N-acetylcysteine protects induced pluripotent stem cells from in vitro stress: impact on differentiation outcome.

Induced pluripotent stem cells (iPSCs) have the ability to differentiate towards various cell types of the adult organism and are a potential source of transplantable material in regenerative medicine. The entire process of conversion of iPSCs into terminally differentiated cells takes place in vitro and requires long periods of time. During in vitro culture, cells are exposed to environmental factors, which are capable of decreasing cellular performance and viability. Oxidative stress is the major underlying mechanism of such negative impact of in vitro environmental factors. We aimed to study the alteration of cellular properties during in vitro hematopoietic differentiation of human iPSCs and the ability of N-acetylcysteine (NAC), a potent free radical scavenger, to prevent such alterations. IPSCs were differentiated towards hematopoietic cells in the presence of 1 mM NAC. Intracellular reactive oxygen species (ROS), nitric oxide (NO), senescence, apoptosis and mitochondrial membrane potential (MMP) were evaluated at 1 and 3 weeks of differentiation. In the course of hematopoietic differentiation of iPSCs, cells progressively accumulated intracellular ROS and NO, increased the levels of apoptosis and senescence, and showed a decrease in mitochondrial functionality. NAC supplementation reversed all these phenomena. NAC administration also improved hematopoietic differentiation of iPSCs in terms of production of CD34, CD45 and CD43 positive cells. In conclusion, when supplemented during hematopoietic differentiation of iPSCs, NAC decreased oxidative stress, rescued the decline in cellular properties induced by long-term in vitro culture and promoted hematopoietic differentiation of iPSCs.