Purpose:
To identify the nature of cells released in the vitreous humor of proliferative diabetic retinopathy patients.
Methods:
Vitreous humor was collected from 5 eyes of patients who underwent surgery for diabetic and non-diabetic retinal pathologies. Molecular analysis of the samples was done by extraction mRNA and performing real-time quantitative PCR using stem cell marker genes, Oct4, Sox2, Nanog, Klf4 and apoptotic markers BAX (pro-apoptotic) and BCl2 (anti-apoptotic). We also investigated the mRNA expression level of Neurglycan C. The experiments were done in triplicates and statistical analysis was done with 2-tailed student.
Results:
Enhanced expression in mRNA levels of BAX (pro-apoptotic gene) was found in the vitreous of diabetics versus the non diabetic samples. Neuroglycan C, an activity dependant protein also seems to be released in the vitreous of the proliferative diabetic retinopathy (PDR) patients in increased amount in comparison to non- diabetic patients. Mild increase in mRNA levels of stem cell markers is suggestive of the loss of most likely retinal progenitors in diabetic retinopathy. This presence of stem cell markers in vitreous fluid most likely represents possibly a selective loss of retinal stem/progenitor cells population from the intact retina. Detection of the mRNA levels in PDR indicates loss of neural connectivity in the retina of PDR patients
Conclusions:
In PDR, there may be a targeted loss of retinal stem/progenitor population, released in the vitreous fluid. Further increase in the sample number would also support our initial findings. The findings of the study can be investigated by an elaborate study on the retina of the patients, and looking at their regenerative potential in animal or in-vitro studies. The finds of this study would provide additional evidence for the inability of the retina to repair caused in the PDR. It would also provide indications of activating the residing retinal stem/progenitor cells to regenerate in-vivo. The mRNA expression profile indicates decrease in the anti-apoptotic gene expression, indicating the increased potential of the cells to undergo apoptosis.
Keywords: apoptosis/cell death • diabetic retinopathy • vitreous