Abstract
Microgravity-induced alterations in the autonomic nervous system (ANS) contribute to derangements in both the mechanical and electrophysiological function of the cardiovascular system, leading to severe symptoms in humans following space travel. Because the ANS forms embryonically from neural crest (NC) progenitors, we hypothesized that microgravity can impair NC-derived cardiac structures. Accordingly, we conducted in vitro simulated microgravity experiments employing NC genetic lineage tracing in mice with
cKit
CreERT2/+
,
Isl1nLacZ
, and
Wnt1-Cre
reporter alleles. Inducible fate mapping in adult mouse hearts and pluripotent stem cells (iPSCs) demonstrated reduced
cKit
CreERT2/+
-
mediated labeling of both NC-derived cardiomyocytes and autonomic neurons (
P
< 0.0005 vs. controls). Whole transcriptome analysis, suggested that this effect was associated with repressed cardiac NC- and upregulated mesoderm-related gene expression profiles, coupled with abnormal bone morphogenetic protein (BMP)/transforming growth factor beta (TGF-β) and Wnt/β-catenin signaling. To separate the manifestations of simulated microgravity on NC versus mesodermal-cardiac derivatives, we conducted
Isl1nLacZ
lineage analyses, which indicated an approximately 3-fold expansion (
P
< 0.05) in mesoderm-derived
Isl-1
+
pacemaker sinoatrial nodal cells; and an approximately 3-fold reduction (
P
< 0.05) in cardiac NC-derived ANS cells, including sympathetic nerves and
Isl-1
+
cardiac ganglia. Finally, NC-specific fate mapping with a
Wnt1-Cre
reporter iPSC model of murine NC development confirmed that simulated microgravity directly impacted the in vitro development of cardiac NC progenitors and their contribution to the sympathetic and parasympathetic innervation of the iPSC-derived myocardium. Altogether, these findings reveal an important role for gravity in the development of NCs and their postnatal derivatives, and have important therapeutic implications for human space exploration, providing insights into cellular and molecular mechanisms of microgravity-induced cardiomyopathies/channelopathies.
