenitors acquired characteristics of dedifferentiating cells.

Cardiovascular progenitor cells cultured aboard the International Space Station exhibit altered developmental and functional properties

“…Recent research in our own laboratory has shown that neonatal human CPCs cultured under two-dimensional (2D) clinorotation, which approximates weightlessness by rotating the cell culture vessel about a horizontal axis, exhibit increased expression of markers of early cardiovascular development and pluripotency (i.e., MESP1 , T (Brachyury), and OCT4 ) as well as broad changes to microRNA expression. 1 The changes in microRNA expression experienced by CPCs in these experiments mirrored the expression of similar microRNAs in human embryonic stem cells (ESC) under normal conditions of early cardiovascular development, thereby suggesting that such culture conditions induce an epigenetic environment that favors an earlier development status. Such a state appears increasingly beneficial for cardiovascular repair.…”

“…MicroRNA array profiling was performed as previously described. 1 Briefly, the miScript II RT Kit (Qiagen, Valencia, CA) was used to convert 500 ng of total RNA into cDNA, which was diluted, added to miScript SYBR Green PCR master mix and 10× universal primer mix (Qiagen, Valencia, CA), and run on human development and differentiation miScript plates (MIHS-103ZA; Qiagen, Valencia, CA). Fold changes were determined for each clone using the Qiagen Data Analysis Center ( http://www.qiagen.com/us/shop/genes-and-pathways/data-analysis-center-overview-page/ ) using all available housekeeping genes.…”

Simulated Microgravity and 3D Culture Enhance Induction, Viability, Proliferation and Differentiation of Cardiac Progenitors from Human Pluripotent Stem Cells

“…The effect of simulated microgravity on cells is known to vary depending on factors including cell type, specific bioreactor used and duration of exposure to simulated microgravity 40 41 42 . Our study suggests that a short-term exposure of cardiac progenitors to simulated microgravity in an RPM may be leveraged to improve the expansion and viability of cardiac progenitors and subsequent generation of CMs.…”

“…In other studies, up-regulation of heat shock proteins was also observed in rat hypothalamus tissues 45 , the Jurkat cells 46 and myelomonocytic U937 cells 47 as a result of exposure to microgravity, and BIRC5 was up-regulated in thymus after mice returned from a spaceflight 48 . In addition, a study on neonatal and adult cardiovascular progenitors reported that simulated microgravity could affect cell differently depending on age 42 . Among many differential responses, final number of cells and expression of DNA repair genes were increased in neonatal but not adult cardiac progenitors upon exposure to simulated microgravity 42 .…”

“…In addition, a study on neonatal and adult cardiovascular progenitors reported that simulated microgravity could affect cell differently depending on age 42 . Among many differential responses, final number of cells and expression of DNA repair genes were increased in neonatal but not adult cardiac progenitors upon exposure to simulated microgravity 42 . These studies suggest that simulated microgravity can improve cell proliferation and survival in a cell type dependent manner.…”