Abstract

Immunological Senescence in Space Affects Stem Cell Behavior and Function

Xiaomeng Hu, Scientist, University of California-San Francisco

Aging is associated with dysregulation of the immune response, which is also termed “immunosenescence.” Each part of the immune system is influenced to some extent by the aging process. However, adaptive immunity seems more extensively affected, and it is especially the T cells that are altered. In fact, the number and proportion of late-differentiated T cells (so called TEMRA cells), is higher in the elderly than in the young and their accumulation may contribute to the enhanced systemic pro-inflammatory milieu commonly seen in elderly individuals. We do not know exactly what causes these observed changes, but an understanding of the possible causes is now beginning to emerge. Spaceflight causes a suite of negative health effects that may be comparable to immunosenescence, which seems to be a key regulator of the regenerative capacity of tissue- and organ-specific stem cells. Specifically, studies examining the effects of bone healing (by mesenchymal stromal cells; MSCs) and vascular regeneration (by endothelial progenitor cells; EPCs) were performed using tissue mimics on chip to represent “semi-3D” architectures.