• aspirin;
  • circulation;
  • platelets;
  • stem cells;
  • vasculature



Bone marrow-derived circulating CD34+ progenitor cells participate in remodeling and repair of the vasculature. Coexpression of the kinase-insert domain-containing receptor (KDR) has been proposed to identify the regenerative capacity. Recently, we provided evidence that the major fraction of circulating CD34+/KDR+ cells is not mobilized from bone marrow, but is generated at sites of vascular injury through interaction with platelets.


To determine the relationship between platelet activation, the recruitment of naïve CD34+ cells and the generation of CD34+/KDR+ progenitor cells in a broad range of (patho)physiologic conditions, a detailed meta-regression analysis was conducted.


Twenty-eight conditions were found in which the numbers of CD34+ and/or CD34+/KDR+ cells and the levels of soluble P-selectin, as a marker for in vivo platelet activation, were documented. To combine heterogeneous data from 214 selected articles, results were standardized to a uniform scale by calculating standardized mean differences (SMDs) obtained from patient and control cohorts. Subsequently, a random-effects meta-regression analysis was performed on pooled SMDs.


Our systemic survey supports a model in which activated platelets are a determinant for mobilization of CD34+ cells from the bone marrow and the generation of CD34+/KDR+ cells in the circulation.