Simulated Lunar Microgravity Transiently Arrests Growth and Induces Osteocyte-Chondrocyte Lineage Differentiation in Human Wharton's jelly stem cells.

Human Wharton's jelly stem cells (hWJSCs) are multipotent stem cells extensively employed in biotechnology applications and can be differentiated into distinct lineages through various culture approaches. However, the impact of simulated microgravity (sµG) on the growth, differentiation, and viability of this cell population is incompletely characterized. We aimed to determine whether acute (72 hour) exposure to lunar sµG (0.16 G) elicited changes in growth, viability and lineage differentiation in hWJSCs and if putative changes were maintained once exposure to terrestrial gravity (1.0G) was restored. Our data support earlier findings that acute sµG significantly reduces cell division potential of hWJSCs, and suggest that actute sµG-exposure induces reversible changes in cell growth accompanied by osteocyte – chondrocyte changes in lineage differentiation. Overall design: hWJSCs (n=7) were cultured under standard 1.0G conditions, prior to being passaged and cultured under sµG (0.16G) using a Random Positioning Machine. Separate control lines accounting for alterations in cell culture gas exchange and sµG were ran in parallel for a total of 72 hours. Cells were sampled before passage and cultured for a further 72-hour period of growth at 1.0G. Cells were sampled for cell morphology imaging, cell counts using both an automated cell counter and trypan blue vital count, cell viability (MTS) assay, FACS analysis for CD34, CD45, CD73, CD90 and CD105, total RNA extraction for qRT-PCR and RNA sequencing.