OBJECTIVE
Diabetes mellitus (DM) increases cardiovascular risk, at least in part, through shortage of vascular regenerative cells derived from the bone marrow (BM). In experimental models, DM causes morphological and functional BM alterations, but information on BM function in human DM is missing. Herein, we sought to assay mobilization of stem and proangiogenic cells in subjects with and without DM.

RESEARCH DESIGN AND METHODS
In a prospective trial (NCT01102699), we tested BM responsiveness to 5 μg/kg human recombinant granulocyte colony-stimulating factor (hrG-CSF) in 24 individuals with DM (10 type 1 and 14 type 2) and 14 individuals without DM. Before and 24 h after hrG-CSF, we quantified circulating stem/progenitor cells and total and differential white blood cell counts. We also evaluated in vivo the proangiogenic capacity of peripheral blood mononuclear cells using the Matrigel plug assay.

RESULTS
In response to hrG-CSF, levels of CD34(+) cells and other progenitor cell phenotypes increased in subjects without DM. Patients with DM had significantly impaired mobilization of CD34(+), CD133(+), and CD34(+)CD133(+) hematopoietic stem cells and CD133(+)KDR(+) endothelial progenitors, independently of potential confounders. The in vivo angiogenic capacity of peripheral blood mononuclear cells significantly increased after hrG-CSF in control subjects without DM, but not in patients with DM. DM was also associated with inability to upregulate CD26/DPP-4 on CD34(+) cells, which is required for the mobilizing effect of granulocyte colony-stimulating factor.

CONCLUSIONSStem and proangiogenic cell mobilization in response to hrG-CSF is impaired in DM, possibly because of maladaptive CD26/DPP-4 regulation. These alterations may hamper tissue repair and favor the development of cardiovascular complications.