Chromosomal instability in in vitro cultured mouse hematopoietic cells associated with oxidative stress

Hematopoietic stem cells (HSCs) that give rise to all blood cell types are important vehicles for cell-based and gene therapies. After isolation from the bone marrow, HSCs are often cultured in laboratory settings for purposes of ex vivo expansion, gene transduction, and bone marrow transplantation for the treatment of various disorders of the blood and immune systems. Here we demonstrate that during in vitro culturing outside of hypoxic bone marrow niches, HSCs may genetically alter even after short durations of time. Lineage(-) Scal-1(+) c-Kit(+) (LSK) cells that are enriched with HSCs revealed significant levels of genomic instability following culture, as evidenced by the emergence of aneuploid cells. To further determine the effects of in vitro culturing conditions, whole bone marrow cells were cultured in a hypoxic environment of 3% oxygen, mimicking conditions within the body's bone marrow, following which, cells proved to undergo less genetic alterations. Proper dosages of the antioxidant N-Acetyl-Cysteine (NAC) similarly decreased occurrences of chromosomal change. Furthermore, analysis of aged hematopoietic cells revealed enhanced in vitro normoxic culture-induced chromosomal instability compared to that of young hematopoietic cells due to noted increased oxidative stress in aged cells. These results reveal that in vitro cell culturing does indeed cause genomic instability in hematopoietic cells. Reduced oxygen to physiological levels and additions of antioxidants can be employed as possible strategies to lower oxidative stress and decrease chances of chromosomal transformation. Because hematopoietic cells are commonly processed in laboratory settings before transplantation for patient treatment, our findings also raise a concern on the therapeutic use of cultured hematopoietic cells.