C17.2 신경줄기세포 및 일차 신경줄기세포의 허혈 내성

Abstract

Background: It has not been studied whether neural stem cells (NCSs) have ischemic tolerance phenomenon, which could protect the cells when exposed to non-permissive environments. Methods: C17.2 neural precursor cells (NPCs) and freshly-isolated NPCs growing as neurospheres were used to study: (a) if NPCs survival rate could be decreased by exposing them to in vitro ischemia, and (b) if the survival rate could be improved by a preceding hypoxia of short duration. After a baseline experiment to verify that the cells have characteristics of NSCs, 30 min or 1 hour of ischemia was applied to the cells of the preconditioning-only group and ischemia-after-preconditioning group. Forty eight hours later, 12 or 24 hours of main ischemia was given to the cells of the ischemia-after-preconditioning group and ischemia-without-preconditioning group. Control group cells were incubated under normoxic conditions for equivalent durations. After 2 or 12 hours of reperfusion period, luciferase viability assays, lactate dehydrogenase release cytotoxicity assays, and annexin/propidium-iodide flow cytometry assays of apoptosis/necrosis were performed. Results: The C17.2-Luc NPCs and primary NPCs had well-established characteristics of neural stem cells. Intact NPCs were decreased in numbers after 12 or 24 hours of in vitro ischemia followed by 2 or 12 hours of reperfusion. The cell death rate could be reduced (20%~60%) by a preceding hypoxia of 30 min or 1 hour duration. The flowcytometry study suggested that the decreased rates of aopototic or apopto-necrotic deaths were responsible for the improved cell viability. Conclusions: In summary, this study demonstrated that the hypoxic preconditioning could protect NSCs against subsequent lethal ischemia.