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The Scientific World Journal
Volume 2012, Article ID 384936, 11 pages
Research Article

Monocytes Do Not Transdifferentiate into Proper Osteoblasts

1Department of Traumatology, MRI, Technical University Munich, 81675 Munich, Germany
2Department of Sports Orthopedics, “Klinikum rechts der Isar”, Technical University Munich, MRI, Ismaningerstrasse 22, 81675 Munich, Germany
3Eberhard-Karls University, BG Trauma Clinic, 72076 Tübingen, Germany
4Department of Vascular Surgery, MRI, Technical University Munich, 81675 Munich, Germany

Received 24 December 2011; Accepted 11 January 2012

Academic Editors: A. Aronheim and H. Nakagami

Copyright © 2012 Andreas Schmitt et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Recent publications suggested that monocytes might be an attractive cell type to transdifferentiate into various cellular phenotypes. Aim was, therefore, to evaluate the potential of blood monocytes to transdifferentiate into osteoblasts. Monocytes isolated from peripheral blood were subjected to two previously published treatments to obtain unique, multipotent cell fractions, named programmable cells of monocytic origin (PCMOs) and monocyte-derived mesenchymal progenitor cells (MOMPs). Subsequently, MOMPs and PCMOs were treated with osteogenic differentiation medium (including either vitamin D or dexamethasone) for 14 days. Regarding a variety of surface markers, no differences between MOMPs, PCMOs, and primary monocytes could be detected. The treatment with osteogenic medium neither resulted in loss of hematopoietic markers nor in adoption of mesenchymal phenotype in all cell types. No significant effect was observed regarding the expression of osteogenic transcription factors, bone-related genes, or production of mineralized matrix. Osteogenic medium resulted in activation of monocytes and appearance of osteoclasts. In conclusion, none of the investigated monocyte cell types showed any transdifferentiation characteristics under the tested circumstances. Based on our data, we rather see an activation and maturation of monocytes towards macrophages and osteoclasts.