BoneKEy Reports | BoneKEy Watch
MSCs in peripheral blood and bone marrow increase after femur injury
DOI:10.1038/bonekey.2012.88
It is becoming increasingly well accepted that mesenchymal stem cells (MSCs) are involved in the bone fracture healing process, and that MSCs from the peripheral blood may undergo expansion and migration to the site of injury.
In this study, Iwakura et al. looked at the levels of MSCs in arterial and venous blood, and also in the bone marrow of rabbits in the days following an induced femur fracture in one leg. The numbers of MSCs present at all three sites increased after injury; the levels in venous blood peaked within one day, the levels in arterial blood peaked at day 4 and the levels in the bone marrow of the opposite femur continued to rise between day 1 and day 7.
The authors say that the exact source of the extra MSCs is not clear; circulating progenitor cells may be mobilized and directed to the fracture site, or newly differentiated MSCs may be produced from progenitor cells in response to injury.
Editor's comment: This study in rabbits documents the time course of circulating progenitor cells. There is current interest in the collection of these progenitors after fracture to promote repair but, as the authors note, the behavior of circulating MSCs from humans and rabbits has been observed to be significantly different. Further work will be needed to understand the clinical relevance.
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