Table 1.
Summary of studies evaluating endothelial progenitor cells in diabetic retinopathy.
| Study | Patients | Controls | Study design | EPCs studied | Results |
|---|---|---|---|---|---|
| Lombardo et al. (68) | DM type 2 = 54 - Without angiopathy = 27 - With angiography = 27 (severe NPDR or PDR) | n = 24 | Cross-sectional | Pre-EPC: CD34+/CD133+/CD117+ EPCs = CD34+/CD133+/VEGF-R2 Late EPC = CD31+/VEGF-R2/CD144+ | Decreased late-EPCs in DM compared with controls |
| Zerbini et al. (74) | DM type 1 (n = 56) - DM ≥ 23 years no DR = 17 - DM ≤ 7 years no DR = 19 - DM ≤ 20 years NPDR = 20 | n = 47 | Cross-sectional | CD34+/CD45−/VEGF-R2 | No statistically significant difference on EPCs between groups |
| Brunner et al. (72) | DM type 2 = 126 - With MVD = 66 - Without MVD = 60 - Without DR = 55 - Mild NPDR = 19 - moderate-severe NPDR = 16 - Early PDR = 19 - PDR = 17 | none | Cross-sectional | CPCs = CD34+/CD133+ EPC = CD34+/CD133+/CD309+ Mature EPC = CD34+/CD133+/CD309+/CD31+ | MVD: Reduced numbers of EPCs with advanced stages of retinopathy No MVD: no statistically significant changes in EPCs and mature EPCs; number of CPCs declined in mild NPDR, increase in PDR, decrease in high-risk PDR |
| Liu et al. (75) | DM type 2 = 40 - With DR (severe NPDR and PDR) = 20 - With peripheral arterial disease (PAD) = 20 | n = 20 | Cross-sectional | CD34+/CD133+ | Increased EPCs in DR compared with controls |
| Tan et al. (67) | DM type 1 = 9 and DM type 2 = 13 (undetermined = 1) - With PDR = 23 (~95% had PRP) | n = 22 | Cross-sectional | CD34+/CD45− | Increased EPCs in PDR compared with controls |
| Brunner et al. (71) | DM type 1 = 90 - No DR = 30 - Mild NPDR = 30 - Moderate-severe NPDR = 10 - Early PDR = 10 - High-risk PDR = 10 | n = 30 | Cross-sectional | CPCs = CD34+/CD133+ EPC = CD34+/CD133+/CD309+Mature EPC = CD34+/CD133+/CD309+/CD31+ | When compared with diabetics with no DR, EPCs decreased in NPDR EPCs increased in high-risk PDR EPCs decreased in diabetics compared with control group |
| Fadini et al. (69) | DM type 2 = 60 - No DR = 45 - DR = 15 | none | Cross-sectional | EPC = CD34+ and CD34+/KDR+* | Decreased CD34+ in DR. (No decrease in CD34+/KDR+ in DR detected) |
| Lee et al. (73) | DM type 2 = 45 - No DR = 15 - NPDR = 15 - PDR = 15 | n = 15 | Cross-sectional | CD34+ | Increased CD34+ in DM compared with control. Increased CD34+ with increasing severity of DR (no DR–NPDR–PDR) |
DM, diabetes mellitus; DR, diabetic retinopathy; NPDR, non-proliferative diabetic retinopathy; PDR, proliferative diabetic retinopathy; EPC, endothelial progenitor cell; CFU, colony-forming unit; MVD, macrovascular disease.
*Both CD34+ and CD34+/KDR+ were measured.