Endothelial Progenitor Cells Carrying Monocyte Markers are Selectively Abnormal in Type 1 Diabetic Patients with Early Retinopathy

Endothelial progenitor cells (EPCs) enter the systemic circulation
in response to cues related to vascular damage and need for
neovascularization. Thus, EPCs could become readily accessible
informers of vascular status and enable the survey of vascular
pathologies during preclinical stages. To identify EPC changes
with biomarker potential, we investigated whether discrete EPC
abnormalities were associated with early nonproliferative diabetic
retinopathy (NPDR). Two EPC subtypes with different functions
have been characterized to date—one solely committed to the
endothelial lineage and the other carrying both endothelial and
monocytic markers. We found that only the latter, colony-forming
units (CFU)-Hill cells, manifested abnormalities in type 1 diabetic
patients with NPDR compared with control subjects. The abnormalities
consisted in an increased number of colonies formed in
vitro and downregulation of the molecules that facilitate homing at
sites of vascular injury. The abnormalities were absent in type 1
diabetic patients free of retinopathy and other complications, despite
long diabetes duration, but were detected in some of the
patients without clinical retinopathy after short diabetes duration.
CFU-Hill cells are potential informers of diabetic microangiopathy
but may be preempted from carrying out reparative functions if the
molecular abnormalities compromise interactions with the damaged
vascular wall. Diabetes 61:908–914, 2012