Bisphosphonates are commonly used for treatment of osteoporosis. They inhibit osteoclast activity and thus bone resorption. It was shown that they also affect some other cell types including tumour and endothelial cells. The effects of risedronate on bone marrow microenvironment were not studied yet. As endothelial cells are integral part of bone marrow microenvironment, it is important to know whether prolonged administration of bisphosphonates does not affect haematopoietic stem cells and bone marrow haematopoiesis. We fed mice two weeks with risedronate. We found no effect of risedronate treatment on bone marrow stem cells using the method of congenic bone marrow repopulation. Risedronate administration in the dose which is considered to be comparable to a dose of risedronate used for treatment of osteoporosis in women seems to be safe in terms of effects on mouse haematopoiesis.

Institute of Pathophysiology Charles University Prague 1st Faculty of Medicine Prague Czech Republic