Abstract
Purpose:
Bone marrow derived CD34+ cells mediate endothelial repair but exhibit altered function in diabetes. There cells provide paracrine support to the vasculature by signaling cytokines/chemokines in relation to the development of retinopathy. In this study, we investigated the role of aqueous of PDR on the alteration of expression of Nitric Oxide ( NO) and migration of CD34+ cells.
Methods:
Aqueous fluid was collected from individuals who underwent pars plana vitrecotmy for the treatment of PDR. Aqueous fluid from otherwise healthy individuals who underwent cataract extraction without any other ocular diseases were served as controls. Mobilized healthy human CD34+ cells were treated with aqueous (5%) obtained from PDR as well as control subjects.NO production was quantified in CD34+ cells using NO-sensitive 4-amino-5-methylamino-2’,7’-difluorofluorescein. CD34+ cells (10,000 cells/well) enriched either with PDR or control aqueous samples at a concentration of 5% were loaded into the upper chamber of migration assay kit. The positive control group was treated with 20% fetal bovine serum (FBS) whereas the negative control group was treated with Ham’s F-12 media. The fluorescent dye was read by using a microplate reader. Number of migrating cells were expressed in arbitrary fluorescent units (AFU).
Results:
Cells treated with PDR aqueous (5%) showed 66.7±2.9% of NO levels. The reduction in bioavailable NO levels were highly significant (P<0.01). CD34+ cells that were treated with control aqueous showed higher NO levels than untreated CD34+ cells (p<0.01). The migratory response of CD34+ cells to SDF-1 was mirrored when they were exposed to 5% of PDR aqueous. The migratory response in cells treated with PDR aqueous was 736.75±101.7 AFU compared to 876.3±70.9 AFU in cells treated with control aqueous (p=0.008). The migratory response in the positive and negative control were 2034.6±303.9 and 221.3±24.2 AFU respectively.
Conclusions:
Our study demonstrated that cytokines/chemokines that are present in the PDR aqueous significantly depress the concentration of NO in CD34+ cells and affects the migration of CD34+ cells.
Keywords: 499 diabetic retinopathy •
721 stem cells •
427 aqueous