In line with these studies, we have previously demonstrated a significant upregulation of the chemokine platelet factor-4 (PF-4/CXCL4) in vitreous samples from patients with proliferative diabetic retinopathy (PDR) and diabetes-induced enhanced PF-4/CXCL4 levels in the retina of rats [7]. Here, PF4 is linked to diabetes mellitus.