Stem Cell Treatment after Ischemic Stroke Alters the Expression of DNA Damage Signaling Molecules

Accumulating evidence suggests that oxidative DNA damage plays a critical role in cell death associated with ischemic stroke. Endogenous oxidative DNA damage can be detected in the ischemic brain during the stages that precedes the manifestation of cell death and is believed to trigger cell death via various intracellular signaling pathways. Inhibiting the signaling associated with DNA damage induction or facilitating the signaling associated with the DNA repair process can be neuroprotective against brain injury after ischemic stroke. Recent reports demonstrated that human umbilical cord blood-derived mesenchymal stem cells (HUCB-MSCs) prevented the upregulation of apoptotic signaling pathway molecules and thereby attenuated the extent of apoptosis after focal cerebral ischemia as well as improved the neurological recovery. Therefore, we hypothesized that HUCB-MSCs treatment after focal cerebral ischemia prevents the overexpression of molecules associated with DNA damage induction as well as augments the expression of molecules associated with DNA repair process. In order to test our hypothesis, we administered HUCB-MSCs (0.25x106cells/animal) intravenously via tail vein to male Sprague-Dawley rats that were subjected to a two-hour middle cerebral artery occlusion followed by one-day reperfusion. Ischemic brain tissues obtained from various groups seven days’ post reperfusion were subjected to DNA damage signaling pathway PCR microarray. Our results demonstrated the induction of both DNA damage inducing and repair genes after focal cerebral ischemia and reperfusion. HUCB-MSCs treatment downregulated the DNA damage inducing genes and upregulated the DNA repair genes without disturbing the endogenous defense mechanisms.