Ionizing radiation (5 Gy) induced primary senescence and a pro-inflammatory secretory profile in human cardiac stromal cells, but did not propagate secondary senescence to recipient cells.
Ionizing radiation induces primary senescence in human cardiac stromal cells, suggesting a potential cellular mechanism for radiation-induced cardiac dysfunction, though paracrine propagation of senescence was not observed.
Abstract Background Cardiotoxicity is a well-documented adverse effect of ionizing radiation (IR) therapy. IR can induce senescence in different cells, which may contribute to radiation-related cardiac dysfunction. The effects of IR on human cardiac stromal cells (hCStCs) and their senescence-associated secretory phenotype (SASP) have not yet been characterized. Purpose We thoroughly studied IR-induced senescence, as well as replicative senescence (Rep), in primary hCStCs (defined as primary senescence). We also assessed whether senescent hCStCs propagated senescence to recipient cells through their secretory activity (defined as secondary senescence). Methods hCStCs were isolated from specimens of right atrial appendages, collected during cardiac surgery with extracorporeal circulation. These cells were exposed to IR (5 Gray, Gy) and analyzed at 2 days and 14 days to assess acute and chronic response. Additionally, hCStCs were passaged until Rep was reached (P12-P14), used as positive control. Senescence was assessed by staining for senescence-associated β-galactosidase (SA-β-gal), EdU uptake and by RT-PCR analysis for LMNB1 expression, and for IL-6, IL-8 expression as hallmarks of pro-inflammatory secretory profile. Conditioned media (CM) from senescent hCStCs was collected to assess paracrine senescence in recipient hCStCs and murine neonatal ventricular cardiomyocytes (mNVCMs), as shown in the graphical abstract. Results IR, and prolonged culturing consistently induced senescence in hCStCs, highlighted by significantly reduced EdU uptake (Fig 1A), significantly increased SA-β-gal activity (Fig 1B), and significantly LMNB1 downregulation (Fig 1C upper panel). Senescent hCStCs showed the typical SASP profile, with significantly increased expression of IL-6 at IR day 14 and the presence of a trend for IL-8 in Rep (Fig 1C lower panels). Edu uptake, SA-β-gal activity, and LMNB1 expression in recipient cells showed no statistically significant changes relative to control upon incubation with CM of senescent hCStCs, pointing against the occurrence of secondary senescence (Fig 1D-1E). Conclusions IR exposure induced primary senescence in hCStCs, with distinct acute and chronic response, suggesting a potential role of stromal cell senescence in IR-induced cardiac dysfunction. Cells exposed to the CM of senescent hCStCs showed no features of secondary senescence, indicating limited paracrine impact in our experimental settings. RNA sequencing and cytokine array of senescent hCStCs are ongoing to provide a more comprehensive profiling.For image description, please refer to the figure legend and surrounding text. For image description, please refer to the figure legend and surrounding text.
Grigo et al. (Fri,) conducted a other in Ionizing radiation-induced senescence. Ionizing radiation vs. Replicative senescence / Control was evaluated on Senescence (SA-β-gal activity, EdU uptake, LMNB1 expression) and secondary senescence. Ionizing radiation (5 Gy) induced primary senescence and a pro-inflammatory secretory profile in human cardiac stromal cells, but did not propagate secondary senescence to recipient cells.