J Appl Physiol (1985). 2016 Nov 23;:jap.00696.2016
Hematopoietic stem and progenitor cells are necessary to maintain, repair, and reconstitute the hematopoietic blood cell system. Mobilization of these cells from bone marrow to blood can be greatly increased under certain conditions, one such being exercise. The purpose of this study was to identify the importance of exercise intensity in hematopoietic mobilization, to better understand the mobilization kinetics post exercise, and to determine if exercise is capable of mobilizing several specific populations of hematopoietic cells that have clinical relevance in a transplant setting. Healthy individuals were exercised on a cycle ergometer at 70% of their WRpeak until volitional fatigue and at 30% of their WRpeak work matched to the 70% WRpeak bout. Blood was collected prior to, immediately post, and 10, 30 and 60 minutes post exercise. Total blood cells, hematocrit, and mononuclear cells isolated by density gradient centrifugation were counted. Specific populations of hematopoietic stem cells were analyzed by flow cytometry. Mononuclear cells, CD34(+), CD34(+)/CD38(-), CD34(+)/CD110(+), CD3(-)/CD16(+)/CD56(+), CD11c(+)/CD123(-), and CD11c(-)/CD123(+) cells per mL of blood increased post exercise. Overall, the 70% WRpeak exercise group showed greater mobilization immediately post exercise, while there was no observable increase in mobilization in the work matched 30% WRpeak exercise group. Mobilization of specific populations of hematopoietic cells mirrored changes in the general mobilization of mononuclear cells, suggesting that exercise serves as a non-specific mobilization stimulus. Evidently, higher intensity exercise is capable of mobilizing hematopoietic cells to a large extent and immediately post exercise is an ideal timepoint for their collection.