Involvement of Circulating Endothelial Progenital Cells and Vasculogenic Factors in Diabetic Retinopathy

PURPOSE: Retinal neovascularization in diabetes has been thought to follow the release of local angiogenic factors in the retina. We hypothesized that neovascularization of diabetic retinopathy is a systemic vasculogenesis rather than a local angiogenesis. Thus, we evaluated 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 2 diabetic patients [non-DR group (n=15), NPDR group (n=15), and PDR group (n=15)]. We measured circulating CD34+mononuclear cells (CD34+MNCs) and 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). The serum level of VEGF was increased in the NPDR and PDR groups compared with the control group (P<0.05). The level of EPO was exclusively elevated in the non-DR group compared with the other three groups (P<0.01). The circulating SP level increased in the NPDR and PDR groups compared with the control group (P<0.05). 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 VEGF, EPO and SP may be involved in the progression of diabetic retinopathy.

The Involvement of Multipotential Progenitor Cells in Mooren's Ulcer

The aim of this study was to assess the involvement of multipotential progenitor cells in the pathogenesis of Mooren's ulcer using immunohistochemical staining techniques. Tissue specimens were collected from 3 Mooren's ulcer patients who underwent lamellar keratectomy. Immunohistochemical staining patterns were analyzed using antibodies: CD34, c-kit, STRO-1, CD45RO, VEGF and alpha-SMA. Strong positive CD34, c-kit and STRO-1 cells were revealed in Mooren's ulcer specimens, especially in the superficial stroma. A few weakly expressed CD34 stroma cells were seen in normal limbal cornea but no immunoreactivity for c-kit and STRO-1 could be found. CD45RO positive T cells were found to have infiltrated in Mooren's ulcer. The immunostaining pattern of VEGF and yen a- SMA was closely correlated with the degree of expression and the number of CD34 positive cells. Bone marrow-derived multipotential progenitor cells may be involved in the pathogenesis of Mooren's ulcer by synergizing with other factors to amplify autoimmune destructive reactions and to contribute to the regeneration process. Specific therapeutic strategies that target the role of these cells in the disease are warranted.

Suppression of VEGF by Aminoguanidine in RPE Cells Cultured in the Hyperglycemic Condition

PURPOSE: We evaluated whether aminoguanidine could inhibit VEGF mRNA expression in the retinal pigment epithelial cells cultured at various glucose concentrations. METHODS: Human retinal pigment epithelial cells were cultured in the culture media containing 5.5 mM, or 11 mM, or 16 mM glucose for 5 days, or 7 days, or 14 days respectively. To evaluate an inhibitory effect of aminoguanidine on VEGF mRNA expression, 1 micro M, or 3 micro M, or 10 micro M aminoguanidine was added in the culture media. The VEGF mRNA expression was assayed by northern blot analysis. RESULTS: The VEGF mRNA expression of the cultured retinal pigment epithelial cells increased proportionally with media glucose concentration in culture media. At each glucose concentration of the media, VEGF mRNA expression increased with a prolongation of incubation period. An aminoguanidine inhibited the expression of VEGF mRNA by concentration-dependent manner in 5 day and 7 day incubation, but not in 14 day incubation. CONCLUSIONS: The aminoguanidine could inhibit a new vessel formation in the diabetic retina, and be useful for therapeutic or preventive drug in the diabetic retinopathy.