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Analysis of circulating mesenchymal progenitor cells in arterial and venous blood after fracture

Mesenchymal progenitor cells (MPCs) play a critical role in fracture healing. Increasing evidence suggests that circulating MPCs in peripheral blood are mobilized during fracture healing and may contribute to fracture repair. However, to date, there have been no reports comparing the number of circulating MPCs in arterial blood (AB) with that in venous blood (VB) after fracture. In this study, we investigated the numbers of MPCs in AB, VB and bone marrow (BM) after fracture in rabbits via the colony‐forming unit–fibroblasts (CFU‐Fs) assay, and clarified the time‐course change. After femoral fracture in one side, the number of BM‐MPCs in the contralateral femur increased from day 1 to day 7. Correspondingly, the number of circulating MPCs in AB and VB increased. The number of circulating MPCs in AB was highest at post‐fracture day 4, whereas that in VB was highest at post‐fracture day 1, with significant difference compared to the control. Circulating MPCs in AB and VB after fracture may serve as new cell sources for bone tissue engineering. As the peaks of the number of circulating MPCs in AB and VB after fracture were different, our findings may provide new insights about when to collect circulating MPCs after fracture and from which blood to obtain them. Copyright © 2012 John Wiley & Sons, Ltd.