Protection of hematopoietic progenitor cells by nitric oxide

The free radical gas nitric oxide (NO) has been reported to trigger apoptosis of a variety of cell types, but there have also been contradictory reports of an inhibitory effect of NO on this form of programmed cell death. We hypothesized that NO may inhibit apoptosis of hematopoietic cells. In this study, therefore, hematopoietic cells obtained from umbilical cord blood (CB) were incubated with NO, and NO inhibited apoptosis of hematopoietic cells in umbilical CB, although it did not affect the number of mononuclear cells (MNC). Inhibition of apoptosis of hematopoietic cells is important for their use in transplantation. Our results suggest that it might be possible to prevent the loss of hematopoietic cells using NO.