Nitric oxide (NO) is a diffusible free radical, which serves as a pluripotent intracellular messenger in numerous cell systems. NO has been demonstrated to regulate actin dependent cellular functions and functions as a putative inductive agent in directing stem cells differentiation. In this study, we investigated the effect of exogenous NO on the kinetics of movement and morphological changes in adult bone marrow stromal cells (BMSCs) in a wound healing model of cellular migration. Cellular migration and morphological changes were determined by measurement of changes in the area and fractal dimension of BMSCs monolayer as a function of time in the presence of an NO donor (S-Nitroso-N-Acetyl-D,L-Penicillamine, SNAP) compared to untreated BMSCs. Response of the BMSCs' actin cytoskeleton and desmin to NO was assessed by determining changes in their integrated optical density (IOD) and fractal dimension at 24 h and 7 days. NO suppressed BMSCs' migration accompanied by a reduction in cell size, with maintenance of their stellate to polygonal morphology. In response to NO, the actin cytoskeleton expressed an increase in randomness but maintained a constant amount of F-actin relative to the cell size. The presence of NO also induced an increase in randomly organized cytoplasmic desmin. These data suggest that NO has an apparent inductive effect on adult BMSCs and is capable of initiating phenotypic change at the gross cellular, cytoskeletal and molecular levels. It is apparent, however, that additional factors or conditions are required to further drive the differentiation of adult BMSCs into specific phenotypes, such as cardiomyocytes.
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