Clinical Study
Eye (2006) 20, 546–552. doi:10.1038/sj.eye.6701920; published online 20 May 2005
Involvement of circulating endothelial progenitor cells and vasculogenic factors in the pathogenesis of diabetic retinopathy
I G Lee1, S L Chae2 and J C Kim1
- 1Department of Ophthalmology, College of Medicine, Chung Ang University, Seoul, Korea
- 2Department of Laboratory Medicine, College of Medicine, Chung Ang University, Seoul, Korea
Correspondence: JC Kim, Department of Ophthalmology, College of Medicine, Chung-Ang University, Yongsan Hospital, #65-207 Hangangro-3 Ga, Yongsan-Gu, Seoul 140-757, Korea. Tel: +82.2 748 9838; Fax: +82.2 792 6295; E-mail: jck50ey@kornet.net
Received 11 October 2004; Accepted 21 March 2005; Published online 20 May 2005.
Abstract
Purpose
Retinal neovascularization in diabetes has been thought to follow the release of local angiogenic factors in the retina. We hypothesize that neovascularization of diabetic retinopathy is a systemic vasculogenesis rather than a local angiogenesis. Thus, we evaluate the concentrations of circulating endothelial progenitor cells (EPCs) and stem cell modulation factors such as vascular endothelial growth factor (VEGF), erythropoietin (Epo), and substance p (SP) in the peripheral blood of diabetic retinopathy patients.
Methods
We studied 15 normal controls and 45 type II diabetic patients (no DR group (n=15), NPDR group (n=15), and PDR group (n=15)). We measured circulating CD34+mononuclear cells (CD34+MNCs), c-Kit+mononuclear cells (c-Kit+MNCs) by flow cytometry. VEGF, Epo, and SP in the peripheral blood were measured by ELISA.
Results
The circulating CD34+MNCs and c-Kit+MNCs increased in the NPDR and PDR groups compared with the control group (P<0.01). Serum level of VEGF increased in the NPDR and PDR groups compared with the control group (P<0.05). The level of Epo elevated exclusively in the no DR group compared with the other three groups (P<0.01). Circulating SP level increased in the NPDR and PDR groups compared with the control group (P<0.05). SP and CD34+MNCs were shown to have increased correlation according to the diabetic retinopathy in the NPDR and PDR groups (r=0.440, P<0.05 and r=0.460, P<0.05, respectively).
Conclusions
The present study is the first to demonstrate that CD34+MNCs, c-Kit+MNCs and their modulator are elevated in diabetic retinopathy patients. Therefore, it is possible that circulating EPCs and serum Epo, VEGF, and SP may be involved in the progression of diabetic retinopathy.
Keywords:
endothelial progenitor cells, erythropoietin, diabetic retinopathy, substance p, vascular endothelial growth factor
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