This study builds upon previously reported space flight data in GenLab, as well as our own published data whereby the investigator evaluate the effect of microgravity on the differentiation and functional potential of circulating stem cells. The goal of this work is to leverage the powerful genetic analyses done in the SPHINX study and look at the consequences these changes have on cell-cell communications essential for vascular homeostasis, for a possible correlation to cardiovascular deconditioning. The application of this work is targeted at possible "cell based" countermeasures to address the negative effects of microgravity on the vasculature.