Objective: We used sodium nitroprusside (SNP), a nitric oxide (NO) releasing molecule, to understand its effect on viability and proliferation of rat bone marrow mesenchymal stem cells (BM-MSCs). Materials and Methods: This experimental study evaluated the viability and morphology of MSCs in the presence of SNP (100 to 2000 μM) at 1, 5, and 15 hours. We chose the 100, 1000, and 2000 μM concentrations of SNP for one hour exposure for further analyses. Cell proliferation was investigated by the colony forming assay and population doubling number (PDN). Na+, K+, and Ca2+ levels as well as activities of lactate dehydrogenase (LDH), alkaline phosphatase (ALP), aspartate transaminase (AST), and alanine transaminase (ALT) were measured. Results: The viability of MSCs dose-dependently reduced from 750 μM at one hour and 250 μM at 5 and 15 hours. The 100 μM caused no change in viability, however we observed a reduction in the cytoplasmic area at 5 and 15 hours. This change was not observed at one hour. The one hour treatment with 100 μM of SNP reduced the mean colony numbers but not the diameter when the cells were incubated for 7 and 14 days. In addition, one hour treatment with 100 μM of SNP significantly reduced ALT, AST, and ALP activities whereas the activity of LDH increased when incubated for 24 hours. The same treatment caused an increase in Ca2+ and reduction in Na+ content. The 1000 and 2000 μM concentrations reduced all the factors except Ca2+ and LDH which increased. Conclusion: The high dose of SNP, even for a short time, was toxic. The low dose was safe with respect to viability and proliferation, especially over a short time. However elevated LDH activity might increase anaerobic metabolism.
