Background: Recent studies have revealed that exposure to hexavalent chromium compounds (Cr (VI)) could lead to various types of cancers. Bone marrow is a main tissue in which hematopoiesis occurs. In this process, a single type of stem cell (multi potent hematopoietic cells (MHCs) gives rise to all the mature blood cells in the body. Since this process is very important for developing blood cells, any toxic agent which can affect cells may result in diseases.

Materials and Methods: In the present study, we investigated the toxicity effect of Chromium oxide on bone marrow stem cells using the tryphan blue exclusion and MTT assay. For this purpose, the non-adherent multipotent hematopoietic cells of bone marrow were prepared and then cultured in the absence and presence of various concentrations of Chromium oxide. Viability of the cells was determined by tryphan blue exclusion and MTT assay. Apoptotic and necrotic effects of the metal was studied using the ethidium bromide/acridine orange staining method using fluorescence microscopy.

Results: The results showed that Chromium oxide decreased cell viability, in a dose dependent manner, to 50% of the control viability at high concentration of the metal (200 µg/ml). Morphological studies showed that as metal concentration increased, features of apoptosis such as Chromatin condensation, nuclear fragmentation, alterations in the size and the shape of the cells occurred.

Conclusion: It can be concluded that Chromium oxide has toxic effect on hematopoietic cells of mouse bone marrow and precedes the cells into apoptosis and necrosis.